本文简单介绍了PG插入数据部分的源码，主要内容包括ProcessQuery函数的实现逻辑，该函数位于文件pquery.c中。
一、基础信息
ProcessQuery函数使用的数据结构、宏定义以及依赖的函数等。
数据结构/宏定义
1、NodeTag
//节点标记，枚举类型
/*
* The first field of every node is NodeTag. Each node created (with makeNode)
* will have one of the following tags as the value of its first field.
*
* Note that inserting or deleting node types changes the numbers of other
* node types later in the list. This is no problem during development, since
* the node numbers are never stored on disk. But don't do it in a released
* branch, because that would represent an ABI break for extensions.
*/
typedef enum NodeTag
{
T_Invalid = 0,
/*
* TAGS FOR EXECUTOR NODES (execnodes.h)
*/
T_IndexInfo,
T_ExprContext,
T_ProjectionInfo,
T_JunkFilter,
T_OnConflictSetState,
T_ResultRelInfo,
T_EState,
T_TupleTableSlot,
/*
* TAGS FOR PLAN NODES (plannodes.h)
*/
T_Plan,
T_Result,
T_ProjectSet,
T_ModifyTable,
T_Append,
T_MergeAppend,
T_RecursiveUnion,
T_BitmapAnd,
T_BitmapOr,
T_Scan,
T_SeqScan,
T_SampleScan,
T_IndexScan,
T_IndexOnlyScan,
T_BitmapIndexScan,
T_BitmapHeapScan,
T_TidScan,
T_SubqueryScan,
T_FunctionScan,
T_ValuesScan,
T_TableFuncScan,
T_CteScan,
T_NamedTuplestoreScan,
T_WorkTableScan,
T_ForeignScan,
T_CustomScan,
T_Join,
T_nestLoop,
T_MergeJoin,
T_HashJoin,
T_Material,
T_Sort,
T_Group,
T_Agg,
T_WindowAgg,
T_Unique,
T_Gather,
T_GatherMerge,
T_Hash,
T_Setop,
T_LockRows,
T_Limit,
/* these aren't subclasses of Plan: */
T_nestLoopParam,
T_PlanRowMark,
T_PartitionPruneInfo,
T_PartitionedRelPruneInfo,
T_PartitionPrunestepOp,
T_PartitionPrunestepCombine,
T_PlanInvalItem,
/*
* TAGS FOR PLAN STATE NODES (execnodes.h)
*
* These should correspond one-to-one with Plan node types.
*/
T_PlanState,
T_ResultState,
T_ProjectSetState,
T_ModifyTableState,
T_AppendState,
T_MergeAppendState,
T_RecursiveUnionState,
T_BitmapAndState,
T_BitmapOrState,
T_ScanState,
T_SeqScanState,
T_SampleScanState,
T_IndexScanState,
T_IndexOnlyScanState,
T_BitmapIndexScanState,
T_BitmapHeapScanState,
T_TidScanState,
T_SubqueryScanState,
T_FunctionScanState,
T_TableFuncScanState,
T_ValuesScanState,
T_CteScanState,
T_NamedTuplestoreScanState,
T_WorkTableScanState,
T_ForeignScanState,
T_CustomScanState,
T_JoinState,
T_nestLoopState,
T_MergeJoinState,
T_HashJoinState,
T_MaterialState,
T_SortState,
T_GroupState,
T_AggState,
T_WindowAggState,
T_UniqueState,
T_GatherState,
T_GatherMergeState,
T_HashState,
T_SetopState,
T_LockRowsstate,
T_LimitState,
/*
* TAGS FOR PRIMITIVE NODES (primnodes.h)
*/
T_Alias,
T_RangeVar,
T_TableFunc,
T_Expr,
T_Var,
T_Const,
T_Param,
T_Aggref,
T_GroupingFunc,
T_WindowFunc,
T_ArrayRef,
T_FuncExpr,
T_NamedArgExpr,
T_OpExpr,
T_distinctExpr,
T_NullIfExpr,
T_ScalararrayOpExpr,
T_BoolExpr,
T_SubLink,
T_SubPlan,
T_AlternativeSubPlan,
T_FieldSelect,
T_FieldStore,
T_RelabelType,
T_CoerceViaIO,
T_ArrayCoerceExpr,
T_ConvertRowtypeExpr,
T_CollateExpr,
T_CaseExpr,
T_CaseWhen,
T_CaseTestExpr,
T_ArrayExpr,
T_RowExpr,
T_RowCompareExpr,
T_CoalesceExpr,
T_MinMaxExpr,
T_sqlValueFunction,
T_XmlExpr,
T_NullTest,
T_BooleanTest,
T_CoercetoDomain,
T_CoercetoDomainValue,
T_SetToDefault,
T_CurrentOfExpr,
T_NextValueExpr,
T_InferenceElem,
T_TargetEntry,
T_RangeTblRef,
T_JoinExpr,
T_FromExpr,
T_OnConflictExpr,
T_IntoClause,
/*
* TAGS FOR EXPRESSION STATE NODES (execnodes.h)
*
* ExprState represents the evaluation state for a whole expression tree.
* Most Expr-based plan nodes do not have a corresponding expression state
* node, they're fully handled within execExpr* - but sometimes the state
* needs to be shared with other parts of the executor, as for example
* with AggrefExprState, which nodeAgg.c has to modify.
*/
T_ExprState,
T_AggrefExprState,
T_WindowFuncExprState,
T_SetExprState,
T_SubPlanState,
T_AlternativeSubPlanState,
T_DomainConstraintState,
/*
* TAGS FOR PLANNER NODES (relation.h)
*/
T_PlannerInfo,
T_PlannerGlobal,
T_RelOptInfo,
T_IndexOptInfo,
T_ForeignKeyOptInfo,
T_ParamPathInfo,
T_Path,
T_IndexPath,
T_BitmapHeapPath,
T_BitmapAndpath,
T_BitmapOrPath,
T_Tidpath,
T_SubqueryScanPath,
T_ForeignPath,
T_CustomPath,
T_nestPath,
T_MergePath,
T_HashPath,
T_Appendpath,
T_MergeAppendpath,
T_ResultPath,
T_MaterialPath,
T_UniquePath,
T_GatherPath,
T_GatherMergePath,
T_ProjectionPath,
T_ProjectSetPath,
T_SortPath,
T_GroupPath,
T_UpperUniquePath,
T_AggPath,
T_GroupingSetsPath,
T_MinMaxAggPath,
T_WindowAggPath,
T_SetopPath,
T_RecursiveUnionPath,
T_LockRowsPath,
T_ModifyTablePath,
T_LimitPath,
/* these aren't subclasses of Path: */
T_EquivalenceClass,
T_EquivalenceMember,
T_PathKey,
T_PathTarget,
T_RestrictInfo,
T_PlaceHolderVar,
T_SpecialJoinInfo,
T_AppendRelInfo,
T_PlaceHolderInfo,
T_MinMaxAggInfo,
T_PlannerParamItem,
T_RollupData,
T_GroupingSetData,
T_StatisticExtInfo,
/*
* TAGS FOR MEMORY NODES (memnodes.h)
*/
T_MemoryContext,
T_AllocSetContext,
T_SlabContext,
T_GenerationContext,
/*
* TAGS FOR VALUE NODES (value.h)
*/
T_Value,
T_Integer,
T_Float,
T_String,
T_BitString,
T_Null,
/*
* TAGS FOR LIST NODES (pg_list.h)
*/
T_List,
T_IntList,
T_OidList,
/*
* TAGS FOR EXTENSIBLE NODES (extensible.h)
*/
T_ExtensibleNode,
/*
* TAGS FOR STATEMENT NODES (mostly in parsenodes.h)
*/
T_RawStmt,
T_Query,
T_PlannedStmt,
T_InsertStmt,
T_DeleteStmt,
T_UpdateStmt,
T_SelectStmt,
T_AlterTableStmt,
T_AlterTableCmd,
T_AlterDomainStmt,
T_SetoperationStmt,
T_GrantStmt,
T_GrantRoleStmt,
T_AlterDefaultPrivilegesstmt,
T_ClosePortalStmt,
T_ClusterStmt,
T_copyStmt,
T_CreateStmt,
T_Definestmt,
T_DropStmt,
T_TruncateStmt,
T_CommentStmt,
T_FetchStmt,
T_IndexStmt,
T_CreateFunctionStmt,
T_AlterFunctionStmt,
T_DoStmt,
T_RenameStmt,
T_RuleStmt,
T_NotifyStmt,
T_ListenStmt,
T_UnlistenStmt,
T_TransactionStmt,
T_ViewStmt,
T_LoadStmt,
T_CreateDomainStmt,
T_CreatedbStmt,
T_DropdbStmt,
T_VacuumStmt,
T_ExplainStmt,
T_CreateTableAsstmt,
T_CreateSeqStmt,
T_AlterSeqStmt,
T_VariableSetStmt,
T_VariableShowStmt,
T_discardStmt,
T_CreateTrigStmt,
T_CreatePLangStmt,
T_CreateRoleStmt,
T_AlterRoleStmt,
T_DropRoleStmt,
T_LockStmt,
T_ConstraintsSetStmt,
T_ReindexStmt,
T_CheckPointStmt,
T_CreateSchemaStmt,
T_AlterDatabaseStmt,
T_AlterDatabaseSetStmt,
T_AlterRoleSetStmt,
T_CreateConversionStmt,
T_CreateCastStmt,
T_CreateOpClassstmt,
T_CreateOpFamilyStmt,
T_AlterOpFamilyStmt,
T_PrepareStmt,
T_ExecuteStmt,
T_DeallocateStmt,
T_DeclareCursorStmt,
T_CreateTableSpaceStmt,
T_DropTableSpaceStmt,
T_AlterObjectDependsstmt,
T_AlterObjectSchemaStmt,
T_AlterOwnerStmt,
T_AlterOperatorStmt,
T_DropOwnedStmt,
T_ReassigNownedStmt,
T_CompositeTypestmt,
T_CreateEnumStmt,
T_CreaterangeStmt,
T_AlterEnumStmt,
T_AlterTSDictionaryStmt,
T_AlterTSConfigurationStmt,
T_CreateFdwStmt,
T_AlterFdwStmt,
T_CreateForeignServerStmt,
T_AlterForeignServerStmt,
T_createuserMappingStmt,
T_AlterUserMappingStmt,
T_DropUserMappingStmt,
T_AlterTableSpaceOptionsstmt,
T_AlterTableMoveAllStmt,
T_SecLabelStmt,
T_CreateForeignTableStmt,
T_ImportForeignSchemaStmt,
T_CreateExtensionStmt,
T_AlterExtensionStmt,
T_AlterExtensionContentsstmt,
T_CreateEventTrigStmt,
T_AlterEventTrigStmt,
T_RefreshMatViewStmt,
T_ReplicaIdentityStmt,
T_AlterSystemStmt,
T_CreatePolicyStmt,
T_AlterPolicyStmt,
T_CreateTransformStmt,
T_CreateAmStmt,
T_CreatePublicationStmt,
T_AlterPublicationStmt,
T_CreateSubscriptionStmt,
T_AlterSubscriptionStmt,
T_DropSubscriptionStmt,
T_CreateStatsstmt,
T_AlterCollationStmt,
T_CallStmt,
/*
* TAGS FOR PARSE TREE NODES (parsenodes.h)
*/
T_A_Expr,
T_ColumnRef,
T_ParamRef,
T_A_Const,
T_FuncCall,
T_A_Star,
T_A_Indices,
T_A_Indirection,
T_A_ArrayExpr,
T_ResTarget,
T_MultiAssignRef,
T_TypeCast,
T_CollateClause,
T_SortBy,
T_WindowDef,
T_RangeSubselect,
T_RangeFunction,
T_RangeTableSample,
T_RangeTableFunc,
T_RangeTableFuncCol,
T_TypeName,
T_ColumnDef,
T_IndexElem,
T_Constraint,
T_DefElem,
T_RangeTblEntry,
T_RangeTblFunction,
T_TableSampleClause,
T_WithCheckOption,
T_SortGroupClause,
T_GroupingSet,
T_WindowClause,
T_ObjectWithArgs,
T_Accesspriv,
T_CreateOpClassItem,
T_TableLikeClause,
T_FunctionParameter,
T_LockingClause,
T_RowMarkClause,
T_XmlSerialize,
T_WithClause,
T_InferClause,
T_OnConflictClause,
T_CommonTableExpr,
T_RoleSpec,
T_TriggerTransition,
T_PartitionElem,
T_PartitionSpec,
T_PartitionBoundSpec,
T_PartitionRangeDatum,
T_PartitionCmd,
T_VacuumRelation,
/*
* TAGS FOR REPLICATION GRAMMAR PARSE NODES (replnodes.h)
*/
T_IdentifySystemCmd,
T_BaseBackupCmd,
T_CreateReplicationSlotCmd,
T_DropReplicationSlotCmd,
T_StartReplicationCmd,
T_TimeLineHistoryCmd,
T_sqlCmd,
/*
* TAGS FOR RANDOM OTHER STUFF
*
* These are objects that aren't part of parse/plan/execute node tree
* structures, but we give them NodeTags anyway for identification
* purposes (usually because they are involved in APIs where we want to
* pass multiple object types through the same pointer).
*/
T_TriggerData, /* in commands/trigger.h */
T_EventTriggerData, /* in commands/event_trigger.h */
T_ReturnSetInfo, /* in nodes/execnodes.h */
T_WindowObjectData, /* private in nodeWindowAgg.c */
T_TIDBitmap, /* in nodes/tidbitmap.h */
T_InlineCodeBlock, /* in nodes/parsenodes.h */
T_FdwRoutine, /* in foreign/fdwapi.h */
T_IndexAmRoutine, /* in access/amapi.h */
T_TsmRoutine, /* in access/tsmapi.h */
T_ForeignKeyCacheInfo, /* in utils/rel.h */
T_CallContext /* in nodes/parsenodes.h */
} NodeTag;
/*
* The first field of a node of any type is guaranteed to be the NodeTag.
* Hence the type of any node can be gotten by casting it to Node. Declaring
* a variable to be of Node * (instead of void *) can also facilitate
* debugging.
*/
typedef struct Node
{
NodeTag type;
} Node;
#define nodeTag(nodeptr) (((const Node*)(nodeptr))->type)
2、MemoryContext
//内存上下文
//AllocSetContext结构体的MemoryContextData与其共享
//
typedef struct MemoryContextData
{
NodeTag type; /* identifies exact kind of context */
/* these two fields are placed here to minimize alignment wastage: */
bool isReset; /* T = no space alloced since last reset */
bool allowInCritSection; /* allow palloc in critical section */
const MemoryContextMethods *methods; /* virtual function table */
MemoryContext parent; /* NULL if no parent (toplevel context) */
MemoryContext firstchild; /* head of linked list of children */
MemoryContext prevchild; /* prevIoUs child of same parent */
MemoryContext nextchild; /* next child of same parent */
const char *name; /* context name (just for debugging) */
const char *ident; /* context ID if any (just for debugging) */
MemoryContextCallback *reset_cbs; /* list of reset/delete callbacks */
} MemoryContextData;
/* utils/palloc.h contains typedef struct MemoryContextData *MemoryContext */
/*
* Type MemoryContextData is declared in nodes/memnodes.h. Most users
* of memory allocation should just treat it as an abstract type, so we
* do not provide the struct contents here.
*/
typedef struct MemoryContextData *MemoryContext;
3、AllocSet
/*
* AllocSetContext is our standard implementation of MemoryContext.
*
* Note: header.isReset means there is nothing for AllocSetReset to do.
* This is different from the aset being physically empty (empty blocks list)
* because we will still have a keeper block. It's also different from the set
* being logically empty, because we don't attempt to detect pfree'ing the
* last active chunk.
*/
typedef struct AllocSetContext
{
MemoryContextData header; /* Standard memory-context fields */
/* Info about storage allocated in this context: */
AllocBlock blocks; /* head of list of blocks in this set */
AllocChunk freelist[ALLOCSET_NUM_FREELISTS]; /* free chunk lists */
/* Allocation parameters for this context: */
Size initBlockSize; /* initial block size */
Size maxBlockSize; /* maximum block size */
Size nextBlockSize; /* next block size to allocate */
Size allocChunkLimit; /* effective chunk size limit */
AllocBlock keeper; /* keep this block over resets */
/* freelist this context Could be put in, or -1 if not a candidate: */
int freeListIndex; /* index in context_freelists[], or -1 */
} AllocSetContext;
typedef AllocSetContext *AllocSet;
4、AllocBlock
/*
* AllocBlock
* An AllocBlock is the unit of memory that is obtained by aset.c
* from malloc(). It contains one or more AllocChunks, which are
* the units requested by palloc() and freed by pfree(). AllocChunks
* cannot be returned to malloc() individually, instead they are put
* on freelists by pfree() and re-used by the next palloc() that has
* a matching request size.
*
* AllocBlockData is the header data for a block --- the usable space
* within the block begins at the next alignment boundary.
*/
typedef struct AllocBlockData
{
AllocSet aset; /* aset that owns this block */
AllocBlock prev; /* prev block in aset's blocks list, if any */
AllocBlock next; /* next block in aset's blocks list, if any */
char *freeptr; /* start of free space in this block */
char *endptr; /* end of space in this block */
} AllocBlockData;
typedef struct AllocBlockData *AllocBlock; /* forward reference */
5、AllocChunk
/*
* AllocChunk
* The prefix of each piece of memory in an AllocBlock
*
* Note: to meet the memory context APIs, the payload area of the chunk must
* be maxaligned, and the "aset" link must be immediately adjacent to the
* payload area (cf. GetMemoryChunkContext). We simplify matters for this
* module by requiring sizeof(AllocChunkData) to be maxaligned, and then
* we can ensure things work by adding any required alignment padding before
* the "aset" field. There is a static assertion below that the alignment
* is done correctly.
*/
typedef struct AllocChunkData
{
/* size is always the size of the usable space in the chunk */
Size size;
#ifdef MEMORY_CONTEXT_CHECKING
/* when debugging memory usage, also store actual requested size */
/* this is zero in a free chunk */
Size requested_size;
#define ALLOCCHUNK_RAWSIZE (SIZEOF_SIZE_T * 2 + SIZEOF_VOID_P)
#else
#define ALLOCCHUNK_RAWSIZE (SIZEOF_SIZE_T + SIZEOF_VOID_P)
#endif /* MEMORY_CONTEXT_CHECKING */
/* ensure proper alignment by adding padding if needed */
#if (ALLOCCHUNK_RAWSIZE % MAXIMUM_ALIGNOF) != 0
char padding[MAXIMUM_ALIGNOF - ALLOCCHUNK_RAWSIZE % MAXIMUM_ALIGNOF];
#endif
/* aset is the owning aset if allocated, or the freelist link if free */
void *aset;
/* there must not be any padding to reach a MAXALIGN boundary here! */
} AllocChunkData;
typedef struct AllocChunkData *AllocChunk;
6、AllocSetFreeList
typedef struct AllocSetFreeList
{
int num_free; /* current list length */
AllocSetContext *first_free; /* list header */
} AllocSetFreeList;
7、context_freelists
/* context_freelists[0] is for default params, [1] for small params */
static AllocSetFreeList context_freelists[2] =
{
{
0, NULL
},
{
0, NULL
}
};
8、AllocSetMethods
//内存管理方法
typedef struct MemoryContextMethods
{
void *(*alloc) (MemoryContext context, Size size);
/* call this free_p in case someone #define's free() */
void (*free_p) (MemoryContext context, void *pointer);
void *(*realloc) (MemoryContext context, void *pointer, Size size);
void (*reset) (MemoryContext context);
void (*delete_context) (MemoryContext context);
Size (*get_chunk_space) (MemoryContext context, void *pointer);
bool (*is_empty) (MemoryContext context);
void (*stats) (MemoryContext context,
MemoryStatsPrintFunc printfunc, void *passthru,
MemoryContextCounters *totals);
#ifdef MEMORY_CONTEXT_CHECKING
void (*check) (MemoryContext context);
#endif
} MemoryContextMethods;
//预定义
/*
* This is the virtual function table for AllocSet contexts.
*/
static const MemoryContextMethods AllocSetMethods = {
AllocSetAlloc,
AllocSetFree,
AllocSetRealloc,
AllocSetReset,
AllocSetDelete,
AllocSetGetChunkSpace,
AllocSetIsEmpty,
AllocSetStats
#ifdef MEMORY_CONTEXT_CHECKING
,AllocSetCheck
#endif
};
9、宏定义
#define ALLOC_BLOCKHDRSZ MAXALIGN(sizeof(AllocBlockData))
#define ALLOC_CHUNKHDRSZ sizeof(struct AllocChunkData)
/*
* Recommended default alloc parameters, suitable for "ordinary" contexts
* that might hold quite a lot of data.
*/
#define ALLOCSET_DEFAULT_MINSIZE 0
#define ALLOCSET_DEFAULT_INITSIZE (8 * 1024)
#define ALLOCSET_DEFAULT_MAXSIZE (8 * 1024 * 1024)
#define ALLOCSET_DEFAULT_SIZES \
ALLOCSET_DEFAULT_MINSIZE, ALLOCSET_DEFAULT_INITSIZE, ALLOCSET_DEFAULT_MAXSIZE
#define VALGRIND_MAKE_MEM_NOACCESS(addr, size) do {} while (0)
#define ALLOC_MINBITS 3 /* smallest chunk size is 8 bytes */
#define ALLOCSET_NUM_FREELISTS 11
#define ALLOC_CHUNK_LIMIT (1 << (ALLOCSET_NUM_FREELISTS-1+ALLOC_MINBITS))
#define ALLOCSET_SEParaTE_THRESHOLD 8192
#define ALLOC_CHUNK_FRACTION 4
/* We allow chunks to be at most 1/4 of maxBlockSize (less overhead) */
依赖的函数
1、createqueryDesc
//根据输入的参数构造QueryDesc
/*
* createqueryDesc
*/
QueryDesc *
createqueryDesc(PlannedStmt *plannedstmt,
const char *sourceText,
Snapshot snapshot,
Snapshot crosscheck_snapshot,
DestReceiver *dest,
ParamListInfo params,
QueryEnvironment *queryEnv,
int instrument_options)
{
QueryDesc *qd = (QueryDesc *) palloc(sizeof(QueryDesc));
qd->operation = plannedstmt->commandType; /* operation */
qd->plannedstmt = plannedstmt; /* plan */
qd->sourceText = sourceText; /* query text */
qd->snapshot = RegisterSnapshot(snapshot); /* snapshot */
/* RI check snapshot */
qd->crosscheck_snapshot = RegisterSnapshot(crosscheck_snapshot);
qd->dest = dest; /* output dest */
qd->params = params; /* parameter values passed into query */
qd->queryEnv = queryEnv;
qd->instrument_options = instrument_options; /* instrumentation wanted? */
/* null these fields until set by ExecutorStart */
qd->tupDesc = NULL;
qd->estate = NULL;
qd->planstate = NULL;
qd->totaltime = NULL;
/* not yet executed */
qd->already_executed = false;
return qd;
}
2、CreateExecutorState
/* ----------------
* CreateExecutorState
*
* Create and initialize an EState node, which is the root of
* working storage for an entire Executor invocation.
*
* Principally, this creates the per-query memory context that will be
* used to hold all working data that lives till the end of the query.
* Note that the per-query context will become a child of the caller's
* CurrentMemoryContext.
* ----------------
*/
EState *
CreateExecutorState(void)//构建EState
{
EState *estate;//EState指针
MemoryContext qcontext;
MemoryContext oldcontext;
/*
* Create the per-query context for this Executor run.
*/
qcontext = AllocSetContextCreate(CurrentMemoryContext,
"ExecutorState",
ALLOCSET_DEFAULT_SIZES);//创建MemoryContext
/*
* Make the EState node within the per-query context. This way, we don't
* need a separate pfree() operation for it at shutdown.
*/
oldcontext = MemoryContextSwitchTo(qcontext);//切换至新创建的MemoryContext
estate = makeNode(EState);//创建Node
/*
* Initialize all fields of the Executor State structure
*/
//初始化Executor State structure
estate->es_direction = ForwardScanDirection;
estate->es_snapshot = InvalidSnapshot; /* caller must initialize this */
estate->es_crosscheck_snapshot = InvalidSnapshot; /* no crosscheck */
estate->es_range_table = NIL;
estate->es_plannedstmt = NULL;
estate->es_junkFilter = NULL;
estate->es_output_cid = (CommandId) 0;
estate->es_result_relations = NULL;
estate->es_num_result_relations = 0;
estate->es_result_relation_info = NULL;
estate->es_root_result_relations = NULL;
estate->es_num_root_result_relations = 0;
estate->es_tuple_routing_result_relations = NIL;
estate->es_trig_target_relations = NIL;
estate->es_trig_tuple_slot = NULL;
estate->es_trig_oldtup_slot = NULL;
estate->es_trig_newtup_slot = NULL;
estate->es_param_list_info = NULL;
estate->es_param_exec_vals = NULL;
estate->es_queryEnv = NULL;
estate->es_query_cxt = qcontext;
estate->es_tupleTable = NIL;
estate->es_rowMarks = NIL;
estate->es_processed = 0;
estate->es_lastoid = InvalidOid;
estate->es_top_eflags = 0;
estate->es_instrument = 0;
estate->es_finished = false;
estate->es_exprcontexts = NIL;
estate->es_subplanstates = NIL;
estate->es_auxmodifytables = NIL;
estate->es_per_tuple_exprcontext = NULL;
estate->es_epqTuple = NULL;
estate->es_epqTupleSet = NULL;
estate->es_epqScanDone = NULL;
estate->es_sourceText = NULL;
estate->es_use_parallel_mode = false;
estate->es_jit_flags = 0;
estate->es_jit = NULL;
/*
* Return the executor state structure
*/
MemoryContextSwitchTo(oldcontext);
return estate;
}
/*------------------ makeNode --------------------*/
#define makeNode(_type_) ((_type_ *) newNode(sizeof(_type_),T_##_type_))
/*
* newNode -
* create a new node of the specified size and tag the node with the
* specified tag.
*
* !WARNING!: Avoid using newNode directly. You should be using the
* macro makeNode. eg. to create a Query node, use makeNode(Query)
*
* Note: the size argument should always be a compile-time constant, so the
* apparent risk of multiple evaluation doesn't matter in practice.
*/
#ifdef __GNUC__
/* With GCC, we can use a compound statement within an expression */
#define newNode(size, tag) \
({ Node *_result; \
AssertMacro((size) >= sizeof(Node)); /* need the tag, at least */ \
_result = (Node *) palloc0fast(size); \
_result->type = (tag); \
_result; \
})
#else
/*
* There is no way to dereference the palloc'ed pointer to assign the
* tag, and also return the pointer itself, so we need a holder variable.
* Fortunately, this macro isn't recursive so we just define
* a global variable for this purpose.
*/
extern PGDLLIMPORT Node *newNodeMacroHolder;
#define newNode(size, tag) \
( \
AssertMacro((size) >= sizeof(Node)), /* need the tag, at least */ \
newNodeMacroHolder = (Node *) palloc0fast(size), \
newNodeMacroHolder->type = (tag), \
newNodeMacroHolder \
)
#endif /* __GNUC__ */
/*------------------ AllocSetContextCreate --------------------*/
#define AllocSetContextCreate(parent, name, allocparams) \
AllocSetContextCreateExtended(parent, name, allocparams)
#endif
/*
* AllocSetContextCreateExtended
* Create a new AllocSet context.
*
* parent: parent context, or NULL if top-level context
* name: name of context (must be statically allocated)
* minContextSize: minimum context size
* initBlockSize: initial allocation block size
* maxBlockSize: maximum allocation block size
*
* Most callers should abstract the context size parameters using a macro
* such as ALLOCSET_DEFAULT_SIZES. (This is Now *required* when going
* through the AllocSetContextCreate macro.)
*/
MemoryContext
AllocSetContextCreateExtended(MemoryContext parent,//上一级的内存上下文
const char *name,//MemoryContext名称
Size minContextSize,//最小大小
Size initBlockSize,//初始化大小
Size maxBlockSize)//最大大小
{
int freeListIndex;//空闲列表索引
Size firstBlockSize;//第一个Block的Size
AllocSet set;//AllocSetContext指针
AllocBlock block;//Context中的Block
/* Assert we padded AllocChunkData properly */
StaticAssertStmt(ALLOC_CHUNKHDRSZ == MAXALIGN(ALLOC_CHUNKHDRSZ),
"sizeof(AllocChunkData) is not maxaligned");//对齐
StaticAssertStmt(offsetof(AllocChunkData, aset) + sizeof(MemoryContext) ==
ALLOC_CHUNKHDRSZ,
"padding calculation in AllocChunkData is wrong");//对齐
/*
* First, validate allocation parameters. Once these were regular runtime
* test and elog's, but in practice Asserts seem sufficient because nobody
* varies their parameters at runtime. We somewhat arbitrarily enforce a
* minimum 1K block size.
*/
//验证参数
Assert(initBlockSize == MAXALIGN(initBlockSize) &&
initBlockSize >= 1024);
Assert(maxBlockSize == MAXALIGN(maxBlockSize) &&
maxBlockSize >= initBlockSize &&
AllocHugeSizeIsValid(maxBlockSize)); /* must be safe to double */
Assert(minContextSize == 0 ||
(minContextSize == MAXALIGN(minContextSize) &&
minContextSize >= 1024 &&
minContextSize <= maxBlockSize));
/*
* Check whether the parameters match either available freelist. We do
* not need to demand a match of maxBlockSize.
*/
if (minContextSize == ALLOCSET_DEFAULT_MINSIZE &&
initBlockSize == ALLOCSET_DEFAULT_INITSIZE)
freeListIndex = 0;
else if (minContextSize == ALLOCSET_SMALL_MINSIZE &&
initBlockSize == ALLOCSET_SMALL_INITSIZE)
freeListIndex = 1;
else
freeListIndex = -1;//默认为-1
/*
* If a suitable freelist entry exists, just recycle that context.
*/
if (freeListIndex >= 0)//SMALL/DEFAULT值
{
AllocSetFreeList *freelist = &context_freelists[freeListIndex];//使用预定义的freelist
if (freelist->first_free != NULL)
{
/* Remove entry from freelist */
set = freelist->first_free;//使用第一个空闲的AllocSetContext
freelist->first_free = (AllocSet) set->header.nextchild;//指针指向下一个空闲的AllocSetContext
freelist->num_free--;//free计数器减一
/* Update its maxBlockSize; everything else should be OK */
set->maxBlockSize = maxBlockSize;//更新AllocSetContext的相关信息
/* Reinitialize its header, installing correct name and parent */
MemoryContextCreate((MemoryContext) set,
T_AllocSetContext,
&AllocSetMethods,
parent,
name);//创建MemoryContext
return (MemoryContext) set;//返回
}
}
//freeListIndex = -1，定制化自己的MemoryContext
/* Determine size of initial block */
firstBlockSize = MAXALIGN(sizeof(AllocSetContext)) +
ALLOC_BLOCKHDRSZ + ALLOC_CHUNKHDRSZ;//申请内存：AllocSetContext大小+Block头部大小+Chunk头部大小
if (minContextSize != 0)
firstBlockSize = Max(firstBlockSize, minContextSize);
else
firstBlockSize = Max(firstBlockSize, initBlockSize);
/*
* Allocate the initial block. Unlike other aset.c blocks, it starts with
* the context header and its block header follows that.
*/
set = (AllocSet) malloc(firstBlockSize);//分配内存
if (set == NULL)//OOM？
{
if (TopMemoryContext)
MemoryContextStats(TopMemoryContext);
ereport(ERROR,
(errcode(ERRCODE_OUT_OF_MEMORY),
errmsg("out of memory"),
errdetail("Failed while creating memory context \"%s\".",
name)));
}
/*
* Avoid writing code that can fail between here and MemoryContextCreate;
* we'd leak the header/initial block if we ereport in this stretch.
*/
/* Fill in the initial block's block header */
//获取Block头部指针，开始填充Block头部信息
block = (AllocBlock) (((char *) set) + MAXALIGN(sizeof(AllocSetContext)));
block->aset = set;
block->freeptr = ((char *) block) + ALLOC_BLOCKHDRSZ;
block->endptr = ((char *) set) + firstBlockSize;
block->prev = NULL;
block->next = NULL;
/* Mark unallocated space NOACCESS; leave the block header alone. */
VALGRIND_MAKE_MEM_NOACCESS(block->freeptr, block->endptr - block->freeptr);
/* Remember block as part of block list */
set->blocks = block;
/* Mark block as not to be released at reset time */
set->keeper = block;
/* Finish filling in aset-specific parts of the context header */
MemSetAligned(set->freelist, 0, sizeof(set->freelist));//对齐
set->initBlockSize = initBlockSize;//初始化set的各项属性
set->maxBlockSize = maxBlockSize;
set->nextBlockSize = initBlockSize;
set->freeListIndex = freeListIndex;
/*
* Compute the allocation chunk size limit for this context. It can't be
* more than ALLOC_CHUNK_LIMIT because of the fixed number of freelists.
* If maxBlockSize is small then requests exceeding the maxBlockSize, or
* even a significant fraction of it, should be treated as large chunks
* too. For the typical case of maxBlockSize a power of 2, the chunk size
* limit will be at most 1/8th maxBlockSize, so that given a stream of
* requests that are all the maximum chunk size we will waste at most
* 1/8th of the allocated space.
*
* We have to have allocChunkLimit a power of two, because the requested
* and actually-allocated sizes of any chunk must be on the same side of
* the limit, else we get confused about whether the chunk is "big".
*
* Also, allocChunkLimit must not exceed ALLOCSET_SEParaTE_THRESHOLD.
*/
StaticAssertStmt(ALLOC_CHUNK_LIMIT == ALLOCSET_SEParaTE_THRESHOLD,//ALLOCSET_SEParaTE_THRESHOLD,8192
"ALLOC_CHUNK_LIMIT != ALLOCSET_SEParaTE_THRESHOLD");
set->allocChunkLimit = ALLOC_CHUNK_LIMIT;
while ((Size) (set->allocChunkLimit + ALLOC_CHUNKHDRSZ) >
(Size) ((maxBlockSize - ALLOC_BLOCKHDRSZ) / ALLOC_CHUNK_FRACTION))//ALLOC_CHUNK_FRACTION-4
set->allocChunkLimit >>= 1;//计算ChunkLimit上限，每次/2
/* Finally, do the type-independent part of context creation */
MemoryContextCreate((MemoryContext) set,
T_AllocSetContext,
&AllocSetMethods,
parent,
name);//创建MemoryContext
return (MemoryContext) set;
}
/*
* MemoryContextCreate
* Context-type-independent part of context creation.
*
* This is only intended to be called by context-type-specific
* context creation routines, not by the unwashed masses.
*
* The memory context creation procedure goes like this:
* 1. Context-type-specific routine makes some initial space allocation,
* including enough space for the context header. If it fails,
* it can ereport() with no damage done.
* 2. Context-type-specific routine sets up all type-specific fields of
* the header (those beyond MemoryContextData proper), as well as any
* other management fields it needs to have a fully valid context.
* Usually, failure in this step is impossible, but if it's possible
* the initial space allocation should be freed before ereport'ing.
* 3. Context-type-specific routine calls MemoryContextCreate() to fill in
* the generic header fields and link the context into the context tree.
* 4. We return to the context-type-specific routine, which finishes
* up type-specific initialization. This routine can Now do things
* that might fail (like allocate more memory), so long as it's
* sure the node is left in a state that delete will handle.
*
* node: the as-yet-uninitialized common part of the context header node.
* tag: NodeTag code identifying the memory context type.
* methods: context-type-specific methods (usually statically allocated).
* parent: parent context, or NULL if this will be a top-level context.
* name: name of context (must be statically allocated).
*
* Context routines generally assume that MemoryContextCreate can't fail,
* so this can contain Assert but not elog/ereport.
*/
void
MemoryContextCreate(MemoryContext node,
NodeTag tag,
const MemoryContextMethods *methods,
MemoryContext parent,
const char *name)
{
/* Creating new memory contexts is not allowed in a critical section */
Assert(CritSectionCount == 0);
/* Initialize all standard fields of memory context header */
node->type = tag;
node->isReset = true;
node->methods = methods;
node->parent = parent;
node->firstchild = NULL;
node->prevchild = NULL;
node->name = name;
node->ident = NULL;
node->reset_cbs = NULL;
/* OK to link node into context tree */
if (parent)
{
node->nextchild = parent->firstchild;
if (parent->firstchild != NULL)
parent->firstchild->prevchild = node;
parent->firstchild = node;
/* inherit allowInCritSection flag from parent */
node->allowInCritSection = parent->allowInCritSection;
}
else
{
node->nextchild = NULL;
node->allowInCritSection = false;
}
VALGRIND_CREATE_MEMPOOL(node, 0, false);
}
3、InitPlan
/* ----------------------------------------------------------------
* InitPlan
*
* Initializes the query plan: open files, allocate storage
* and start up the rule manager
* ----------------------------------------------------------------
*/
static void
InitPlan(QueryDesc *queryDesc, int eflags)
{
CmdType operation = queryDesc->operation;//操作类型
PlannedStmt *plannedstmt = queryDesc->plannedstmt;//已规划的Statement
Plan *plan = plannedstmt->planTree;//执行计划
List *rangeTable = plannedstmt->rtable;//本次执行涉及的Table
EState *estate = queryDesc->estate;//执行状态
PlanState *planstate;//计划状态
TupleDesc tupType;//Tuple信息
ListCell *l;//
int i;//
/*
* Do permissions checks
*/
ExecCheckRTPerms(rangeTable, true);//权限检查
/*
* initialize the node's execution state
*/
estate->es_range_table = rangeTable;
estate->es_plannedstmt = plannedstmt;
/*
* initialize result relation stuff, and open/lock the result rels.
*
* We must do this before initializing the plan tree, else we might try to
* do a lock upgrade if a result rel is also a source rel.
*/
//初始化结果Relation
if (plannedstmt->resultRelations)
{
List *resultRelations = plannedstmt->resultRelations;
int numResultRelations = list_length(resultRelations);
ResultRelInfo *resultRelInfos;
ResultRelInfo *resultRelInfo;
resultRelInfos = (ResultRelInfo *)
palloc(numResultRelations * sizeof(ResultRelInfo));
resultRelInfo = resultRelInfos;
foreach(l, resultRelations)
{
Index resultRelationIndex = lfirst_int(l);
Oid resultRelationOid;
Relation resultRelation;
resultRelationOid = getrelid(resultRelationIndex, rangeTable);
resultRelation = heap_open(resultRelationOid, RowExclusiveLock);
InitResultRelInfo(resultRelInfo,
resultRelation,
resultRelationIndex,
NULL,
estate->es_instrument);
resultRelInfo++;
}
estate->es_result_relations = resultRelInfos;
estate->es_num_result_relations = numResultRelations;
/* es_result_relation_info is NULL except when within ModifyTable */
estate->es_result_relation_info = NULL;
/*
* In the partitioned result relation case, lock the non-leaf result
* relations too. A subset of these are the roots of respective
* partitioned tables, for which we also allocate ResultRelInfos.
*/
estate->es_root_result_relations = NULL;
estate->es_num_root_result_relations = 0;
if (plannedstmt->nonleafResultRelations)
{
int num_roots = list_length(plannedstmt->rootResultRelations);
/*
* Firstly, build ResultRelInfos for all the partitioned table
* roots, because we will need them to fire the statement-level
* triggers, if any.
*/
resultRelInfos = (ResultRelInfo *)
palloc(num_roots * sizeof(ResultRelInfo));
resultRelInfo = resultRelInfos;
foreach(l, plannedstmt->rootResultRelations)
{
Index resultRelIndex = lfirst_int(l);
Oid resultRelOid;
Relation resultRelDesc;
resultRelOid = getrelid(resultRelIndex, rangeTable);
resultRelDesc = heap_open(resultRelOid, RowExclusiveLock);
InitResultRelInfo(resultRelInfo,
resultRelDesc,
lfirst_int(l),
NULL,
estate->es_instrument);
resultRelInfo++;
}
estate->es_root_result_relations = resultRelInfos;
estate->es_num_root_result_relations = num_roots;
/* Simply lock the rest of them. */
foreach(l, plannedstmt->nonleafResultRelations)
{
Index resultRelIndex = lfirst_int(l);
/* We locked the roots above. */
if (!list_member_int(plannedstmt->rootResultRelations,
resultRelIndex))
LockRelationOid(getrelid(resultRelIndex, rangeTable),
RowExclusiveLock);
}
}
}
else
{
/*
* if no result relation, then set state appropriately
*/
estate->es_result_relations = NULL;
estate->es_num_result_relations = 0;
estate->es_result_relation_info = NULL;
estate->es_root_result_relations = NULL;
estate->es_num_root_result_relations = 0;
}
/*
* Similarly, we have to lock relations selected FOR [KEY] UPDATE/SHARE
* before we initialize the plan tree, else we'd be risking lock upgrades.
* While we are at it, build the ExecRowMark list. Any partitioned child
* tables are ignored here (because isParent=true) and will be locked by
* the first Append or MergeAppend node that references them. (Note that
* the RowMarks corresponding to partitioned child tables are present in
* the same list as the rest, i.e., plannedstmt->rowMarks.)
*/
estate->es_rowMarks = NIL;
foreach(l, plannedstmt->rowMarks)
{
PlanRowMark *rc = (PlanRowMark *) lfirst(l);
Oid relid;
Relation relation;
ExecRowMark *erm;
/* ignore "parent" rowmarks; they are irrelevant at runtime */
if (rc->isParent)
continue;
/* get relation's OID (will produce InvalidOid if subquery) */
relid = getrelid(rc->rti, rangeTable);
/*
* If you change the conditions under which rel locks are acquired
* here, be sure to adjust ExecopenScanRelation to match.
*/
switch (rc->markType)
{
case ROW_MARK_EXCLUSIVE:
case ROW_MARK_NOKEYEXCLUSIVE:
case ROW_MARK_SHARE:
case ROW_MARK_KEYSHARE:
relation = heap_open(relid, RowShareLock);
break;
case ROW_MARK_REFERENCE:
relation = heap_open(relid, AccessShareLock);
break;
case ROW_MARK_copY:
/* no physical table access is required */
relation = NULL;
break;
default:
elog(ERROR, "unrecognized markType: %d", rc->markType);
relation = NULL; /* keep compiler quiet */
break;
}
/* Check that relation is a legal target for marking */
if (relation)
CheckValidRowMarkRel(relation, rc->markType);
erm = (ExecRowMark *) palloc(sizeof(ExecRowMark));
erm->relation = relation;
erm->relid = relid;
erm->rti = rc->rti;
erm->prti = rc->prti;
erm->rowmarkId = rc->rowmarkId;
erm->markType = rc->markType;
erm->strength = rc->strength;
erm->waitPolicy = rc->waitPolicy;
erm->ermActive = false;
ItemPointerSetInvalid(&(erm->curCtid));
erm->ermExtra = NULL;
estate->es_rowMarks = lappend(estate->es_rowMarks, erm);
}
/*
* Initialize the executor's tuple table to empty.
*/
estate->es_tupleTable = NIL;
estate->es_trig_tuple_slot = NULL;
estate->es_trig_oldtup_slot = NULL;
estate->es_trig_newtup_slot = NULL;
/* mark EvalPlanQual not active */
estate->es_epqTuple = NULL;
estate->es_epqTupleSet = NULL;
estate->es_epqScanDone = NULL;
/*
* Initialize private state information for each SubPlan. We must do this
* before running ExecInitNode on the main query tree, since
* ExecInitSubPlan expects to be able to find these entries.
*/
Assert(estate->es_subplanstates == NIL);
i = 1; /* subplan indices count from 1 */
//初始化子Plan
foreach(l, plannedstmt->subplans)
{
Plan *subplan = (Plan *) lfirst(l);
PlanState *subplanstate;
int sp_eflags;
/*
* A subplan will never need to do BACKWARD scan nor MARK/RESTORE. If
* it is a parameterless subplan (not initplan), we suggest that it be
* prepared to handle REWIND efficiently; otherwise there is no need.
*/
sp_eflags = eflags
& (EXEC_FLAG_EXPLAIN_ONLY | EXEC_FLAG_WITH_NO_DATA);
if (bms_is_member(i, plannedstmt->rewindplanIDs))
sp_eflags |= EXEC_FLAG_REWIND;
subplanstate = ExecInitNode(subplan, estate, sp_eflags);
estate->es_subplanstates = lappend(estate->es_subplanstates,
subplanstate);
i++;
}
/*
* Initialize the private state information for all the nodes in the query
* tree. This opens files, allocates storage and leaves us ready to start
* processing tuples.
*/
planstate = ExecInitNode(plan, estate, eflags);
/*
* Get the tuple descriptor describing the type of tuples to return.
*/
tupType = ExecGetResultType(planstate);
/*
* Initialize the junk filter if needed. SELECT queries need a filter if
* there are any junk attrs in the top-level tlist.
*/
if (operation == CMD_SELECT)
{
bool junk_filter_needed = false;
ListCell *tlist;
foreach(tlist, plan->targetlist)
{
TargetEntry *tle = (TargetEntry *) lfirst(tlist);
if (tle->resjunk)
{
junk_filter_needed = true;
break;
}
}
if (junk_filter_needed)
{
JunkFilter *j;
j = ExecInitJunkFilter(planstate->plan->targetlist,
tupType->tdhasoid,
ExecInitExtraTupleSlot(estate, NULL));
estate->es_junkFilter = j;
/* Want to return the cleaned tuple type */
tupType = j->jf_cleanTupType;
}
}
queryDesc->tupDesc = tupType;
queryDesc->planstate = planstate;
}
/*
* ExecCheckRTPerms
* Check access permissions for all relations listed in a range table.
*
* Returns true if permissions are adequate. Otherwise, throws an appropriate
* error if ereport_on_violation is true, or simply returns false otherwise.
*
* Note that this does NOT address row level security policies (aka: RLS). If
* rows will be returned to the user as a result of this permission check
* passing, then RLS also needs to be consulted (and check_enable_rls()).
*
* See rewrite/rowsecurity.c.
*/
bool
ExecCheckRTPerms(List *rangeTable, bool ereport_on_violation)
{
ListCell *l;
bool result = true;
foreach(l, rangeTable)
{
RangeTblEntry *rte = (RangeTblEntry *) lfirst(l);
result = ExecCheckRTEPerms(rte);//基于ACL Mode的权限检查
if (!result)
{
Assert(rte->rtekind == RTE_RELATION);
if (ereport_on_violation)
aclcheck_error(ACLCHECK_NO_PRIV, get_relkind_objtype(get_rel_relkind(rte->relid)),
get_rel_name(rte->relid));
return false;
}
}
if (ExecutorCheckPerms_hook)
result = (*ExecutorCheckPerms_hook) (rangeTable,
ereport_on_violation);
return result;
}
/* ------------------------------------------------------------------------
* ExecInitNode
*
* Recursively initializes all the nodes in the plan tree rooted
* at 'node'.
*
* Inputs:
* 'node' is the current node of the plan produced by the query planner
* 'estate' is the shared execution state for the plan tree
* 'eflags' is a bitwise OR of flag bits described in executor.h
*
* Returns a PlanState node corresponding to the given Plan node.
* ------------------------------------------------------------------------
*/
//初始化节点，返回Plan状态
PlanState *
ExecInitNode(Plan *node, EState *estate, int eflags)
{
PlanState *result;
List *subps;
ListCell *l;
/*
* do nothing when we get to the end of a leaf on tree.
*/
if (node == NULL)
return NULL;
/*
* Make sure there's enough stack available. Need to check here, in
* addition to ExecProcNode() (via ExecProcNodeFirst()), to ensure the
* stack isn't overrun while initializing the node tree.
*/
check_stack_depth();
switch (nodeTag(node))
{
/*
* control nodes
*/
case T_Result:
result = (PlanState *) ExecInitResult((Result *) node,
estate, eflags);
break;
case T_ProjectSet:
result = (PlanState *) ExecInitProjectSet((ProjectSet *) node,
estate, eflags);
break;
case T_ModifyTable://插入数据
result = (PlanState *) ExecInitModifyTable((ModifyTable *) node,
estate, eflags);
break;
case T_Append:
result = (PlanState *) ExecInitAppend((Append *) node,
estate, eflags);
break;
case T_MergeAppend:
result = (PlanState *) ExecInitMergeAppend((MergeAppend *) node,
estate, eflags);
break;
case T_RecursiveUnion:
result = (PlanState *) ExecInitRecursiveUnion((RecursiveUnion *) node,
estate, eflags);
break;
case T_BitmapAnd:
result = (PlanState *) ExecInitBitmapAnd((BitmapAnd *) node,
estate, eflags);
break;
case T_BitmapOr:
result = (PlanState *) ExecInitBitmapOr((BitmapOr *) node,
estate, eflags);
break;
/*
* scan nodes
*/
case T_SeqScan:
result = (PlanState *) ExecInitSeqScan((SeqScan *) node,
estate, eflags);
break;
case T_SampleScan:
result = (PlanState *) ExecInitSampleScan((SampleScan *) node,
estate, eflags);
break;
case T_IndexScan:
result = (PlanState *) ExecInitIndexScan((IndexScan *) node,
estate, eflags);
break;
case T_IndexOnlyScan:
result = (PlanState *) ExecInitIndexOnlyScan((IndexOnlyScan *) node,
estate, eflags);
break;
case T_BitmapIndexScan:
result = (PlanState *) ExecInitBitmapIndexScan((BitmapIndexScan *) node,
estate, eflags);
break;
case T_BitmapHeapScan:
result = (PlanState *) ExecInitBitmapHeapScan((BitmapHeapScan *) node,
estate, eflags);
break;
case T_TidScan:
result = (PlanState *) ExecInitTidScan((TidScan *) node,
estate, eflags);
break;
case T_SubqueryScan:
result = (PlanState *) ExecInitSubqueryScan((SubqueryScan *) node,
estate, eflags);
break;
case T_FunctionScan:
result = (PlanState *) ExecInitFunctionScan((FunctionScan *) node,
estate, eflags);
break;
case T_TableFuncScan:
result = (PlanState *) ExecInitTableFuncScan((TableFuncScan *) node,
estate, eflags);
break;
case T_ValuesScan:
result = (PlanState *) ExecInitValuesScan((ValuesScan *) node,
estate, eflags);
break;
case T_CteScan:
result = (PlanState *) ExecInitCteScan((CteScan *) node,
estate, eflags);
break;
case T_NamedTuplestoreScan:
result = (PlanState *) ExecInitNamedTuplestoreScan((NamedTuplestoreScan *) node,
estate, eflags);
break;
case T_WorkTableScan:
result = (PlanState *) ExecInitWorkTableScan((WorkTableScan *) node,
estate, eflags);
break;
case T_ForeignScan:
result = (PlanState *) ExecInitForeignScan((ForeignScan *) node,
estate, eflags);
break;
case T_CustomScan:
result = (PlanState *) ExecInitCustomScan((CustomScan *) node,
estate, eflags);
break;
/*
* join nodes
*/
case T_nestLoop:
result = (PlanState *) ExecInitnestLoop((nestLoop *) node,
estate, eflags);
break;
case T_MergeJoin:
result = (PlanState *) ExecInitMergeJoin((MergeJoin *) node,
estate, eflags);
break;
case T_HashJoin:
result = (PlanState *) ExecInitHashJoin((HashJoin *) node,
estate, eflags);
break;
/*
* materialization nodes
*/
case T_Material:
result = (PlanState *) ExecInitMaterial((Material *) node,
estate, eflags);
break;
case T_Sort:
result = (PlanState *) ExecInitSort((Sort *) node,
estate, eflags);
break;
case T_Group:
result = (PlanState *) ExecInitGroup((Group *) node,
estate, eflags);
break;
case T_Agg:
result = (PlanState *) ExecInitAgg((Agg *) node,
estate, eflags);
break;
case T_WindowAgg:
result = (PlanState *) ExecInitwindowAgg((WindowAgg *) node,
estate, eflags);
break;
case T_Unique:
result = (PlanState *) ExecInitUnique((Unique *) node,
estate, eflags);
break;
case T_Gather:
result = (PlanState *) ExecInitGather((Gather *) node,
estate, eflags);
break;
case T_GatherMerge:
result = (PlanState *) ExecInitGatherMerge((GatherMerge *) node,
estate, eflags);
break;
case T_Hash:
result = (PlanState *) ExecInitHash((Hash *) node,
estate, eflags);
break;
case T_Setop:
result = (PlanState *) ExecInitSetop((Setop *) node,
estate, eflags);
break;
case T_LockRows:
result = (PlanState *) ExecInitLockRows((LockRows *) node,
estate, eflags);
break;
case T_Limit:
result = (PlanState *) ExecInitLimit((Limit *) node,
estate, eflags);
break;
default:
elog(ERROR, "unrecognized node type: %d", (int) nodeTag(node));
result = NULL; /* keep compiler quiet */
break;
}
ExecSetExecProcNode(result, result->ExecProcNode);
/*
* Initialize any initPlans present in this node. The planner put them in
* a separate list for us.
*/
subps = NIL;
foreach(l, node->initPlan)
{
SubPlan *subplan = (SubPlan *) lfirst(l);
SubPlanState *sstate;
Assert(IsA(subplan, SubPlan));
sstate = ExecInitSubPlan(subplan, result);
subps = lappend(subps, sstate);
}
result->initPlan = subps;
/* Set up instrumentation for this node if requested */
if (estate->es_instrument)
result->instrument = InstrAlloc(1, estate->es_instrument);
return result;
}
/* ----------------------------------------------------------------
* ExecInitModifyTable
* ----------------------------------------------------------------
*/
ModifyTableState *
ExecInitModifyTable(ModifyTable *node, EState *estate, int eflags)
{
ModifyTableState *mtstate;//返回结果
CmdType operation = node->operation;//操作类型
int nplans = list_length(node->plans);//节点中的plan个数
ResultRelInfo *saved_resultRelInfo;
ResultRelInfo *resultRelInfo;//结果Relation信息
Plan *subplan;//子Plan
ListCell *l;//临时变量
int i;
Relation rel;
bool update_tuple_routing_needed = node->partColsUpdated;
/* check for unsupported flags */
Assert(!(eflags & (EXEC_FLAG_BACKWARD | EXEC_FLAG_MARK)));
/*
* create state structure
*/
mtstate = makeNode(ModifyTableState);//构建节点
mtstate->ps.plan = (Plan *) node;//设置Plan
mtstate->ps.state = estate;//设置执行状态
mtstate->ps.ExecProcNode = ExecModifyTable;//设置处理函数为ExecModifyTable
mtstate->operation = operation;//操作类型
mtstate->canSetTag = node->canSetTag;
mtstate->mt_done = false;
mtstate->mt_plans = (PlanState **) palloc0(sizeof(PlanState *) * nplans);//分配内存
mtstate->resultRelInfo = estate->es_result_relations + node->resultRelIndex;//结果Relation信息
/* If modifying a partitioned table, initialize the root table info */
if (node->rootResultRelIndex >= 0)
mtstate->rootResultRelInfo = estate->es_root_result_relations +
node->rootResultRelIndex;
mtstate->mt_arowmarks = (List **) palloc0(sizeof(List *) * nplans);
mtstate->mt_nplans = nplans;
/* set up epqstate with dummy subplan data for the moment */
EvalPlanQualInit(&mtstate->mt_epqstate, estate, NULL, NIL, node->epqParam);
mtstate->fireBSTriggers = true;
/*
* call ExecInitNode on each of the plans to be executed and save the
* results into the array "mt_plans". This is also a convenient place to
* verify that the proposed target relations are valid and open their
* indexes for insertion of new index entries. Note we *must* set
* estate->es_result_relation_info correctly while we initialize each
* sub-plan; ExecContextForcesOids depends on that!
*/
saved_resultRelInfo = estate->es_result_relation_info;
resultRelInfo = mtstate->resultRelInfo;
i = 0;
//初始化每个子Plan，保存在mt_plans数组中
foreach(l, node->plans)
{
subplan = (Plan *) lfirst(l);
/* Initialize the usesFdwDirectModify flag */
resultRelInfo->ri_usesFdwDirectModify = bms_is_member(i,
node->fdwDirectModifyPlans);
/*
* Verify result relation is a valid target for the current operation
*/
CheckValidResultRel(resultRelInfo, operation);
/*
* If there are indices on the result relation, open them and save
* descriptors in the result relation info, so that we can add new
* index entries for the tuples we add/update. We need not do this
* for a DELETE, however, since deletion doesn't affect indexes. Also,
* inside an EvalPlanQual operation, the indexes might be open
* already, since we share the resultrel state with the original
* query.
*/
if (resultRelInfo->ri_RelationDesc->rd_rel->relhasindex &&
operation != CMD_DELETE &&
resultRelInfo->ri_IndexRelationDescs == NULL)
ExecopenIndices(resultRelInfo,
node->onConflictAction != ONCONFLICT_NONE);//初始化Index
/*
* If this is an UPDATE and a BEFORE UPDATE trigger is present, the
* trigger itself might modify the partition-key values. So arrange
* for tuple routing.
*/
if (resultRelInfo->ri_TrigDesc &&
resultRelInfo->ri_TrigDesc->trig_update_before_row &&
operation == CMD_UPDATE)
update_tuple_routing_needed = true;
/* Now init the plan for this result rel */
estate->es_result_relation_info = resultRelInfo;
mtstate->mt_plans[i] = ExecInitNode(subplan, estate, eflags);//初始化子节点
/* Also let FDWs init themselves for foreign-table result rels */
if (!resultRelInfo->ri_usesFdwDirectModify &&
resultRelInfo->ri_FdwRoutine != NULL &&
resultRelInfo->ri_FdwRoutine->BeginForeignModify != NULL)
{
List *fdw_private = (List *) list_nth(node->fdwPrivLists, i);
resultRelInfo->ri_FdwRoutine->BeginForeignModify(mtstate,
resultRelInfo,
fdw_private,
i,
eflags);
}
resultRelInfo++;
i++;
}
estate->es_result_relation_info = saved_resultRelInfo;
/* Get the target relation */
rel = (getTargetResultRelInfo(mtstate))->ri_RelationDesc;
/*
* If it's not a partitioned table after all, UPDATE tuple routing should
* not be attempted.
*/
if (rel->rd_rel->relkind != RELKIND_PARTITIONED_TABLE)
update_tuple_routing_needed = false;
/*
* Build state for tuple routing if it's an INSERT or if it's an UPDATE of
* partition key.
*/
if (rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE &&
(operation == CMD_INSERT || update_tuple_routing_needed))
mtstate->mt_partition_tuple_routing =
ExecSetupPartitionTupleRouting(mtstate, rel);
/*
* Build state for collecting transition tuples. This requires having a
* valid trigger query context, so skip it in explain-only mode.
*/
if (!(eflags & EXEC_FLAG_EXPLAIN_ONLY))
ExecSetupTransitionCaptureState(mtstate, estate);
/*
* Construct mapping from each of the per-subplan partition attnos to the
* root attno. This is required when during update row movement the tuple
* descriptor of a source partition does not match the root partitioned
* table descriptor. In such a case we need to convert tuples to the root
* tuple descriptor, because the search for destination partition starts
* from the root. Skip this setup if it's not a partition key update.
*/
if (update_tuple_routing_needed)
ExecSetupChildParentMapForSubplan(mtstate);
/*
* Initialize any WITH CHECK OPTION constraints if needed.
*/
resultRelInfo = mtstate->resultRelInfo;
i = 0;
//设置Check选项
foreach(l, node->withCheckOptionLists)
{
List *wcoList = (List *) lfirst(l);
List *wcoExprs = NIL;
ListCell *ll;
foreach(ll, wcoList)
{
WithCheckOption *wco = (WithCheckOption *) lfirst(ll);
ExprState *wcoExpr = ExecInitQual((List *) wco->qual,
mtstate->mt_plans[i]);
wcoExprs = lappend(wcoExprs, wcoExpr);
}
resultRelInfo->ri_WithCheckOptions = wcoList;
resultRelInfo->ri_WithCheckOptionExprs = wcoExprs;
resultRelInfo++;
i++;
}
/*
* Initialize RETURNING projections if needed.
*/
if (node->returningLists)
{
TupleTableSlot *slot;
ExprContext *econtext;
/*
* Initialize result tuple slot and assign its rowtype using the first
* RETURNING list. We assume the rest will look the same.
*/
mtstate->ps.plan->targetlist = (List *) linitial(node->returningLists);
/* Set up a slot for the output of the RETURNING projection(s) */
ExecInitResultTupleSlottL(estate, &mtstate->ps);
slot = mtstate->ps.ps_ResultTupleSlot;
/* Need an econtext too */
if (mtstate->ps.ps_ExprContext == NULL)
ExecAssignExprContext(estate, &mtstate->ps);
econtext = mtstate->ps.ps_ExprContext;
/*
* Build a projection for each result rel.
*/
resultRelInfo = mtstate->resultRelInfo;
foreach(l, node->returningLists)
{
List *rlist = (List *) lfirst(l);
resultRelInfo->ri_returningList = rlist;
resultRelInfo->ri_projectReturning =
ExecBuildProjectionInfo(rlist, econtext, slot, &mtstate->ps,
resultRelInfo->ri_RelationDesc->rd_att);
resultRelInfo++;
}
}
else
{
/*
* We still must construct a dummy result tuple type, because InitPlan
* expects one (maybe should change that?).
*/
mtstate->ps.plan->targetlist = NIL;
ExecInitResultTupleSlottL(estate, &mtstate->ps);
mtstate->ps.ps_ExprContext = NULL;
}
/* Set the list of arbiter indexes if needed for ON CONFLICT */
resultRelInfo = mtstate->resultRelInfo;
if (node->onConflictAction != ONCONFLICT_NONE)
resultRelInfo->ri_onConflictArbiterIndexes = node->arbiterIndexes;
/*
* If needed, Initialize target list, projection and qual for ON CONFLICT
* DO UPDATE.
*/
if (node->onConflictAction == ONCONFLICT_UPDATE)
{
ExprContext *econtext;
TupleDesc relationDesc;
TupleDesc tupDesc;
/* insert may only have one plan, inheritance is not expanded */
Assert(nplans == 1);
/* already exists if created by RETURNING processing above */
if (mtstate->ps.ps_ExprContext == NULL)
ExecAssignExprContext(estate, &mtstate->ps);
econtext = mtstate->ps.ps_ExprContext;
relationDesc = resultRelInfo->ri_RelationDesc->rd_att;
/*
* Initialize slot for the existing tuple. If we'll be performing
* tuple routing, the tuple descriptor to use for this will be
* determined based on which relation the update is actually applied
* to, so we don't set its tuple descriptor here.
*/
mtstate->mt_existing =
ExecInitExtraTupleSlot(mtstate->ps.state,
mtstate->mt_partition_tuple_routing ?
NULL : relationDesc);
/* carried forward solely for the benefit of explain */
mtstate->mt_excludedtlist = node->exclRelTlist;
/* create state for DO UPDATE SET operation */
resultRelInfo->ri_onConflict = makeNode(OnConflictSetState);
/*
* Create the tuple slot for the UPDATE SET projection.
*
* Just like mt_existing above, we leave it without a tuple descriptor
* in the case of partitioning tuple routing, so that it can be
* changed by ExecPrepareTupleRouting. In that case, we still save
* the tupdesc in the parent's state: it can be reused by partitions
* with an identical descriptor to the parent.
*/
tupDesc = ExecTypeFromTL((List *) node->onConflictSet,
relationDesc->tdhasoid);
mtstate->mt_conflproj =
ExecInitExtraTupleSlot(mtstate->ps.state,
mtstate->mt_partition_tuple_routing ?
NULL : tupDesc);
resultRelInfo->ri_onConflict->oc_ProjTupdesc = tupDesc;
/* build UPDATE SET projection state */
resultRelInfo->ri_onConflict->oc_ProjInfo =
ExecBuildProjectionInfo(node->onConflictSet, econtext,
mtstate->mt_conflproj, &mtstate->ps,
relationDesc);
/* initialize state to evaluate the WHERE clause, if any */
if (node->onConflictWhere)
{
ExprState *qualexpr;
qualexpr = ExecInitQual((List *) node->onConflictWhere,
&mtstate->ps);
resultRelInfo->ri_onConflict->oc_WhereClause = qualexpr;
}
}
/*
* If we have any secondary relations in an UPDATE or DELETE, they need to
* be treated like non-locked relations in SELECT FOR UPDATE, ie, the
* EvalPlanQual mechanism needs to be told about them. Locate the
* relevant ExecRowMarks.
*/
foreach(l, node->rowMarks)
{
PlanRowMark *rc = lfirst_node(PlanRowMark, l);
ExecRowMark *erm;
/* ignore "parent" rowmarks; they are irrelevant at runtime */
if (rc->isParent)
continue;
/* find ExecRowMark (same for all subplans) */
erm = ExecFindRowMark(estate, rc->rti, false);
/* build ExecAuxRowMark for each subplan */
for (i = 0; i < nplans; i++)
{
ExecAuxRowMark *aerm;
subplan = mtstate->mt_plans[i]->plan;
aerm = ExecBuildAuxRowMark(erm, subplan->targetlist);
mtstate->mt_arowmarks[i] = lappend(mtstate->mt_arowmarks[i], aerm);
}
}
/* select first subplan */
mtstate->mt_whichplan = 0;
subplan = (Plan *) linitial(node->plans);
EvalPlanQualSetPlan(&mtstate->mt_epqstate, subplan,
mtstate->mt_arowmarks[0]);
/*
* Initialize the junk filter(s) if needed. INSERT queries need a filter
* if there are any junk attrs in the tlist. UPDATE and DELETE always
* need a filter, since there's always at least one junk attribute present
* --- no need to look first. Typically, this will be a 'ctid' or
* 'wholerow' attribute, but in the case of a foreign data wrapper it
* might be a set of junk attributes sufficient to identify the remote
* row.
*
* If there are multiple result relations, each one needs its own junk
* filter. Note multiple rels are only possible for UPDATE/DELETE, so we
* can't be fooled by some needing a filter and some not.
*
* This section of code is also a convenient place to verify that the
* output of an INSERT or UPDATE matches the target table(s).
*/
{
bool junk_filter_needed = false;
switch (operation)
{
case CMD_INSERT:
foreach(l, subplan->targetlist)
{
TargetEntry *tle = (TargetEntry *) lfirst(l);
if (tle->resjunk)
{
junk_filter_needed = true;
break;
}
}
break;
case CMD_UPDATE:
case CMD_DELETE:
junk_filter_needed = true;
break;
default:
elog(ERROR, "unkNown operation");
break;
}
if (junk_filter_needed)
{
resultRelInfo = mtstate->resultRelInfo;
for (i = 0; i < nplans; i++)
{
JunkFilter *j;
subplan = mtstate->mt_plans[i]->plan;
if (operation == CMD_INSERT || operation == CMD_UPDATE)
ExecCheckPlanOutput(resultRelInfo->ri_RelationDesc,
subplan->targetlist);
j = ExecInitJunkFilter(subplan->targetlist,
resultRelInfo->ri_RelationDesc->rd_att->tdhasoid,
ExecInitExtraTupleSlot(estate, NULL));
if (operation == CMD_UPDATE || operation == CMD_DELETE)
{
/* For UPDATE/DELETE, find the appropriate junk attr Now */
char relkind;
relkind = resultRelInfo->ri_RelationDesc->rd_rel->relkind;
if (relkind == RELKIND_RELATION ||
relkind == RELKIND_MATVIEW ||
relkind == RELKIND_PARTITIONED_TABLE)
{
j->jf_junkAttNo = ExecFindJunkAttribute(j, "ctid");
if (!AttributeNumberIsValid(j->jf_junkAttNo))
elog(ERROR, "Could not find junk ctid column");
}
else if (relkind == RELKIND_FOREIGN_TABLE)
{
/*
* When there is a row-level trigger, there should be
* a wholerow attribute.
*/
j->jf_junkAttNo = ExecFindJunkAttribute(j, "wholerow");
}
else
{
j->jf_junkAttNo = ExecFindJunkAttribute(j, "wholerow");
if (!AttributeNumberIsValid(j->jf_junkAttNo))
elog(ERROR, "Could not find junk wholerow column");
}
}
resultRelInfo->ri_junkFilter = j;
resultRelInfo++;
}
}
else
{
if (operation == CMD_INSERT)
ExecCheckPlanOutput(mtstate->resultRelInfo->ri_RelationDesc,
subplan->targetlist);
}
}
/*
* Set up a tuple table slot for use for trigger output tuples. In a plan
* containing multiple ModifyTable nodes, all can share one such slot, so
* we keep it in the estate.
*/
if (estate->es_trig_tuple_slot == NULL)
estate->es_trig_tuple_slot = ExecInitExtraTupleSlot(estate, NULL);
/*
* Lastly, if this is not the primary (canSetTag) ModifyTable node, add it
* to estate->es_auxmodifytables so that it will be run to completion by
* ExecPostprocessplan. (It'd actually work fine to add the primary
* ModifyTable node too, but there's no need.) Note the use of lcons not
* lappend: we need later-initialized ModifyTable nodes to be shut down
* before earlier ones. This ensures that we don't throw away RETURNING
* rows that need to be seen by a later CTE subplan.
*/
if (!mtstate->canSetTag)
estate->es_auxmodifytables = lcons(mtstate,
estate->es_auxmodifytables);
return mtstate;
}
/* ----------------
* ModifyTable node -
* Apply rows produced by subplan(s) to result table(s),
* by inserting, updating, or deleting.
*
* Note that rowMarks and epqParam are presumed to be valid for all the
* subplan(s); they can't contain any info that varies across subplans.
* ----------------
*/
typedef struct ModifyTable
{
Plan plan;
CmdType operation; /* INSERT, UPDATE, or DELETE */
bool canSetTag; /* do we set the command tag/es_processed? */
Index nominalRelation; /* Parent RT index for use of EXPLAIN */
/* RT indexes of non-leaf tables in a partition tree */
List *partitioned_rels;
bool partColsUpdated; /* some part key in hierarchy updated */
List *resultRelations; /* integer list of RT indexes */
int resultRelIndex; /* index of first resultRel in plan's list */
int rootResultRelIndex; /* index of the partitioned table root */
List *plans; /* plan(s) producing source data */
List *withCheckOptionLists; /* per-target-table WCO lists */
List *returningLists; /* per-target-table RETURNING tlists */
List *fdwPrivLists; /* per-target-table FDW private data lists */
Bitmapset *fdwDirectModifyPlans; /* indices of FDW DM plans */
List *rowMarks; /* PlanRowMarks (non-locking only) */
int epqParam; /* ID of Param for EvalPlanQual re-eval */
OnConflictAction onConflictAction; /* ON CONFLICT action */
List *arbiterIndexes; /* List of ON CONFLICT arbiter index OIDs */
List *onConflictSet; /* SET for INSERT ON CONFLICT DO UPDATE */
Node *onConflictWhere; /* WHERE for ON CONFLICT UPDATE */
Index exclRelRTI; /* RTI of the EXCLUDED pseudo relation */
List *exclRelTlist; /* tlist of the EXCLUDED pseudo relation */
} ModifyTable;
4、ExecutorStart
/* ----------------------------------------------------------------
* ExecutorStart
*
* This routine must be called at the beginning of any execution of any
* query plan
*
* Takes a QueryDesc prevIoUsly created by createqueryDesc (which is separate
* only because some places use QueryDescs for utility commands). The tupDesc
* field of the QueryDesc is filled in to describe the tuples that will be
* returned, and the internal fields (estate and planstate) are set up.
*
* eflags contains flag bits as described in executor.h.
*
* NB: the CurrentMemoryContext when this is called will become the parent
* of the per-query context used for this Executor invocation.
*
* We provide a function hook variable that lets loadable plugins
* get control when ExecutorStart is called. Such a plugin would
* normally call standard_ExecutorStart().
*
* ----------------------------------------------------------------
*/
void
ExecutorStart(QueryDesc *queryDesc, int eflags)//eflags见后
{
if (ExecutorStart_hook)
(*ExecutorStart_hook) (queryDesc, eflags);//提供了钩子函数
else
standard_ExecutorStart(queryDesc, eflags);//标准函数
}
void
standard_ExecutorStart(QueryDesc *queryDesc, int eflags)//标准函数
{
EState *estate;//执行器状态信息
MemoryContext oldcontext;//原内存上下文
/* sanity checks: queryDesc must not be started already */
Assert(queryDesc != NULL);
Assert(queryDesc->estate == NULL);
/*
* If the transaction is read-only, we need to check if any writes are
* planned to non-temporary tables. EXPLAIN is considered read-only.
*
* Don't allow writes in parallel mode. Supporting UPDATE and DELETE
* would require (a) storing the combocid hash in shared memory, rather
* than synchronizing it just once at the start of parallelism, and (b) an
* alternative to heap_update()'s reliance on xmax for mutual exclusion.
* INSERT may have no such troubles, but we forbid it to simplify the
* checks.
*
* We have lower-level defenses in CommandCounterIncrement and elsewhere
* against performing unsafe operations in parallel mode, but this gives a
* more user-friendly error message.
*/
if ((XactReadOnly || IsInParallelMode()) &&
!(eflags & EXEC_FLAG_EXPLAIN_ONLY))
ExecCheckXactReadOnly(queryDesc->plannedstmt);//ReadOnly？
/*
* Build EState, switch into per-query memory context for startup.
*/
estate = CreateExecutorState();//创建执行器状态信息
queryDesc->estate = estate;//赋值
oldcontext = MemoryContextSwitchTo(estate->es_query_cxt);//切换上下文
/*
* Fill in external parameters, if any, from queryDesc; and allocate
* workspace for internal parameters
*/
estate->es_param_list_info = queryDesc->params;//设置参数
if (queryDesc->plannedstmt->paramExecTypes != NIL)//Todo
{
int nParamExec;
nParamExec = list_length(queryDesc->plannedstmt->paramExecTypes);
estate->es_param_exec_vals = (ParamExecData *)
palloc0(nParamExec * sizeof(ParamExecData));
}
estate->es_sourceText = queryDesc->sourceText;//源sql语句
/*
* Fill in the query environment, if any, from queryDesc.
*/
estate->es_queryEnv = queryDesc->queryEnv;//查询环境
/*
* If non-read-only query, set the command ID to mark output tuples with
*/
switch (queryDesc->operation)
{
case CMD_SELECT://查询语句 Todo
/*
* SELECT FOR [KEY] UPDATE/SHARE and modifying CTEs need to mark
* tuples
*/
if (queryDesc->plannedstmt->rowMarks != NIL ||
queryDesc->plannedstmt->hasModifyingCTE)
estate->es_output_cid = GetCurrentCommandId(true);
/*
* A SELECT without modifying CTEs can't possibly queue triggers,
* so force skip-triggers mode. This is just a marginal efficiency
* hack, since AfterTriggerBeginQuery/AfterTriggerEndQuery aren't
* all that expensive, but we might as well do it.
*/
if (!queryDesc->plannedstmt->hasModifyingCTE)
eflags |= EXEC_FLAG_SKIP_TRIGGERS;
break;
case CMD_INSERT://插入语句
case CMD_DELETE:
case CMD_UPDATE:
estate->es_output_cid = GetCurrentCommandId(true);
break;
default:
elog(ERROR, "unrecognized operation code: %d",
(int) queryDesc->operation);
break;
}
/*
* copy other important information into the EState
*/
estate->es_snapshot = RegisterSnapshot(queryDesc->snapshot);
estate->es_crosscheck_snapshot = RegisterSnapshot(queryDesc->crosscheck_snapshot);
estate->es_top_eflags = eflags;
estate->es_instrument = queryDesc->instrument_options;
estate->es_jit_flags = queryDesc->plannedstmt->jitFlags;
/*
* Set up an AFTER-trigger statement context, unless told not to, or
* unless it's EXPLAIN-only mode (when ExecutorFinish won't be called).
*/
if (!(eflags & (EXEC_FLAG_SKIP_TRIGGERS | EXEC_FLAG_EXPLAIN_ONLY)))
AfterTriggerBeginQuery();
/*
* Initialize the plan state tree
*/
InitPlan(queryDesc, eflags);//初始化Plan State tree
MemoryContextSwitchTo(oldcontext);
}
/*
* GetCurrentCommandId
*
* "used" must be true if the caller intends to use the command ID to mark
* inserted/updated/deleted tuples. false means the ID is being fetched
* for read-only purposes (ie, as a snapshot validity cutoff). See
* CommandCounterIncrement() for discussion.
*/
CommandId
GetCurrentCommandId(bool used)
{
/* this is global to a transaction, not subtransaction-local */
if (used)
{
/*
* Forbid setting currentCommandIdUsed in a parallel worker, because
* we have no provision for communicating this back to the master. We
* Could relax this restriction when currentCommandIdUsed was already
* true at the start of the parallel operation.
*/
Assert(!IsParallelWorker());
currentCommandIdUsed = true;
}
return currentCommandId;
}
/*
* The "eflags" argument to ExecutorStart and the varIoUs ExecInitNode
* routines is a bitwise OR of the following flag bits, which tell the
* called plan node what to expect. Note that the flags will get modified
* as they are passed down the plan tree, since an upper node may require
* functionality in its subnode not demanded of the plan as a whole
* (example: MergeJoin requires mark/restore capability in its inner input),
* or an upper node may shield its input from some functionality requirement
* (example: Materialize shields its input from needing to do backward scan).
*
* EXPLAIN_ONLY indicates that the plan tree is being initialized just so
* EXPLAIN can print it out; it will not be run. Hence, no side-effects
* of startup should occur. However, error checks (such as permission checks)
* should be performed.
*
* REWIND indicates that the plan node should try to efficiently support
* rescans without parameter changes. (Nodes must support ExecReScan calls
* in any case, but if this flag was not given, they are at liberty to do it
* through complete recalculation. Note that a parameter change forces a
* full recalculation in any case.)
*
* BACKWARD indicates that the plan node must respect the es_direction flag.
* When this is not passed, the plan node will only be run forwards.
*
* MARK indicates that the plan node must support Mark/Restore calls.
* When this is not passed, no Mark/Restore will occur.
*
* SKIP_TRIGGERS tells ExecutorStart/ExecutorFinish to skip calling
* AfterTriggerBeginQuery/AfterTriggerEndQuery. This does not necessarily
* mean that the plan can't queue any AFTER triggers; just that the caller
* is responsible for there being a trigger context for them to be queued in.
*
* WITH/WITHOUT_OIDS tell the executor to emit tuples with or without space
* for OIDs, respectively. These are currently used only for CREATE TABLE AS.
* If neither is set, the plan may or may not produce tuples including OIDs.
*/
#define EXEC_FLAG_EXPLAIN_ONLY 0x0001 /* EXPLAIN, no ANALYZE */
#define EXEC_FLAG_REWIND 0x0002 /* need efficient rescan */
#define EXEC_FLAG_BACKWARD 0x0004 /* need backward scan */
#define EXEC_FLAG_MARK 0x0008 /* need mark/restore */
#define EXEC_FLAG_SKIP_TRIGGERS 0x0010 /* skip AfterTrigger calls */
#define EXEC_FLAG_WITH_OIDS 0x0020 /* force OIDs in returned tuples */
#define EXEC_FLAG_WITHOUT_OIDS 0x0040 /* force no OIDs in returned tuples */
#define EXEC_FLAG_WITH_NO_DATA 0x0080 /* rel scannability doesn't matter */
5、ExecutorRun
//上一节已介绍
6、ExecutorFinish
/* ----------------------------------------------------------------
* ExecutorFinish
*
* This routine must be called after the last ExecutorRun call.
* It performs cleanup such as firing AFTER triggers. It is
* separate from ExecutorEnd because EXPLAIN ANALYZE needs to
* include these actions in the total runtime.
*
* We provide a function hook variable that lets loadable plugins
* get control when ExecutorFinish is called. Such a plugin would
* normally call standard_ExecutorFinish().
*
* ----------------------------------------------------------------
*/
void
ExecutorFinish(QueryDesc *queryDesc)
{
if (ExecutorFinish_hook)
(*ExecutorFinish_hook) (queryDesc);
else
standard_ExecutorFinish(queryDesc);
}
void
standard_ExecutorFinish(QueryDesc *queryDesc)
{
EState *estate;
MemoryContext oldcontext;
/* sanity checks */
Assert(queryDesc != NULL);
estate = queryDesc->estate;
Assert(estate != NULL);
Assert(!(estate->es_top_eflags & EXEC_FLAG_EXPLAIN_ONLY));
/* This should be run once and only once per Executor instance */
Assert(!estate->es_finished);
/* Switch into per-query memory context */
oldcontext = MemoryContextSwitchTo(estate->es_query_cxt);
/* Allow instrumentation of Executor overall runtime */
if (queryDesc->totaltime)
InstrStartNode(queryDesc->totaltime);
/* Run ModifyTable nodes to completion */
ExecPostprocessplan(estate);
/* Execute queued AFTER triggers, unless told not to */
if (!(estate->es_top_eflags & EXEC_FLAG_SKIP_TRIGGERS))
AfterTriggerEndQuery(estate);
if (queryDesc->totaltime)
InstrStopNode(queryDesc->totaltime, 0);
MemoryContextSwitchTo(oldcontext);
estate->es_finished = true;
}
/* ----------------------------------------------------------------
* ExecPostprocessplan
*
* Give plan nodes a final chance to execute before shutdown
* ----------------------------------------------------------------
*/
static void
ExecPostprocessplan(EState *estate)
{
ListCell *lc;
/*
* Make sure nodes run forward.
*/
estate->es_direction = ForwardScanDirection;
/*
* Run any secondary ModifyTable nodes to completion, in case the main
* query did not fetch all rows from them. (We do this to ensure that
* such nodes have predictable results.)
*/
foreach(lc, estate->es_auxmodifytables)
{
PlanState *ps = (PlanState *) lfirst(lc);
for (;;)
{
TupleTableSlot *slot;
/* Reset the per-output-tuple exprcontext each time */
ResetPerTupleExprContext(estate);
slot = ExecProcNode(ps);
if (TupIsNull(slot))
break;
}
}
7、ExecutorEnd
/* ----------------------------------------------------------------
* ExecutorEnd
*
* This routine must be called at the end of execution of any
* query plan
*
* We provide a function hook variable that lets loadable plugins
* get control when ExecutorEnd is called. Such a plugin would
* normally call standard_ExecutorEnd().
*
* ----------------------------------------------------------------
*/
void
ExecutorEnd(QueryDesc *queryDesc)
{
if (ExecutorEnd_hook)
(*ExecutorEnd_hook) (queryDesc);
else
standard_ExecutorEnd(queryDesc);
}
void
standard_ExecutorEnd(QueryDesc *queryDesc)
{
EState *estate;
MemoryContext oldcontext;
/* sanity checks */
Assert(queryDesc != NULL);
estate = queryDesc->estate;
Assert(estate != NULL);
/*
* Check that ExecutorFinish was called, unless in EXPLAIN-only mode. This
* Assert is needed because ExecutorFinish is new as of 9.1, and callers
* might forget to call it.
*/
Assert(estate->es_finished ||
(estate->es_top_eflags & EXEC_FLAG_EXPLAIN_ONLY));
/*
* Switch into per-query memory context to run ExecEndplan
*/
oldcontext = MemoryContextSwitchTo(estate->es_query_cxt);
ExecEndplan(queryDesc->planstate, estate);
/* do away with our snapshots */
UnregisterSnapshot(estate->es_snapshot);
UnregisterSnapshot(estate->es_crosscheck_snapshot);
/*
* Must switch out of context before destroying it
*/
MemoryContextSwitchTo(oldcontext);
/*
* Release EState and per-query memory context. This should release
* everything the executor has allocated.
*/
FreeExecutorState(estate);
/* Reset queryDesc fields that no longer point to anything */
queryDesc->tupDesc = NULL;
queryDesc->estate = NULL;
queryDesc->planstate = NULL;
queryDesc->totaltime = NULL;
}
/* ----------------------------------------------------------------
* ExecEndplan
*
* Cleans up the query plan -- closes files and frees up storage
*
* NOTE: we are no longer very worried about freeing storage per se
* in this code; FreeExecutorState should be guaranteed to release all
* memory that needs to be released. What we are worried about doing
* is closing relations and dropping buffer pins. Thus, for example,
* tuple tables must be cleared or dropped to ensure pins are released.
* ----------------------------------------------------------------
*/
static void
ExecEndplan(PlanState *planstate, EState *estate)
{
ResultRelInfo *resultRelInfo;
int i;
ListCell *l;
/*
* shut down the node-type-specific query processing
*/
ExecEndNode(planstate);
/*
* for subplans too
*/
foreach(l, estate->es_subplanstates)
{
PlanState *subplanstate = (PlanState *) lfirst(l);
ExecEndNode(subplanstate);
}
/*
* destroy the executor's tuple table. Actually we only care about
* releasing buffer pins and tupdesc refcounts; there's no need to pfree
* the TupleTableSlots, since the containing memory context is about to go
* away anyway.
*/
ExecResetTupleTable(estate->es_tupleTable, false);
/*
* close the result relation(s) if any, but hold locks until xact commit.
*/
resultRelInfo = estate->es_result_relations;
for (i = estate->es_num_result_relations; i > 0; i--)
{
/* Close indices and then the relation itself */
ExeccloseIndices(resultRelInfo);
heap_close(resultRelInfo->ri_RelationDesc, NoLock);
resultRelInfo++;
}
/* Close the root target relation(s). */
resultRelInfo = estate->es_root_result_relations;
for (i = estate->es_num_root_result_relations; i > 0; i--)
{
heap_close(resultRelInfo->ri_RelationDesc, NoLock);
resultRelInfo++;
}
/* likewise close any trigger target relations */
ExeccleanUpTriggerState(estate);
/*
* close any relations selected FOR [KEY] UPDATE/SHARE, again keeping
* locks
*/
foreach(l, estate->es_rowMarks)
{
ExecRowMark *erm = (ExecRowMark *) lfirst(l);
if (erm->relation)
heap_close(erm->relation, NoLock);
}
}
8、FreeQueryDesc
//释放资源
/*
* FreeQueryDesc
*/
void
FreeQueryDesc(QueryDesc *qdesc)
{
/* Can't be a live query */
Assert(qdesc->estate == NULL);
/* forget our snapshots */
UnregisterSnapshot(qdesc->snapshot);
UnregisterSnapshot(qdesc->crosscheck_snapshot);
/* Only the QueryDesc itself need be freed */
pfree(qdesc);
}
二、源码解读
/*
* ProcessQuery
* Execute a single plannable query within a PORTAL_MULTI_QUERY,
* PORTAL_ONE_RETURNING, or PORTAL_ONE_MOD_WITH portal
*
* plan: the plan tree for the query
* sourceText: the source text of the query
* params: any parameters needed
* dest: where to send results
* completionTag: points to a buffer of size COMPLETION_TAG_BUFSIZE
* in which to store a command completion status string.
*
* completionTag may be NULL if caller doesn't want a status string.
*
* Must be called in a memory context that will be reset or deleted on
* error; otherwise the executor's memory usage will be leaked.
*/
/*
输入：
plan-已生成执行计划的语句
sourceText-源sql语句
params-Todo
queryEnv-查询执行的环境
dest-目标接收器
completionTag-完成标记
输出：
无
*/
static void
ProcessQuery(PlannedStmt *plan,
const char *sourceText,
ParamListInfo params,
QueryEnvironment *queryEnv,
DestReceiver *dest,
char *completionTag)
{
QueryDesc *queryDesc;//查询描述符
/*
* Create the QueryDesc object
*/
queryDesc = createqueryDesc(plan, sourceText,
GetActiveSnapshot(), InvalidSnapshot,
dest, params, queryEnv, 0);//构造查询描述符
/*
* Call ExecutorStart to prepare the plan for execution
*/
ExecutorStart(queryDesc, 0);//启动执行器
/*
* Run the plan to completion.
*/
ExecutorRun(queryDesc, ForwardScanDirection, 0L, true);//执行
/*
* Build command completion status string, if caller wants one.
*/
if (completionTag)//如果需要完成标记
{
Oid lastOid;
switch (queryDesc->operation)
{
case CMD_SELECT:
snprintf(completionTag, COMPLETION_TAG_BUFSIZE,
"SELECT " UINT64_FORMAT,
queryDesc->estate->es_processed);
break;
case CMD_INSERT://插入语句
if (queryDesc->estate->es_processed == 1)
lastOid = queryDesc->estate->es_lastoid;
else
lastOid = InvalidOid;
snprintf(completionTag, COMPLETION_TAG_BUFSIZE,
"INSERT %u " UINT64_FORMAT,
lastOid, queryDesc->estate->es_processed);
break;
case CMD_UPDATE:
snprintf(completionTag, COMPLETION_TAG_BUFSIZE,
"UPDATE " UINT64_FORMAT,
queryDesc->estate->es_processed);
break;
case CMD_DELETE:
snprintf(completionTag, COMPLETION_TAG_BUFSIZE,
"DELETE " UINT64_FORMAT,
queryDesc->estate->es_processed);
break;
default:
strcpy(completionTag, "???");
break;
}
}
/*
* Now, we close down all the scans and free allocated resources.
*/
ExecutorFinish(queryDesc);//完成
ExecutorEnd(queryDesc);//结束
FreeQueryDesc(queryDesc);//释放资源
}
三、跟踪分析
插入测试数据：
testdb=# -- #9.1 ProcessQuery
testdb=# -- 获取pid
testdb=# select pg_backend_pid();
pg_backend_pid
----------------
2551
(1 row)
testdb=# -- 插入1行
testdb=# insert into t_insert values(17,'ProcessQuery','ProcessQuery','ProcessQuery');
(挂起)
启动gdb，跟踪调试：
[root@localhost ~]# gdb -p 2551
GNU gdb (GDB) Red Hat Enterprise Linux 7.6.1-100.el7
copyright (C) 2013 Free Software Foundation, Inc.
...
(gdb) b ProcessQuery
Breakpoint 1 at 0x851d19: file pquery.c, line 149.
(gdb) c
Continuing.
Breakpoint 1, ProcessQuery (plan=0x2ccb378, sourceText=0x2c09ef0 "insert into t_insert values(17,'ProcessQuery','ProcessQuery','ProcessQuery');", params=0x0, queryEnv=0x0, dest=0x2ccb4d8,
completionTag=0x7ffe94ba4940 "") at pquery.c:149
149 queryDesc = createqueryDesc(plan, sourceText,
#查看参数
#1、plan
(gdb) p *plan
$1 = {type = T_PlannedStmt, commandType = CMD_INSERT, queryId = 0, hasReturning = false, hasModifyingCTE = false, canSetTag = true, transientPlan = false, dependsOnRole = false,
parallelModeNeeded = false, jitFlags = 0, planTree = 0x2ccafe8, rtable = 0x2ccb2a8, resultRelations = 0x2ccb348, nonleafResultRelations = 0x0, rootResultRelations = 0x0, subplans = 0x0,
rewindplanIDs = 0x0, rowMarks = 0x0, relationOids = 0x2ccb2f8, invalItems = 0x0, paramExecTypes = 0x2c31370, utilityStmt = 0x0, stmt_location = 0, stmt_len = 76}
(gdb) p *(plan->planTree)
#执行树，左右均无兄弟节点
$2 = {type = T_ModifyTable, startup_cost = 0, total_cost = 0.01, plan_rows = 1, plan_width = 298, parallel_aware = false, parallel_safe = false, plan_node_id = 0, targetlist = 0x0, qual = 0x0,
lefttree = 0x0, righttree = 0x0, initPlan = 0x0, extParam = 0x0, allParam = 0x0}
(gdb) p *(plan->rtable)
$3 = {type = T_List, length = 1, head = 0x2ccb288, tail = 0x2ccb288}
(gdb) p *(plan->rtable->head)
#Oid=46969208，可使用pg_class查询
$4 = {data = {ptr_value = 0x2ccb178, int_value = 46969208, oid_value = 46969208}, next = 0x0}
(gdb) p *(plan->resultRelations)
$5 = {type = T_IntList, length = 1, head = 0x2ccb328, tail = 0x2ccb328}
(gdb) p *(plan->resultRelations->head)
#Oid=1？，可使用pg_class查询
$6 = {data = {ptr_value = 0x1, int_value = 1, oid_value = 1}, next = 0x0}
(gdb) p *(plan->relationOids)
$7 = {type = T_OidList, length = 1, head = 0x2ccb2d8, tail = 0x2ccb2d8}
(gdb) p *(plan->relationOids->head)
#Oid=26731，可使用pg_class查询
$8 = {data = {ptr_value = 0x686b, int_value = 26731, oid_value = 26731}, next = 0x0}
#2、sourceText
(gdb) p sourceText
$11 = 0x2c09ef0 "insert into t_insert values(17,'ProcessQuery','ProcessQuery','ProcessQuery');"
#3、params
(gdb) p params
#NULL
$12 = (ParamListInfo) 0x0
#4、queryEnv
(gdb) p queryEnv
#NULL
$13 = (QueryEnvironment *) 0x0
#5、dest
(gdb) p dest
$14 = (DestReceiver *) 0x2ccb4d8
(gdb) p *dest
$15 = {receiveSlot = 0x4857ad <printtup>, rStartup = 0x485196 <printtup_startup>, rShutdown = 0x485bad <printtup_shutdown>, rDestroy = 0x485c21 <printtup_destroy>, mydest = DestRemote}
(gdb)
#6、completionTag
(gdb) p completionTag
#空字符串
$16 = 0x7ffe94ba4940 ""
(gdb) next
156 ExecutorStart(queryDesc, 0);
(gdb)
161 ExecutorRun(queryDesc, ForwardScanDirection, 0L, true);
(gdb)
166 if (completionTag)
(gdb)
170 switch (queryDesc->operation)
(gdb)
178 if (queryDesc->estate->es_processed == 1)
(gdb)
179 lastOid = queryDesc->estate->es_lastoid;
(gdb) p queryDesc->estate->es_lastoid
$18 = 0
(gdb)
$19 = 0
(gdb) next
184 lastOid, queryDesc->estate->es_processed);
(gdb) p lastOid
$20 = 0
(gdb) next
182 snprintf(completionTag, COMPLETION_TAG_BUFSIZE,
(gdb)
185 break;
(gdb) p completionTag
#返回标记，在psql中输出的信息
$21 = 0x7ffe94ba4940 "INSERT 0 1"
(gdb)
$22 = 0x7ffe94ba4940 "INSERT 0 1"
(gdb) next
205 ExecutorFinish(queryDesc);
(gdb)
206 ExecutorEnd(queryDesc);
(gdb)
208 FreeQueryDesc(queryDesc);
(gdb)
209 }
(gdb)
PortalRunMulti (portal=0x2c6f490, isTopLevel=true, setHoldSnapshot=false, dest=0x2ccb4d8, altdest=0x2ccb4d8, completionTag=0x7ffe94ba4940 "INSERT 0 1") at pquery.c:1302
1302 if (log_executor_stats)
(gdb)
#DONE！
为了更深入理解整个执行过程中最重要的两个数据结构PlanState和EState，对子函数InitPlan和CreateExecutorState作进一步的跟踪分析：
InitPlan
testdb=# -- 插入1行
testdb=# insert into t_insert values(18,'ProcessQuery.InitPlan','ProcessQuery.InitPlan','ProcessQuery.InitPlan');
（挂起）
(gdb) b InitPlan
Breakpoint 1 at 0x691560: file execMain.c, line 811.
#查看参数
#1、queryDesc
(gdb) p *queryDesc
$8 = {operation = CMD_INSERT, plannedstmt = 0x2ccb408, sourceText = 0x2c09ef0 "insert into t_insert values(18,'ProcessQuery.InitPlan','ProcessQuery.InitPlan','ProcessQuery.InitPlan');",
snapshot = 0x2c2d920, crosscheck_snapshot = 0x0, dest = 0x2ccb568, params = 0x0, queryEnv = 0x0, instrument_options = 0, tupDesc = 0x0, estate = 0x2cbcc70, planstate = 0x0, already_executed = false,
totaltime = 0x0}
#2、eflags
(gdb) p eflags
$9 = 0
(gdb) next
812 PlannedStmt *plannedstmt = queryDesc->plannedstmt;
(gdb)
813 Plan *plan = plannedstmt->planTree;
(gdb)
814 List *rangeTable = plannedstmt->rtable;
(gdb) p *(queryDesc->plannedstmt)
$10 = {type = T_PlannedStmt, commandType = CMD_INSERT, queryId = 0, hasReturning = false, hasModifyingCTE = false, canSetTag = true, transientPlan = false, dependsOnRole = false,
parallelModeNeeded = false, jitFlags = 0, planTree = 0x2ccb078, rtable = 0x2ccb338, resultRelations = 0x2ccb3d8, nonleafResultRelations = 0x0, rootResultRelations = 0x0, subplans = 0x0,
rewindplanIDs = 0x0, rowMarks = 0x0, relationOids = 0x2ccb388, invalItems = 0x0, paramExecTypes = 0x2c313f8, utilityStmt = 0x0, stmt_location = 0, stmt_len = 103}
(gdb) next
815 EState *estate = queryDesc->estate;
(gdb)
824 ExecCheckRTPerms(rangeTable, true);
(gdb)
829 estate->es_range_table = rangeTable;
(gdb)
830 estate->es_plannedstmt = plannedstmt;
(gdb) p *rangeTable
$11 = {type = T_List, length = 1, head = 0x2ccb318, tail = 0x2ccb318}
(gdb) p *(rangeTable->head)
$12 = {data = {ptr_value = 0x2ccb208, int_value = 46969352, oid_value = 46969352}, next = 0x0}
(gdb) next
838 if (plannedstmt->resultRelations)
(gdb)
840 List *resultRelations = plannedstmt->resultRelations;
(gdb)
841 int numResultRelations = list_length(resultRelations);
(gdb)
846 palloc(numResultRelations * sizeof(ResultRelInfo));
(gdb) p numResultRelations
$13 = 1
(gdb) p *(resultRelations->head)
$14 = {data = {ptr_value = 0x1, int_value = 1, oid_value = 1}, next = 0x0}
(gdb)
(gdb) next
845 resultRelInfos = (ResultRelInfo *)
(gdb)
847 resultRelInfo = resultRelInfos;
(gdb)
848 foreach(l, resultRelations)
(gdb)
850 Index resultRelationIndex = lfirst_int(l);
(gdb)
854 resultRelationOid = getrelid(resultRelationIndex, rangeTable);
(gdb)
855 resultRelation = heap_open(resultRelationOid, RowExclusiveLock);
(gdb)
857 InitResultRelInfo(resultRelInfo,
(gdb) p resultRelationOid
$15 = 26731
(gdb) p resultRelation
$16 = (Relation) 0x7f3a64247b78
#目标Relation，t_insert
(gdb) p *resultRelation
$17 = {rd_node = {spcNode = 1663, dbnode = 16477, relNode = 26747}, rd_smgr = 0x2c99328, rd_refcnt = 1, rd_backend = -1, rd_islocaltemp = false, rd_isnailed = false, rd_isvalid = true,
rd_indexvalid = 1 '\001', rd_statvalid = true, rd_createSubid = 0, rd_newRelfilenodeSubid = 0, rd_rel = 0x7f3a64247d88, rd_att = 0x7f3a64247e98, rd_id = 26731, rd_lockInfo = {lockRelId = {
relId = 26731, dbId = 16477}}, rd_rules = 0x0, rd_rulescxt = 0x0, trigdesc = 0x0, rd_rsdesc = 0x0, rd_fkeylist = 0x0, rd_fkeyvalid = false, rd_partkeycxt = 0x0, rd_partkey = 0x0, rd_pdcxt = 0x0,
rd_partdesc = 0x0, rd_partcheck = 0x0, rd_indexlist = 0x7f3a64249cf0, rd_oidindex = 0, rd_pkindex = 26737, rd_replidindex = 26737, rd_statlist = 0x0, rd_indexattr = 0x0, rd_projindexattr = 0x0,
rd_keyattr = 0x0, rd_pkattr = 0x0, rd_idattr = 0x0, rd_projidx = 0x0, rd_pubactions = 0x0, rd_options = 0x0, rd_index = 0x0, rd_indextuple = 0x0, rd_amhandler = 0, rd_indexcxt = 0x0,
rd_amroutine = 0x0, rd_opfamily = 0x0, rd_opcintype = 0x0, rd_support = 0x0, rd_supportinfo = 0x0, rd_indoption = 0x0, rd_indexprs = 0x0, rd_indpred = 0x0, rd_exclops = 0x0, rd_exclprocs = 0x0,
rd_exclstrats = 0x0, rd_amcache = 0x0, rd_indcollation = 0x0, rd_fdwroutine = 0x0, rd_toastoid = 0, pgstat_info = 0x2c8ae98}
(gdb)
gdb) next
848 foreach(l, resultRelations)
(gdb)
864 estate->es_result_relations = resultRelInfos;
(gdb)
865 estate->es_num_result_relations = numResultRelations;
(gdb)
867 estate->es_result_relation_info = NULL;
(gdb)
874 estate->es_root_result_relations = NULL;
(gdb)
875 estate->es_num_root_result_relations = 0;
(gdb)
876 if (plannedstmt->nonleafResultRelations)
(gdb) p *plannedstmt->nonleafResultRelations
Cannot access memory at address 0x0
(gdb) next
941 estate->es_rowMarks = NIL;
942 foreach(l, plannedstmt->rowMarks)
(gdb) p plannedstmt->rowMarks
$19 = (List *) 0x0
(gdb) next
1003 estate->es_tupleTable = NIL;
(gdb)
1004 estate->es_trig_tuple_slot = NULL;
(gdb)
1005 estate->es_trig_oldtup_slot = NULL;
(gdb)
1006 estate->es_trig_newtup_slot = NULL;
(gdb)
1009 estate->es_epqTuple = NULL;
(gdb)
1010 estate->es_epqTupleSet = NULL;
(gdb)
1011 estate->es_epqScanDone = NULL;
(gdb)
1019 i = 1; /* subplan indices count from 1 */
(gdb)
1020 foreach(l, plannedstmt->subplans)
(gdb) p *plannedstmt->subplans
Cannot access memory at address 0x0
(gdb) next
1049 planstate = ExecInitNode(plan, estate, eflags);
(gdb) step
ExecInitNode (node=0x2ccb078, estate=0x2cbcc70, eflags=0) at execProcnode.c:148
148 if (node == NULL)
(gdb) next
156 check_stack_depth();
(gdb)
158 switch (nodeTag(node))
(gdb)
174 result = (PlanState *) ExecInitModifyTable((ModifyTable *) node,
(gdb) step
ExecInitModifyTable (node=0x2ccb078, estate=0x2cbcc70, eflags=0) at nodeModifyTable.c:2179
2179 CmdType operation = node->operation;
(gdb) next
2180 int nplans = list_length(node->plans);
(gdb)
2187 bool update_tuple_routing_needed = node->partColsUpdated;
(gdb) p node->plans
$20 = (List *) 0x2c317c8
(gdb) p *(node->plans)
$21 = {type = T_List, length = 1, head = 0x2ccb058, tail = 0x2ccb058}
(gdb) p *(node->plans->head)
$22 = {data = {ptr_value = 0x2c315b8, int_value = 46339512, oid_value = 46339512}, next = 0x0}
(gdb) next
2195 mtstate = makeNode(ModifyTableState);
(gdb)
2196 mtstate->ps.plan = (Plan *) node;
(gdb) p *mtstate
$23 = {ps = {type = T_ModifyTableState, plan = 0x0, state = 0x0, ExecProcNode = 0x0, ExecProcNodeReal = 0x0, instrument = 0x0, worker_instrument = 0x0, qual = 0x0, lefttree = 0x0, righttree = 0x0,
initPlan = 0x0, subPlan = 0x0, chgParam = 0x0, ps_ResultTupleSlot = 0x0, ps_ExprContext = 0x0, ps_ProjInfo = 0x0, scandesc = 0x0}, operation = CMD_UNKNowN, canSetTag = false, mt_done = false,
mt_plans = 0x0, mt_nplans = 0, mt_whichplan = 0, resultRelInfo = 0x0, rootResultRelInfo = 0x0, mt_arowmarks = 0x0, mt_epqstate = {estate = 0x0, planstate = 0x0, origslot = 0x0, plan = 0x0,
arowMarks = 0x0, epqParam = 0}, fireBSTriggers = false, mt_existing = 0x0, mt_excludedtlist = 0x0, mt_conflproj = 0x0, mt_partition_tuple_routing = 0x0, mt_transition_capture = 0x0,
mt_oc_transition_capture = 0x0, mt_per_subplan_tupconv_maps = 0x0}
(gdb) next
2197 mtstate->ps.state = estate;
(gdb)
2198 mtstate->ps.ExecProcNode = ExecModifyTable;
(gdb)
2200 mtstate->operation = operation;
(gdb)
2201 mtstate->canSetTag = node->canSetTag;
(gdb)
2202 mtstate->mt_done = false;
(gdb)
2204 mtstate->mt_plans = (PlanState **) palloc0(sizeof(PlanState *) * nplans);
(gdb)
2205 mtstate->resultRelInfo = estate->es_result_relations + node->resultRelIndex;
(gdb)
2208 if (node->rootResultRelIndex >= 0)
(gdb)
2212 mtstate->mt_arowmarks = (List **) palloc0(sizeof(List *) * nplans);
(gdb)
2213 mtstate->mt_nplans = nplans;
(gdb)
2216 EvalPlanQualInit(&mtstate->mt_epqstate, estate, NULL, NIL, node->epqParam);
(gdb)
2217 mtstate->fireBSTriggers = true;
(gdb)
2227 saved_resultRelInfo = estate->es_result_relation_info;
(gdb) p *(mtstate->mt_epqstate)
Structure has no component named operator*.
(gdb) p mtstate->mt_epqstate
$24 = {estate = 0x0, planstate = 0x0, origslot = 0x0, plan = 0x0, arowMarks = 0x0, epqParam = 0}
(gdb) next
2229 resultRelInfo = mtstate->resultRelInfo;
(gdb)
2230 i = 0;
(gdb)
2231 foreach(l, node->plans)
(gdb)
2233 subplan = (Plan *) lfirst(l);
(gdb)
2237 node->fdwDirectModifyPlans);
(gdb)
2236 resultRelInfo->ri_usesFdwDirectModify = bms_is_member(i,
(gdb)
2242 CheckValidResultRel(resultRelInfo, operation);
(gdb)
2253 if (resultRelInfo->ri_RelationDesc->rd_rel->relhasindex &&
(gdb)
2255 resultRelInfo->ri_IndexRelationDescs == NULL)
(gdb)
2254 operation != CMD_DELETE &&
(gdb)
2257 node->onConflictAction != ONCONFLICT_NONE);
(gdb)
2256 ExecopenIndices(resultRelInfo,
(gdb)
2264 if (resultRelInfo->ri_TrigDesc &&
(gdb)
2270 estate->es_result_relation_info = resultRelInfo;
(gdb)
2271 mtstate->mt_plans[i] = ExecInitNode(subplan, estate, eflags);
(gdb) finish
Run till exit from #0 ExecInitModifyTable (node=0x2ccb078, estate=0x2cbcc70, eflags=0) at nodeModifyTable.c:2294
0x000000000069a21a in ExecInitNode (node=0x2ccb078, estate=0x2cbcc70, eflags=0) at execProcnode.c:174
174 result = (PlanState *) ExecInitModifyTable((ModifyTable *) node,
Value returned is $25 = (ModifyTableState *) 0x2cbcfc0
(gdb) next
176 break;
(gdb)
373 ExecSetExecProcNode(result, result->ExecProcNode);
(gdb) p result->ExecProcNode
$26 = (ExecProcNodeMtd) 0x6c2485 <ExecModifyTable>
(gdb) finish
Run till exit from #0 ExecInitNode (node=0x2ccb078, estate=0x2cbcc70, eflags=0) at execProcnode.c:392
0x0000000000691c2f in InitPlan (queryDesc=0x2cc1580, eflags=0) at execMain.c:1049
1049 planstate = ExecInitNode(plan, estate, eflags);
Value returned is $27 = (PlanState *) 0x2cbcfc0
(gdb) next
1054 tupType = ExecGetResultType(planstate);
(gdb)
1060 if (operation == CMD_SELECT)
(gdb) p tupType
$28 = (TupleDesc) 0x2cbdd40
(gdb) p *tupType
$29 = {natts = 0, tdtypeid = 2249, tdtypmod = -1, tdhasoid = false, tdrefcount = -1, constr = 0x0, attrs = 0x2cbdd60}
(gdb) next
1090 queryDesc->tupDesc = tupType;
(gdb)
1091 queryDesc->planstate = planstate;
(gdb)
1092 }
(gdb)
standard_ExecutorStart (queryDesc=0x2cc1580, eflags=0) at execMain.c:266
266 MemoryContextSwitchTo(oldcontext);
(gdb)
#DONE!
CreateExecutorState
#gdb
(gdb) b CreateExecutorState
Breakpoint 1 at 0x69f2c5: file execUtils.c, line 89.
#psql
testdb=# -- 插入1行
testdb=# insert into t_insert values(19,'ProcessQuery.CreateExecutorState','ProcessQuery.CreateExecutorState','ProcessQuery.CreateExecutorState');
（挂起）
#gdb
(gdb) c
Continuing.
Breakpoint 1, CreateExecutorState () at execUtils.c:89
89 qcontext = AllocSetContextCreate(CurrentMemoryContext,
#查看输入参数
#该函数无输入参数
(gdb) step #进入AllocSetContextCreate函数内部
AllocSetContextCreateExtended (parent=0x2c09de0, name=0xb1a840 "ExecutorState", minContextSize=0, initBlockSize=8192, maxBlockSize=8388608) at aset.c:426
426 if (minContextSize == ALLOCSET_DEFAULT_MINSIZE &&
(gdb) next
428 freeListIndex = 0;
#查看AllocSetContextCreate的输入参数
#1、parent
(gdb) p *parent
$3 = {type = T_AllocSetContext, isReset = false, allowInCritSection = false, methods = 0xb8c720 <AllocSetMethods>, parent = 0x2c04ba0, firstchild = 0x0, prevchild = 0x2c7fc60, nextchild = 0x2cb6b30,
name = 0xb4e87c "MessageContext", ident = 0x0, reset_cbs = 0x0}
#顶层Context
(gdb) p *(parent->parent)
$4 = {type = T_AllocSetContext, isReset = false, allowInCritSection = false, methods = 0xb8c720 <AllocSetMethods>, parent = 0x0, firstchild = 0x2c2d7e0, prevchild = 0x0, nextchild = 0x0,
name = 0xb8d050 "TopMemoryContext", ident = 0x0, reset_cbs = 0x0}
#2、name
(gdb) p name
$5 = 0xb1a840 "ExecutorState"
#3、minContextSize
(gdb) p minContextSize
$6 = 0
#4、initBlockSize
(gdb) p initBlockSize
$7 = 8192 #8KB
#5、maxBlockSize
(gdb) p maxBlockSize
$8 = 8388608 #8MB
(gdb) next
440 AllocSetFreeList *freelist = &context_freelists[freeListIndex];
(gdb) p freeListIndex
$9 = 0
(gdb)
$10 = 0
(gdb) next
442 if (freelist->first_free != NULL)
(gdb) p *freelist
$11 = {num_free = 4, first_free = 0x2cbcb60}
(gdb) p *(freelist->first_free)
$12 = {header = {type = T_AllocSetContext, isReset = true, allowInCritSection = false, methods = 0xb8c720 <AllocSetMethods>, parent = 0x0, firstchild = 0x0, prevchild = 0x0, nextchild = 0x2cbeb70,
name = 0xb1a840 "ExecutorState", ident = 0x0, reset_cbs = 0x0}, blocks = 0x2cbcc38, freelist = {0x0 <repeats 11 times>}, initBlockSize = 8192, maxBlockSize = 8388608, nextBlockSize = 8192,
allocChunkLimit = 8192, keeper = 0x2cbcc38, freeListIndex = 0}
(gdb) next
445 set = freelist->first_free;
(gdb)
446 freelist->first_free = (AllocSet) set->header.nextchild;
(gdb)
447 freelist->num_free--;
(gdb)
450 set->maxBlockSize = maxBlockSize;
(gdb)
453 MemoryContextCreate((MemoryContext) set,
(gdb)
459 return (MemoryContext) set;
(gdb) p *set
$13 = {header = {type = T_AllocSetContext, isReset = true, allowInCritSection = false, methods = 0xb8c720 <AllocSetMethods>, parent = 0x2c09de0, firstchild = 0x0, prevchild = 0x0, nextchild = 0x0,
name = 0xb1a840 "ExecutorState", ident = 0x0, reset_cbs = 0x0}, blocks = 0x2cbcc38, freelist = {0x0 <repeats 11 times>}, initBlockSize = 8192, maxBlockSize = 8388608, nextBlockSize = 8192,
allocChunkLimit = 8192, keeper = 0x2cbcc38, freeListIndex = 0}
(gdb) next
548 }
(gdb)
CreateExecutorState () at execUtils.c:97
97 oldcontext = MemoryContextSwitchTo(qcontext);
(gdb)
99 estate = makeNode(EState);
(gdb)
104 estate->es_direction = ForwardScanDirection;
(gdb) finish
Run till exit from #0 CreateExecutorState () at execUtils.c:104
0x000000000078cc2f in evaluate_expr (expr=0x2c30520, result_type=1043, result_typmod=44, result_collation=100) at clauses.c:4858
4858 estate = CreateExecutorState();
Value returned is $14 = (EState *) 0x2cbcc70
四、小结
1、Todo：更进一步的理解，在执行查询语句时再进一步解读；
2、EState&PlanState数据结构：在此函数中构造，需进一步理解；
3、List数据结构：PG广泛的使用List这样的数据结构对各种信息进行管理。
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