postgresql数据库支持数据库分表,但是有时会遇到,现场的数据库已经在跑了,但是新的需求,需要增加一个字段,
字段增加,分表会自动增加的,但是规则不会实时更新,规则不更新的话,分表新的字段的值就不会更新掉。
其实只需要把所有的规则修改下就可以了,但是有时规则比较多,手动修改还是有点麻烦,所以,就写了一个函数来
做这个功能,这个使用起来还是很快很方便的,这里使用到的就是游标、函数
-------------该函数只需要主表名称和时间字段,即可针对主表字段有增加、修改、删除的情况时,一键修改规则------------------------------ ----------------------------定制项目有时会遇到有分表需要增加字段的情况,但是现场不会重新安装,但是---------------------------------------------------------------- create or replace function cursor_demo ( tabname character varying,timefield character varying ) returns refcursor as $body$ declare sub_tab_name varchar (1000) ; column_name_desc varchar (1000) ; declare fetch_sub_tab_refcursor cursor for select tablename from pg_tables where tablename like tabname || '_%' ; declare fetch_sub_column_refcursor cursor for select column_name from information_schema. columns where table_name = tabname ; declare sql_desc varchar (1000) ; declare value_desc varchar (1000) ; declare all_sql_desc varchar (2000) ; declare st_time varchar (100) ; begin open fetch_sub_tab_refcursor ; loop fetch fetch_sub_tab_refcursor into sub_tab_name ; if found then if ( length (tabname) = (length(sub_tab_name) - 7) ) then if ( tabname = ( substring ( sub_tab_name from 1 for length (tabname) ) ) ) then st_time := substring ( sub_tab_name from length (tabname) + 2 for length (sub_tab_name) ) ; st_time := substring (st_time from 1 for 4) || '-' || substring (st_time from 5 for 6) ; sql_desc := 'create or replace rule insert_' || sub_tab_name || ' as on insert to ' || tabname || ' where new.' || timefield || ' >= ''' || substring ( to_char( to_timestamp(st_time,'yyyy-mm-dd'),'yyyy-mm-dd' ) from 1 for 10 ) || '''::date and new.' || timefield || ' <''' || substring ( to_char( to_timestamp(st_time,'yyyy-mm-dd') + interval '1 month','yyyy-mm-dd' ) from 1 for 10 ) || '''::date do instead insert into ' || sub_tab_name || '(' ; value_desc := 'values (' ; open fetch_sub_column_refcursor ; loop fetch fetch_sub_column_refcursor into column_name_desc ; if found then sql_desc := sql_desc || column_name_desc || ',' ; value_desc := value_desc || 'new.' || column_name_desc || ',' ; else exit ; end if ; end loop ; sql_desc := substring ( sql_desc from 1 for length (sql_desc) - 1 ) || ')' ; value_desc := substring ( value_desc from 1 for length (value_desc) - 1 ) || ');' ; all_sql_desc := sql_desc || value_desc ; execute all_sql_desc ; close fetch_sub_column_refcursor ; else end if ; else end if ; else exit ; end if ; end loop ; close fetch_sub_tab_refcursor ; return fetch_sub_tab_refcursor ; exception when others then raise exception 'error--(%)',sqlerrm ; end ; $body$ language plpgsql; --------调用方式----有两个参数,第一个是主表名,第二个是根据哪个字段进行分表------ begin ; select cursor_demo ( 'your_table_name','your_field' ); commit;
原文地址:https://www.jb51.cc/postgresql/193475.html
版权声明:本文内容由互联网用户自发贡献,该文观点与技术仅代表作者本人。本站仅提供信息存储空间服务,不拥有所有权,不承担相关法律责任。如发现本站有涉嫌侵权/违法违规的内容, 请发送邮件至 dio@foxmail.com 举报,一经查实,本站将立刻删除。