在Postgres 9.0+中使用PL/pgSQL在表上循环 [英] Loop on tables with PL/pgSQL in Postgres 9.0+

问题描述

我想遍历所有表以对每个表中的行进行计数.以下查询给我一个错误:

I want to loop through all my tables to count rows in each of them. The following query gets me an error:

DO $$
DECLARE
    tables CURSOR FOR
        SELECT tablename FROM pg_tables
        WHERE tablename NOT LIKE 'pg_%'
        ORDER BY tablename;
    tablename varchar(100);
    nbRow int;
BEGIN
    FOR tablename IN tables LOOP
        EXECUTE 'SELECT count(*) FROM ' || tablename INTO nbRow;
        -- Do something with nbRow
    END LOOP;
END$$;

错误:

ERROR:  syntax error at or near ")"
LINE 1: SELECT count(*) FROM (sql_features)
                                          ^
QUERY:  SELECT count(*) FROM (sql_features)
CONTEXT:  PL/pgSQL function inline_code_block line 8 at EXECUTE statement

sql_features是数据库中表的名称.我已经尝试使用quote_ident()，但无济于事.

sql_features is a table's name in my DB. I already tried to use quote_ident() but to no avail.

推荐答案

游标返回记录，而不是标量值，因此"tablename"不是字符串变量.

The cursor returns a record, not a scalar value, so "tablename" is not a string variable.

串联将记录转换成类似于(sql_features)的字符串.如果您选择了如果使用具有表名的模式名，则该记录的文本表示形式为(public,sql_features).

The concatenation turns the record into a string that looks like this (sql_features). If you had selected e.g. the schemaname with the tablename, the text representation of the record would have been (public,sql_features).

因此，您需要访问记录内的列以创建您的SQL语句:

So you need to access the column inside the record to create your SQL statement:

DO $$
DECLARE
    tables CURSOR FOR
        SELECT tablename
        FROM pg_tables
        WHERE tablename NOT LIKE 'pg_%'
        ORDER BY tablename;
    nbRow int;
BEGIN
    FOR table_record IN tables LOOP
        EXECUTE 'SELECT count(*) FROM ' || table_record.tablename INTO nbRow;
        -- Do something with nbRow
    END LOOP;
END$$;

您可能要使用WHERE schemaname = 'public'而不是not like 'pg_%'来排除Postgres系统表.

You might want to use WHERE schemaname = 'public' instead of not like 'pg_%' to exclude the Postgres system tables.

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