sql - Postgres : find all integer columns with its current max value in it

Question

如何从 Postgres 实例中所有数据库的所有表中找到所有整数类型的主键列及其当前最大值？

我想从所有接近溢出其最大值 2147483647 的表中找到所有 int 类型的主键列。

Answer 1

CREATE OR REPLACE FUNCTION intpkmax() RETURNS
   TABLE(schema_name name, table_name name, column_name name, max_value integer)
   LANGUAGE plpgsql STABLE AS
$$BEGIN
   /* loop through tables with a simgle integer column as primary key */
   FOR schema_name, table_name, column_name IN
      SELECT sch.nspname, tab.relname, col.attname
         FROM pg_class tab
            JOIN pg_constraint con ON con.conrelid = tab.oid
            JOIN pg_attribute col ON col.attrelid = tab.oid
            JOIN pg_namespace sch ON sch.oid = tab.relnamespace
         WHERE con.contype = 'p'
            AND array_length(con.conkey, 1) = 1
            AND col.atttypid = 'integer'::regtype
            AND NOT col.attisdropped
   LOOP
      /* get the maximum value of the primary key column */
      EXECUTE 'SELECT max(' || quote_ident(column_name) ||
              ') FROM ' || quote_ident(schema_name) ||
              '.' || quote_ident(table_name) || ''
         INTO max_value;
      /* return the next result */
      RETURN NEXT;
   END LOOP;
END;$$;

然后你可以得到一个列表

SELECT * FROM intpkmax();