在执行大计数时,这两个sql count语句之间的性能差异是否很大(在这里,大意味着100k以上的记录)SELECT count(*) FROM table1 WHERE <some very complex conditions>SELECT count(*) FROM (SELECT * FROM table1 WHERE <some very complex conditions>) subquery_alias
我想知道为什么分区剪枝不适用于横向连接和聚合。下面是我在PostgreSQL 12.1 (Ubuntu12.1-1.pgdg18.04+1)上测试的示例:CREATE TABLE demo_key_1 PARTITION OF demo FOR VALUES IN (1);INSERT INTO demo(key) VALUES (1), (2);
ANALYZ