Rows Removed by Filter: 1146337Planning Time: 6.637 msExecution Time: 41297.038 ms(5 rows)# 顺序扫描产生太多没有聚合的行。因此,查询由一个CPU核执行。Parallel sequential scan· 并行查询tpch=# explain analyze select sum(l_quantity) as sum_qty from lineitem where l_shipdate <= date '1998-12-...
(actual time=0.167..5.289 rows=8555 loops=1)表明了这个节点的真实执行信息。 Filter: (found_time > '2000-02-03'::date) 表明了Seq Scan 节点之上的Filter 操作,即全表扫描时对每行记录进行过滤操作。 Rows Removed by Filter表明过滤操作过滤了多少行记录。 Planning time表明生成查询计划的时间。 Executio...
-> Partial Aggregate (cost=1348771.65..1348771.66 rows=1 width=32) (actual time=31951.809..31951.809 rows=1 loops=5) -> Parallel Seq Scan on lineitem (cost=0.00..1312000.57 rows=14708428 width=5) (actual time=1.491..29217.070 rows=11767943 loop s=5) Filter: (l_shipdate Rows Removed by ...
-> Partial Aggregate (cost=96389.55..96389.56 rows=1 width=8) (actual time=379.597..379.597 rows=1 loops=3) -> Parallel Seq Scan on people (cost=0.00..96382.26 rows=2917 width=0) (actual time=378.831..379.341 rows=3333 loops=3) Filter: (atpgconn2018 = 'Y'::bpchar) Rows Removed by...
Filter: (t.rn = 1) Rows Removed by Filter: 90863 Buffers: shared hit=40000, temp read=37391 written=37391 -> WindowAgg (cost=423098.84..445598.84 rows=1000000 width=300) (actual time=1715.276..3345.392 rows=1000000 loops=1) Output: row_number() OVER (?), tbl_dup.id, tbl_dup.sid,...
Rows Removed by Filter: 9900 Planning Time: 0.127 ms Execution Time: 0.848 ms (5 rows) 从上面可以看出当我们建了相关列上建组合的直方图统计信息后,执行计划中估计的函数与实际一致了。3.5 一些其它功能 hash索引从PostgreSQL 10开始可以放心大胆的使用:PostgreSQL 9.X 版本hash索引走不了流复制,所以基本没有...
Filter: (aid > 10000000) Rows Removed by Filter: 10000000 Planning time: 0.161 ms Execution time: 18394.457 ms (12 rows) 明显两次查询的结果是不一致的,使用索引和不使用索引的结果是不同的. 这已经能证明索引出了问题. 当然可以通过 pg_catcheck 来进行系统的数据的完整性的检查. ...
Filter: (get_bit((t_tags.userids)::"bit", 10000) = 1) Rows Removed by Filter: 180 Buffers: shared hit=15909973 Worker 0: actual time=24.376..5791.799 rows=158 loops=1 Buffers: shared hit=528366 Worker 1: actual time=23.143..6749.264 rows=198 loops=1 ...
(10 rows) Time: 0.620 ms 1. 2. 3. 因为测试表具有 serial 数据类型的 id 字段, 所以对于我们使用排序操作去限制输出前 10, 100, 1000 或者更多记录, 同时random_text 字段没有索引, 将会执行非常大的排序。 开始第一个测试 show work_mem
(SetOpState *) node); break; case T_LockRowsState: result = ExecLockRows((LockRowsState *) node); break; case T_LimitState: result = ExecLimit((LimitState *) node); break; default: elog(ERROR, "unrecognized node type: %d", (int) nodeTag(node)); result = NULL; break; } if (...