查询计划的入口函数是pg_plan_queries,调用关系如下: exec_simple_query ->pg_plan_queries ->pg_plan_query ->planner ->standard_planner ->subquery_planner // 预处理 ->preprocess_xxx ->pull_up_sublinks ->pull_up_subqueries // 生成计划树 ->grouping_planner ->query_planner ->SS_finalize_plan ...
(4rows)Time:0.873ms--6.但是在执行checkpint的时候就会失败postgres=# checkpoint; 错误: 检查点请求失败 HINT: 详细信息请参考服务器日志.Time:301.294ms--7.这个时候查询仍然可以走索引postgres=# explain analyzeselect*fromtestwheren_bh=1; QUERY PLAN---Index Scanusingtest_pkeyontest (cost=0.28..8.30ro...
( ) * 1 ) :: INT :: TEXT, 1, '0' ); QUERY PLAN --- Insert on t_user (cost=0.00..925000.03 rows=0 width=0) (actual time=53327.150..53327.162 rows=0 loops=1) -> Subquery Scan on "*SELECT*" (cost=0.00..925000.03 rows=10000000 width=1194) (actual time=0.067....
innerPlanState(hjstate)= ExecInitNode((Plan *) hashNode, estate, eflags);...returnhjstate; } 可以看到其实 outerNode = outerPlan(node) 就是: outerNode = (((Plan *)(node))->lefttree) hashNode = (Hash *) innerPlan(node) 就是:hashNode = (((Plan *)(node))->righttree) outerPlanSt...
The output shows a performance report for the rangequery statement with parameter bindings of 1 and 10,000. The new unapproved plan (Baseline+1) is better than the best previously approved plan (Baseline). To confirm that the new plan is now Approved, check the apg_plan_mgmt.dba_plans ...
postgres=# set pg_strom.enabled=on; SET postgres=# set max_parallel_workers_per_gather =0; SET postgres=# explain (analyze,verbose,timing,costs,buffers) select count(*) from test2; QUERY PLAN --- Aggregate (cost=1234571.56..1234571.57 rows=1 width=8) (actual time=19079.585..19079.585 rows...
CREATE [ OR REPLACE ] VIEW name [ ( column_name [, ...] ) ] AS queryDEALLOCATE删除一个准备好的查询。DEALLOCATE [ PREPARE ] plan_nameDECLARE定义一个游标。DECLARE name [ BINARY ] [ INSENSITIVE ] [ [ NO ] SCROLL ] CURSOR [ { WITH | WITHOUT } HOLD ] FOR query [ FOR { READ ONLY...
* query levels will make available to this query level. */List *plan_params;/* list of PlannerParamItems, see below */Bitmapset *outer_params;/* * simple_rel_array holds pointers to "base rels" and "other rels" (see * comments for RelOptInfo for more info). It is indexed by ran...
QE(Query Executor、查询执行器):Segment 上负责执行 QD 分发来的查询任务的进程称为 QE。Segment 实例运行的也是一个 PostgreSQL,所以对于 QE 而言,QD 是一个 PostgreSQL 的客户端,它们之间通过 PostgreSQL 标准的 libpq 协议进行通讯。对于 QD 而言,QE 是负责执行其查询请求的 PostgreSQL Backend 进程。通常 QE ...
为使SQL Hint生效,需要确保pg_hint_plan插件已经被添加到GUC参数shared_preload_libraries中。 在查询前添加/*+ PX() */表示对该查询使用ePQ: => /*+ PX() */ EXPLAIN SELECT * FROM t1; QUERY PLAN --- PX Coordinator 6:1 (slice1; segments: 6) (cost=0.00..431.03 rows=1000 width=8) -> P...