租户端 数据库 TDSQL PostgreSQL 版 开发指南 执行计划分类 并行扫描

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最近更新时间: 2025-02-18 16:02:00

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postgres=# set max_parallel_workers_per_gather to 2;
postgres=# explain select count(1) from t1;
                                            QUERY PLAN                                            
--------------------------------------------------------------------------------------------------
 Parallel Finalize Aggregate  (cost=9387.28..9387.29 rows=1 width=8)
   ->  Parallel Remote Subquery Scan on all (dn001,dn002)  (cost=9387.17..9387.28 rows=1 width=0)
         ->  Gather  (cost=9287.17..9287.28 rows=1 width=8)
               Workers Planned: 2
               ->  Partial Aggregate  (cost=8287.17..8287.18 rows=1 width=8)
                     ->  Parallel Seq Scan on t1  (cost=0.00..7766.33 rows=208333 width=0)
(6 rows)