The query is running inside of another query that is already parallel. For example, if a function called by a parallel query issues an SQL query itself, that query will never use a parallel plan. This is a limitation of the current implementation, but it may not be desirable to remove th...
The first suspicion would be that the pool ofmax_parallel_workerswas exhausted. But no other queries are running on this server! Time to dig deeper. Limitations for parallel query The PostgreSQL documentation has achapter on the limitations of parallel query. For example, most data modifying stat...
让我们看一下通过小写值搜索列的查询计划: EXPLAIN (ANALYZE, BUFFERS)SELECT * FROM users WHERE lower(email) = 'email@example.com' ;-> Parallel Seq Scan on users Filter: (lower((email)::text) = 'email@example.com'::text) Rows Removed by Filter: 333667 Buffers: shared hit=1248 read=41725...
create index pgbench_accounts_bid_key on pgbench_accounts_bak(bid); youge=# set parallel_setup_cost=1; SET youge=# set parallel_tuple_cost=0.001; SET youge=# explain select * from pgbench_accounts_bak a join pgbench_branches_bak b on a.bid=b.bid ; QUERY PLAN --- Gather (cost=262...
-> Parallel Seq Scan on users Filter: ((email)::text ~~ '%@example.com'::text) Execution Time: 111.263 ms 和以前一样,查询计划器无法利用索引,不得不求助于低效Seq ScanFilter. 为了加快这个查询的速度,我们必须添加一个自定义扩展和索引类型。运行以下命令: 代码语言:javascript 代码运行次数:0 运行...
Query example: SELECT * FROM products WHERE to_tsvector('english', description) @@ to_tsquery('analytics'); Partial Index Example: CREATE INDEX idx_active_customers ON customers(customer_status) WHERE customer_status = 'active'; 2. Partitioning for Managing Large Datasets ...
可以是具体的 IP 地址,如 192.168.1.100;all 或 0.0.0.0 表示任何 IP 地址;::1 表示 IPv6 的本地环回地址;localhost 表示通过主机名解析的本地连接;% 表示通配符,匹配任何地址;.example.com 表示以 .example.com 结尾的任何主机名。 5、METHOD: 指定用于身份验证的方法。可能的值包括: trust: 不需要任何...
* In a parallel query, the leader process may or may not have run the * hash join, and even if it did it may not have built a hash table due to * timing (if it started late it might have seen no tuples in the outer * relation and skipped building the hash table). Therefore ...
700..86.880 rows=1 loops=1) Workers Planned: 2 Workers Launched: 2 -> Parallel Bitmap Heap Scan on example (cost=16.26..806981.82 rows=1 width=4) (actual time=56.477..80.759 rows=0 loops=3) Recheck Cond: (id = 492167) Rows Removed by Index Recheck: 77141 Heap Blocks: lossy=...
2 调试plpgsql存储过程,输出每一次调用的QUERY详细执行计划 3 调试plpgsql函数 四、SQL 函数 五、触发器 1 触发器函数 2 事件触发器函数 六、类型转换 第五章:函数、存储过程和触发器 https://www.postgresql.org/docs/9.6/static/functions.html 运算符与函数 ...