postgresql通过explain命令查看查询性能 explain(ANALYZE,VERBOSE,BUFFERS) select c.* from tb_classification c left join tb_operate_log o on c.id=o.object_id where 1=1 and c.parent_code = 'root000000' and o.operate_type >= 0 and o.id in (select max(so.id) from tb_operate_log so gro...
EXPLAIN [ ANALYZE ] [ VERBOSE ] [ COSTS | BUFFERS | FORMAT format_name ] query 1. ANALYZE:执行查询并报告实际运行时间和统计信息。 VERBOSE:显示更详细的查询计划信息。 COSTS:显示查询计划中的成本估算。 BUFFERS:显示查询计划中每个操作的磁盘缓冲区访问统计信息。 FORMAT:指定查询计划的输出格式。 执行EXPL...
explain(ANALYZE,VERBOSE,BUFFERS) select c.* from tb_classification c left join tb_operate_log o on c.id=o.object_id where 1=1 and c.parent_code = ‘root000000’ and o.operate_type >= 0 and o.id in (select max(so.id) from tb_operate_log so group by so.object_code) and o.o...
EXPLAIN有一个BUFFERS选项可以和ANALYZE一起使用来得到更多运行时统计信息,BUFFERS提供的数字帮助我们标识查询的哪些部分是对 I/O 最敏感的。 postgres=# create table user_infopostgres-# (userid int,postgres(# name text,postgres(# birthday date,postgres(# crt_time timestamp without time zonepostgres(# )...
EXPLAIN [ ( option [, ...] ) ] statement EXPLAIN [ ANALYZE ] [ VERBOSE ] statement where option can be one of: ANALYZE [ boolean ] VERBOSE [ boolean ] COSTS [ boolean ] BUFFERS [ boolean ] TIMING [ boolean ] SUMMARY [ boolean ] ...
这个查询实际输出的记录数是7000,但是评估是个近似值,多次运行可能略有差别,这中情况可以通过ANALYZE命令改善。 现在再修改一下条件 Sql代码 EXPLAIN SELECT * FROM tenk1 WHERE unique1 < 100; QUERY PLAN --- Bitmap Heap Scan on tenk1 (cost=5.07..229.20 rows=101 width=244) Recheck Cond: (unique1 ...
EXPLAIN (analyze,buffers,verbose) select max(employee.id), max(employee.id), max(user_profile.name), max(employee.login_name), max(employee.status), max(employee.create_at), max(user_profile.wx_id), array_to_string(group_concat(role.name),',') ...
EXPLAIN [ ANALYZE ] [ VERBOSE ] statement where option can be one of: ANALYZE [ boolean ] VERBOSE [ boolean ] COSTS [ boolean ] SETTINGS [ boolean ] BUFFERS [ boolean ] TIMING [ boolean ] SUMMARY [ boolean ] FORMAT { TEXT | XML | JSON | YAML } ...
排查慢 SQL 首先要分析下 SQL 的执行计划。 PostgreSQL 中通过 EXPLAIN 指令查看执行计划。有关EXPLAIN 指令使用方法参考介绍和指令。其中分析慢 SQL 常用的选项是 ANALYZE/BUFFERS/VERBOSE。PostgreSQL 的执行计划为树状结构,有关执行计划的解读参考PostgreSQL 执行计划解读。
[PostgreSQL] - explain SQL分析介绍 一、图形化在线分析工具 https://explain.dalibo.com/ 二、执行分析语句 代码语言:javascript 复制 EXPLAIN(ANALYZE,COSTS,VERBOSE,BUFFERS,FORMATJSON)select*from... 生成分析JSON之后,填入图形化分析页面,进行分析。