Subquery Scan on t (cost=0.43..770563.03 rows=3333326 width=20) Filter: (t.rn <= 10) -> WindowAgg (cost=0.43..645563.31 rows=9999977 width=12) -> Index Scan using idx1 on tbl (cost=0.43..470563.72 rows=9999977 width=12) (4 rows) 使用窗口查询的结果举例 postgres=# select * from ...
stddev_exec_time | 0.036137014177393116 //执行语句花费的时间的总体标准偏差, rows | 17277 //语句检索或影响的总行数 shared_blks_hit | 394706 //语句的共享块缓存命中总数 shared_blks_read | 7 //语句读取的共享块总数 shared_blks_dirtied | 6 //被语句弄脏的共享块总数 shared_blks_written | 0 //...
stddev_exec_time | 0.036137014177393116 //执行语句花费的时间的总体标准偏差, rows | 17277 //语句检索或影响的总行数 shared_blks_hit | 394706 //语句的共享块缓存命中总数 shared_blks_read | 7 //语句读取的共享块总数 shared_blks_dirtied | 6 //被语句弄脏的共享块总数 shared_blks_written | 0 //...
SQL 优化是数据库优化的手段之一,而为了达到 SQL 优化的最佳效果,您首先需要了解最消耗资源的 SQL(Top SQL),例如 IO 消耗最高的 SQL。 数据库资源分为多个维度,包括CPU、内存、IO 等,为了能够从各个维度层面查找最消耗数据库资源的 SQL,您可以使用 pg_stat_statements 插件统计数据库的资源开销和分析...
To retrieve the top 10 rows, you have to use the “ORDER BY” clause. Using this clause you can order the results in ascending or descending order. For example, to retrieve the top 10 students by highest points, your query would look something like this ...
MATCH(ROW(1:1),$E$4:$E$24,0) this part will match the rows with the rank data and as we have declared 0 as the third argument, it will consider an exact match. Lastly, the INDEX function will figure out the data of the matched cell. You will see the sales for cell I6. Use...
PostgreSQL and MySQL have a cool feature that will let you return an arbitrary range of rows (eg return rows 10-20). This is very handy for displaying pages of records: SELECT column FROM table LIMIT 10 OFFSET 20 The above query will return rows 20-30...
PostgreSQL , gin , 倒排 , rum , gin_fuzzy_search_limit , 随机采样 , 分区索引 , 分段索引 , score分段 背景 任意字段组合查询的几种优化方法: 1、列存 2、RUM 3、GIN 4、多个INDEX的BITMAP AND|OR SCAN 5、BLOOM FILTER 《PostgreSQL 实践 - 广告位推荐 1》采用了RUM的方法,采用rum的目的是避免GIN...
digoal=# alter table test_1 alter column appidSETSTATISTICS100;ALTERTABLEdigoal=# analyze verbose test_1;INFO: analyzing"public.test_1"INFO:"test_1": scanned20619of20619pages, containing2000000live rows and0dead rows;30000rowsinsample,2000000estimated total rowsANALYZEdigoal=# select most_common_va...
而是使用VBA代码来实现。...下面的VBA代码将遍历一系列单元格,并评估最接近的匹配值。...As Range Dim r As Range Dim Mx As Single Dim i As Long Dim target As Integer '要查找的值所在的单元格...target = Range("D10").Value '要查找的区域 Set rng = Range([B10], Range("B" & Rows....