在压力较大的生产环境中, 推荐此方法; 方法8 步骤稍繁, 在实际生产环境中由于table的字段可能较多,且整个table的(包括所有index)都会重建, 所以速度并不占优, 但却顺便把table彻底维护了一下 , 对于udpate, delete非常频繁的table, total size(包括所有index)会大为缩小(由于MVCC), 综合性能会明显提升. 总结 ...
->IndexScanusingt_pkeyont (cost=0.42..8.44rows=1width=10)IndexCond: (id = t1.id) (11rows) 使用with模拟必须有PK或者非空UK,否则需要用行号,但是行号来扫就慢了,没走tid scan方法。 postgres=#witht1as(selectctidfromtwhereidbetween1and100000limit10)deletefromtwherectidin(selectctidfromt1);DELET...
PostgreSQL’s delete performance therefore does not depend on the number of indexes on the table. The physical deletion of the table row and the related index maintenance is carried out only during the VACUUM process. Previous pageNext page...
The use ofctidin this example is PostgreSQL system column which provides a unique identifier for each row. By selectingctidvalues in the subquery, you can limit the number of rows affected in each iteration. This approach is more efficient than usingLIMITdirectly in the main query, as it avoi...
PostgreSQL , Greenplum , trigger , rule , 逻辑更新 , 逻辑删除 , 增量复制 背景 异构数据的增量同步是比较繁琐的事情,需要考虑很多事情,比如: 1、同步延迟 2、DDL的同步 3、同步时对上游性能的影响 4、上下游数据一致性 5、上游事务原子性在目标端是否能保证原子性 ...
index updated UPDATE scale_write_1 SET id2 = r WHERE id1=d1; WHEN 2 THEN -- one index updated UPDATE scale_write_2 SET id2 = r WHERE id1=d1; WHEN 3 THEN -- one index updated UPDATE scale_write_3 SET id3 = r WHERE id1=d1; WHEN 4 THEN -- one index updated UPDATE scale...
这部分包含那些 PostgreSQL 支持的 SQL 命令的信息.这里的 "SQL" 就是该语言通常的含义; 每条命令的与标准有关的兼容性的信息可以在相关的参考页中找到. Table of Contents ABORT -- 退出当前事务 ALTER GROUP -- 向组中增加用户或从组中删除用户
Add months to GETDATE() function in sql server Add new row to datagridview one by one dynamically Add Node existing XML file Add one Column runtime to datagrid view at specific index in C# Add picture into specified Excel cell Add registry values in setup project ADD Root Node to XML in...
语句:ALTER TABLE `表名` ADD 索引类型 INDEX `索引名称`(`字段名`, `字段名`) USING 索引方法; 例子:ALTER TABLE `ttt` ADD NORMAL INDEX `name_`(`aa`, `bb`) USING BTREE; 删除:ALTER TABLE `数据库名`.`表名` DROP INDEX `索引名称`; ...
;2=uniquenonclusteredindex;3=clusteredindex;32=full-textindex;#收缩空间再后进行观察MySQL内部不会...