] type_name [ (precision [ , scale ]) ] <column_constraint> ::= [ CONSTRAINT constraint_name ] { { PRIMARY KEY | UNIQUE } { NONCLUSTERED | NONCLUSTERED HASH WITH ( BUCKET_COUNT = bucket_count ) } [ ( <column_name> [ ,... n ] ) ] | [ FOREIGN KEY ] REFERENCES [ schema_...
USE AdventureWorks2022; SELECT COUNT(*) AS BeforeTruncateCount FROM HumanResources.JobCandidate; TRUNCATE TABLE HumanResources.JobCandidate; SELECT COUNT(*) AS AfterTruncateCount FROM HumanResources.JobCandidate; B. Truncate table partitionsApplies to: SQL Server 2016 (13.x) and later versions.The...
The maximum value for BUCKET_COUNT in hash indexes is 1,073,741,824. For more information about bucket counts, see Indexes for Memory-Optimized Tables. Bucket_count is a required argument. INDEX Applies to: SQL Server 2014 (12.x) and later, Azure SQL Database, and Azure SQL Managed ...
SQL USEAdventureWorks2022; GOSELECTCOUNT(*)ASBeforeTruncateCountFROMHumanResources.JobCandidate; GOTRUNCATETABLEHumanResources.JobCandidate; GOSELECTCOUNT(*)ASAfterTruncateCountFROMHumanResources.JobCandidate; GO B. 截断表分区 适用于:SQL Server 2016 (13.x) 及更高版本。
SELECT count(1) FROM course; 1)DROP TABLE,提示表不存在 2)创建并初始化一张实验表 3)DROP TABLE 执行成功 4)查看执行结果 四、GaussDB的TRUNCATE命令及示例 1、功能描述 从表或表分区中移除所有数据,TRUNCATE快速地从表中删除所有行。它和在目标表上进行无条件的DELETE有同样的效果,但由于TRUNCATE不做表扫描...
(NewName, NewReasonType)ONTarget.Name = Source.NewNameWHENMATCHEDTHENUPDATESETReasonType = Source.NewReasonTypeWHENNOTMATCHEDBYTARGETTHENINSERT(Name, ReasonType)VALUES(NewName, NewReasonType)OUTPUT$actionINTO@SummaryOfChanges;-- Query the results of the table variable.SELECTChange,COUNT(*)ASCountPer...
] type_name REBUILD [ [ NONCLUSTERED ] WITH ( BUCKET_COUNT = bucket_count ) ] } | ADD { <column_definition> | <computed_column_definition> | <table_constraint> | <table_index> | <column_index> } [ ,...n ] | DROP [ { CONSTRAINT [ IF EXISTS ] { constraint_name } [ ,......
] type_name REBUILD [ [ NONCLUSTERED ] WITH ( BUCKET_COUNT = bucket_count ) ] } | ADD { <column_definition> | <computed_column_definition> | <table_constraint> | <table_index> | <column_index> } [ ,...n ] | DROP [ { CONSTRAINT [ IF EXISTS ] { constraint_name } [ ,......
然而很多次的类似sql出现,对数据库的性能也是一种不必要的损耗,因为这对业务发展并没有很深的意义。我们知道对于select count(*) from table_name这样的sql是没有办法通过索引优化的,那么只能通过改写sql进行优化了,这也是一个精通sql优化高手必备的技能。
1 Does fast count from sysindexes.rows. Counting rows in sysindexes is much faster than counting rows in the actual table. However, because sysindexes is lazily updated, the rowcount might not be accurate. 2 (default) Does conditional fast counting by first trying the fast method. If fast met...