Note:Although the index is created for only unique values, the original data in the table remains unaltered. Remove Index From Tables To removeINDEXfrom a table, we can use theDROP INDEXcommand. For example, SQL Server DROPINDEXColleges.college_index; PostgreSQL, Oracle DROPINDEXcollege_index; ...
默认值为OFF“超大规模”Azure SQL 数据库除外。 对于“超大规模”中的所有索引生成作,除非使用可恢复索引生成,否则始终 ONSORT_IN_TEMPDB。 对于可恢复索引生成,SORT_IN_TEMPDB 始终OFF。 ON 用于生成索引的中间排序结果存储在其中 tempdb。 这可以减少创建索引所需的时间。 但是,这会增加索引生成期间所使用的磁盘...
For example, when MAXDOP = 4, the number of processors used is 4 or less. 0 (default), which means to use the actual number of processors, or fewer, based on the current system workload. SQL コピー CREATE CLUSTERED COLUMNSTORE INDEX cci ON Sales.OrderLines WITH (MAXDOP = 2); ...
For example, this might occur with INSERT ... WITH (TABLOCK) operations. In this case, you get error 10637: Cannot perform this operation on '' with ID () as one or more indexes are currently in resumable index rebuild state. Please refer to sys.index_resumable_operations for more...
The following example returns information for all indexes and partitions of thePerson.Addresstable in the AdventureWorks2022 database. Executing this query requires, at a minimum, CONTROL permission onPerson.Addresstable. Important When you are using the Transact-SQL functions DB_ID and OBJECT_ID to...
SQL_TRACE, 8-15 TRANSACTIONS, 4-28 TRANSACTIONS_PER_ROLLBACK_SEGMENT, 4-28 USE_INDIRECT_DATA_BUFFERS, 7-14 initially deferred constraints, 25-24 initially immediate constraints, 25-24 INIT.ORA. See initialization parameter file. inline views, 10-17 example, 10-17 INSERT statement...
When clustered and nonclustered indexes are built, or rebuilt, in a single online index operation (for example, during the initial clustered index creation on a table that contains one or more nonclustered indexes) two short-term S locks are acquired during the build phase followed by long-...
最近用explain命令分析查询sql执行计划,时而能看到Extra中显示为"Using index"或者"Using where; Using Index",对这两者之间的明确区别产生了一些疑惑,于是通过网上搜索、自行实验探究了一番其具体区别。 测试数据准备 以下表作为测试表进行sql分析。 CREATE TABLE `test_table`(`id` bigint(20)unsigned NOTNULLAU...
SQL USEmaster; GO-- In this example, OBJECT_ID is evaluated in the context of the master database.-- Because Person.Address does not exist in master, the function returns NULL.-- When NULL is specified as an object_id, all objects in the database are returned.-- The same results are...
For a functional key part containing the SUBSTRING() function to be used in a query, the WHERE clause must contain SUBSTRING() with the same arguments. In the following example, only the second SELECT is able to use the index because that is the only query in which the arguments to ...