SQL Server 的查询优化器总是尝试找到最佳的执行计划,有时候虽然你建立了索引视图,但优化器依然使用了原始表上的索引,此时你可以使用 WITH NOEXPAND 来强制使用索引视图上的索引(而不是原始表上的索引)。 索引视图在 SQL Server 2012 的各个版本上都有支持,在开发版或企业版中查询处理器甚至能以此来把匹配索引视图...
CPU time=0ms, elapsed time=6ms.Table'computed_column_test_computed'. Scancount0, logical reads302521, physical reads0,read-ahead reads0, lob logical reads0, lob physical reads0, lobread-ahead reads0.Table'Numbers'. Scancount1, logical reads487, physical reads1,read-ahead reads330, lob lo...
This means that the Database Engine stores the computed values in the table, and updates them when any other columns on which the computed column depends are updated. The Database Engine uses these persisted values when it creates an index on the column, and when the index is referenced in...
Statistics的维护:刚才我们在谈到这个属性 is_auto_update_statistics_asnyc_on时,建议维护statistics的最佳方法是放在一个维护窗口期,更有可能的话应该放在index rebuilt或者碎片化整理之后,这样对于index statistics的维护更新也更有利,既节约了时间,还能使用full scan 对全表做抽样: update statistics dbo.cdc_driven s...
What is SQL Server? Connect to the Database Engine What's new? Editions and features Release notes Business continuity Database design Hierarchical Data Collation Databases Event notification FILESTREAM, FileTable & BLOB Indexes Overview Heaps (tables without a clustered index) ...
Notice that the index I've created includes a computed column. This is not always possible, depending of the definition of the computed column.After creating this index and executing the same query, I get the new execution plan shown in Figure 5....
is_computed bit 1 = 列为计算列。 is_filestream bit 1 = 列为 FILESTREAM 列。 is_replicated bit 1 = 列已复制。 is_non_sql_subscribed bit 1 = 列具有非 SQL Server 订阅服务器。 is_merge_published bit 1 = 列已合并发布。 is_dts_replicated bit 1 = 使用 SSIS 复制列。 is_xml_document ...
Applies to: SQL Server Azure SQL Database Azure SQL Managed Instance Azure Synapse Analytics Analytics Platform System (PDW) SQL database in Microsoft FabricConvert a rowstore table to a clustered columnstore index, or create a nonclustered columnstore index. Use a columnstore index to efficiently ...
PropertynameAsclassname[SqlComputeCode=sqlcomputecode,SqlComputed]; 其中sqlcomputecode在SqlComputeCode中描述。 否则,省略此关键字或将单词Not放在关键字的前面。 详解 如果此关键字为真(并且属性还指定了SqlComputeCode),则此属性是计算属性。 如果一个属性具有SqlComputed关键字的值, IRIS将使用该值来计算该属性...
Applies to: SQL Server Azure SQL Database Azure SQL Managed Instance Azure Synapse Analytics Analytics Platform System (PDW) SQL database in Microsoft FabricConvert a rowstore table to a clustered columnstore index, or create a nonclustered columnstore index. Use a columnstore index to efficiently ...