Switching out and truncating partitions that aren't needed is an efficient strategy to delete data without generating fragmentation. 避免刪除大量資料。 從數據列群組中移除壓縮的數據列不是同步作業。 解壓縮資料列群組、刪除資料列然後將其重新壓縮,會十分昂貴。 因此,當您從壓縮的數據列群組...
This sounds like you are looking for an audit trail of the database. There is nothing in SQL Server which does unless you build one.If you are using SQL 2008 R2+, you can use the CDC functions to create "audit tables" but you will need to write reports, etc to do what you want....
SQL Server 2005 ships with a set of DMVs that can help you identify the missing indexes for your workload, Analyze the effectiveness of the existing ones and help find out index fragmentation.Using DMVs to find out the index usage history...
SQL Server performance is affected by many factors. The most common SQL Server performance killers are poor database design, poor indexing, poor query design, not reusable execution plans, frequent query recompilation, excessive fragmentation, and more. With these factors present on your machine, ev...
Query Performance Tuning is aimed at developers and database administrators having responsibility for application performance in SQL Server environments. Programmers and administrators alike will find the book a trove of good insight into bottlenecks, how to recognize them, how to eliminated them. SQL ...
For example, if you see a spike in parallelism waits on the SQL Server Waits chart, highlight the spike, and then select Jump To > Query Plans. Sort by the Parallel Operations column to determine which queries caused the spike. Note: The same approach can be used to find queries with ...
For example, if you see a spike in parallelism waits on the SQL Server Waits chart, highlight the spike, and then select Jump To > Query Plans. Sort by the Parallel Operations column to determine which queries caused the spike. Note: The same approach can be used to find queries with ...
If index fragmentation is causing single-page reads on the secondary replica but not on the primary replica, you would expect to see a larger number of read IO/sec and a smaller number of read bytes/sec when the database is in the Availability Group as compared to when it's...
3. **Page Splits and Fragmentation**: If the table already has data and is subject to updates, the index may experience page splits and fragmentation, which can degrade performance. SQL Server has to rearrange the index pages to accommodate the new data, which can be more costly than the...
data modifications may corrupt the logical orders of the indexes. In this type of fragmentation, the new page isn’t in the same order as the physical order so logical fragmentation occurs. In order to resolve this problem, we can rebuild the logical order of the index pages. Through the ...