Start Sql server updating large databases

Sql server updating large databases

Indexing strategy is complex; it depends on many factors, including database structure, queries, and stored procedures used.

ALTER INDEX [PK_Test] ON [dbo].[Test] REBUILD WITH (ONLINE=ON) ALTER INDEX [IX_Text] ON [dbo].[Test] REBUILD WITH (ONLINE=ON) ALTER INDEX [PK_Test] ON [dbo].[Test] REBUILD WITH (ONLINE=OFF) ALTER INDEX [IX_Text] ON [dbo].[Test] REBUILD WITH (ONLINE=OFF) It's pretty obvious from these results that the ONLINE index rebuild does not perform even close to as well as when run in OFFLINE mode as it uses considerably more resources to complete the rebuild.

The extra reads and writes can be attributed to the second copy of the index that SQL Server creates during the initial phase of the index rebuild. Next, let's take a look at what happens when there is some activity (inserts/updates/selects) on the table while the index is being rebuilt.

Although some DBAs and developers don’t prefer having clustered indexes on tables frequently inserted or updated, others consider that a clustered index on the right column can improve performance in these situations.

Creating a clustered index on every table is highly recommended, the challenge is to create the right index.

With a proper clustered index, less reads are required to retrieve the records requested by a query or stored procedure.

Therefore, fewer disk I/O are preformed and the operation is completed faster.

There are a few things I want to mention regarding online index rebuilds before we get into the details.

First, I want to make sure you understand the difference between rebuilding and reorganizing an index. If you would like to learn more about the differences between the two operations you can read more here.

A clustered index provides more efficient search for values in a specific range.

When you already have a table where the records are sorted ascending by e.g.

Both features utilize a synchronous tracking mechanism, which means SQL Server is minimally impacted.