Deleting From Heaps

Uwe Ricken discusses a downside to leaving an active table as a heap:

The simplest way of removing empty data pages from a heap is via the exclusive locking of the table. But keep in mind that there is no such thing as a free lunch. Blocking the table from other processes will lead to a system that will not scale. As long as the DELETE process locks the table, no other process can access the table. The only exception is the “SNAPSHOT ISOLATION” but explaining the pros and cons of this technique is outside the scope of this article.

The next example (with the new created table) demonstrates the behavior.

The section on lock escalation was rather interesting.

Related Posts

Query Store Indexes

Arthur Daniels shows what you can learn from the indexes on Query Store tables: It looks like internally Query Store is referred to as plan_persist. That makes sense, thinking about how the Query Store persists query plans to your database’s storage. Let’s take a look at those catalog views vs their clustered and nonclustered indexes. […]

Read More

Gotchas When Indexing Partitioned Tables

Andrew Pruski gives us a couple of considerations when creating indexes on partitioned tables in SQL Server: Looking at that data page, we can see that SQL has added a UNIQUIFIER column. Now this is standard SQL behaviour, SQL does this to all non-unique clustered indexes whether they are on a partitioned table or not. But also […]

Read More


September 2016
« Aug Oct »