Index Changes And Recompilation

Kendra Little explains how index modifications affect the plan cache:

Creating an index doesn’t remove a plan from cache

We run our Demo Query five times. Querying sys.dm_exec_query_stats and related DMVs, we see five executions, plan_generation_num = one.

Then we create an index on a table referenced by the query.

Querying the DMVs we still see five executions, plan_generation_num = one, and the query plan in cache. It hasn’t been removed!

Read on for more, including what happens when you run the query again, what happens when you rebuild indexes, and what happens when you drop an index.

Related Posts

Foreign Key Checks and Index Usage Stats

Marek Masko walks through an attendee question: Last week I was speaking at SQLDay 2019 conference in Wroclaw, Poland. My session was about things you should focus on during work with Legacy Databases. One of the topics I discussed was concerning the database usage statistics collection and aggregation (mainly indexes and stored procedures). After the session, one of […]

Read More

Minimal Logging into Empty Clustered Indexes

Paul White explains how to perform minimal logging when using the INSERT..SELECT pattern to insert into an empty table with a clustered index: The summary top row suggests that all inserts to an empty clustered index will be minimally logged as long as TABLOCK and ORDER hints are specified. The TABLOCK hint is required to enable the RowSetBulk facility as used for heap table bulk loads. An ORDER hint […]

Read More

Categories

August 2017
MTWTFSS
« Jul Sep »
 123456
78910111213
14151617181920
21222324252627
28293031