Do temp tables have statistics?
Temp tables can help performance! You create a temp table, populate it, and reference it in future queries. This can lead to improved estimates and reliability, because temporary tables can have column and index related statistics. It’s easy to forget that statistics can be tricky– just like with real tables.
What is faster CTE or temp table?
Temp tables are always on disk – so as long as your CTE can be held in memory, it would most likely be faster (like a table variable, too). But then again, if the data load of your CTE (or temp table variable) gets too big, it’ll be stored on disk, too, so there’s no big benefit.
How are temp tables and CBO statistics used?
I was reading your “Expert Oracle Database Architecture” where it says, that (p. 409) “The second technique that works with ON COMMIT PRESERVE ROWS global temporary tables is to user GATHER_TABLE_STATS directly on that table. You would populate the global temporary table and then execute GATHER_TABLE_STATS on that global temporary table”.
How to create a statistic on a temp table?
The first step is to load up a temp table with some rows: Now let’s say I query the temp table in some way. My where clause is for a specific TempValue. The act of running this query causes a column level statistic to be created on the TempValue column: We can see the statistic, too.
What are the rules for using a temp table?
Temp tables are a great tool to use, but remember a few key rules: Column level statistics will be created for you when you run queries using the temp table If you modify the temp table in multiple steps, those statistics may get out of date
How to auto update statistics threshold of temp table?
Here is an example in compatibility level 150 in SQL 2019. 1.Enable the AUTO_update_STATISTICS for temp table and create a table with 30,000 rows. select top 30000 ROW_NUMBER () over (order by c.object_id) id from sys.columns c cross join sys.all_objects 2.Create a stored procedure.