Question

Say we have some poorly written SQL that does not release temp tables when done, or well written SQL that gets killed after it creates temp tables but before it drops them.

Could this result in a SQL Server instance sucking up a lot of memory and not releasing it? How would I reclaim this memory?

Answer 1

a temp table will be dropped after it gets out of scope…and I am talking about a local temp table here not a global one (with 2 pound signs)

SQL Server will always suck up a lot of memory, it will put as much data in cache as possible, getting data from RAM is 1000 times faster than getting data from disk

Run this in SSMS

CREATE TABLE #MyTemp(id INT)
GO
SELECT * FROM tempdb.sys.tables
WHERE name LIKE '#MyTemp%'

Now close that window in SSMS

run this in another window

SELECT * FROM tempdb.sys.tables
WHERE name LIKE '#MyTemp%'

Is the table still there?

If the table is created in a proc, it is not there when the proc is done

CREATE PROCEDURE prtestTemp
AS 
CREATE TABLE #temp(id INT)

SELECT * FROM tempdb.sys.tables
WHERE name LIKE '#Temp%'

GO

Run proc

EXEC prtestTemp

Now run this, table is not there

SELECT * FROM #temp

SELECT * FROM tempdb.sys.tables
WHERE name LIKE '#Temp%'