Question

I have the following SQL code below. It is taking forever to complete but if I run just the SELECT DISTINCT ID, ParentID FROM Y WHERE ID IN (3,4), it completes instantly.

DECLARE @table TABLE
(
  ID int,
  ParentID int
)

INSERT INTO @table 
SELECT DISTINCT ID, ParentID FROM Y WHERE ID IN (3,4)

SELECT * FROM @table

What is going on, this makes no sense.

Answer 1

Try to use a temporary table instead. The table variable is optimized for one row only and assumes that is what it will be getting.

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