3
votes
1answer
124 views

Why does my query end up with two seeks instead of one and how do I fix that?

I have these two tables: CREATE TABLE [TaskItems] ( [ItemId] UNIQUEIDENTIFIER NOT NULL UNIQUE PRIMARY KEY, [LastOperationTime] DATETIME NULL DEFAULT GETUTCDATE(), [OwnerId] ...
2
votes
2answers
3k views

Will altering order of columns in GROUP BY affect performance?

I have a SQL query like this: SELECT A, B, (CASE WHEN C=0 THEN 0 ELSE 1 END), COUNT(D) FROM SomeTable GROUP BY A, B, (CASE WHEN C=0 THEN 0 ELSE 1 END) On a huge dataset the actual execution plan ...
3
votes
2answers
277 views

How do I count rows with two properties in one index scan in SQL?

I have a table Units where I have rows ItemId, ItemCreationDate, ItemUnitsCount. ItemId is a primary key and I have a clustered index over it. I need to output the following: for each day I need to ...