quote:

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Originally posted by Kristen

Look at query plan to see what indexes are being used, and whether there are indexes you expected to be used which are not! or if there are places you could try adding an index.

As a very general rule / beginners guide:

Speed fastest-to-slowest is:

Index Seek
Index Scan
Table Seek
Table Scan

Also where you see an INDEX being used and the Index is the Clustered Index (which is usually the Primary Key too) and the columns in the Clustered Index are NOT the ones needed for the search, then although this seems to be an INDEX approach actually this is a last-ditch approach! because there is no other, and thus the Clustered Index is being used to check every single row in the table.

But your best way to make it faster is to post the query here and ask for advice. It will help, and get tyoua faster answer, if you post a script for the DDL - CREATE TABLE / COLUMNs and all CREATE INDEX. It will also help if can see the QUERY PLAN (in text format)

My money is on:

No / Wrong indexes
Function / Cast used in a JOIN
and possibly DISTINCT instead of careful JOINs to avoid duplicates in the first place.

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quote:

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Originally posted by Kristen

Speed fastest-to-slowest is:

Index Seek
Index Scan
Table Seek
Table Scan

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quote:

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Also where you see an INDEX being used and the Index is the Clustered Index (which is usually the Primary Key too) and the columns in the Clustered Index are NOT the ones needed for the search, then although this seems to be an INDEX approach actually this is a last-ditch approach! because there is no other, and thus the Clustered Index is being used to check every single row in the table.

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