BETWEEN in a SELECT is slow.
I’m using SQL Server 2000 and a BETWEEN in the WHERE clause.
My basic query is:
SELECT * FROM mytable WHERE 3507184416 between RangeLow AND RangeHigh
There is a clustered index on RangeLow and a nonclustered index on RangeHigh.
Both fields are BigInt and there are about 7 million records in the table.
A query like the following will complete immediately. .
SELECT MAX(RangeLow) from mytable where RangeLow <= 3507184416
If I use between it takes about 4.5 minutes.
Anyone know what I should be doing for this to work properly?
TIA,
Chris
My basic query is:
SELECT * FROM mytable WHERE 3507184416 between RangeLow AND RangeHigh
There is a clustered index on RangeLow and a nonclustered index on RangeHigh.
Both fields are BigInt and there are about 7 million records in the table.
A query like the following will complete immediately. .
SELECT MAX(RangeLow) from mytable where RangeLow <= 3507184416
If I use between it takes about 4.5 minutes.
Anyone know what I should be doing for this to work properly?
TIA,
Chris
Last Comment
ASKER
It is doing a clustered index seek. IO cost 310 CPU Cost 4.16 which accounts for 100% of the cost.
When I said "my basic query" above, that's really the whole thing.
I have tried using <= and >= but it performs the same.
It seems that the non clustered index is not getting used.
When I said "my basic query" above, that's really the whole thing.
I have tried using <= and >= but it performs the same.
It seems that the non clustered index is not getting used.
You also may want to look at index fragmentation - large range queries will result in an index scan, and if your indexes are fragmented this will hurt performance.
Check the indexes on your table with DBCC SHOWCONTIG ('tablename').
Check the indexes on your table with DBCC SHOWCONTIG ('tablename').
What data do you want from the table? Try including only the columns you need instead of SELECT * - if these are all included in the non-clustered you will get better performance.
Also, how many rows do you expect to be returned by the query?
Also, how many rows do you expect to be returned by the query?
ASKER
Here is the execution plan:
http://www.dotnetassets.com/between.jpg
http://www.dotnetassets.com/between.jpg
ASKER
I only expect 1 row back. The table was just created and indexed so I do not suspect fragmentation. This seems like SQL server does not know how to use the indexes.
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ASKER
Yep,
That one screams and I can also add rangeHigh >= 3507184416 and ..
to the where clause and it still goes real fast.
Thank you very much. It now completes immediately.
Chris
That one screams and I can also add rangeHigh >= 3507184416 and ..
to the where clause and it still goes real fast.
Thank you very much. It now completes immediately.
Chris
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what about this?
SELECT * FROM mytable
WHERE RangeLow <= 3507184416
AND RangeHigh >= 3507184416