Question

The below MSSQL2005 query is very slow. I feel like their ought to be a way to speed it up, but am unsure how. Note that I editted the inner join to use select statements to make it more obvious (to people reading this question) what is going on, though this has no impact on speed (probably the Execution plan is the same either way). Interestingly, I never actually use keywordvaluegroups for anything more than a count, but I’m not sure if there is a way to capitalize on this.

select top 1 cde.processPath as 'keywordValue', count(*) as 'total'
from dbo.ClientDefinitionEntry AS cde INNER JOIN dbo.KeywordValueGroups  AS kvg
ON cde.keywordGroupId = kvg.keywordValueGrpId
where kvg.[name] = @definitionName
group by cde.processPath
order by total desc      

Edit: Apparently, people keep complaining about my use of subqueries. In fact, it makes no difference. I added them right before posting this question to make it easier to see what is going on. But they only made things more confusing, so I changed it not to use them.

Edit: Indexes in use:

ClientDefinitionEntry:
IX_ClientDefinitionEntry   |nonclustered located on PRIMARY|clientId, keywordGroupId

KeyWordValueGroups
IX_KeywordValueGroups      |nonclustered located on PRIMARY|keywordValueGrpId
IX_KeywordValueGroups_2    |nonclustered located on PRIMARY|version
IX_KeywordValueGroups_Name |nonclustered located on PRIMARY|name

Answer 1

I’d make sure you had the following indexes.

The ID on KeywordValueGroups.

The Name on KeywordValueGroups.

The ID on ClientDefinitionEntry with an INCLUDE for the processPath.

CREATE INDEX [IX_ClientDefinitionEntry_Id_ProcessPath] ON [dbo].[ClientDefinitionEntry] ( [keywordGroupId] ASC ) INCLUDE ( [processPath]) ON [PRIMARY]
CREATE INDEX [IX_KeywordValueGroups_Id] ON [dbo].[KeywordValueGroups] ( [keywordValueGrpId] ASC )
CREATE INDEX [IX_KeywordValueGroups_Name] ON [dbo].[KeywordValueGroups] ( [name] ASC )

I’d also change the query to the following.

select top 1
    cde.processPath as 'keywordValue',
    count(*) as 'total'
from
    dbo.ClientDefinitionEntry AS cde
INNER JOIN
    dbo.KeywordValueGroups  AS kvg
ON
    cde.keywordGroupId = kvg.keywordValueGrpId
where
    kvg.[name] = @definitionName
group by
    processPath
order by
    total desc