Re: SQL - Slow Like or Between

[Vernon Hamberg <vhamberg@xxxxxxxxxxxxxxx>]

Have you run your queries through Visual Explain? I find it to be 
essential to do this when doing this kind of work.

For the ones with parameter markers or host variables, you can put in 
actual values in the Navigator tool.

Vern

On 10/24/2013 11:59 AM, Michael Ryan wrote:
> Note: Cross posted because it's SQL in RPG, but I think it's just an SQL
> issue.
>
> A continuation of an email that I sent a couple of days ago, and got some
> good feedback. I'm returning a result set to RPG or PHP via a stored
> procedure.
>
> On further analysis, I need to provide a starting point for record access.
> I was using static SQL and a Between clause for each of 10 fields between
> *LOVAL and *HIVAL. Takes too long to run...like 60 seconds over an 800K
> record file.
>
> I created individual indexes (EVI's) over each of the 10 possible columns.
>
> Tried static SQL with a technique like this: Where :xxvnda1 in (' ',
> IMVNDA)  And.... Still too slow.
>
> Tried dynamic SQL by creating the statement using equal, like this:
>   SQLStmt = SQLStmt + cBlank + 'IMVNDA =' + cBlank + cQuote + xxvnda1 +
> cQuote; Much faster when looking for an equal, but doesn't return records
> that don't match exactly.
>
> Tried dynamic SQL using Like, and it's as slow as the initial static
> technique.
>
> I'm going to try dynamic SQL using a Between clause, but not as far as
> *LOVAL and *HIVAL, and only including the columns I want to search in the
> Where clause. I'm not anticipating good results though.
>
> Question (finally): What's the best technique for an SQL-based search where
> I return a result set from a search of multiple fields?
>
> Thanks for any ideas.