Re: SQL - Slow Like or Between

The main thing is, you don't want a table scan anywhere, if possible.
Anything else, bring some details here, maybe someone of us can help
interpret things.

On 10/24/2013 12:16 PM, Michael Ryan wrote:

I'm going to do that, but I find that it's difficult to interpret (for me
obviously). I can tell if an index is needed - it tells me. But other

than

that, it's tough for me to figure out what it's telling me.


On Thu, Oct 24, 2013 at 1:09 PM, Vernon Hamberg <

vhamberg@xxxxxxxxxxxxxxx>wrote:

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.

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