Re: Speeding up LIKE with placeholders?

At 5:55 PM -0400 9/10/04, Tom Lane wrote:
>Dan Sugalski <dan@sidhe.org> writes:
>>  Would I regret it if I asked where in the source this lies so I could
>>  go fix it?
>
>If it were easy to fix it would have been fixed before now ...

Oh, I wasn't expecting it to be an *easy* fix... :) The question is
whether it's less work to make the fix in Postgres or in my back-end
library code. Worst case I fix it in my code and submit a doc patch,
but I'm up for at least investigating the general fix.

Since the only difference in this case is that the parameters are
pulled out for transport rather than being in band (a
properly-escaped string substitution could turn this case from a
PQexecParams call into a PQexec call) I was thinking the thing to do
would be to either teach the planner to look in the parameter list
when it gets handed $xxx variables, or have the back-end do the
substitution to the SQL before handing the code to the planner.

I'm not sure I like either option (the pre-substitution's got some
issues when handed large parameters, while teaching the planner to
use a parameter list may require thumping a lot of back-end code) and
it may amount to nothing, but I figured it was worth a look, if for
no other reason than to find a big mass of code I can safely run
screaming from. ;-)
--
                Dan

--------------------------------------it's like this-------------------
Dan Sugalski                          even samurai
dan@sidhe.org                         have teddy bears and even
                                       teddy bears get drunk