Re: GiST indexing problems... - Mailing list pgsql-hackers

David,

could you provide more info (scheme, query, postgresql version)
Regards,
    Oleg
On Sat, 5 May 2001, David McWherter wrote:

>
>      I've been doing some research work using the GiST indexes,
> but I persistently develop a problem where the system doesn't
> make use of the indexes during the execution of a query.  If
> I use the examples provided here:
>
>   http://wit.mcs.anl.gov/~selkovjr/pg_extensions/
>
> For instance, and I place an elog( DEBUG, "functionname" )
> in each of the GiST accessor functions, I can witness when
> the database is making use of the index.  During the construction
> of the index, I never have a problem, although during query
> execution, it seems that my indices aren't getting used at
> all, and the database is simply searching through all of
> the entries in the database.
>
> This is a terribly frustrating problem that I encountered
> once before, but which mysteriously went away after fiddling
> with the problem for a while.  This time, the problem isn't
> going away, however.  When I trace through the postgres
> application I can see that it at least examines the opclass
> for my specialized data types, and detects that there exists
> an index that could be used, but it seems to decide not to
> make use of it regardless.
>
> Is there an easy way that I can force the use of an index
> during a query?
>
> -David
>
> ----------------------[=========]------------------------
> David T. McWherter                udmcwher@mcs.drexel.edu
>
>    vdiff
> =====
>  /vee'dif/ v.,n.  Visual diff.  The operation offinding
> differences between two files by {eyeball search}.  Theterm
> `optical diff' has also been reported, and is sometimes more
> specifically used for the act of superimposing two nearly identical
> printouts on one another and holding them up to a light to spot
> differences.  Though this method is poor for detecting omissions in
> the `rear' file, it can also be used with printouts of graphics, a
> claim few if any diff programs can make.  See {diff}.
>
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Regards,    Oleg
_____________________________________________________________
Oleg Bartunov, sci.researcher, hostmaster of AstroNet,
Sternberg Astronomical Institute, Moscow University (Russia)
Internet: oleg@sai.msu.su, http://www.sai.msu.su/~megera/
phone: +007(095)939-16-83, +007(095)939-23-83