Re: Moving GiST index constant to parameter - Mailing list pgsql-hackers

From Tom Lane
Subject Re: Moving GiST index constant to parameter
Date
Msg-id 26034.1491145839@sss.pgh.pa.us
Whole thread Raw
List pgsql-hackers
Thomas Mercieca <tmercieca@msn.com> writes:
> I have tried introducing a GUC variable (entry in guc.c/config_real) and I have also tried having the parser
recognizeit (same as fillfactor is recognized), but irrelevant of what I set the value to at run-time, I always get the
sameunusual index stats (cannot reproduce results) and the following messages in the logfile, suggesting that I broke
thefunction: 

A GUC is certainly not the right thing; you should use an index storage
parameter.  However, it seems like your problem is independent of that.

> "DEBUG:  picksplit method for column 1 of index "idx2243" failed
> HINT:  The index is not optimal. To optimize it, contact a developer, or try to use the column as the second one in
theCREATE INDEX command. 
> STATEMENT:  create index idx2243 on geom_table using gist(geom)"

It looks like picksplit would necessarily fail if you tried to use
a ratio >= 0.5, or even very close to 0.5, because you'd be demanding
unachievable perfection of the split.

Beyond that observation, it's hard to say much without seeing what
you changed.
        regards, tom lane



pgsql-hackers by date:

Previous
From: Emre Hasegeli
Date:
Subject: Re: BRIN cost estimate
Next
From: Pavel Stehule
Date:
Subject: Re: Variable substitution in psql backtick expansion