From: Tom Lane <tgl@sss.pgh.pa.us>
To: Merlin Moncure <merlin.moncure@rcsonline.com>
Cc: pgsql-performance@postgresql.org, "Kelly Burkhart" <kelly@tradebotsystems.com>
Subject: Re: 8.x index insert performance
Date: Mon, 31 Oct 2005 16:08:12 -0500
Message-ID: <18970.1130792892@sss.pgh.pa.us> (raw)
In-Reply-To: <6EE64EF3AB31D5448D0007DD34EEB3417DD731@Herge.rcsinc.local>
References: <6EE64EF3AB31D5448D0007DD34EEB3417DD731@Herge.rcsinc.local>
"Merlin Moncure" <merlin.moncure@rcsonline.com> writes:
>> You're mistaken, at least with regard to btree indexes.
> hmm. I tried several different ways to filter/extract null values from
> an indexed key and got a seq scan every time.
I said they were stored, not that you could query against them ;-)
IS NULL isn't considered an indexable operator, mainly because it's
not an operator at all in the strict sense of the word; and our index
access APIs only support querying on indexable operators.
The reason they're stored is that they have to be in order to make
multi-column indexes work right. I suppose we could special-case
single-column indexes, but we don't. In any case, it's more likely
that someone would one day get around to making IS NULL an indexable
operator than that we'd insert a special case like that.
regards, tom lane
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To: pgsql-performance@postgresql.org
Cc: tgl@sss.pgh.pa.us, merlin.moncure@rcsonline.com, kelly@tradebotsystems.com
Subject: Re: 8.x index insert performance
In-Reply-To: <18970.1130792892@sss.pgh.pa.us>
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