From: | Greg Stark <gsstark(at)mit(dot)edu> |
---|---|
To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
Cc: | Greg Stark <gsstark(at)mit(dot)edu>, pgsql-patches(at)postgresql(dot)org |
Subject: | Re: BTree tid operators and opclass |
Date: | 2006-07-07 05:16:51 |
Message-ID: | 873bdenge4.fsf@stark.xeocode.com |
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Lists: | pgsql-patches |
Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> writes:
> Greg Stark <gsstark(at)mit(dot)edu> writes:
> > Here's a small patch to add the full suite of btree operators for tids and the
> > corresponding btree opclass.
>
> This has been proposed and rejected before, mainly on the basis that
> there's no conceivable application for an index on TID. What's your
> use case?
IIRC the use case that was previously suggested was the common Oracle idiom
for removing duplicates. The Postgrse equivalent would something like:
delete from tab where exists (
select 1 from tab as x where x.pk = tab.pk and x.ctid > tab.ctid
)
In my case I don't want to create an index on tid, I just have a list of tids
that I want to sort so I can process them in heap order.
I was going to just write a qsort comparator but this way I can use tuplesort
and not worry about what happens if it doesn't fit in memory.
--
greg
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