| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Robert Haas <robertmhaas(at)gmail(dot)com> |
| Cc: | Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>, Jesper Pedersen <jesper(dot)pedersen(at)redhat(dot)com>, Jeff Janes <jeff(dot)janes(at)gmail(dot)com>, Mithun Cy <mithun(dot)cy(at)enterprisedb(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Hash Indexes |
| Date: | 2016-10-18 17:38:14 |
| Message-ID: | 24404.1476812294@sss.pgh.pa.us |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-hackers |
Robert Haas <robertmhaas(at)gmail(dot)com> writes:
> On Tue, Oct 18, 2016 at 5:37 AM, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
>> I have implemented this idea and it works for MVCC scans. However, I
>> think this might not work for non-MVCC scans. Consider a case where
>> in Process-1, hash scan has returned one row and before it could check
>> it's validity in heap, vacuum marks that tuple as dead and removed the
>> entry from heap and some new tuple has been placed at that offset in
>> heap.
> Oops, that's bad.
Do we care? Under what circumstances would a hash index be used for a
non-MVCC scan?
regards, tom lane
| From | Date | Subject | |
|---|---|---|---|
| Next Message | Dmitry Dolgov | 2016-10-18 17:41:33 | Re: [PATCH] Generic type subscription |
| Previous Message | Robert Haas | 2016-10-18 17:36:09 | Re: Aggregate Push Down - Performing aggregation on foreign server |