| From: | Ashwin Agrawal <aagrawal(at)pivotal(dot)io> |
|---|---|
| To: | Andres Freund <andres(at)anarazel(dot)de> |
| Cc: | Heikki Linnakangas <hlinnaka(at)iki(dot)fi>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Justin Pryzby <pryzby(at)telsasoft(dot)com>, Haribabu Kommi <kommi(dot)haribabu(at)gmail(dot)com>, Kyotaro HORIGUCHI <horiguchi(dot)kyotaro(at)lab(dot)ntt(dot)co(dot)jp>, Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>, David Rowley <david(dot)rowley(at)2ndquadrant(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com>, Asim R P <apraveen(at)pivotal(dot)io>, PostgreSQL mailing lists <pgsql-hackers(at)postgresql(dot)org>, Dmitry Dolgov <9erthalion6(at)gmail(dot)com>, Alexander Korotkov <a(dot)korotkov(at)postgrespro(dot)ru> |
| Subject: | Re: Pluggable Storage - Andres's take |
| Date: | 2019-05-17 23:56:04 |
| Message-ID: | CALfoeiuuWUt-xPnekcVdhp-a-CRDGyCYV-Jcg=W_xuZDd1xopw@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Wed, May 15, 2019 at 11:54 AM Andres Freund <andres(at)anarazel(dot)de> wrote:
> Attached is a prototype of a variation of this. I added a
> table_tuple_tid_valid(TableScanDesc sscan, ItemPointer tid)
> callback / wrapper. Currently it just takes a "plain" scan, but we could
> add a separate table_beginscan variant too.
>
> For heap that just means we can just use HeapScanDesc's rs_nblock to
> filter out invalid tids, and we only need to call
> RelationGetNumberOfBlocks() once, rather than every
> table_tuple_tid_valid(0 / table_get_latest_tid() call. Which is a good
> improvement for nodeTidscan's table_get_latest_tid() call (for WHERE
> CURRENT OF) - which previously computed the relation size once per
> tuple.
>
Question on the patch, if not too late
Why call table_beginscan() in TidNext() and not in ExecInitTidScan() ?
Seems cleaner to have it in ExecInitTidScan().
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