| From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
|---|---|
| To: | Heikki Linnakangas <hlinnaka(at)iki(dot)fi> |
| Cc: | Dilip Kumar <dilipbalaut(at)gmail(dot)com>, Melanie Plageman <melanieplageman(at)gmail(dot)com>, Nazir Bilal Yavuz <byavuz81(at)gmail(dot)com>, Andres Freund <andres(at)anarazel(dot)de>, Pg Hackers <pgsql-hackers(at)postgresql(dot)org>, Thomas Munro <thomas(dot)munro(at)gmail(dot)com>, Tomas Vondra <tomas(dot)vondra(at)enterprisedb(dot)com> |
| Subject: | Re: BitmapHeapScan streaming read user and prelim refactoring |
| Date: | 2024-03-14 12:34:37 |
| Message-ID: | CA+TgmoYiYQLSyj_-yjrtAkUTt+2i-k_NUek+tpr37EzAGXKO3A@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Thu, Mar 14, 2024 at 6:37 AM Heikki Linnakangas <hlinnaka(at)iki(dot)fi> wrote:
> If es_snapshot was different from the active snapshot, things would get
> weird, even without parallel query. The scans would use es_snapshot for
> the visibility checks, but any functions you execute in quals would use
> the active snapshot.
Hmm, that's an interesting point.
The case where the query is suspended and resumed - i.e. cursors are
used - probably needs more analysis. In that case, perhaps there's
more room for the snapshots to diverge.
--
Robert Haas
EDB: http://www.enterprisedb.com
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