From: | Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> |
---|---|
To: | Dilip Kumar <dilipbalaut(at)gmail(dot)com> |
Cc: | Erik Rijkers <er(at)xs4all(dot)nl>, Kuntal Ghosh <kuntalghosh(dot)2007(at)gmail(dot)com>, Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com>, Michael Paquier <michael(at)paquier(dot)xyz>, Peter Eisentraut <peter(dot)eisentraut(at)2ndquadrant(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: PATCH: logical_work_mem and logical streaming of large in-progress transactions |
Date: | 2020-08-21 03:58:10 |
Message-ID: | CAA4eK1LiwC03=tBUnh9ub1aLJO-ea0baZ-mMNG1BXNudrVQHkw@mail.gmail.com |
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Lists: | pgsql-hackers |
On Fri, Aug 21, 2020 at 9:14 AM Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
>
> On Thu, Aug 20, 2020 at 5:42 PM Dilip Kumar <dilipbalaut(at)gmail(dot)com> wrote:
> >
> > On Thu, Aug 20, 2020 at 2:30 PM Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
> > >
> > >
> > > Right, I think this can happen if one has changed those by BufFileSeek
> > > before doing truncate. We should fix that case as well.
> >
> > Right.
> >
> > > > I will work on those along with your other comments and
> > > > submit the updated patch.
> >
> > I have fixed this in the attached patch along with your other
> > comments. I have also attached a contrib module that is just used for
> > testing the truncate API.
> >
>
> Few comments:
> ==============
> +void
> +BufFileTruncateShared(BufFile *file, int fileno, off_t offset)
> {
> ..
> + if ((i != fileno || offset == 0) && i != 0)
> + {
> + SharedSegmentName(segment_name, file->name, i);
> + FileClose(file->files[i]);
> + if (!SharedFileSetDelete(file->fileset, segment_name, true))
> + ereport(ERROR,
> + (errcode_for_file_access(),
> + errmsg("could not delete shared fileset \"%s\": %m",
> + segment_name)));
> + numFiles--;
> + newOffset = MAX_PHYSICAL_FILESIZE;
> +
> + if (i == fileno)
> + newFile--;
> + }
>
> Here, shouldn't it be i <= fileno? Because we need to move back the
> curFile up to newFile whenever curFile is greater than newFile
>
> 2.
> + /*
> + * If the new location is smaller then the current location in file then
> + * we need to set the curFile and the curOffset to the new values and also
> + * reset the pos and nbytes. Otherwise nothing to do.
> + */
> + else if ((newFile < file->curFile) ||
> + newOffset < file->curOffset + file->pos)
> + {
> + file->curFile = newFile;
> + file->curOffset = newOffset;
> + file->pos = 0;
> + file->nbytes = 0;
> + }
>
> Shouldn't there be && instead of || because if newFile is greater than
> curFile then there is no meaning to update it?
>
Wait, actually, it is not clear to me which case second condition
(newOffset < file->curOffset + file->pos) is trying to cover, so I
can't recommend anything for this. Can you please explain to me why
you have added the second condition in the above check?
--
With Regards,
Amit Kapila.
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