Re: PATCH: logical_work_mem and logical streaming of large in-progress transactions

On Wed, Jun 10, 2020 at 4:00 PM Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
>
> On Wed, Jun 10, 2020 at 2:30 PM Dilip Kumar <dilipbalaut(at)gmail(dot)com> wrote:
> >
> >
> > Currently, I am done with a working prototype of using the BufFile
> > infrastructure for the tempfile. Meanwhile, I want to discuss a few
> > interface changes required for the BufFIle infrastructure.
> >
> > 1. Support read-write mode for "BufFileOpenShared", Basically, in
> > workers we will be opening the xid's changes and subxact files per
> > stream, so we need an RW mode even in the open. I have passed a flag
> > for the same.
> >
>
> Generally file open APIs have mode as a parameter to indicate
> read_only or read_write. Using flag here seems a bit odd to me.

Let me think about it, we can try to pass the mode.

> > 2. Files should not be closed at the end of the transaction:
> > Currently, files opened with BufFileCreateShared/BufFileOpenShared are
> > registered to be closed on EOXACT. Basically, we need to open the
> > changes file on the stream start and keep it open until stream stop,
> > so we can not afford to get it closed on the EOXACT. I have added a
> > flag for the same.
> >
>
> But where do we end the transaction before the stream stop which can
> lead to closure of this file?

Currently, I am keeping the transaction only while creating/opening
the files and closing immediately after that, maybe we can keep the
transaction until stream stop, then we can avoid this changes, and we
can also avoid creating extra resource owner? What is your thought on
this?

--
Regards,
Dilip Kumar
EnterpriseDB: http://www.enterprisedb.com