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

On Sat, Aug 22, 2020 at 8:38 AM Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
>
> On Fri, Aug 21, 2020 at 5:10 PM Dilip Kumar <dilipbalaut(at)gmail(dot)com> wrote:
> >
> > I have reviewed and tested the patch and the changes look fine to me.
> >
>
> Thanks, I will push the next patch early next week (by Tuesday) unless
> you or someone else has any more comments on it. The summary of the
> patch (v52-0001-Extend-the-BufFile-interface, attached with my
> previous email) I am planning to push is: "It extends the BufFile
> interface to support temporary files that can be used by the single
> backend when the corresponding files need to be survived across the
> transaction and need to be opened and closed multiple times. Such
> files need to be created as a member of a SharedFileSet. We have
> implemented the interface for BufFileTruncate to allow files to be
> truncated up to a particular offset and extended the BufFileSeek API
> to support SEEK_END case. We have also added an option to provide a
> mode while opening the shared BufFiles instead of always opening in
> read-only mode. These enhancements in BufFile interface are required
> for the upcoming patch to allow the replication apply worker, to
> properly handle streamed in-progress transactions."

While reviewing 0002, I realized that instead of using individual
shared fileset for each transaction, we can use just one common shared
file set. We can create individual buffile under one shared fileset
and whenever a transaction commits/aborts we can just delete its
buffile and the shared fileset can stay.

I have attached a POC patch for this idea and if we agree with this
approach then I will prepare a final patch in a couple of days.

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