Re: Switching XLog source from archive to streaming when primary available

Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>

From: Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>

To: Nathan Bossart <nathandbossart@gmail.com>

Cc: Japin Li <japinli@hotmail.com>, Ian Lawrence Barwick <barwick@gmail.com>, Kyotaro Horiguchi <horikyota.ntt@gmail.com>, Cary Huang <cary.huang@highgo.ca>, SATYANARAYANA NARLAPURAM <satyanarlapuram@gmail.com>, pgsql-hackers@lists.postgresql.org

Date: 2024-03-06T04:32:43Z

Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

Add basic TAP tests for the low-level backup method, take two
- 071e3ad59d6f 17.0 cited
Add a failover option to subscriptions.
- 776621a5e479 17.0 cited
Make all Perl warnings fatal
- c5385929593d 17.0 cited
Add PostgreSQL::Test::Cluster::advance_wal
- c161ab74f76a 17.0 cited
Rename wal_keep_segments to wal_keep_size.
- c3fe108c025e 14.0 cited

Attachments

v22-0001-Allow-standby-to-switch-WAL-source-from-archive-.patch (application/x-patch) patch v22-0001

On Wed, Mar 6, 2024 at 1:22 AM Nathan Bossart <nathandbossart@gmail.com> wrote:
>
> I was thinking of something more like
>
>         typedef enum
>         {
>                 NO_FORCE_SWITCH_TO_STREAMING,           /* no switch necessary */
>                 FORCE_SWITCH_TO_STREAMING_PENDING,      /* exhausting pg_wal */
>                 FORCE_SWITCH_TO_STREAMING,                      /* switch to streaming now */
>         } WALSourceSwitchState;
>
> At least, that illustrates my mental model of the process here.  IMHO
> that's easier to follow than two similarly-named bool variables.

I played with that idea and it came out very nice. Please see the
attached v22 patch. Note that personally I didn't like "FORCE" being
there in the names, so I've simplified them a bit.

--
Bharath Rupireddy
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.com