Horton

Re: Minimal logical decoding on standbys

Amit Khandekar <amitdkhan.pg@gmail.com>

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From: Amit Khandekar <amitdkhan.pg@gmail.com>
To: Andres Freund <andres@anarazel.de>
Cc: tushar <tushar.ahuja@enterprisedb.com>, Petr Jelinek <petr.jelinek@2ndquadrant.com>, Robert Haas <robertmhaas@gmail.com>, Craig Ringer <craig@2ndquadrant.com>, Petr Jelinek <petr@2ndquadrant.com>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2019-06-10T05:07:44Z
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 →

  1. Reduce the log level in 035_standby_logical_decoding.pl.

  2. 035_standby_logical_decoding: Add missing waits for replication

  3. For cascading replication, wake physical and logical walsenders separately

  4. Handle logical slot conflicts on standby

  5. Support invalidating replication slots due to horizon and wal_level

  6. Prevent use of invalidated logical slot in CreateDecodingContext()

  7. Replace replication slot's invalidated_at LSN with an enum

  8. Pass down table relation into more index relation functions

  9. Assert only valid flag bits are passed to visibilitymap_set()

  10. Remove unused _bt_delitems_delete() argument.

  11. Add xl_btree_delete optimization.

On Tue, 4 Jun 2019 at 21:28, Andres Freund <andres@anarazel.de> wrote:
>
> Hi,
>
> On 2019-06-04 15:51:01 +0530, Amit Khandekar wrote:
> > After giving more thought on this, I think it might make sense to
> > arrange for the xl_running_xact record to be sent from master to the
> > standby, when a logical slot is to be created on standby. How about
> > standby sending a new message type to the master, requesting for
> > xl_running_xact record ? Then on master, ProcessStandbyMessage() will
> > process this new message type and call LogStandbySnapshot().
>
> I think that should be a secondary feature. You don't necessarily know
> the upstream master, as the setup could be cascading one.
Oh yeah, cascading setup makes it more complicated.

> I think for
> now just having to wait, perhaps with a comment to manually start a
> checkpoint, ought to suffice?

Ok.

Since this requires the test to handle the
fire-create-slot-and-then-fire-checkpoint-from-master actions, I was
modifying the test file to do this. After doing that, I found that the
slave gets an assertion failure in XLogReadRecord()=>XRecOffIsValid().
This happens only when the restart_lsn is set to ReplayRecPtr.
Somehow, this does not happen when I manually create the logical slot.
It happens only while running testcase. Working on it ...



-- 
Thanks,
-Amit Khandekar
EnterpriseDB Corporation
The Postgres Database Company