Re: Minimal logical decoding on standbys

Bertrand Drouvot <bertranddrouvot.pg@gmail.com>

From: "Drouvot, Bertrand" <bertranddrouvot.pg@gmail.com>

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

Cc: Andres Freund <andres@anarazel.de>, Robert Haas <robertmhaas@gmail.com>, Thomas Munro <thomas.munro@gmail.com>, Alvaro Herrera <alvherre@2ndquadrant.com>, Ibrar Ahmed <ibrar.ahmad@gmail.com>, Amit Khandekar <amitdkhan.pg@gmail.com>, fabriziomello@gmail.com, tushar <tushar.ahuja@enterprisedb.com>, Rahila Syed <rahila.syed@2ndquadrant.com>, pgsql-hackers <pgsql-hackers@postgresql.org>

Date: 2023-02-07T10:36:48Z

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 →

Reduce the log level in 035_standby_logical_decoding.pl.
- 3034dc56ef4b 16.0 landed
035_standby_logical_decoding: Add missing waits for replication
- 57411c82ce86 16.0 landed
For cascading replication, wake physical and logical walsenders separately
- e101dfac3a53 16.0 landed
Handle logical slot conflicts on standby
- 26669757b6a7 16.0 landed
Support invalidating replication slots due to horizon and wal_level
- be87200efd93 16.0 landed
Prevent use of invalidated logical slot in CreateDecodingContext()
- 4397abd0a2af 16.0 landed
Replace replication slot's invalidated_at LSN with an enum
- 15f8203a5975 16.0 landed
Pass down table relation into more index relation functions
- 61b313e47eb9 16.0 landed
Assert only valid flag bits are passed to visibilitymap_set()
- a88a18b1250b 16.0 landed
Remove unused _bt_delitems_delete() argument.
- dc43492e46c7 14.0 cited
Add xl_btree_delete optimization.
- d2e5e20e5711 13.0 cited

Attachments

v48-0006-Doc-changes-describing-details-about-logical-dec.patch (text/plain) patch v48-0006
v48-0005-New-TAP-test-for-logical-decoding-on-standby.patch (text/plain) patch v48-0005
v48-0004-Fixing-Walsender-corner-case-with-logical-decodi.patch (text/plain) patch v48-0004
v48-0003-Allow-logical-decoding-on-standby.patch (text/plain) patch v48-0003
v48-0002-Handle-logical-slot-conflicts-on-standby.patch (text/plain) patch v48-0002
v48-0001-Add-info-in-WAL-records-in-preparation-for-logic.patch (text/plain) patch v48-0001

Hi,

On 1/11/23 4:23 PM, Drouvot, Bertrand wrote:
> Hi,
> 
> On 1/11/23 8:32 AM, Bharath Rupireddy wrote:
>> On Tue, Jan 10, 2023 at 2:03 PM Drouvot, Bertrand
>> <bertranddrouvot.pg@gmail.com> wrote:
>>>
>>> Please find attached, V37 taking care of:
>>
>> Thanks. I started to digest the design specified in the commit message
>> and these patches. 
> 
> Thanks for looking at it!
> 
>> Here are some quick comments:
>>
>> 1. Does logical decoding on standby work without any issues if the
>> standby is set for cascading replication?
>>
> 
> Without "any issues" is hard to guarantee ;-) But according to my tests:
> 
> Primary -> Standby1 with or without logical replication slot -> Standby2 with or without logical replication slot
> 
> works as expected (and also with cascading promotion).
> We can add some TAP tests in 0004 though.

Cascading standby tests have been added in V48 attached.

It does test that:

- a sql logical decoding session on the cascading standby get expected output before/after the standby promotion
- a pg_recvlogical logical decoding session on the cascading standby (started before the standby promotion) get expected output before/after the standby promotion

Regards,

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