Re: Minimal logical decoding on standbys

Bertrand Drouvot <bertranddrouvot.pg@gmail.com>

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

To: Robert Haas <robertmhaas@gmail.com>, Andres Freund <andres@anarazel.de>

Cc: 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: 2022-12-20T20:35:13Z

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

v34-0006-Fixing-Walsender-corner-case-with-logical-decodi.patch (text/plain) patch v34-0006
v34-0005-Doc-changes-describing-details-about-logical-dec.patch (text/plain) patch v34-0005
v34-0004-New-TAP-test-for-logical-decoding-on-standby.patch (text/plain) patch v34-0004
v34-0003-Allow-logical-decoding-on-standby.patch (text/plain) patch v34-0003
v34-0002-Handle-logical-slot-conflicts-on-standby.patch (text/plain) patch v34-0002
v34-0001-Add-info-in-WAL-records-in-preparation-for-logic.patch (text/plain) patch v34-0001

Hi,

On 12/20/22 7:31 PM, Robert Haas wrote:
> On Tue, Dec 20, 2022 at 1:19 PM Andres Freund <andres@anarazel.de> wrote:
>> I don't understand what the "may*" or "*Possible" really are
>> about. snapshotConflictHorizon is a conflict with a certain xid - there
>> commonly won't be anything to conflict with. If there's a conflict in
>> the logical-decoding-on-standby case, we won't be able to apply it only
>> sometimes or such.
> 
> The way I was imagining it is that snapshotConflictHorizon tells us
> whether there is a conflict with this record and then, if there is,
> this new Boolean tells us whether it's relevant to logical decoding as
> well.
> 

the "may*" or "*Possible" was, most probably, because I preferred to have the uncertainty of the conflict mentioned in the name.
But, somehow, I was forgetting about the relationship with snapshotConflictHorizon.
So, agree with both of you that mentioning about the uncertainty of the conflict is useless.

>> How about "affectsLogicalDecoding", "conflictsWithSlots" or
>> "isCatalogRel" or such?
> 
> isCatalogRel seems fine to me.

For me too, please find attached v34 using it.

Regards,

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