Re: Minimal logical decoding on standbys

Andres Freund <andres@anarazel.de>

From: Andres Freund <andres@anarazel.de>

To: tushar <tushar.ahuja@enterprisedb.com>

Cc: Amit Khandekar <amitdkhan.pg@gmail.com>, Robert Haas <robertmhaas@gmail.com>, Petr Jelinek <petr.jelinek@2ndquadrant.com>, Craig Ringer <craig@2ndquadrant.com>, Petr Jelinek <petr@2ndquadrant.com>, pgsql-hackers <pgsql-hackers@postgresql.org>

Date: 2019-07-16T17:26:44Z

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 →

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

Hi,

On 2019-07-12 14:53:21 +0530, tushar wrote:
> On 07/10/2019 05:12 PM, Amit Khandekar wrote:
> > All right. Will do that in the next patch set. For now, I have quickly
> > done the below changes in a single patch again (attached), in order to
> > get early comments if any.
> Thanks Amit for your patch. i am able to see 1 issues  on Standby server -
> (where  logical replication slot created ) ,
> a)size of  pg_wal folder  is NOT decreasing even after firing get_changes
> function

Even after calling pg_logical_slot_get_changes() multiple times? What
does
SELECT * FROM pg_replication_slots; before and after multiple calls return?

Does manually forcing a checkpoint with CHECKPOINT; first on the primary
and then the standby "fix" the issue?

> b)pg_wal files are not recycling  and every time it is creating new files
> after firing get_changes function

I'm not sure what you mean by this. Are you saying that
pg_logical_slot_get_changes() causes WAL to be written?

Greetings,

Andres Freund