Re: logical decoding and replication of sequences, take 2

Dilip Kumar <dilipbalaut@gmail.com>

From: Dilip Kumar <dilipbalaut@gmail.com>

To: Tomas Vondra <tomas.vondra@enterprisedb.com>

Cc: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>, Amit Kapila <amit.kapila16@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>, Masahiko Sawada <sawada.mshk@gmail.com>, Peter Eisentraut <peter.eisentraut@enterprisedb.com>

Date: 2023-09-20T09:53:43Z

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 →

Migrate logical slots to the new node during an upgrade.
- 29d0a77fa660 17.0 cited
Make test_decoding ddl.out shorter
- d6677b93c79b 17.0 landed
- c5c5832600e9 14.9 landed
- b1dc946eee3d 16.0 landed
- 3bb8b9342f8a 15.4 landed
Fix snapshot handling in logicalmsg_decode
- 949ac32e1267 15.3 landed
- 8b9cbd42b61f 14.8 landed
- 4df581fa0f4b 13.11 landed
- 497f863f0598 12.15 landed
- 8de91ebf2ac1 11.20 landed
- 7fe1aa991b62 16.0 landed
doc: Adjust a few more references to "postmaster"
- 17e72ec45d31 16.0 cited
Revert "Logical decoding of sequences"
- 2c7ea57e56ca 15.0 cited

On Wed, Aug 16, 2023 at 7:57 PM Tomas Vondra
<tomas.vondra@enterprisedb.com> wrote:
>

I was reading through 0001, I noticed this comment in
ReorderBufferSequenceIsTransactional() function

+ * To decide if a sequence change should be handled as transactional or applied
+ * immediately, we track (sequence) relfilenodes created by each transaction.
+ * We don't know if the current sub-transaction was already assigned to the
+ * top-level transaction, so we need to check all transactions.

It says "We don't know if the current sub-transaction was already
assigned to the top-level transaction, so we need to check all
transactions". But IIRC as part of the steaming of in-progress
transactions we have ensured that whenever we are logging the first
change by any subtransaction we include the top transaction ID in it.

Refer this code

LogicalDecodingProcessRecord(LogicalDecodingContext *ctx,
XLogReaderState *record)
{
...
/*
* If the top-level xid is valid, we need to assign the subxact to the
* top-level xact. We need to do this for all records, hence we do it
* before the switch.
*/
if (TransactionIdIsValid(txid))
{
ReorderBufferAssignChild(ctx->reorder,
txid,
XLogRecGetXid(record),
buf.origptr);
}
}

-- 
Regards,
Dilip Kumar
EnterpriseDB: http://www.enterprisedb.com