Re: BUG #17865: Logical decoding : JDBC - Out of memory exception (WAL2JSON Format -1) gives a wrong associated LSN

On Thu, Mar 23, 2023, at 9:22 AM, PG Bug reporting form wrote:
> This issue happens while reading from the logical replication slot (WAL2JSON
> plugin).
> When there are multiple sessions writing to Postgres tables and there is a
> Postgres StringBuffer limit exceeded exception (processing transactions
> greater than 1GB size), the associated LSN reported in the SQLException
> object is incorrect.

If you have a big transaction then it is a format 1 limitation. In this case,
you have 2 options:

* use write-in-chunks parameter. It is only available for format 1;
* use format 2.

Format 1 is the default but format 2 avoid issues with big transactions.

> Now, the Java logical decoding API reading from the slot will fail with Out
> of memory error while processing the session 2's transaction. Exception
> object received contains irrelevant LSN marked as associated LSN.
> Note: Incase of single session writing to the database the Associated LSN is
> clearly of the failing transaction.
>

I know nothing about JDBC, if the options above does not solve your problem, I
suggest that you ask in pgsql-jdbc mailing list. If after investigation, you
conclude that it is a wal2json limitation/bug, open a issue [1].

[1] https://github.com/eulerto/wal2json/issues

--
Euler Taveira
EDB https://www.enterprisedb.com/