Re: Log a warning in pg_createsubscriber for max_slot_wal_keep_size

Hi Shubham,

Some review comments for patch v8=0001.

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Commit message.

1.
By ensuring 'max_slot_wal_keep_size' is -1, this patch prevents the potential
deletion of required WAL files on the publisher that could disrupt logical
replication. A test case has been added to validate correct warning reporting
when 'max_slot_wal_keep_size' is misconfigured.

~

AFAIK the patch only logs a warning. It is not *enforcing* anything at all.

So, saying "ensuring" and "preventing" is misleading.

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src/bin/pg_basebackup/pg_createsubscriber.c

check_publisher:

2.
+ max_slot_wal_keep_size = strtoi64(PQgetvalue(res, 0, 6), NULL, 0);

Is passing base 0 here ok?

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src/bin/pg_basebackup/t/040_pg_createsubscriber.pl

3.
+# reload configuration
+$node_p->append_conf('postgresql.conf', 'max_slot_wal_keep_size = 10MB');
+$node_p->reload;
+
+# dry run mode on node S and verify the warning message for misconfigured
+# 'max_slot_wal_keep_size'
+command_checks_all(

Because of the --verbose I expected to see the pg_log_debug message
getting output showing the large (10MB) value for
max_slot_wal_keep_size.

But, I can only see a value of -1 in the log file
'tmp_check/log/regress_log_040_pg_createsubscriber', which may not
even be from the same test. Am I looking in the wrong place (???) e.g.
Where is the logging evidence of that publisher's bad GUC (10MB) value
in the logs before the warning is emitted?

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Kind Regards,
Peter Smith.
Fujitsu Australia