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From: Fabrízio de Royes Mello <[email protected]>
To: Drouvot, Bertrand <[email protected]>
Cc: Alvaro Herrera <[email protected]>
Cc: Andres Freund <[email protected]>
Cc: tushar <[email protected]>
Cc: [pgdg] Robert Haas <[email protected]>
Cc: Amit Khandekar <[email protected]>
Cc: Rahila Syed <[email protected]>
Cc: pgsql-hackers <[email protected]>
Subject: Re: Minimal logical decoding on standbys
Date: Tue, 23 Mar 2021 11:29:41 -0300
Message-ID: <CAFcNs+q9FvSW7gMqM__aeWOoDNqfcQCoB8LiO-X33fvqGO8mkQ@mail.gmail.com> (raw)
In-Reply-To: <CAFcNs+rwMtfBkNkAodB9mZUAxyqvYHV0FzANm+uRiDLW6O7q1g@mail.gmail.com>
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On Tue, Mar 23, 2021 at 10:18 AM Fabrízio de Royes Mello <
[email protected]> wrote:
>
> LGTM too... Reviewing new changes now to move it forward and make this
patch set ready for commiter review.
>

According to the feature LGTM and all tests passed. Documentation is also
OK. Some minor comments:

+    <para>
+     A logical replication slot can also be created on a hot standby. To
prevent
+     <command>VACUUM</command> from removing required rows from the system
+     catalogs, <varname>hot_standby_feedback</varname> should be set on the
+     standby. In spite of that, if any required rows get removed, the slot
gets
+     dropped.  Existing logical slots on standby also get dropped if
wal_level
+     on primary is reduced to less than 'logical'.
+    </para>

Remove extra space before "Existing logical slots..."

+            pg_stat_get_db_conflict_logicalslot(D.oid) AS
confl_logicalslot,

Move it to the end of pg_stat_database_conflicts columns


+            * is being reduced.  Hence this extra check.

Remove extra space before "Hence this..."


+       /* Send the other backend, a conflict recovery signal */
+
+       SetInvalidVirtualTransactionId(vxid);

Remove extra empty line


+               if (restart_lsn % XLOG_BLCKSZ != 0)
+                   elog(ERROR, "invalid replay pointer");

Add an empty line after this "IF" for code readability


+void
+ResolveRecoveryConflictWithLogicalSlots(Oid dboid, TransactionId xid,
+                                       char *conflict_reason)
+{
+   int         i;
+   bool        found_conflict = false;
+
+   if (max_replication_slots <= 0)
+       return;

What about adding an "Assert(max_replication_slots >= 0);" before the
replication slots check?

One last thing is about the name of TAP tests, we should rename them
because there are other TAP tests starting with 022_ and 023_. It should be
renamed to:

src/test/recovery/t/022_standby_logical_decoding_xmins.pl ->
src/test/recovery/t/024_standby_logical_decoding_xmins.pl
src/test/recovery/t/023_standby_logical_decoding_conflicts.pl
-> src/test/recovery/t/025_standby_logical_decoding_conflicts.pl

Regards,

-- 
   Fabrízio de Royes Mello
   PostgreSQL Developer at OnGres Inc. - https://ongres.com


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