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Make logical WAL sender report streaming state appropriately 

WAL senders sending logically-decoded data fail to properly report in
"streaming" state when starting up, hence as long as one extra record is
not replayed, such WAL senders would remain in a "catchup" state, which
is inconsistent with the physical cousin.

This can be easily reproduced by for example using pg_recvlogical and
restarting the upstream server.  The TAP tests have been slightly
modified to detect the failure and strengthened so as future tests also
make sure that a node is in streaming state when waiting for its
catchup.

Backpatch down to 9.4 where this code has been introduced.

Reported-by: Sawada Masahiko
Author: Simon Riggs, Sawada Masahiko
Reviewed-by: Petr Jelinek, Michael Paquier, Vaishnavi Prabakaran
Discussion: https://postgr.es/m/CAD21AoB2ZbCCqOx=bgKMcLrAvs1V0ZMqzs7wBTuDySezTGtMZA@mail.gmail.com
This commit is contained in:
Michael Paquier 2018-07-12 10:19:35 +09:00
parent 39a96512b3
commit 9a7b7adc13
3 changed files with 23 additions and 7 deletions
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20
src/backend/replication/walsender.c
View File

@ -2169,7 +2169,7 @@ WalSndLoop(WalSndSendDataCallback send_data)
if (MyWalSnd->state == WALSNDSTATE_CATCHUP)
{
ereport(DEBUG1,
(errmsg("standby \"%s\" has now caught up with primary",
(errmsg("\"%s\" has now caught up with upstream server",
application_name)));
WalSndSetState(WALSNDSTATE_STREAMING);
}
@ -2758,10 +2758,10 @@ XLogSendLogical(void)
char *errm;
/*
* Don't know whether we've caught up yet. We'll set it to true in
* WalSndWaitForWal, if we're actually waiting. We also set to true if
* XLogReadRecord() had to stop reading but WalSndWaitForWal didn't wait -
* i.e. when we're shutting down.
* Don't know whether we've caught up yet. We'll set WalSndCaughtUp to
* true in WalSndWaitForWal, if we're actually waiting. We also set to
* true if XLogReadRecord() had to stop reading but WalSndWaitForWal
* didn't wait - i.e. when we're shutting down.
*/
WalSndCaughtUp = false;
@ -2774,6 +2774,9 @@ XLogSendLogical(void)
if (record != NULL)
{
/* XXX: Note that logical decoding cannot be used while in recovery */
XLogRecPtr flushPtr = GetFlushRecPtr();
/*
* Note the lack of any call to LagTrackerWrite() which is handled by
* WalSndUpdateProgress which is called by output plugin through
@ -2782,6 +2785,13 @@ XLogSendLogical(void)
LogicalDecodingProcessRecord(logical_decoding_ctx, logical_decoding_ctx->reader);
sentPtr = logical_decoding_ctx->reader->EndRecPtr;
/*
* If we have sent a record that is at or beyond the flushed point, we
* have caught up.
*/
if (sentPtr >= flushPtr)
WalSndCaughtUp = true;
}
else
{

5
src/test/perl/PostgresNode.pm
View File

@ -1535,7 +1535,8 @@ also works for logical subscriptions)
until its replication location in pg_stat_replication equals or passes the
upstream's WAL insert point at the time this function is called. By default
the replay_lsn is waited for, but 'mode' may be specified to wait for any of
sent|write|flush|replay.
sent|write|flush|replay. The connection catching up must be in a streaming
state.
If there is no active replication connection from this peer, waits until
poll_query_until timeout.
@ -1580,7 +1581,7 @@ sub wait_for_catchup
. $lsn_expr . " on "
. $self->name . "\n";
my $query =
qq[SELECT $lsn_expr <= ${mode}_lsn FROM pg_catalog.pg_stat_replication WHERE application_name = '$standby_name';];
qq[SELECT $lsn_expr <= ${mode}_lsn AND state = 'streaming' FROM pg_catalog.pg_stat_replication WHERE application_name = '$standby_name';];
$self->poll_query_until('postgres', $query)
or croak "timed out waiting for catchup";
print "done\n";

5
src/test/subscription/t/001_rep_changes.pl
View File

@ -188,6 +188,11 @@ $node_publisher->safe_psql('postgres',
"INSERT INTO tab_ins SELECT generate_series(1001,1100)");
$node_publisher->safe_psql('postgres', "DELETE FROM tab_rep");
# Restart the publisher and check the state of the subscriber which
# should be in a streaming state after catching up.
$node_publisher->stop('fast');
$node_publisher->start;
$node_publisher->wait_for_catchup($appname);
$result = $node_subscriber->safe_psql('postgres',