Re: Skipping logical replication transactions on subscriber side

On Thu, Jul 29, 2021 at 11:18 AM Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com> wrote:
>
> On Thu, Jul 29, 2021 at 2:04 PM Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com> wrote:
> >
> > > Yeah, it seems to be introduced by commit 0926e96c493. I've attached
> > > the patch for that.
> > >
> > > Also, I've attached the updated version patches. This version patch
> > > has pg_stat_reset_subscription_error() SQL function and sends a clear
> > > message after skipping the transaction. 0004 patch includes the
> > > skipping transaction feature and introducing RESET to ALTER
> > > SUBSCRIPTION. It would be better to separate them.
> > >

+1, to separate out the reset part.

> >
> > I've attached the new version patches that fix cfbot failure.
>
> Sorry I've attached wrong ones. Reattached the correct version patches.
>

Pushed the 0001* patch that removes the unused parameter.

Few comments on v4-0001-Add-errcontext-to-errors-of-the-applying-logical-
===========================================================
1.
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -78,6 +78,7 @@
#include "partitioning/partbounds.h"
#include "partitioning/partdesc.h"
#include "pgstat.h"
+#include "replication/logicalworker.h"
#include "rewrite/rewriteDefine.h"
#include "rewrite/rewriteHandler.h"
#include "rewrite/rewriteManip.h"
@@ -1899,6 +1900,9 @@ ExecuteTruncateGuts(List *explicit_rels,
continue;
}

+ /* Set logical replication error callback info if necessary */
+ set_logicalrep_error_context_rel(rel);
+
/*
* Build the lists of foreign tables belonging to each foreign server
* and pass each list to the foreign data wrapper's callback function,
@@ -2006,6 +2010,9 @@ ExecuteTruncateGuts(List *explicit_rels,
pgstat_count_truncate(rel);
}

+ /* Reset logical replication error callback info */
+ reset_logicalrep_error_context_rel();
+

Setting up logical rep error context in a generic function looks a bit
odd to me. Do we really need to set up error context here? I
understand we can't do this in caller but anyway I think we are not
sending this to logical replication view as well, so not sure we need
to do it here.

2.
+/* Struct for saving and restoring apply information */
+typedef struct ApplyErrCallbackArg
+{
+ LogicalRepMsgType command; /* 0 if invalid */
+
+ /* Local relation information */
+ char *nspname; /* used for error context */
+ char *relname; /* used for error context */
+
+ TransactionId remote_xid;
+ TimestampTz committs;
+} ApplyErrCallbackArg;
+static ApplyErrCallbackArg apply_error_callback_arg =
+{
+ .command = 0,
+ .relname = NULL,
+ .nspname = NULL,
+ .remote_xid = InvalidTransactionId,
+ .committs = 0,
+};
+

Better to have a space between the above two declarations.

3. commit message:
This commit adds the error context to errors happening during applying
logical replication changes, showing the command, the relation
relation, transaction ID, and commit timestamp in the server log.

'relation' is mentioned twice.

The patch is not getting applied probably due to yesterday's commit in
this area.

--
With Regards,
Amit Kapila.