From 66fd0adc73a8d3b0c43423c7d263cba37edaa36b Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter@eisentraut.org>
Date: Mon, 6 Jan 2020 08:21:14 +0100
Subject: [PATCH] Have logical replication subscriber fire column triggers

The logical replication apply worker did not fire per-column update
triggers because the updatedCols bitmap in the RTE was not populated.
This fixes that.

Reviewed-by: Euler Taveira <euler@timbira.com.br>
Discussion: https://www.postgresql.org/message-id/flat/21673e2d-597c-6afe-637e-e8b10425b240%402ndquadrant.com
---
 src/backend/replication/logical/worker.c   | 18 ++++++++++++
 src/test/subscription/t/003_constraints.pl | 34 +++++++++++++++++++---
 2 files changed, 48 insertions(+), 4 deletions(-)

diff --git a/src/backend/replication/logical/worker.c b/src/backend/replication/logical/worker.c
index 67126088385..7e3f3f0b0c0 100644
--- a/src/backend/replication/logical/worker.c
+++ b/src/backend/replication/logical/worker.c
@@ -27,6 +27,7 @@
 #include "pgstat.h"
 #include "funcapi.h"
 
+#include "access/sysattr.h"
 #include "access/xact.h"
 #include "access/xlog_internal.h"
 
@@ -703,6 +704,8 @@ apply_handle_update(StringInfo s)
 	bool		has_oldtup;
 	TupleTableSlot *localslot;
 	TupleTableSlot *remoteslot;
+	RangeTblEntry *target_rte;
+	int			i;
 	bool		found;
 	MemoryContext oldctx;
 
@@ -732,6 +735,21 @@ apply_handle_update(StringInfo s)
 	ExecSetSlotDescriptor(localslot, RelationGetDescr(rel->localrel));
 	EvalPlanQualInit(&epqstate, estate, NULL, NIL, -1);
 
+	/*
+	 * Populate updatedCols so that per-column triggers can fire.  This could
+	 * include more columns than were actually changed on the publisher
+	 * because the logical replication protocol doesn't contain that
+	 * information.  But it would for example exclude columns that only exist
+	 * on the subscriber, since we are not touching those.
+	 */
+	target_rte = list_nth(estate->es_range_table, 0);
+	for (i = 0; i < remoteslot->tts_tupleDescriptor->natts; i++)
+	{
+		if (newtup.changed[i])
+			target_rte->updatedCols = bms_add_member(target_rte->updatedCols,
+													 i + 1 - FirstLowInvalidHeapAttributeNumber);
+	}
+
 	PushActiveSnapshot(GetTransactionSnapshot());
 	ExecOpenIndices(estate->es_result_relation_info, false);
 
diff --git a/src/test/subscription/t/003_constraints.pl b/src/test/subscription/t/003_constraints.pl
index 06863aef84a..65528edf537 100644
--- a/src/test/subscription/t/003_constraints.pl
+++ b/src/test/subscription/t/003_constraints.pl
@@ -3,7 +3,7 @@ use strict;
 use warnings;
 use PostgresNode;
 use TestLib;
-use Test::More tests => 4;
+use Test::More tests => 6;
 
 # Initialize publisher node
 my $node_publisher = get_new_node('publisher');
@@ -88,6 +88,8 @@ BEGIN
         ELSE
             RETURN NULL;
         END IF;
+    ELSIF (TG_OP = 'UPDATE') THEN
+        RETURN NULL;
     ELSE
         RAISE WARNING 'Unknown action';
         RETURN NULL;
@@ -95,7 +97,7 @@ BEGIN
 END;
 \$\$ LANGUAGE plpgsql;
 CREATE TRIGGER filter_basic_dml_trg
-    BEFORE INSERT ON tab_fk_ref
+    BEFORE INSERT OR UPDATE OF bid ON tab_fk_ref
     FOR EACH ROW EXECUTE PROCEDURE filter_basic_dml_fn();
 ALTER TABLE tab_fk_ref ENABLE REPLICA TRIGGER filter_basic_dml_trg;
 });
@@ -107,10 +109,34 @@ $node_publisher->safe_psql('postgres',
 $node_publisher->poll_query_until('postgres', $caughtup_query)
   or die "Timed out while waiting for subscriber to catch up";
 
-# The row should be skipped on subscriber
+# The trigger should cause the insert to be skipped on subscriber
 $result = $node_subscriber->safe_psql('postgres',
 	"SELECT count(*), min(bid), max(bid) FROM tab_fk_ref;");
-is($result, qq(2|1|2), 'check replica trigger applied on subscriber');
+is($result, qq(2|1|2), 'check replica insert trigger applied on subscriber');
+
+# Update data
+$node_publisher->safe_psql('postgres',
+	"UPDATE tab_fk_ref SET bid = 2 WHERE bid = 1;");
+
+$node_publisher->poll_query_until('postgres', $caughtup_query)
+  or die "Timed out while waiting for subscriber to catch up";
+
+# The trigger should cause the update to be skipped on subscriber
+$result = $node_subscriber->safe_psql('postgres',
+	"SELECT count(*), min(bid), max(bid) FROM tab_fk_ref;");
+is($result, qq(2|1|2), 'check replica update column trigger applied on subscriber');
+
+# Update on a column not specified in the trigger, but it will trigger
+# anyway because logical replication ships all columns in an update.
+$node_publisher->safe_psql('postgres',
+	"UPDATE tab_fk_ref SET id = 6 WHERE id = 1;");
+
+$node_publisher->poll_query_until('postgres', $caughtup_query)
+  or die "Timed out while waiting for subscriber to catch up";
+
+$result = $node_subscriber->safe_psql('postgres',
+	"SELECT count(*), min(id), max(id) FROM tab_fk_ref;");
+is($result, qq(2|1|2), 'check column trigger applied on even for other column');
 
 $node_subscriber->stop('fast');
 $node_publisher->stop('fast');