From d341305e072b64595b28d6550f51c513dd47a634 Mon Sep 17 00:00:00 2001
From: Hayato Kuroda <kuroda.hayato@fujitsu.com>
Date: Wed, 13 Mar 2024 07:30:05 +0000
Subject: [PATCH] fix snapbuild bug by approach a

---
 contrib/test_decoding/Makefile                |  3 +-
 .../expected/skip_snapshot_restore.out        | 81 +++++++++++++++++++
 contrib/test_decoding/meson.build             |  1 +
 .../specs/skip_snapshot_restore.spec          | 57 +++++++++++++
 src/backend/replication/logical/logical.c     | 11 +--
 src/backend/replication/slotfuncs.c           |  1 -
 src/backend/replication/walsender.c           |  8 +-
 src/include/replication/logical.h             |  1 -
 8 files changed, 146 insertions(+), 17 deletions(-)
 create mode 100644 contrib/test_decoding/expected/skip_snapshot_restore.out
 create mode 100644 contrib/test_decoding/specs/skip_snapshot_restore.spec

diff --git a/contrib/test_decoding/Makefile b/contrib/test_decoding/Makefile
index c7ce603706..a4ba1a509a 100644
--- a/contrib/test_decoding/Makefile
+++ b/contrib/test_decoding/Makefile
@@ -8,7 +8,8 @@ REGRESS = ddl xact rewrite toast permissions decoding_in_xact \
 	spill slot truncate stream stats twophase twophase_stream
 ISOLATION = mxact delayed_startup ondisk_startup concurrent_ddl_dml \
 	oldest_xmin snapshot_transfer subxact_without_top concurrent_stream \
-	twophase_snapshot slot_creation_error catalog_change_snapshot
+	twophase_snapshot slot_creation_error catalog_change_snapshot \
+	skip_snapshot_restore
 
 REGRESS_OPTS = --temp-config $(top_srcdir)/contrib/test_decoding/logical.conf
 ISOLATION_OPTS = --temp-config $(top_srcdir)/contrib/test_decoding/logical.conf
diff --git a/contrib/test_decoding/expected/skip_snapshot_restore.out b/contrib/test_decoding/expected/skip_snapshot_restore.out
new file mode 100644
index 0000000000..cb0040660b
--- /dev/null
+++ b/contrib/test_decoding/expected/skip_snapshot_restore.out
@@ -0,0 +1,81 @@
+Parsed test spec with 3 sessions
+
+starting permutation: s0_init s0_begin s0_insert1 s1_init s2_checkpoint s2_get_changes_slot0 s0_insert2 s0_commit s1_get_changes_slot0 s1_get_changes_slot1
+step s0_init: SELECT 'init' FROM pg_create_logical_replication_slot('slot0', 'test_decoding');
+?column?
+--------
+init    
+(1 row)
+
+step s0_begin: BEGIN;
+step s0_insert1: INSERT INTO tbl VALUES (1);
+step s1_init: SELECT 'init' FROM pg_create_logical_replication_slot('slot1', 'test_decoding'); <waiting ...>
+step s2_checkpoint: CHECKPOINT;
+step s2_get_changes_slot0: SELECT data FROM pg_logical_slot_get_changes('slot0', NULL, NULL, 'skip-empty-xacts', '1', 'include-xids', '0');
+data
+----
+(0 rows)
+
+step s0_insert2: INSERT INTO tbl VALUES (2);
+step s0_commit: COMMIT;
+step s1_init: <... completed>
+?column?
+--------
+init    
+(1 row)
+
+step s1_get_changes_slot0: SELECT data FROM pg_logical_slot_get_changes('slot0', NULL, NULL, 'skip-empty-xacts', '1', 'include-xids', '0');
+data                                     
+-----------------------------------------
+BEGIN                                    
+table public.tbl: INSERT: val1[integer]:1
+table public.tbl: INSERT: val1[integer]:2
+COMMIT                                   
+(4 rows)
+
+step s1_get_changes_slot1: SELECT data FROM pg_logical_slot_get_changes('slot1', NULL, NULL, 'skip-empty-xacts', '1', 'include-xids', '0');
+data
+----
+(0 rows)
+
+?column?
+--------
+stop    
+(1 row)
+
+
+starting permutation: s0_init s0_begin s0_savepoint s0_insert1 s1_init s2_checkpoint s2_get_changes_slot0 s0_insert_cat s0_commit s1_get_changes_slot1
+step s0_init: SELECT 'init' FROM pg_create_logical_replication_slot('slot0', 'test_decoding');
+?column?
+--------
+init    
+(1 row)
+
+step s0_begin: BEGIN;
+step s0_savepoint: SAVEPOINT sp0;
+step s0_insert1: INSERT INTO tbl VALUES (1);
+step s1_init: SELECT 'init' FROM pg_create_logical_replication_slot('slot1', 'test_decoding'); <waiting ...>
+step s2_checkpoint: CHECKPOINT;
+step s2_get_changes_slot0: SELECT data FROM pg_logical_slot_get_changes('slot0', NULL, NULL, 'skip-empty-xacts', '1', 'include-xids', '0');
+data
+----
+(0 rows)
+
+step s0_insert_cat: INSERT INTO tbl VALUES (1);
+step s0_commit: COMMIT;
+step s1_init: <... completed>
+?column?
+--------
+init    
+(1 row)
+
+step s1_get_changes_slot1: SELECT data FROM pg_logical_slot_get_changes('slot1', NULL, NULL, 'skip-empty-xacts', '1', 'include-xids', '0');
+data
+----
+(0 rows)
+
+?column?
+--------
+stop    
+(1 row)
+
diff --git a/contrib/test_decoding/meson.build b/contrib/test_decoding/meson.build
index f1548c0faf..f643dc81a2 100644
--- a/contrib/test_decoding/meson.build
+++ b/contrib/test_decoding/meson.build
@@ -62,6 +62,7 @@ tests += {
       'concurrent_stream',
       'twophase_snapshot',
       'slot_creation_error',
+      'skip_snapshot_restore',
     ],
     'regress_args': [
       '--temp-config', files('logical.conf'),
diff --git a/contrib/test_decoding/specs/skip_snapshot_restore.spec b/contrib/test_decoding/specs/skip_snapshot_restore.spec
new file mode 100644
index 0000000000..6cb6c83ad8
--- /dev/null
+++ b/contrib/test_decoding/specs/skip_snapshot_restore.spec
@@ -0,0 +1,57 @@
+# Test that a slot creation skips to restore serialized snapshot to reach
+# the consistent state.
+
+setup
+{
+    DROP TABLE IF EXISTS tbl;
+    DROP TABLE IF EXISTS user_cat;
+    CREATE TABLE tbl (val1 integer);
+    CREATE TABLE user_cat (val1 integer) WITH (user_catalog_table = true);
+}
+
+teardown
+{
+    DROP TABLE tbl;
+    DROP TABLE user_cat;
+    SELECT 'stop' FROM pg_drop_replication_slot('slot0');
+    SELECT 'stop' FROM pg_drop_replication_slot('slot1');
+}
+
+session "s0"
+setup { SET synchronous_commit = on; }
+step "s0_init" { SELECT 'init' FROM pg_create_logical_replication_slot('slot0', 'test_decoding'); }
+step "s0_begin" { BEGIN; }
+step "s0_insert1" { INSERT INTO tbl VALUES (1); }
+step "s0_insert2" { INSERT INTO tbl VALUES (2); }
+step "s0_insert_cat" { INSERT INTO tbl VALUES (1); }
+step "s0_savepoint" { SAVEPOINT sp0; }
+step "s0_commit" { COMMIT; }
+
+session "s1"
+setup { SET synchronous_commit = on; }
+step "s1_init" { SELECT 'init' FROM pg_create_logical_replication_slot('slot1', 'test_decoding'); }
+step "s1_get_changes_slot0" { SELECT data FROM pg_logical_slot_get_changes('slot0', NULL, NULL, 'skip-empty-xacts', '1', 'include-xids', '0'); }
+step "s1_get_changes_slot1" { SELECT data FROM pg_logical_slot_get_changes('slot1', NULL, NULL, 'skip-empty-xacts', '1', 'include-xids', '0'); }
+
+session "s2"
+setup { SET synchronous_commit = on ;}
+step "s2_checkpoint" { CHECKPOINT; }
+step "s2_get_changes_slot0" { SELECT data FROM pg_logical_slot_get_changes('slot0', NULL, NULL, 'skip-empty-xacts', '1', 'include-xids', '0'); }
+
+
+# While 'slot1' creation by "s1_init" waits for s0-transaction to commit, the
+# RUNNING_XACTS record is written by "s2_checkpoint" and "s2_get_changes_slot1"
+# serializes consistent snapshots to the disk at LSNs where are before
+# s0-transaction's commit. After s0-transaction commits, "s1_init" resumes but
+# must not restore any serialized snapshots and reach the consistent state until
+# decoding s0-transaction's commit recrod. We check if the get_changes on 'slot1'
+# will not return any s0-transaction's changes as its confirmed_flush_lsn will
+# be after the s0-transaction's commit record.
+permutation "s0_init" "s0_begin" "s0_insert1" "s1_init" "s2_checkpoint" "s2_get_changes_slot0" "s0_insert2" "s0_commit" "s1_get_changes_slot0" "s1_get_changes_slot1"
+
+# The last decoding restarts from the NEW_CID record in the subtransaction.
+# While processing it, a same ReorderBufferChange entry would be associated
+# with both the top and the sub transaction, as the first entry. This breaks
+# an assumption in AssertTXNLsnOrder() which the first_lsn of entries must be
+# strictly higher than previous.
+permutation "s0_init" "s0_begin" "s0_savepoint" "s0_insert1" "s1_init" "s2_checkpoint" "s2_get_changes_slot0" "s0_insert_cat" "s0_commit" "s1_get_changes_slot1"
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index 51ffb623c0..e1d60f244d 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -306,8 +306,6 @@ StartupDecodingContext(List *output_plugin_options,
  *
  * plugin -- contains the name of the output plugin
  * output_plugin_options -- contains options passed to the output plugin
- * need_full_snapshot -- if true, must obtain a snapshot able to read all
- *		tables; if false, one that can read only catalogs is acceptable.
  * restart_lsn -- if given as invalid, it's this routine's responsibility to
  *		mark WAL as reserved by setting a convenient restart_lsn for the slot.
  *		Otherwise, we set for decoding to start from the given LSN without
@@ -327,7 +325,6 @@ StartupDecodingContext(List *output_plugin_options,
 LogicalDecodingContext *
 CreateInitDecodingContext(const char *plugin,
 						  List *output_plugin_options,
-						  bool need_full_snapshot,
 						  XLogRecPtr restart_lsn,
 						  XLogReaderRoutine *xl_routine,
 						  LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -420,13 +417,12 @@ CreateInitDecodingContext(const char *plugin,
 	 */
 	LWLockAcquire(ProcArrayLock, LW_EXCLUSIVE);
 
-	xmin_horizon = GetOldestSafeDecodingTransactionId(!need_full_snapshot);
+	xmin_horizon = GetOldestSafeDecodingTransactionId(false);
 
 	SpinLockAcquire(&slot->mutex);
 	slot->effective_catalog_xmin = xmin_horizon;
 	slot->data.catalog_xmin = xmin_horizon;
-	if (need_full_snapshot)
-		slot->effective_xmin = xmin_horizon;
+	slot->effective_xmin = xmin_horizon;
 	SpinLockRelease(&slot->mutex);
 
 	ReplicationSlotsComputeRequiredXmin(true);
@@ -437,7 +433,8 @@ CreateInitDecodingContext(const char *plugin,
 	ReplicationSlotSave();
 
 	ctx = StartupDecodingContext(NIL, restart_lsn, xmin_horizon,
-								 need_full_snapshot, false,
+								 true,		/* need_full_snapshot */
+								 false,		/* fast_forward */
 								 xl_routine, prepare_write, do_write,
 								 update_progress);
 
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index ad79e1fccd..6fb0fd0010 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -148,7 +148,6 @@ create_logical_replication_slot(char *name, char *plugin,
 	 * this point that the output plugin is validated.
 	 */
 	ctx = CreateInitDecodingContext(plugin, NIL,
-									false,	/* just catalogs is OK */
 									restart_lsn,
 									XL_ROUTINE(.page_read = read_local_xlog_page,
 											   .segment_open = wal_segment_open,
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index bc40c454de..e2924ba91a 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1237,7 +1237,6 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
 	else
 	{
 		LogicalDecodingContext *ctx;
-		bool		need_full_snapshot = false;
 
 		Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
 
@@ -1265,8 +1264,6 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
 				/*- translator: %s is a CREATE_REPLICATION_SLOT statement */
 						(errmsg("%s must not be called inside a transaction",
 								"CREATE_REPLICATION_SLOT ... (SNAPSHOT 'export')")));
-
-			need_full_snapshot = true;
 		}
 		else if (snapshot_action == CRS_USE_SNAPSHOT)
 		{
@@ -1298,12 +1295,9 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
 				/*- translator: %s is a CREATE_REPLICATION_SLOT statement */
 						(errmsg("%s must not be called in a subtransaction",
 								"CREATE_REPLICATION_SLOT ... (SNAPSHOT 'use')")));
-
-			need_full_snapshot = true;
 		}
 
-		ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
-										InvalidXLogRecPtr,
+		ctx = CreateInitDecodingContext(cmd->plugin, NIL, InvalidXLogRecPtr,
 										XL_ROUTINE(.page_read = logical_read_xlog_page,
 												   .segment_open = WalSndSegmentOpen,
 												   .segment_close = wal_segment_close),
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index dc2df4ce92..f1b40b4b92 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -119,7 +119,6 @@ extern void CheckLogicalDecodingRequirements(void);
 
 extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
 														 List *output_plugin_options,
-														 bool need_full_snapshot,
 														 XLogRecPtr restart_lsn,
 														 XLogReaderRoutine *xl_routine,
 														 LogicalOutputPluginWriterPrepareWrite prepare_write,
-- 
2.43.0

