Matview statistics depend on matview data.

REFRESH MATERIALIZED VIEW replaces the storage, which resets
statistics, so statistics must be restored afterward.

If both statistics and data are being dumped for a materialized view,
add a dependency from the former to the latter. Defer the statistics
to SECTION_POST_DATA, and use RESTORE_PASS_POST_ACL.

Reported-by: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>
Reviewed-by: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>
Discussion: https://postgr.es/m/CAExHW5s47kmubpbbRJzSM-Zfe0Tj2O3GBagB7YAyE8rQ-V24Uw@mail.gmail.com

src/bin/pg_dump/pg_backup_archiver.c

@@ -72,7 +72,7 @@ static void processEncodingEntry(ArchiveHandle *AH, TocEntry *te);
 static void processStdStringsEntry(ArchiveHandle *AH, TocEntry *te);
 static void processSearchPathEntry(ArchiveHandle *AH, TocEntry *te);
 static int	_tocEntryRequired(TocEntry *te, teSection curSection, ArchiveHandle *AH);
-static RestorePass _tocEntryRestorePass(TocEntry *te);
+static RestorePass _tocEntryRestorePass(ArchiveHandle *AH, TocEntry *te);
 static bool _tocEntryIsACL(TocEntry *te);
 static void _disableTriggersIfNecessary(ArchiveHandle *AH, TocEntry *te);
 static void _enableTriggersIfNecessary(ArchiveHandle *AH, TocEntry *te);
@@ -102,7 +102,8 @@ static void pending_list_append(TocEntry *l, TocEntry *te);
 static void pending_list_remove(TocEntry *te);
 static int	TocEntrySizeCompareQsort(const void *p1, const void *p2);
 static int	TocEntrySizeCompareBinaryheap(void *p1, void *p2, void *arg);
-static void move_to_ready_heap(TocEntry *pending_list,
+static void move_to_ready_heap(ArchiveHandle *AH,
+							   TocEntry *pending_list,
 							   binaryheap *ready_heap,
 							   RestorePass pass);
 static TocEntry *pop_next_work_item(binaryheap *ready_heap,
@@ -748,7 +749,7 @@ RestoreArchive(Archive *AHX)
 			if ((te->reqs & (REQ_SCHEMA | REQ_DATA | REQ_STATS)) == 0)
 				continue;		/* ignore if not to be dumped at all */
 
-			switch (_tocEntryRestorePass(te))
+			switch (_tocEntryRestorePass(AH, te))
 			{
 				case RESTORE_PASS_MAIN:
 					(void) restore_toc_entry(AH, te, false);
@@ -767,7 +768,7 @@ RestoreArchive(Archive *AHX)
 			for (te = AH->toc->next; te != AH->toc; te = te->next)
 			{
 				if ((te->reqs & (REQ_SCHEMA | REQ_DATA | REQ_STATS)) != 0 &&
-					_tocEntryRestorePass(te) == RESTORE_PASS_ACL)
+					_tocEntryRestorePass(AH, te) == RESTORE_PASS_ACL)
 					(void) restore_toc_entry(AH, te, false);
 			}
 		}
@@ -777,7 +778,7 @@ RestoreArchive(Archive *AHX)
 			for (te = AH->toc->next; te != AH->toc; te = te->next)
 			{
 				if ((te->reqs & (REQ_SCHEMA | REQ_DATA | REQ_STATS)) != 0 &&
-					_tocEntryRestorePass(te) == RESTORE_PASS_POST_ACL)
+					_tocEntryRestorePass(AH, te) == RESTORE_PASS_POST_ACL)
 					(void) restore_toc_entry(AH, te, false);
 			}
 		}
@@ -3219,7 +3220,7 @@ _tocEntryRequired(TocEntry *te, teSection curSection, ArchiveHandle *AH)
  * See notes with the RestorePass typedef in pg_backup_archiver.h.
  */
 static RestorePass
-_tocEntryRestorePass(TocEntry *te)
+_tocEntryRestorePass(ArchiveHandle *AH, TocEntry *te)
 {
 	/* "ACL LANGUAGE" was a crock emitted only in PG 7.4 */
 	if (strcmp(te->desc, "ACL") == 0 ||
@@ -3240,6 +3241,26 @@ _tocEntryRestorePass(TocEntry *te)
 		strncmp(te->tag, "EVENT TRIGGER ", 14) == 0)
 		return RESTORE_PASS_POST_ACL;
 
+	/*
+	 * If statistics data is dependent on materialized view data, it must be
+	 * deferred to RESTORE_PASS_POST_ACL.
+	 */
+	if (strcmp(te->desc, "STATISTICS DATA") == 0)
+	{
+		for (int i = 0; i < te->nDeps; i++)
+		{
+			DumpId		depid = te->dependencies[i];
+
+			if (depid <= AH->maxDumpId && AH->tocsByDumpId[depid] != NULL)
+			{
+				TocEntry   *otherte = AH->tocsByDumpId[depid];
+
+				if (strcmp(otherte->desc, "MATERIALIZED VIEW DATA") == 0)
+					return RESTORE_PASS_POST_ACL;
+			}
+		}
+	}
+
 	/* All else can be handled in the main pass. */
 	return RESTORE_PASS_MAIN;
 }
@@ -4249,7 +4270,7 @@ restore_toc_entries_prefork(ArchiveHandle *AH, TocEntry *pending_list)
 		 * not set skipped_some in this case, since by assumption no main-pass
 		 * items could depend on these.
 		 */
-		if (_tocEntryRestorePass(next_work_item) != RESTORE_PASS_MAIN)
+		if (_tocEntryRestorePass(AH, next_work_item) != RESTORE_PASS_MAIN)
 			do_now = false;
 
 		if (do_now)
@@ -4331,7 +4352,7 @@ restore_toc_entries_parallel(ArchiveHandle *AH, ParallelState *pstate,
 	 * process in the current restore pass.
 	 */
 	AH->restorePass = RESTORE_PASS_MAIN;
-	move_to_ready_heap(pending_list, ready_heap, AH->restorePass);
+	move_to_ready_heap(AH, pending_list, ready_heap, AH->restorePass);
 
 	/*
 	 * main parent loop
@@ -4380,7 +4401,7 @@ restore_toc_entries_parallel(ArchiveHandle *AH, ParallelState *pstate,
 			/* Advance to next restore pass */
 			AH->restorePass++;
 			/* That probably allows some stuff to be made ready */
-			move_to_ready_heap(pending_list, ready_heap, AH->restorePass);
+			move_to_ready_heap(AH, pending_list, ready_heap, AH->restorePass);
 			/* Loop around to see if anything's now ready */
 			continue;
 		}
@@ -4551,7 +4572,8 @@ TocEntrySizeCompareBinaryheap(void *p1, void *p2, void *arg)
  * which applies the same logic one-at-a-time.)
  */
 static void
-move_to_ready_heap(TocEntry *pending_list,
+move_to_ready_heap(ArchiveHandle *AH,
+				   TocEntry *pending_list,
 				   binaryheap *ready_heap,
 				   RestorePass pass)
 {
@@ -4564,7 +4586,7 @@ move_to_ready_heap(TocEntry *pending_list,
 		next_te = te->pending_next;
 
 		if (te->depCount == 0 &&
-			_tocEntryRestorePass(te) == pass)
+			_tocEntryRestorePass(AH, te) == pass)
 		{
 			/* Remove it from pending_list ... */
 			pending_list_remove(te);
@@ -4958,7 +4980,7 @@ reduce_dependencies(ArchiveHandle *AH, TocEntry *te,
 		 * memberships changed.
 		 */
 		if (otherte->depCount == 0 &&
-			_tocEntryRestorePass(otherte) == AH->restorePass &&
+			_tocEntryRestorePass(AH, otherte) == AH->restorePass &&
 			otherte->pending_prev != NULL &&
 			ready_heap != NULL)
 		{

src/bin/pg_dump/pg_dump.c

@@ -3002,6 +3002,19 @@ makeTableDataInfo(DumpOptions *dopt, TableInfo *tbinfo)
 
 	tbinfo->dataObj = tdinfo;
 
+	/*
+	 * Materialized view statistics must be restored after the data, because
+	 * REFRESH MATERIALIZED VIEW replaces the storage and resets the stats.
+	 *
+	 * The dependency is added here because the statistics objects are created
+	 * first.
+	 */
+	if (tbinfo->relkind == RELKIND_MATVIEW && tbinfo->stats != NULL)
+	{
+		tbinfo->stats->section = SECTION_POST_DATA;
+		addObjectDependency(&tbinfo->stats->dobj, tdinfo->dobj.dumpId);
+	}
+
 	/* Make sure that we'll collect per-column info for this table. */
 	tbinfo->interesting = true;
 }
@@ -6893,7 +6906,32 @@ getRelationStatistics(Archive *fout, DumpableObject *rel, int32 relpages,
 		info->relkind = relkind;
 		info->indAttNames = indAttNames;
 		info->nindAttNames = nindAttNames;
-		info->postponed_def = false;
+
+		/*
+		 * Ordinarily, stats go in SECTION_DATA for tables and
+		 * SECTION_POST_DATA for indexes.
+		 *
+		 * However, the section may be updated later for materialized view
+		 * stats. REFRESH MATERIALIZED VIEW replaces the storage and resets
+		 * the stats, so the stats must be restored after the data. Also, the
+		 * materialized view definition may be postponed to SECTION_POST_DATA
+		 * (see repairMatViewBoundaryMultiLoop()).
+		 */
+		switch (info->relkind)
+		{
+			case RELKIND_RELATION:
+			case RELKIND_PARTITIONED_TABLE:
+			case RELKIND_MATVIEW:
+				info->section = SECTION_DATA;
+				break;
+			case RELKIND_INDEX:
+			case RELKIND_PARTITIONED_INDEX:
+				info->section = SECTION_POST_DATA;
+				break;
+			default:
+				pg_fatal("cannot dump statistics for relation kind '%c'",
+						 info->relkind);
+		}
 
 		return info;
 	}
@@ -7292,9 +7330,17 @@ getTables(Archive *fout, int *numTables)
 
 		/* Add statistics */
 		if (tblinfo[i].interesting)
-			getRelationStatistics(fout, &tblinfo[i].dobj, tblinfo[i].relpages,
+		{
-								  PQgetvalue(res, i, i_reltuples),
+			RelStatsInfo *stats;
-								  relallvisible, tblinfo[i].relkind, NULL, 0);
+
+			stats = getRelationStatistics(fout, &tblinfo[i].dobj,
+										  tblinfo[i].relpages,
+										  PQgetvalue(res, i, i_reltuples),
+										  relallvisible,
+										  tblinfo[i].relkind, NULL, 0);
+			if (tblinfo[i].relkind == RELKIND_MATVIEW)
+				tblinfo[i].stats = stats;
+		}
 
 		/*
 		 * Read-lock target tables to make sure they aren't DROPPED or altered
@@ -10491,34 +10537,6 @@ appendNamedArgument(PQExpBuffer out, Archive *fout, const char *argname,
 	appendPQExpBuffer(out, "::%s", argtype);
 }
 
-/*
- * Decide which section to use based on the relkind of the parent object.
- *
- * NB: materialized views may be postponed from SECTION_PRE_DATA to
- * SECTION_POST_DATA to resolve some kinds of dependency problems. If so, the
- * matview stats will also be postponed to SECTION_POST_DATA. See
- * repairMatViewBoundaryMultiLoop().
- */
-static teSection
-statisticsDumpSection(const RelStatsInfo *rsinfo)
-{
-	switch (rsinfo->relkind)
-	{
-		case RELKIND_RELATION:
-		case RELKIND_PARTITIONED_TABLE:
-		case RELKIND_MATVIEW:
-			return SECTION_DATA;
-		case RELKIND_INDEX:
-		case RELKIND_PARTITIONED_INDEX:
-			return SECTION_POST_DATA;
-		default:
-			pg_fatal("cannot dump statistics for relation kind '%c'",
-					 rsinfo->relkind);
-	}
-
-	return 0;					/* keep compiler quiet */
-}
-
 /*
  * dumpRelationStats --
  *
@@ -10531,8 +10549,6 @@ dumpRelationStats(Archive *fout, const RelStatsInfo *rsinfo)
 	PGresult   *res;
 	PQExpBuffer query;
 	PQExpBuffer out;
-	DumpId	   *deps = NULL;
-	int			ndeps = 0;
 	int			i_attname;
 	int			i_inherited;
 	int			i_null_frac;
@@ -10553,13 +10569,6 @@ dumpRelationStats(Archive *fout, const RelStatsInfo *rsinfo)
 	if (!fout->dopt->dumpStatistics)
 		return;
 
-	/* dependent on the relation definition, if doing schema */
-	if (fout->dopt->dumpSchema)
-	{
-		deps = dobj->dependencies;
-		ndeps = dobj->nDeps;
-	}
-
 	query = createPQExpBuffer();
 	if (!fout->is_prepared[PREPQUERY_GETATTRIBUTESTATS])
 	{
@@ -10737,11 +10746,10 @@ dumpRelationStats(Archive *fout, const RelStatsInfo *rsinfo)
 				 ARCHIVE_OPTS(.tag = dobj->name,
 							  .namespace = dobj->namespace->dobj.name,
 							  .description = "STATISTICS DATA",
-							  .section = rsinfo->postponed_def ?
+							  .section = rsinfo->section,
-							  SECTION_POST_DATA : statisticsDumpSection(rsinfo),
 							  .createStmt = out->data,
-							  .deps = deps,
+							  .deps = dobj->dependencies,
-							  .nDeps = ndeps));
+							  .nDeps = dobj->nDeps));
 
 	destroyPQExpBuffer(out);
 	destroyPQExpBuffer(query);
@@ -19429,7 +19437,7 @@ addBoundaryDependencies(DumpableObject **dobjs, int numObjs,
 				break;
 			case DO_REL_STATS:
 				/* stats section varies by parent object type, DATA or POST */
-				if (statisticsDumpSection((RelStatsInfo *) dobj) == SECTION_DATA)
+				if (((RelStatsInfo *) dobj)->section == SECTION_DATA)
 				{
 					addObjectDependency(dobj, preDataBound->dumpId);
 					addObjectDependency(postDataBound, dobj->dumpId);

src/bin/pg_dump/pg_dump.h

@@ -369,6 +369,7 @@ typedef struct _tableInfo
 	bool	   *notnull_islocal;	/* true if NOT NULL has local definition */
 	struct _attrDefInfo **attrdefs; /* DEFAULT expressions */
 	struct _constraintInfo *checkexprs; /* CHECK constraints */
+	struct _relStatsInfo *stats;	/* only set for matviews */
 	bool		needs_override; /* has GENERATED ALWAYS AS IDENTITY */
 	char	   *amname;			/* relation access method */
 
@@ -449,7 +450,7 @@ typedef struct _relStatsInfo
 	 */
 	char	  **indAttNames;	/* attnames of the index, in order */
 	int32		nindAttNames;	/* number of attnames stored (can be 0) */
-	bool		postponed_def;	/* stats must be postponed into post-data */
+	teSection	section;		/* stats may appear in data or post-data */
 } RelStatsInfo;
 
 typedef struct _statsExtInfo

src/bin/pg_dump/pg_dump_sort.c

@@ -820,7 +820,7 @@ repairMatViewBoundaryMultiLoop(DumpableObject *boundaryobj,
 		RelStatsInfo *nextinfo = (RelStatsInfo *) nextobj;
 
 		if (nextinfo->relkind == RELKIND_MATVIEW)
-			nextinfo->postponed_def = true;
+			nextinfo->section = SECTION_POST_DATA;
 	}
 }