Rearrange pg_dump's handling of large objects for better efficiency.

Commit c0d5be5d6 caused pg_dump to create a separate BLOB metadata TOC
entry for each large object (blob), but it did not touch the ancient
decision to put all the blobs' data into a single "BLOBS" TOC entry.
This is bad for a few reasons: for databases with millions of blobs,
the TOC becomes unreasonably large, causing performance issues;
selective restore of just some blobs is quite impossible; and we
cannot parallelize either dump or restore of the blob data, since our
architecture for that relies on farming out whole TOC entries to
worker processes.

To improve matters, let's group multiple blobs into each blob metadata
TOC entry, and then make corresponding per-group blob data TOC entries.
Selective restore using pg_restore's -l/-L switches is then possible,
though only at the group level.  (Perhaps we should provide a switch
to allow forcing one-blob-per-group for users who need precise
selective restore and don't have huge numbers of blobs.  This patch
doesn't do that, instead just hard-wiring the maximum number of blobs
per entry at 1000.)

The blobs in a group must all have the same owner, since the TOC entry
format only allows one owner to be named.  In this implementation
we also require them to all share the same ACL (grants); the archive
format wouldn't require that, but pg_dump's representation of
DumpableObjects does.  It seems unlikely that either restriction
will be problematic for databases with huge numbers of blobs.

The metadata TOC entries now have a "desc" string of "BLOB METADATA",
and their "defn" string is just a newline-separated list of blob OIDs.
The restore code has to generate creation commands, ALTER OWNER
commands, and drop commands (for --clean mode) from that.  We would
need special-case code for ALTER OWNER and drop in any case, so the
alternative of keeping the "defn" as directly executable SQL code
for creation wouldn't buy much, and it seems like it'd bloat the
archive to little purpose.

Since we require the blobs of a metadata group to share the same ACL,
we can furthermore store only one copy of that ACL, and then make
pg_restore regenerate the appropriate commands for each blob.  This
saves space in the dump file not only by removing duplicative SQL
command strings, but by not needing a separate TOC entry for each
blob's ACL.  In turn, that reduces client-side memory requirements for
handling many blobs.

ACL TOC entries that need this special processing are labeled as
"ACL"/"LARGE OBJECTS nnn..nnn".  If we have a blob with a unique ACL,
continue to label it as "ACL"/"LARGE OBJECT nnn".  We don't actually
have to make such a distinction, but it saves a few cycles during
restore for the easy case, and it seems like a good idea to not change
the TOC contents unnecessarily.

The data TOC entries ("BLOBS") are exactly the same as before,
except that now there can be more than one, so we'd better give them
identifying tag strings.

Also, commit c0d5be5d6 put the new BLOB metadata TOC entries into
SECTION_PRE_DATA, which perhaps is defensible in some ways, but
it's a rather odd choice considering that we go out of our way to
treat blobs as data.  Moreover, because parallel restore handles
the PRE_DATA section serially, this means we'd only get part of the
parallelism speedup we could hope for.  Move these entries into
SECTION_DATA, letting us parallelize the lo_create calls not just the
data loading when there are many blobs.  Add dependencies to ensure
that we won't try to load data for a blob we've not yet created.

As this stands, we still generate a separate TOC entry for any comment
or security label attached to a blob.  I feel comfortable in believing
that comments and security labels on blobs are rare, so this patch
should be enough to get most of the useful TOC compression for blobs.

We have to bump the archive file format version number, since existing
versions of pg_restore wouldn't know they need to do something special
for BLOB METADATA, plus they aren't going to work correctly with
multiple BLOBS entries or multiple-large-object ACL entries.

The directory and tar-file format handlers need some work
for multiple BLOBS entries: they used to hard-wire the file name
as "blobs.toc", which is replaced here with "blobs_<dumpid>.toc".
The 002_pg_dump.pl test script also knows about that and requires
minor updates.  (I had to drop the test for manually-compressed
blobs.toc files with LZ4, because lz4's obtuse command line
design requires explicit specification of the output file name
which seems impractical here.  I don't think we're losing any
useful test coverage thereby; that test stanza seems completely
duplicative with the gzip and zstd cases anyway.)

In passing, centralize management of the lo_buf used to hold data
while restoring blobs.  The code previously had each format handler
create lo_buf, which seems rather pointless given that the format
handlers all make it the same way.  Moreover, the format handlers
never use lo_buf directly, making this setup a failure from a
separation-of-concerns standpoint.  Let's move the responsibility into
pg_backup_archiver.c, which is the only module concerned with lo_buf.
The reason to do this in this patch is that it allows a centralized
fix for the now-false assumption that we never restore blobs in
parallel.  Also, get rid of dead code in DropLOIfExists: it's been a
long time since we had any need to be able to restore to a pre-9.0
server.

Discussion: https://postgr.es/m/a9f9376f1c3343a6bb319dce294e20ac@EX13D05UWC001.ant.amazon.com

src/bin/pg_dump/common.c

@@ -47,6 +47,8 @@ static DumpId lastDumpId = 0;	/* Note: 0 is InvalidDumpId */
  * expects that it can move them around when resizing the table.  So we
  * cannot make the DumpableObjects be elements of the hash table directly;
  * instead, the hash table elements contain pointers to DumpableObjects.
+ * This does have the advantage of letting us map multiple CatalogIds
+ * to one DumpableObject, which is useful for blobs.
  *
  * It turns out to be convenient to also use this data structure to map
  * CatalogIds to owning extensions, if any.  Since extension membership
@@ -700,6 +702,30 @@ AssignDumpId(DumpableObject *dobj)
 	}
 }
 
+/*
+ * recordAdditionalCatalogID
+ *	  Record an additional catalog ID for the given DumpableObject
+ */
+void
+recordAdditionalCatalogID(CatalogId catId, DumpableObject *dobj)
+{
+	CatalogIdMapEntry *entry;
+	bool		found;
+
+	/* CatalogId hash table must exist, if we have a DumpableObject */
+	Assert(catalogIdHash != NULL);
+
+	/* Add reference to CatalogId hash */
+	entry = catalogid_insert(catalogIdHash, catId, &found);
+	if (!found)
+	{
+		entry->dobj = NULL;
+		entry->ext = NULL;
+	}
+	Assert(entry->dobj == NULL);
+	entry->dobj = dobj;
+}
+
 /*
  * Assign a DumpId that's not tied to a DumpableObject.
  *

src/bin/pg_dump/pg_backup_archiver.c

@@ -512,7 +512,20 @@ RestoreArchive(Archive *AHX)
 				 * don't necessarily emit it verbatim; at this point we add an
 				 * appropriate IF EXISTS clause, if the user requested it.
 				 */
-				if (*te->dropStmt != '\0')
+				if (strcmp(te->desc, "BLOB METADATA") == 0)
+				{
+					/* We must generate the per-blob commands */
+					if (ropt->if_exists)
+						IssueCommandPerBlob(AH, te,
+											"SELECT pg_catalog.lo_unlink(oid) "
+											"FROM pg_catalog.pg_largeobject_metadata "
+											"WHERE oid = '", "'");
+					else
+						IssueCommandPerBlob(AH, te,
+											"SELECT pg_catalog.lo_unlink('",
+											"')");
+				}
+				else if (*te->dropStmt != '\0')
 				{
 					if (!ropt->if_exists ||
 						strncmp(te->dropStmt, "--", 2) == 0)
@@ -528,12 +541,12 @@ RestoreArchive(Archive *AHX)
 					{
 						/*
 						 * Inject an appropriate spelling of "if exists".  For
-						 * large objects, we have a separate routine that
+						 * old-style large objects, we have a routine that
 						 * knows how to do it, without depending on
 						 * te->dropStmt; use that.  For other objects we need
 						 * to parse the command.
 						 */
-						if (strncmp(te->desc, "BLOB", 4) == 0)
+						if (strcmp(te->desc, "BLOB") == 0)
 						{
 							DropLOIfExists(AH, te->catalogId.oid);
 						}
@@ -1290,7 +1303,7 @@ EndLO(Archive *AHX, Oid oid)
  **********/
 
 /*
- * Called by a format handler before any LOs are restored
+ * Called by a format handler before a group of LOs is restored
  */
 void
 StartRestoreLOs(ArchiveHandle *AH)
@@ -1309,7 +1322,7 @@ StartRestoreLOs(ArchiveHandle *AH)
 }
 
 /*
- * Called by a format handler after all LOs are restored
+ * Called by a format handler after a group of LOs is restored
  */
 void
 EndRestoreLOs(ArchiveHandle *AH)
@@ -1343,6 +1356,12 @@ StartRestoreLO(ArchiveHandle *AH, Oid oid, bool drop)
 	AH->loCount++;
 
 	/* Initialize the LO Buffer */
+	if (AH->lo_buf == NULL)
+	{
+		/* First time through (in this process) so allocate the buffer */
+		AH->lo_buf_size = LOBBUFSIZE;
+		AH->lo_buf = (void *) pg_malloc(LOBBUFSIZE);
+	}
 	AH->lo_buf_used = 0;
 
 	pg_log_info("restoring large object with OID %u", oid);
@@ -2988,19 +3007,20 @@ _tocEntryRequired(TocEntry *te, teSection curSection, ArchiveHandle *AH)
 	{
 		/*
 		 * Special Case: If 'SEQUENCE SET' or anything to do with LOs, then it
-		 * is considered a data entry.  We don't need to check for the BLOBS
+		 * is considered a data entry.  We don't need to check for BLOBS or
-		 * entry or old-style BLOB COMMENTS, because they will have hadDumper
+		 * old-style BLOB COMMENTS entries, because they will have hadDumper =
-		 * = true ... but we do need to check new-style BLOB ACLs, comments,
+		 * true ... but we do need to check new-style BLOB ACLs, comments,
 		 * etc.
 		 */
 		if (strcmp(te->desc, "SEQUENCE SET") == 0 ||
 			strcmp(te->desc, "BLOB") == 0 ||
+			strcmp(te->desc, "BLOB METADATA") == 0 ||
 			(strcmp(te->desc, "ACL") == 0 &&
-			 strncmp(te->tag, "LARGE OBJECT ", 13) == 0) ||
+			 strncmp(te->tag, "LARGE OBJECT", 12) == 0) ||
 			(strcmp(te->desc, "COMMENT") == 0 &&
-			 strncmp(te->tag, "LARGE OBJECT ", 13) == 0) ||
+			 strncmp(te->tag, "LARGE OBJECT", 12) == 0) ||
 			(strcmp(te->desc, "SECURITY LABEL") == 0 &&
-			 strncmp(te->tag, "LARGE OBJECT ", 13) == 0))
+			 strncmp(te->tag, "LARGE OBJECT", 12) == 0))
 			res = res & REQ_DATA;
 		else
 			res = res & ~REQ_DATA;
@@ -3035,12 +3055,13 @@ _tocEntryRequired(TocEntry *te, teSection curSection, ArchiveHandle *AH)
 		if (!(ropt->sequence_data && strcmp(te->desc, "SEQUENCE SET") == 0) &&
 			!(ropt->binary_upgrade &&
 			  (strcmp(te->desc, "BLOB") == 0 ||
+			   strcmp(te->desc, "BLOB METADATA") == 0 ||
 			   (strcmp(te->desc, "ACL") == 0 &&
-				strncmp(te->tag, "LARGE OBJECT ", 13) == 0) ||
+				strncmp(te->tag, "LARGE OBJECT", 12) == 0) ||
 			   (strcmp(te->desc, "COMMENT") == 0 &&
-				strncmp(te->tag, "LARGE OBJECT ", 13) == 0) ||
+				strncmp(te->tag, "LARGE OBJECT", 12) == 0) ||
 			   (strcmp(te->desc, "SECURITY LABEL") == 0 &&
-				strncmp(te->tag, "LARGE OBJECT ", 13) == 0))))
+				strncmp(te->tag, "LARGE OBJECT", 12) == 0))))
 			res = res & REQ_SCHEMA;
 	}
 
@@ -3607,18 +3628,35 @@ _printTocEntry(ArchiveHandle *AH, TocEntry *te, bool isData)
 	}
 
 	/*
-	 * Actually print the definition.
+	 * Actually print the definition.  Normally we can just print the defn
+	 * string if any, but we have three special cases:
 	 *
-	 * Really crude hack for suppressing AUTHORIZATION clause that old pg_dump
+	 * 1. A crude hack for suppressing AUTHORIZATION clause that old pg_dump
 	 * versions put into CREATE SCHEMA.  Don't mutate the variant for schema
 	 * "public" that is a comment.  We have to do this when --no-owner mode is
 	 * selected.  This is ugly, but I see no other good way ...
+	 *
+	 * 2. BLOB METADATA entries need special processing since their defn
+	 * strings are just lists of OIDs, not complete SQL commands.
+	 *
+	 * 3. ACL LARGE OBJECTS entries need special processing because they
+	 * contain only one copy of the ACL GRANT/REVOKE commands, which we must
+	 * apply to each large object listed in the associated BLOB METADATA.
 	 */
 	if (ropt->noOwner &&
 		strcmp(te->desc, "SCHEMA") == 0 && strncmp(te->defn, "--", 2) != 0)
 	{
 		ahprintf(AH, "CREATE SCHEMA %s;\n\n\n", fmtId(te->tag));
 	}
+	else if (strcmp(te->desc, "BLOB METADATA") == 0)
+	{
+		IssueCommandPerBlob(AH, te, "SELECT pg_catalog.lo_create('", "')");
+	}
+	else if (strcmp(te->desc, "ACL") == 0 &&
+			 strncmp(te->tag, "LARGE OBJECTS", 13) == 0)
+	{
+		IssueACLPerBlob(AH, te);
+	}
 	else
 	{
 		if (te->defn && strlen(te->defn) > 0)
@@ -3639,19 +3677,32 @@ _printTocEntry(ArchiveHandle *AH, TocEntry *te, bool isData)
 		te->owner && strlen(te->owner) > 0 &&
 		te->dropStmt && strlen(te->dropStmt) > 0)
 	{
+		if (strcmp(te->desc, "BLOB METADATA") == 0)
+		{
+			/* BLOB METADATA needs special code to handle multiple LOs */
+			char	   *cmdEnd = psprintf(" OWNER TO %s", fmtId(te->owner));
+
+			IssueCommandPerBlob(AH, te, "ALTER LARGE OBJECT ", cmdEnd);
+			pg_free(cmdEnd);
+		}
+		else
+		{
+			/* For all other cases, we can use _getObjectDescription */
 			PQExpBufferData temp;
 
 			initPQExpBuffer(&temp);
 			_getObjectDescription(&temp, te);
 
 			/*
-		 * If _getObjectDescription() didn't fill the buffer, then there is no
+			 * If _getObjectDescription() didn't fill the buffer, then there
-		 * owner.
+			 * is no owner.
 			 */
 			if (temp.data[0])
-			ahprintf(AH, "ALTER %s OWNER TO %s;\n\n", temp.data, fmtId(te->owner));
+				ahprintf(AH, "ALTER %s OWNER TO %s;\n\n",
+						 temp.data, fmtId(te->owner));
 			termPQExpBuffer(&temp);
 		}
+	}
 
 	/*
 	 * If it's an ACL entry, it might contain SET SESSION AUTHORIZATION
@@ -4749,6 +4800,9 @@ CloneArchive(ArchiveHandle *AH)
 	/* clone has its own error count, too */
 	clone->public.n_errors = 0;
 
+	/* clones should not share lo_buf */
+	clone->lo_buf = NULL;
+
 	/*
 	 * Connect our new clone object to the database, using the same connection
 	 * parameters used for the original connection.

src/bin/pg_dump/pg_backup_archiver.h

@@ -68,10 +68,12 @@
 #define K_VERS_1_15 MAKE_ARCHIVE_VERSION(1, 15, 0)	/* add
 													 * compression_algorithm
 													 * in header */
+#define K_VERS_1_16 MAKE_ARCHIVE_VERSION(1, 16, 0)	/* BLOB METADATA entries
+													 * and multiple BLOBS */
 
 /* Current archive version number (the format we can output) */
 #define K_VERS_MAJOR 1
-#define K_VERS_MINOR 15
+#define K_VERS_MINOR 16
 #define K_VERS_REV 0
 #define K_VERS_SELF MAKE_ARCHIVE_VERSION(K_VERS_MAJOR, K_VERS_MINOR, K_VERS_REV)
 
@@ -448,6 +450,9 @@ extern void InitArchiveFmt_Tar(ArchiveHandle *AH);
 extern bool isValidTarHeader(char *header);
 
 extern void ReconnectToServer(ArchiveHandle *AH, const char *dbname);
+extern void IssueCommandPerBlob(ArchiveHandle *AH, TocEntry *te,
+								const char *cmdBegin, const char *cmdEnd);
+extern void IssueACLPerBlob(ArchiveHandle *AH, TocEntry *te);
 extern void DropLOIfExists(ArchiveHandle *AH, Oid oid);
 
 void		ahwrite(const void *ptr, size_t size, size_t nmemb, ArchiveHandle *AH);

src/bin/pg_dump/pg_backup_custom.c

@@ -140,10 +140,6 @@ InitArchiveFmt_Custom(ArchiveHandle *AH)
 	ctx = (lclContext *) pg_malloc0(sizeof(lclContext));
 	AH->formatData = (void *) ctx;
 
-	/* Initialize LO buffering */
-	AH->lo_buf_size = LOBBUFSIZE;
-	AH->lo_buf = (void *) pg_malloc(LOBBUFSIZE);
-
 	/*
 	 * Now open the file
 	 */
@@ -342,7 +338,7 @@ _EndData(ArchiveHandle *AH, TocEntry *te)
 }
 
 /*
- * Called by the archiver when starting to save all BLOB DATA (not schema).
+ * Called by the archiver when starting to save BLOB DATA (not schema).
  * This routine should save whatever format-specific information is needed
  * to read the LOs back into memory.
  *
@@ -402,7 +398,7 @@ _EndLO(ArchiveHandle *AH, TocEntry *te, Oid oid)
 }
 
 /*
- * Called by the archiver when finishing saving all BLOB DATA.
+ * Called by the archiver when finishing saving BLOB DATA.
  *
  * Optional.
  */
@@ -902,9 +898,6 @@ _Clone(ArchiveHandle *AH)
 	 * share knowledge about where the data blocks are across threads.
 	 * _PrintTocData has to be careful about the order of operations on that
 	 * state, though.
-	 *
-	 * Note: we do not make a local lo_buf because we expect at most one BLOBS
-	 * entry per archive, so no parallelism is possible.
 	 */
 }
 

src/bin/pg_dump/pg_backup_db.c

@@ -541,29 +541,122 @@ CommitTransaction(Archive *AHX)
 	ExecuteSqlCommand(AH, "COMMIT", "could not commit database transaction");
 }
 
+/*
+ * Issue per-blob commands for the large object(s) listed in the TocEntry
+ *
+ * The TocEntry's defn string is assumed to consist of large object OIDs,
+ * one per line.  Wrap these in the given SQL command fragments and issue
+ * the commands.  (cmdEnd need not include a semicolon.)
+ */
 void
-DropLOIfExists(ArchiveHandle *AH, Oid oid)
+IssueCommandPerBlob(ArchiveHandle *AH, TocEntry *te,
+					const char *cmdBegin, const char *cmdEnd)
+{
+	/* Make a writable copy of the command string */
+	char	   *buf = pg_strdup(te->defn);
+	char	   *st;
+	char	   *en;
+
+	st = buf;
+	while ((en = strchr(st, '\n')) != NULL)
+	{
+		*en++ = '\0';
+		ahprintf(AH, "%s%s%s;\n", cmdBegin, st, cmdEnd);
+		st = en;
+	}
+	ahprintf(AH, "\n");
+	pg_free(buf);
+}
+
+/*
+ * Process a "LARGE OBJECTS" ACL TocEntry.
+ *
+ * To save space in the dump file, the TocEntry contains only one copy
+ * of the required GRANT/REVOKE commands, written to apply to the first
+ * blob in the group (although we do not depend on that detail here).
+ * We must expand the text to generate commands for all the blobs listed
+ * in the associated BLOB METADATA entry.
+ */
+void
+IssueACLPerBlob(ArchiveHandle *AH, TocEntry *te)
 {
+	TocEntry   *blobte = getTocEntryByDumpId(AH, te->dependencies[0]);
+	char	   *buf;
+	char	   *st;
+	char	   *st2;
+	char	   *en;
+	bool		inquotes;
+
+	if (!blobte)
+		pg_fatal("could not find entry for ID %d", te->dependencies[0]);
+	Assert(strcmp(blobte->desc, "BLOB METADATA") == 0);
+
+	/* Make a writable copy of the ACL commands string */
+	buf = pg_strdup(te->defn);
+
 	/*
-	 * If we are not restoring to a direct database connection, we have to
+	 * We have to parse out the commands sufficiently to locate the blob OIDs
-	 * guess about how to detect whether the LO exists.  Assume new-style.
+	 * and find the command-ending semicolons.  The commands should not
+	 * contain anything hard to parse except for double-quoted role names,
+	 * which are easy to ignore.  Once we've split apart the first and second
+	 * halves of a command, apply IssueCommandPerBlob.  (This means the
+	 * updates on the blobs are interleaved if there's multiple commands, but
+	 * that should cause no trouble.)
 	 */
-	if (AH->connection == NULL ||
+	inquotes = false;
-		PQserverVersion(AH->connection) >= 90000)
+	st = en = buf;
+	st2 = NULL;
+	while (*en)
+	{
+		/* Ignore double-quoted material */
+		if (*en == '"')
+			inquotes = !inquotes;
+		if (inquotes)
 		{
+			en++;
+			continue;
+		}
+		/* If we found "LARGE OBJECT", that's the end of the first half */
+		if (strncmp(en, "LARGE OBJECT ", 13) == 0)
+		{
+			/* Terminate the first-half string */
+			en += 13;
+			Assert(isdigit((unsigned char) *en));
+			*en++ = '\0';
+			/* Skip the rest of the blob OID */
+			while (isdigit((unsigned char) *en))
+				en++;
+			/* Second half starts here */
+			Assert(st2 == NULL);
+			st2 = en;
+		}
+		/* If we found semicolon, that's the end of the second half */
+		else if (*en == ';')
+		{
+			/* Terminate the second-half string */
+			*en++ = '\0';
+			Assert(st2 != NULL);
+			/* Issue this command for each blob */
+			IssueCommandPerBlob(AH, blobte, st, st2);
+			/* For neatness, skip whitespace before the next command */
+			while (isspace((unsigned char) *en))
+				en++;
+			/* Reset for new command */
+			st = en;
+			st2 = NULL;
+		}
+		else
+			en++;
+	}
+	pg_free(buf);
+}
+
+void
+DropLOIfExists(ArchiveHandle *AH, Oid oid)
+{
 	ahprintf(AH,
 			 "SELECT pg_catalog.lo_unlink(oid) "
 			 "FROM pg_catalog.pg_largeobject_metadata "
 			 "WHERE oid = '%u';\n",
 			 oid);
-	}
-	else
-	{
-		/* Restoring to pre-9.0 server, so do it the old way */
-		ahprintf(AH,
-				 "SELECT CASE WHEN EXISTS("
-				 "SELECT 1 FROM pg_catalog.pg_largeobject WHERE loid = '%u'"
-				 ") THEN pg_catalog.lo_unlink('%u') END;\n",
-				 oid, oid);
-	}
 }

src/bin/pg_dump/pg_backup_directory.c

@@ -5,8 +5,10 @@
  *	A directory format dump is a directory, which contains a "toc.dat" file
  *	for the TOC, and a separate file for each data entry, named "<oid>.dat".
  *	Large objects are stored in separate files named "blob_<oid>.dat",
- *	and there's a plain-text TOC file for them called "blobs.toc". If
+ *	and there's a plain-text TOC file for each BLOBS TOC entry named
- *	compression is used, each data file is individually compressed and the
+ *	"blobs_<dumpID>.toc" (or just "blobs.toc" in archive versions before 16).
+ *
+ *	If compression is used, each data file is individually compressed and the
  *	".gz" suffix is added to the filenames. The TOC files are never
  *	compressed by pg_dump, however they are accepted with the .gz suffix too,
  *	in case the user has manually compressed them with 'gzip'.
@@ -51,7 +53,7 @@ typedef struct
 	char	   *directory;
 
 	CompressFileHandle *dataFH; /* currently open data file */
-	CompressFileHandle *LOsTocFH;	/* file handle for blobs.toc */
+	CompressFileHandle *LOsTocFH;	/* file handle for blobs_NNN.toc */
 	ParallelState *pstate;		/* for parallel backup / restore */
 } lclContext;
 
@@ -81,7 +83,7 @@ static void _StartLOs(ArchiveHandle *AH, TocEntry *te);
 static void _StartLO(ArchiveHandle *AH, TocEntry *te, Oid oid);
 static void _EndLO(ArchiveHandle *AH, TocEntry *te, Oid oid);
 static void _EndLOs(ArchiveHandle *AH, TocEntry *te);
-static void _LoadLOs(ArchiveHandle *AH);
+static void _LoadLOs(ArchiveHandle *AH, TocEntry *te);
 
 static void _PrepParallelRestore(ArchiveHandle *AH);
 static void _Clone(ArchiveHandle *AH);
@@ -143,10 +145,6 @@ InitArchiveFmt_Directory(ArchiveHandle *AH)
 	ctx->dataFH = NULL;
 	ctx->LOsTocFH = NULL;
 
-	/* Initialize LO buffering */
-	AH->lo_buf_size = LOBBUFSIZE;
-	AH->lo_buf = (void *) pg_malloc(LOBBUFSIZE);
-
 	/*
 	 * Now open the TOC file
 	 */
@@ -236,7 +234,10 @@ _ArchiveEntry(ArchiveHandle *AH, TocEntry *te)
 
 	tctx = (lclTocEntry *) pg_malloc0(sizeof(lclTocEntry));
 	if (strcmp(te->desc, "BLOBS") == 0)
-		tctx->filename = pg_strdup("blobs.toc");
+	{
+		snprintf(fn, MAXPGPATH, "blobs_%d.toc", te->dumpId);
+		tctx->filename = pg_strdup(fn);
+	}
 	else if (te->dataDumper)
 	{
 		snprintf(fn, MAXPGPATH, "%d.dat", te->dumpId);
@@ -419,7 +420,7 @@ _PrintTocData(ArchiveHandle *AH, TocEntry *te)
 		return;
 
 	if (strcmp(te->desc, "BLOBS") == 0)
-		_LoadLOs(AH);
+		_LoadLOs(AH, te);
 	else
 	{
 		char		fname[MAXPGPATH];
@@ -430,17 +431,23 @@ _PrintTocData(ArchiveHandle *AH, TocEntry *te)
 }
 
 static void
-_LoadLOs(ArchiveHandle *AH)
+_LoadLOs(ArchiveHandle *AH, TocEntry *te)
 {
 	Oid			oid;
 	lclContext *ctx = (lclContext *) AH->formatData;
+	lclTocEntry *tctx = (lclTocEntry *) te->formatData;
 	CompressFileHandle *CFH;
 	char		tocfname[MAXPGPATH];
 	char		line[MAXPGPATH];
 
 	StartRestoreLOs(AH);
 
-	setFilePath(AH, tocfname, "blobs.toc");
+	/*
+	 * Note: before archive v16, there was always only one BLOBS TOC entry,
+	 * now there can be multiple.  We don't need to worry what version we are
+	 * reading though, because tctx->filename should be correct either way.
+	 */
+	setFilePath(AH, tocfname, tctx->filename);
 
 	CFH = ctx->LOsTocFH = InitDiscoverCompressFileHandle(tocfname, PG_BINARY_R);
 
@@ -636,7 +643,7 @@ _ReopenArchive(ArchiveHandle *AH)
  */
 
 /*
- * Called by the archiver when starting to save all BLOB DATA (not schema).
+ * Called by the archiver when starting to save BLOB DATA (not schema).
  * It is called just prior to the dumper's DataDumper routine.
  *
  * We open the large object TOC file here, so that we can append a line to
@@ -646,10 +653,11 @@ static void
 _StartLOs(ArchiveHandle *AH, TocEntry *te)
 {
 	lclContext *ctx = (lclContext *) AH->formatData;
+	lclTocEntry *tctx = (lclTocEntry *) te->formatData;
 	pg_compress_specification compression_spec = {0};
 	char		fname[MAXPGPATH];
 
-	setFilePath(AH, fname, "blobs.toc");
+	setFilePath(AH, fname, tctx->filename);
 
 	/* The LO TOC file is never compressed */
 	compression_spec.algorithm = PG_COMPRESSION_NONE;
@@ -694,7 +702,7 @@ _EndLO(ArchiveHandle *AH, TocEntry *te, Oid oid)
 		pg_fatal("could not close LO data file: %m");
 	ctx->dataFH = NULL;
 
-	/* register the LO in blobs.toc */
+	/* register the LO in blobs_NNN.toc */
 	len = snprintf(buf, sizeof(buf), "%u blob_%u.dat\n", oid, oid);
 	if (!CFH->write_func(buf, len, CFH))
 	{
@@ -707,7 +715,7 @@ _EndLO(ArchiveHandle *AH, TocEntry *te, Oid oid)
 }
 
 /*
- * Called by the archiver when finishing saving all BLOB DATA.
+ * Called by the archiver when finishing saving BLOB DATA.
  *
  * We close the LOs TOC file.
  */
@@ -799,7 +807,7 @@ _PrepParallelRestore(ArchiveHandle *AH)
 		}
 
 		/*
-		 * If this is the BLOBS entry, what we stat'd was blobs.toc, which
+		 * If this is a BLOBS entry, what we stat'd was blobs_NNN.toc, which
 		 * most likely is a lot smaller than the actual blob data.  We don't
 		 * have a cheap way to estimate how much smaller, but fortunately it
 		 * doesn't matter too much as long as we get the LOs processed
@@ -823,8 +831,6 @@ _Clone(ArchiveHandle *AH)
 	ctx = (lclContext *) AH->formatData;
 
 	/*
-	 * Note: we do not make a local lo_buf because we expect at most one BLOBS
-	 * entry per archive, so no parallelism is possible.  Likewise,
 	 * TOC-entry-local state isn't an issue because any one TOC entry is
 	 * touched by just one worker child.
 	 */

src/bin/pg_dump/pg_backup_null.c

@@ -63,10 +63,6 @@ InitArchiveFmt_Null(ArchiveHandle *AH)
 	AH->ClonePtr = NULL;
 	AH->DeClonePtr = NULL;
 
-	/* Initialize LO buffering */
-	AH->lo_buf_size = LOBBUFSIZE;
-	AH->lo_buf = (void *) pg_malloc(LOBBUFSIZE);
-
 	/*
 	 * Now prevent reading...
 	 */
@@ -117,7 +113,7 @@ _EndData(ArchiveHandle *AH, TocEntry *te)
 }
 
 /*
- * Called by the archiver when starting to save all BLOB DATA (not schema).
+ * Called by the archiver when starting to save BLOB DATA (not schema).
  * This routine should save whatever format-specific information is needed
  * to read the LOs back into memory.
  *
@@ -174,7 +170,7 @@ _EndLO(ArchiveHandle *AH, TocEntry *te, Oid oid)
 }
 
 /*
- * Called by the archiver when finishing saving all BLOB DATA.
+ * Called by the archiver when finishing saving BLOB DATA.
  *
  * Optional.
  */

src/bin/pg_dump/pg_backup_tar.c

@@ -94,7 +94,7 @@ typedef struct
 	char	   *filename;
 } lclTocEntry;
 
-static void _LoadLOs(ArchiveHandle *AH);
+static void _LoadLOs(ArchiveHandle *AH, TocEntry *te);
 
 static TAR_MEMBER *tarOpen(ArchiveHandle *AH, const char *filename, char mode);
 static void tarClose(ArchiveHandle *AH, TAR_MEMBER *th);
@@ -156,10 +156,6 @@ InitArchiveFmt_Tar(ArchiveHandle *AH)
 	ctx->filePos = 0;
 	ctx->isSpecialScript = 0;
 
-	/* Initialize LO buffering */
-	AH->lo_buf_size = LOBBUFSIZE;
-	AH->lo_buf = (void *) pg_malloc(LOBBUFSIZE);
-
 	/*
 	 * Now open the tar file, and load the TOC if we're in read mode.
 	 */
@@ -638,13 +634,13 @@ _PrintTocData(ArchiveHandle *AH, TocEntry *te)
 	}
 
 	if (strcmp(te->desc, "BLOBS") == 0)
-		_LoadLOs(AH);
+		_LoadLOs(AH, te);
 	else
 		_PrintFileData(AH, tctx->filename);
 }
 
 static void
-_LoadLOs(ArchiveHandle *AH)
+_LoadLOs(ArchiveHandle *AH, TocEntry *te)
 {
 	Oid			oid;
 	lclContext *ctx = (lclContext *) AH->formatData;
@@ -655,7 +651,26 @@ _LoadLOs(ArchiveHandle *AH)
 
 	StartRestoreLOs(AH);
 
+	/*
+	 * The blobs_NNN.toc or blobs.toc file is fairly useless to us because it
+	 * will appear only after the associated blob_NNN.dat files.  For archive
+	 * versions >= 16 we can look at the BLOBS entry's te->tag to discover the
+	 * OID of the first blob we want to restore, and then search forward to
+	 * find the appropriate blob_<oid>.dat file.  For older versions we rely
+	 * on the knowledge that there was only one BLOBS entry and just search
+	 * for the first blob_<oid>.dat file.  Once we find the first blob file to
+	 * restore, restore all blobs until we reach the blobs[_NNN].toc file.
+	 */
+	if (AH->version >= K_VERS_1_16)
+	{
+		/* We rely on atooid to not complain about nnnn..nnnn tags */
+		oid = atooid(te->tag);
+		snprintf(buf, sizeof(buf), "blob_%u.dat", oid);
+		th = tarOpen(AH, buf, 'r'); /* Advance to first desired file */
+	}
+	else
 		th = tarOpen(AH, NULL, 'r');	/* Open next file */
+
 	while (th != NULL)
 	{
 		ctx->FH = th;
@@ -685,9 +700,9 @@ _LoadLOs(ArchiveHandle *AH)
 
 			/*
 			 * Once we have found the first LO, stop at the first non-LO entry
-			 * (which will be 'blobs.toc').  This coding would eat all the
+			 * (which will be 'blobs[_NNN].toc').  This coding would eat all
-			 * rest of the archive if there are no LOs ... but this function
+			 * the rest of the archive if there are no LOs ... but this
-			 * shouldn't be called at all in that case.
+			 * function shouldn't be called at all in that case.
 			 */
 			if (foundLO)
 				break;
@@ -851,7 +866,7 @@ _scriptOut(ArchiveHandle *AH, const void *buf, size_t len)
  */
 
 /*
- * Called by the archiver when starting to save all BLOB DATA (not schema).
+ * Called by the archiver when starting to save BLOB DATA (not schema).
  * This routine should save whatever format-specific information is needed
  * to read the LOs back into memory.
  *
@@ -866,7 +881,7 @@ _StartLOs(ArchiveHandle *AH, TocEntry *te)
 	lclContext *ctx = (lclContext *) AH->formatData;
 	char		fname[K_STD_BUF_SIZE];
 
-	sprintf(fname, "blobs.toc");
+	sprintf(fname, "blobs_%d.toc", te->dumpId);
 	ctx->loToc = tarOpen(AH, fname, 'w');
 }
 
@@ -912,7 +927,7 @@ _EndLO(ArchiveHandle *AH, TocEntry *te, Oid oid)
 }
 
 /*
- * Called by the archiver when finishing saving all BLOB DATA.
+ * Called by the archiver when finishing saving BLOB DATA.
  *
  * Optional.
  *

src/bin/pg_dump/pg_dump.c

@@ -163,6 +163,13 @@ static int	nseclabels = 0;
  */
 #define DUMP_DEFAULT_ROWS_PER_INSERT 1
 
+/*
+ * Maximum number of large objects to group into a single ArchiveEntry.
+ * At some point we might want to make this user-controllable, but for now
+ * a hard-wired setting will suffice.
+ */
+#define MAX_BLOBS_PER_ARCHIVE_ENTRY 1000
+
 /*
  * Macro for producing quoted, schema-qualified name of a dumpable object.
  */
@@ -267,7 +274,7 @@ static void dumpDefaultACL(Archive *fout, const DefaultACLInfo *daclinfo);
 
 static DumpId dumpACL(Archive *fout, DumpId objDumpId, DumpId altDumpId,
 					  const char *type, const char *name, const char *subname,
-					  const char *nspname, const char *owner,
+					  const char *nspname, const char *tag, const char *owner,
 					  const DumpableAcl *dacl);
 
 static void getDependencies(Archive *fout);
@@ -3291,7 +3298,7 @@ dumpDatabase(Archive *fout)
 
 	dumpACL(fout, dbDumpId, InvalidDumpId, "DATABASE",
 			qdatname, NULL, NULL,
-			dba, &dbdacl);
+			NULL, dba, &dbdacl);
 
 	/*
 	 * Now construct a DATABASE PROPERTIES archive entry to restore any
@@ -3612,11 +3619,10 @@ getLOs(Archive *fout)
 {
 	DumpOptions *dopt = fout->dopt;
 	PQExpBuffer loQry = createPQExpBuffer();
-	LoInfo	   *loinfo;
-	DumpableObject *lodata;
 	PGresult   *res;
 	int			ntups;
 	int			i;
+	int			n;
 	int			i_oid;
 	int			i_lomowner;
 	int			i_lomacl;
@@ -3624,11 +3630,15 @@ getLOs(Archive *fout)
 
 	pg_log_info("reading large objects");
 
-	/* Fetch LO OIDs, and owner/ACL data */
+	/*
+	 * Fetch LO OIDs and owner/ACL data.  Order the data so that all the blobs
+	 * with the same owner/ACL appear together.
+	 */
 	appendPQExpBufferStr(loQry,
 						 "SELECT oid, lomowner, lomacl, "
 						 "acldefault('L', lomowner) AS acldefault "
-						 "FROM pg_largeobject_metadata");
+						 "FROM pg_largeobject_metadata "
+						 "ORDER BY lomowner, lomacl::pg_catalog.text, oid");
 
 	res = ExecuteSqlQuery(fout, loQry->data, PGRES_TUPLES_OK);
 
@@ -3640,30 +3650,72 @@ getLOs(Archive *fout)
 	ntups = PQntuples(res);
 
 	/*
-	 * Each large object has its own "BLOB" archive entry.
+	 * Group the blobs into suitably-sized groups that have the same owner and
+	 * ACL setting, and build a metadata and a data DumpableObject for each
+	 * group.  (If we supported initprivs for blobs, we'd have to insist that
+	 * groups also share initprivs settings, since the DumpableObject only has
+	 * room for one.)  i is the index of the first tuple in the current group,
+	 * and n is the number of tuples we include in the group.
 	 */
-	loinfo = (LoInfo *) pg_malloc(ntups * sizeof(LoInfo));
+	for (i = 0; i < ntups; i += n)
+	{
+		Oid			thisoid = atooid(PQgetvalue(res, i, i_oid));
+		char	   *thisowner = PQgetvalue(res, i, i_lomowner);
+		char	   *thisacl = PQgetvalue(res, i, i_lomacl);
+		LoInfo	   *loinfo;
+		DumpableObject *lodata;
+		char		namebuf[64];
 
-	for (i = 0; i < ntups; i++)
+		/* Scan to find first tuple not to be included in group */
+		n = 1;
+		while (n < MAX_BLOBS_PER_ARCHIVE_ENTRY && i + n < ntups)
+		{
+			if (strcmp(thisowner, PQgetvalue(res, i + n, i_lomowner)) != 0 ||
+				strcmp(thisacl, PQgetvalue(res, i + n, i_lomacl)) != 0)
+				break;
+			n++;
+		}
+
+		/* Build the metadata DumpableObject */
+		loinfo = (LoInfo *) pg_malloc(offsetof(LoInfo, looids) + n * sizeof(Oid));
+
+		loinfo->dobj.objType = DO_LARGE_OBJECT;
+		loinfo->dobj.catId.tableoid = LargeObjectRelationId;
+		loinfo->dobj.catId.oid = thisoid;
+		AssignDumpId(&loinfo->dobj);
+
+		if (n > 1)
+			snprintf(namebuf, sizeof(namebuf), "%u..%u", thisoid,
+					 atooid(PQgetvalue(res, i + n - 1, i_oid)));
+		else
+			snprintf(namebuf, sizeof(namebuf), "%u", thisoid);
+		loinfo->dobj.name = pg_strdup(namebuf);
+		loinfo->dacl.acl = pg_strdup(thisacl);
+		loinfo->dacl.acldefault = pg_strdup(PQgetvalue(res, i, i_acldefault));
+		loinfo->dacl.privtype = 0;
+		loinfo->dacl.initprivs = NULL;
+		loinfo->rolname = getRoleName(thisowner);
+		loinfo->numlos = n;
+		loinfo->looids[0] = thisoid;
+		/* Collect OIDs of the remaining blobs in this group */
+		for (int k = 1; k < n; k++)
 		{
-		loinfo[i].dobj.objType = DO_LARGE_OBJECT;
+			CatalogId	extraID;
-		loinfo[i].dobj.catId.tableoid = LargeObjectRelationId;
-		loinfo[i].dobj.catId.oid = atooid(PQgetvalue(res, i, i_oid));
-		AssignDumpId(&loinfo[i].dobj);
 
-		loinfo[i].dobj.name = pg_strdup(PQgetvalue(res, i, i_oid));
+			loinfo->looids[k] = atooid(PQgetvalue(res, i + k, i_oid));
-		loinfo[i].dacl.acl = pg_strdup(PQgetvalue(res, i, i_lomacl));
+
-		loinfo[i].dacl.acldefault = pg_strdup(PQgetvalue(res, i, i_acldefault));
+			/* Make sure we can look up loinfo by any of the blobs' OIDs */
-		loinfo[i].dacl.privtype = 0;
+			extraID.tableoid = LargeObjectRelationId;
-		loinfo[i].dacl.initprivs = NULL;
+			extraID.oid = loinfo->looids[k];
-		loinfo[i].rolname = getRoleName(PQgetvalue(res, i, i_lomowner));
+			recordAdditionalCatalogID(extraID, &loinfo->dobj);
+		}
 
 		/* LOs have data */
-		loinfo[i].dobj.components |= DUMP_COMPONENT_DATA;
+		loinfo->dobj.components |= DUMP_COMPONENT_DATA;
 
-		/* Mark whether LO has an ACL */
+		/* Mark whether LO group has a non-empty ACL */
 		if (!PQgetisnull(res, i, i_lomacl))
-			loinfo[i].dobj.components |= DUMP_COMPONENT_ACL;
+			loinfo->dobj.components |= DUMP_COMPONENT_ACL;
 
 		/*
 		 * In binary-upgrade mode for LOs, we do *not* dump out the LO data,
@@ -3673,21 +3725,22 @@ getLOs(Archive *fout)
 		 * pg_largeobject_metadata, after the dump is restored.
 		 */
 		if (dopt->binary_upgrade)
-			loinfo[i].dobj.dump &= ~DUMP_COMPONENT_DATA;
+			loinfo->dobj.dump &= ~DUMP_COMPONENT_DATA;
-	}
 
 		/*
-	 * If we have any large objects, a "BLOBS" archive entry is needed. This
+		 * Create a "BLOBS" data item for the group, too. This is just a
-	 * is just a placeholder for sorting; it carries no data now.
+		 * placeholder for sorting; it carries no data now.
 		 */
-	if (ntups > 0)
-	{
 		lodata = (DumpableObject *) pg_malloc(sizeof(DumpableObject));
 		lodata->objType = DO_LARGE_OBJECT_DATA;
 		lodata->catId = nilCatalogId;
 		AssignDumpId(lodata);
-		lodata->name = pg_strdup("BLOBS");
+		lodata->name = pg_strdup(namebuf);
 		lodata->components |= DUMP_COMPONENT_DATA;
+		/* Set up explicit dependency from data to metadata */
+		lodata->dependencies = (DumpId *) pg_malloc(sizeof(DumpId));
+		lodata->dependencies[0] = loinfo->dobj.dumpId;
+		lodata->nDeps = lodata->allocDeps = 1;
 	}
 
 	PQclear(res);
@@ -3697,97 +3750,113 @@ getLOs(Archive *fout)
 /*
  * dumpLO
  *
- * dump the definition (metadata) of the given large object
+ * dump the definition (metadata) of the given large object group
  */
 static void
 dumpLO(Archive *fout, const LoInfo *loinfo)
 {
 	PQExpBuffer cquery = createPQExpBuffer();
-	PQExpBuffer dquery = createPQExpBuffer();
 
-	appendPQExpBuffer(cquery,
+	/*
-					  "SELECT pg_catalog.lo_create('%s');\n",
+	 * The "definition" is just a newline-separated list of OIDs.  We need to
-					  loinfo->dobj.name);
+	 * put something into the dropStmt too, but it can just be a comment.
-
+	 */
-	appendPQExpBuffer(dquery,
+	for (int i = 0; i < loinfo->numlos; i++)
-					  "SELECT pg_catalog.lo_unlink('%s');\n",
+		appendPQExpBuffer(cquery, "%u\n", loinfo->looids[i]);
-					  loinfo->dobj.name);
 
 	if (loinfo->dobj.dump & DUMP_COMPONENT_DEFINITION)
 		ArchiveEntry(fout, loinfo->dobj.catId, loinfo->dobj.dumpId,
 					 ARCHIVE_OPTS(.tag = loinfo->dobj.name,
 								  .owner = loinfo->rolname,
-								  .description = "BLOB",
+								  .description = "BLOB METADATA",
-								  .section = SECTION_PRE_DATA,
+								  .section = SECTION_DATA,
 								  .createStmt = cquery->data,
-								  .dropStmt = dquery->data));
+								  .dropStmt = "-- dummy"));
+
+	/*
+	 * Dump per-blob comments and seclabels if any.  We assume these are rare
+	 * enough that it's okay to generate retail TOC entries for them.
+	 */
+	if (loinfo->dobj.dump & (DUMP_COMPONENT_COMMENT |
+							 DUMP_COMPONENT_SECLABEL))
+	{
+		for (int i = 0; i < loinfo->numlos; i++)
+		{
+			CatalogId	catId;
+			char		namebuf[32];
+
+			/* Build identifying info for this blob */
+			catId.tableoid = loinfo->dobj.catId.tableoid;
+			catId.oid = loinfo->looids[i];
+			snprintf(namebuf, sizeof(namebuf), "%u", loinfo->looids[i]);
 
-	/* Dump comment if any */
 			if (loinfo->dobj.dump & DUMP_COMPONENT_COMMENT)
-		dumpComment(fout, "LARGE OBJECT", loinfo->dobj.name,
+				dumpComment(fout, "LARGE OBJECT", namebuf,
 							NULL, loinfo->rolname,
-					loinfo->dobj.catId, 0, loinfo->dobj.dumpId);
+							catId, 0, loinfo->dobj.dumpId);
 
-	/* Dump security label if any */
 			if (loinfo->dobj.dump & DUMP_COMPONENT_SECLABEL)
-		dumpSecLabel(fout, "LARGE OBJECT", loinfo->dobj.name,
+				dumpSecLabel(fout, "LARGE OBJECT", namebuf,
 							 NULL, loinfo->rolname,
-					 loinfo->dobj.catId, 0, loinfo->dobj.dumpId);
+							 catId, 0, loinfo->dobj.dumpId);
+		}
+	}
 
-	/* Dump ACL if any */
+	/*
+	 * Dump the ACLs if any (remember that all blobs in the group will have
+	 * the same ACL).  If there's just one blob, dump a simple ACL entry; if
+	 * there's more, make a "LARGE OBJECTS" entry that really contains only
+	 * the ACL for the first blob.  _printTocEntry() will be cued by the tag
+	 * string to emit a mutated version for each blob.
+	 */
 	if (loinfo->dobj.dump & DUMP_COMPONENT_ACL)
-		dumpACL(fout, loinfo->dobj.dumpId, InvalidDumpId, "LARGE OBJECT",
+	{
-				loinfo->dobj.name, NULL,
+		char		namebuf[32];
+
+		/* Build identifying info for the first blob */
+		snprintf(namebuf, sizeof(namebuf), "%u", loinfo->looids[0]);
+
+		if (loinfo->numlos > 1)
+		{
+			char		tagbuf[64];
+
+			snprintf(tagbuf, sizeof(tagbuf), "LARGE OBJECTS %u..%u",
+					 loinfo->looids[0], loinfo->looids[loinfo->numlos - 1]);
+
+			dumpACL(fout, loinfo->dobj.dumpId, InvalidDumpId,
+					"LARGE OBJECT", namebuf, NULL, NULL,
+					tagbuf, loinfo->rolname, &loinfo->dacl);
+		}
+		else
+		{
+			dumpACL(fout, loinfo->dobj.dumpId, InvalidDumpId,
+					"LARGE OBJECT", namebuf, NULL, NULL,
 					NULL, loinfo->rolname, &loinfo->dacl);
+		}
+	}
 
 	destroyPQExpBuffer(cquery);
-	destroyPQExpBuffer(dquery);
 }
 
 /*
  * dumpLOs:
- *	dump the data contents of all large objects
+ *	dump the data contents of the large objects in the given group
  */
 static int
 dumpLOs(Archive *fout, const void *arg)
 {
-	const char *loQry;
+	const LoInfo *loinfo = (const LoInfo *) arg;
-	const char *loFetchQry;
 	PGconn	   *conn = GetConnection(fout);
-	PGresult   *res;
 	char		buf[LOBBUFSIZE];
-	int			ntups;
-	int			i;
-	int			cnt;
-
-	pg_log_info("saving large objects");
-
-	/*
-	 * Currently, we re-fetch all LO OIDs using a cursor.  Consider scanning
-	 * the already-in-memory dumpable objects instead...
-	 */
-	loQry =
-		"DECLARE looid CURSOR FOR "
-		"SELECT oid FROM pg_largeobject_metadata ORDER BY 1";
-
-	ExecuteSqlStatement(fout, loQry);
 
-	/* Command to fetch from cursor */
+	pg_log_info("saving large objects \"%s\"", loinfo->dobj.name);
-	loFetchQry = "FETCH 1000 IN looid";
-
-	do
-	{
-		/* Do a fetch */
-		res = ExecuteSqlQuery(fout, loFetchQry, PGRES_TUPLES_OK);
 
-		/* Process the tuples, if any */
+	for (int i = 0; i < loinfo->numlos; i++)
-		ntups = PQntuples(res);
-		for (i = 0; i < ntups; i++)
 	{
-			Oid			loOid;
+		Oid			loOid = loinfo->looids[i];
 		int			loFd;
+		int			cnt;
 
-			loOid = atooid(PQgetvalue(res, i, 0));
 		/* Open the LO */
 		loFd = lo_open(conn, loOid, INV_READ);
 		if (loFd == -1)
@@ -3812,9 +3881,6 @@ dumpLOs(Archive *fout, const void *arg)
 		EndLO(fout, loOid);
 	}
 
-		PQclear(res);
-	} while (ntups > 0);
-
 	return 1;
 }
 
@@ -10646,28 +10712,34 @@ dumpDumpableObject(Archive *fout, DumpableObject *dobj)
 		case DO_LARGE_OBJECT_DATA:
 			if (dobj->dump & DUMP_COMPONENT_DATA)
 			{
+				LoInfo	   *loinfo;
 				TocEntry   *te;
 
+				loinfo = (LoInfo *) findObjectByDumpId(dobj->dependencies[0]);
+				if (loinfo == NULL)
+					pg_fatal("missing metadata for large objects \"%s\"",
+							 dobj->name);
+
 				te = ArchiveEntry(fout, dobj->catId, dobj->dumpId,
 								  ARCHIVE_OPTS(.tag = dobj->name,
+											   .owner = loinfo->rolname,
 											   .description = "BLOBS",
 											   .section = SECTION_DATA,
-											   .dumpFn = dumpLOs));
+											   .deps = dobj->dependencies,
+											   .nDeps = dobj->nDeps,
+											   .dumpFn = dumpLOs,
+											   .dumpArg = loinfo));
 
 				/*
 				 * Set the TocEntry's dataLength in case we are doing a
 				 * parallel dump and want to order dump jobs by table size.
 				 * (We need some size estimate for every TocEntry with a
 				 * DataDumper function.)  We don't currently have any cheap
-				 * way to estimate the size of LOs, but it doesn't matter;
+				 * way to estimate the size of LOs, but fortunately it doesn't
-				 * let's just set the size to a large value so parallel dumps
+				 * matter too much as long as we get large batches of LOs
-				 * will launch this job first.  If there's lots of LOs, we
+				 * processed reasonably early.  Assume 8K per blob.
-				 * win, and if there aren't, we don't lose much.  (If you want
-				 * to improve on this, really what you should be thinking
-				 * about is allowing LO dumping to be parallelized, not just
-				 * getting a smarter estimate for the single TOC entry.)
 				 */
-				te->dataLength = INT_MAX;
+				te->dataLength = loinfo->numlos * (pgoff_t) 8192;
 			}
 			break;
 		case DO_POLICY:
@@ -10765,7 +10837,7 @@ dumpNamespace(Archive *fout, const NamespaceInfo *nspinfo)
 	if (nspinfo->dobj.dump & DUMP_COMPONENT_ACL)
 		dumpACL(fout, nspinfo->dobj.dumpId, InvalidDumpId, "SCHEMA",
 				qnspname, NULL, NULL,
-				nspinfo->rolname, &nspinfo->dacl);
+				NULL, nspinfo->rolname, &nspinfo->dacl);
 
 	free(qnspname);
 
@@ -11062,7 +11134,7 @@ dumpEnumType(Archive *fout, const TypeInfo *tyinfo)
 		dumpACL(fout, tyinfo->dobj.dumpId, InvalidDumpId, "TYPE",
 				qtypname, NULL,
 				tyinfo->dobj.namespace->dobj.name,
-				tyinfo->rolname, &tyinfo->dacl);
+				NULL, tyinfo->rolname, &tyinfo->dacl);
 
 	PQclear(res);
 	destroyPQExpBuffer(q);
@@ -11215,7 +11287,7 @@ dumpRangeType(Archive *fout, const TypeInfo *tyinfo)
 		dumpACL(fout, tyinfo->dobj.dumpId, InvalidDumpId, "TYPE",
 				qtypname, NULL,
 				tyinfo->dobj.namespace->dobj.name,
-				tyinfo->rolname, &tyinfo->dacl);
+				NULL, tyinfo->rolname, &tyinfo->dacl);
 
 	PQclear(res);
 	destroyPQExpBuffer(q);
@@ -11286,7 +11358,7 @@ dumpUndefinedType(Archive *fout, const TypeInfo *tyinfo)
 		dumpACL(fout, tyinfo->dobj.dumpId, InvalidDumpId, "TYPE",
 				qtypname, NULL,
 				tyinfo->dobj.namespace->dobj.name,
-				tyinfo->rolname, &tyinfo->dacl);
+				NULL, tyinfo->rolname, &tyinfo->dacl);
 
 	destroyPQExpBuffer(q);
 	destroyPQExpBuffer(delq);
@@ -11533,7 +11605,7 @@ dumpBaseType(Archive *fout, const TypeInfo *tyinfo)
 		dumpACL(fout, tyinfo->dobj.dumpId, InvalidDumpId, "TYPE",
 				qtypname, NULL,
 				tyinfo->dobj.namespace->dobj.name,
-				tyinfo->rolname, &tyinfo->dacl);
+				NULL, tyinfo->rolname, &tyinfo->dacl);
 
 	PQclear(res);
 	destroyPQExpBuffer(q);
@@ -11688,7 +11760,7 @@ dumpDomain(Archive *fout, const TypeInfo *tyinfo)
 		dumpACL(fout, tyinfo->dobj.dumpId, InvalidDumpId, "TYPE",
 				qtypname, NULL,
 				tyinfo->dobj.namespace->dobj.name,
-				tyinfo->rolname, &tyinfo->dacl);
+				NULL, tyinfo->rolname, &tyinfo->dacl);
 
 	/* Dump any per-constraint comments */
 	for (i = 0; i < tyinfo->nDomChecks; i++)
@@ -11902,7 +11974,7 @@ dumpCompositeType(Archive *fout, const TypeInfo *tyinfo)
 		dumpACL(fout, tyinfo->dobj.dumpId, InvalidDumpId, "TYPE",
 				qtypname, NULL,
 				tyinfo->dobj.namespace->dobj.name,
-				tyinfo->rolname, &tyinfo->dacl);
+				NULL, tyinfo->rolname, &tyinfo->dacl);
 
 	/* Dump any per-column comments */
 	if (tyinfo->dobj.dump & DUMP_COMPONENT_COMMENT)
@@ -12178,7 +12250,7 @@ dumpProcLang(Archive *fout, const ProcLangInfo *plang)
 	if (plang->lanpltrusted && plang->dobj.dump & DUMP_COMPONENT_ACL)
 		dumpACL(fout, plang->dobj.dumpId, InvalidDumpId, "LANGUAGE",
 				qlanname, NULL, NULL,
-				plang->lanowner, &plang->dacl);
+				NULL, plang->lanowner, &plang->dacl);
 
 	free(qlanname);
 
@@ -12642,7 +12714,7 @@ dumpFunc(Archive *fout, const FuncInfo *finfo)
 		dumpACL(fout, finfo->dobj.dumpId, InvalidDumpId, keyword,
 				funcsig, NULL,
 				finfo->dobj.namespace->dobj.name,
-				finfo->rolname, &finfo->dacl);
+				NULL, finfo->rolname, &finfo->dacl);
 
 	PQclear(res);
 
@@ -14502,7 +14574,7 @@ dumpAgg(Archive *fout, const AggInfo *agginfo)
 		dumpACL(fout, agginfo->aggfn.dobj.dumpId, InvalidDumpId,
 				"FUNCTION", aggsig, NULL,
 				agginfo->aggfn.dobj.namespace->dobj.name,
-				agginfo->aggfn.rolname, &agginfo->aggfn.dacl);
+				NULL, agginfo->aggfn.rolname, &agginfo->aggfn.dacl);
 
 	free(aggsig);
 	free(aggfullsig);
@@ -14899,7 +14971,7 @@ dumpForeignDataWrapper(Archive *fout, const FdwInfo *fdwinfo)
 	/* Handle the ACL */
 	if (fdwinfo->dobj.dump & DUMP_COMPONENT_ACL)
 		dumpACL(fout, fdwinfo->dobj.dumpId, InvalidDumpId,
-				"FOREIGN DATA WRAPPER", qfdwname, NULL,
+				"FOREIGN DATA WRAPPER", qfdwname, NULL, NULL,
 				NULL, fdwinfo->rolname, &fdwinfo->dacl);
 
 	free(qfdwname);
@@ -14986,7 +15058,7 @@ dumpForeignServer(Archive *fout, const ForeignServerInfo *srvinfo)
 	/* Handle the ACL */
 	if (srvinfo->dobj.dump & DUMP_COMPONENT_ACL)
 		dumpACL(fout, srvinfo->dobj.dumpId, InvalidDumpId,
-				"FOREIGN SERVER", qsrvname, NULL,
+				"FOREIGN SERVER", qsrvname, NULL, NULL,
 				NULL, srvinfo->rolname, &srvinfo->dacl);
 
 	/* Dump user mappings */
@@ -15186,6 +15258,8 @@ dumpDefaultACL(Archive *fout, const DefaultACLInfo *daclinfo)
  * 'subname' is the formatted name of the sub-object, if any.  Must be quoted.
  *		(Currently we assume that subname is only provided for table columns.)
  * 'nspname' is the namespace the object is in (NULL if none).
+ * 'tag' is the tag to use for the ACL TOC entry; typically, this is NULL
+ *		to use the default for the object type.
  * 'owner' is the owner, NULL if there is no owner (for languages).
  * 'dacl' is the DumpableAcl struct for the object.
  *
@@ -15196,7 +15270,7 @@ dumpDefaultACL(Archive *fout, const DefaultACLInfo *daclinfo)
 static DumpId
 dumpACL(Archive *fout, DumpId objDumpId, DumpId altDumpId,
 		const char *type, const char *name, const char *subname,
-		const char *nspname, const char *owner,
+		const char *nspname, const char *tag, const char *owner,
 		const DumpableAcl *dacl)
 {
 	DumpId		aclDumpId = InvalidDumpId;
@@ -15268,14 +15342,16 @@ dumpACL(Archive *fout, DumpId objDumpId, DumpId altDumpId,
 
 	if (sql->len > 0)
 	{
-		PQExpBuffer tag = createPQExpBuffer();
+		PQExpBuffer tagbuf = createPQExpBuffer();
 		DumpId		aclDeps[2];
 		int			nDeps = 0;
 
-		if (subname)
+		if (tag)
-			appendPQExpBuffer(tag, "COLUMN %s.%s", name, subname);
+			appendPQExpBufferStr(tagbuf, tag);
+		else if (subname)
+			appendPQExpBuffer(tagbuf, "COLUMN %s.%s", name, subname);
 		else
-			appendPQExpBuffer(tag, "%s %s", type, name);
+			appendPQExpBuffer(tagbuf, "%s %s", type, name);
 
 		aclDeps[nDeps++] = objDumpId;
 		if (altDumpId != InvalidDumpId)
@@ -15284,7 +15360,7 @@ dumpACL(Archive *fout, DumpId objDumpId, DumpId altDumpId,
 		aclDumpId = createDumpId();
 
 		ArchiveEntry(fout, nilCatalogId, aclDumpId,
-					 ARCHIVE_OPTS(.tag = tag->data,
+					 ARCHIVE_OPTS(.tag = tagbuf->data,
 								  .namespace = nspname,
 								  .owner = owner,
 								  .description = "ACL",
@@ -15293,7 +15369,7 @@ dumpACL(Archive *fout, DumpId objDumpId, DumpId altDumpId,
 								  .deps = aclDeps,
 								  .nDeps = nDeps));
 
-		destroyPQExpBuffer(tag);
+		destroyPQExpBuffer(tagbuf);
 	}
 
 	destroyPQExpBuffer(sql);
@@ -15675,8 +15751,8 @@ dumpTable(Archive *fout, const TableInfo *tbinfo)
 		tableAclDumpId =
 			dumpACL(fout, tbinfo->dobj.dumpId, InvalidDumpId,
 					objtype, namecopy, NULL,
-					tbinfo->dobj.namespace->dobj.name, tbinfo->rolname,
+					tbinfo->dobj.namespace->dobj.name,
-					&tbinfo->dacl);
+					NULL, tbinfo->rolname, &tbinfo->dacl);
 	}
 
 	/*
@@ -15769,8 +15845,8 @@ dumpTable(Archive *fout, const TableInfo *tbinfo)
 			 */
 			dumpACL(fout, tbinfo->dobj.dumpId, tableAclDumpId,
 					"TABLE", namecopy, attnamecopy,
-					tbinfo->dobj.namespace->dobj.name, tbinfo->rolname,
+					tbinfo->dobj.namespace->dobj.name,
-					&coldacl);
+					NULL, tbinfo->rolname, &coldacl);
 			free(attnamecopy);
 		}
 		PQclear(res);
@@ -18641,12 +18717,12 @@ addBoundaryDependencies(DumpableObject **dobjs, int numObjs,
 			case DO_FDW:
 			case DO_FOREIGN_SERVER:
 			case DO_TRANSFORM:
-			case DO_LARGE_OBJECT:
 				/* Pre-data objects: must come before the pre-data boundary */
 				addObjectDependency(preDataBound, dobj->dumpId);
 				break;
 			case DO_TABLE_DATA:
 			case DO_SEQUENCE_SET:
+			case DO_LARGE_OBJECT:
 			case DO_LARGE_OBJECT_DATA:
 				/* Data objects: must come between the boundaries */
 				addObjectDependency(dobj, preDataBound->dumpId);

src/bin/pg_dump/pg_dump.h

@@ -582,11 +582,21 @@ typedef struct _defaultACLInfo
 	char		defaclobjtype;
 } DefaultACLInfo;
 
+/*
+ * LoInfo represents a group of large objects (blobs) that share the same
+ * owner and ACL setting.  dobj.components has the DUMP_COMPONENT_COMMENT bit
+ * set if any blob in the group has a comment; similarly for sec labels.
+ * If there are many blobs with the same owner/ACL, we can divide them into
+ * multiple LoInfo groups, which will each spawn a BLOB METADATA and a BLOBS
+ * (data) TOC entry.  This allows more parallelism during restore.
+ */
 typedef struct _loInfo
 {
 	DumpableObject dobj;
 	DumpableAcl dacl;
 	const char *rolname;
+	int			numlos;
+	Oid			looids[FLEXIBLE_ARRAY_MEMBER];
 } LoInfo;
 
 /*
@@ -695,6 +705,7 @@ typedef struct _SubRelInfo
 extern TableInfo *getSchemaData(Archive *fout, int *numTablesPtr);
 
 extern void AssignDumpId(DumpableObject *dobj);
+extern void recordAdditionalCatalogID(CatalogId catId, DumpableObject *dobj);
 extern DumpId createDumpId(void);
 extern DumpId getMaxDumpId(void);
 extern DumpableObject *findObjectByDumpId(DumpId dumpId);

src/bin/pg_dump/t/002_pg_dump.pl

@@ -109,11 +109,11 @@ my %pgdump_runs = (
 			'--format=directory', '--compress=gzip:1',
 			"--file=$tempdir/compression_gzip_dir", 'postgres',
 		],
-		# Give coverage for manually compressed blob.toc files during
+		# Give coverage for manually compressed blobs.toc files during
 		# restore.
 		compress_cmd => {
 			program => $ENV{'GZIP_PROGRAM'},
-			args => [ '-f', "$tempdir/compression_gzip_dir/blobs.toc", ],
+			args => [ '-f', "$tempdir/compression_gzip_dir/blobs_*.toc", ],
 		},
 		# Verify that only data files were compressed
 		glob_patterns => [
@@ -172,16 +172,6 @@ my %pgdump_runs = (
 			'--format=directory', '--compress=lz4:1',
 			"--file=$tempdir/compression_lz4_dir", 'postgres',
 		],
-		# Give coverage for manually compressed blob.toc files during
-		# restore.
-		compress_cmd => {
-			program => $ENV{'LZ4'},
-			args => [
-				'-z', '-f', '--rm',
-				"$tempdir/compression_lz4_dir/blobs.toc",
-				"$tempdir/compression_lz4_dir/blobs.toc.lz4",
-			],
-		},
 		# Verify that data files were compressed
 		glob_patterns => [
 			"$tempdir/compression_lz4_dir/toc.dat",
@@ -242,14 +232,13 @@ my %pgdump_runs = (
 			'--format=directory', '--compress=zstd:1',
 			"--file=$tempdir/compression_zstd_dir", 'postgres',
 		],
-		# Give coverage for manually compressed blob.toc files during
+		# Give coverage for manually compressed blobs.toc files during
 		# restore.
 		compress_cmd => {
 			program => $ENV{'ZSTD'},
 			args => [
 				'-z', '-f',
-				'--rm', "$tempdir/compression_zstd_dir/blobs.toc",
+				'--rm', "$tempdir/compression_zstd_dir/blobs_*.toc",
-				"-o", "$tempdir/compression_zstd_dir/blobs.toc.zst",
 			],
 		},
 		# Verify that data files were compressed
@@ -413,7 +402,7 @@ my %pgdump_runs = (
 		},
 		glob_patterns => [
 			"$tempdir/defaults_dir_format/toc.dat",
-			"$tempdir/defaults_dir_format/blobs.toc",
+			"$tempdir/defaults_dir_format/blobs_*.toc",
 			$supports_gzip ? "$tempdir/defaults_dir_format/*.dat.gz"
 			: "$tempdir/defaults_dir_format/*.dat",
 		],
@@ -923,7 +912,7 @@ my %tests = (
 			column_inserts => 1,
 			data_only => 1,
 			inserts => 1,
-			section_pre_data => 1,
+			section_data => 1,
 			test_schema_plus_large_objects => 1,
 		},
 		unlike => {
@@ -1336,7 +1325,7 @@ my %tests = (
 			column_inserts => 1,
 			data_only => 1,
 			inserts => 1,
-			section_pre_data => 1,
+			section_data => 1,
 			test_schema_plus_large_objects => 1,
 		},
 		unlike => {
@@ -1544,7 +1533,7 @@ my %tests = (
 			column_inserts => 1,
 			data_only => 1,
 			inserts => 1,
-			section_pre_data => 1,
+			section_data => 1,
 			test_schema_plus_large_objects => 1,
 		},
 		unlike => {
@@ -4289,7 +4278,7 @@ my %tests = (
 			column_inserts => 1,
 			data_only => 1,
 			inserts => 1,
-			section_pre_data => 1,
+			section_data => 1,
 			test_schema_plus_large_objects => 1,
 			binary_upgrade => 1,
 		},
@@ -4893,8 +4882,13 @@ foreach my $run (sort keys %pgdump_runs)
 		# not defined.
 		next if (!defined($compress_program) || $compress_program eq '');
 
-		my @full_compress_cmd =
+		# Arguments may require globbing.
-		  ($compress_cmd->{program}, @{ $compress_cmd->{args} });
+		my @full_compress_cmd = ($compress_program);
+		foreach my $arg (@{ $compress_cmd->{args} })
+		{
+			push @full_compress_cmd, glob($arg);
+		}
+
 		command_ok(\@full_compress_cmd, "$run: compression commands");
 	}