pg_restore_truncate_v4.patch

diff --git a/doc/src/sgml/ref/pg_restore.sgml b/doc/src/sgml/ref/pg_restore.sgml
index 1b9db6b..23b0d16 100644
--- a/doc/src/sgml/ref/pg_restore.sgml
+++ b/doc/src/sgml/ref/pg_restore.sgml
@@ -546,6 +546,26 @@
      </varlistentry>
 
      <varlistentry>
+      <term><option>--truncate-tables</></term>
+      <listitem>
+       <para>
+        This option is only relevant when performing a data-only
+        restore.  It instructs <application>pg_restore</application>
+        to execute commands to truncate the target tables while the
+        data is reloaded.  Use this when restoring tables or schemas
+        and <option>--clean</option> cannot be used because dependent
+        objects would be destroyed.
+       </para>
+
+       <para>
+         The <option>--disable-triggers</option> will almost always
+         always need to be used in conjunction with this option to
+         disable check constraints on foreign keys.
+       </para>
+      </listitem>
+     </varlistentry>
+
+     <varlistentry>
       <term><option>--use-set-session-authorization</option></term>
       <listitem>
        <para>
diff --git a/src/bin/pg_dump/pg_backup.h b/src/bin/pg_dump/pg_backup.h
index 3b49395..0aaf1d3 100644
--- a/src/bin/pg_dump/pg_backup.h
+++ b/src/bin/pg_dump/pg_backup.h
@@ -101,6 +101,8 @@ typedef struct _restoreOptions
 	int			noTablespace;	/* Don't issue tablespace-related commands */
 	int			disable_triggers;		/* disable triggers during data-only
 										 * restore */
+	int			truncate_tables;		/* truncate tables during data-only
+										 * restore */
 	int			use_setsessauth;/* Use SET SESSION AUTHORIZATION commands
 								 * instead of OWNER TO */
 	int			no_security_labels;		/* Skip security label entries */
diff --git a/src/bin/pg_dump/pg_backup_archiver.c b/src/bin/pg_dump/pg_backup_archiver.c
index 1fead28..c7fdc79 100644
--- a/src/bin/pg_dump/pg_backup_archiver.c
+++ b/src/bin/pg_dump/pg_backup_archiver.c
@@ -309,6 +309,11 @@ RestoreArchive(Archive *AHX)
 	if (ropt->createDB && ropt->single_txn)
 		exit_horribly(modulename, "-C and -1 are incompatible options\n");
 
+	/* When the schema is dropped and re-created then no point
+	 * truncating tables. */
+	if (ropt->dropSchema && ropt->truncate_tables)
+		exit_horribly(modulename, "-c and --truncate-tables are incompatible options\n");
+
 	/*
 	 * If we're going to do parallel restore, there are some restrictions.
 	 */
@@ -403,6 +408,10 @@ RestoreArchive(Archive *AHX)
 		}
 	}
 
+	/* Truncate tables only when restoring data. */
+	if (!ropt->dataOnly && ropt->truncate_tables)
+		exit_horribly(modulename, "--truncate-tables requires the --data-only option\n");
+
 	/*
 	 * Setup the output file if necessary.
 	 */
@@ -562,6 +571,7 @@ restore_toc_entry(ArchiveHandle *AH, TocEntry *te,
 	int			retval = 0;
 	teReqs		reqs;
 	bool		defnDumped;
+	bool		truncate;
 
 	AH->currentTE = te;
 
@@ -696,14 +706,21 @@ restore_toc_entry(ArchiveHandle *AH, TocEntry *te,
 						 * server, so no need to see if we should issue BEGIN.
 						 */
 						StartTransaction(AH);
+						truncate = 1;
+					} else
+						/* Truncate the table when asked to. */
+						truncate = ropt->truncate_tables;
 
+					if (truncate) {
 						/*
 						 * If the server version is >= 8.4, make sure we issue
 						 * TRUNCATE with ONLY so that child tables are not
-						 * wiped.
+						 * wiped.  If we don't know the server version
+						 * then err on the side of safety.
 						 */
 						ahprintf(AH, "TRUNCATE TABLE %s%s;\n\n",
-								 (PQserverVersion(AH->connection) >= 80400 ?
+								 ((!AH->connection ||
+								   PQserverVersion(AH->connection) >= 80400) ?
 								  "ONLY " : ""),
 								 fmtId(te->tag));
 					}
diff --git a/src/bin/pg_dump/pg_restore.c b/src/bin/pg_dump/pg_restore.c
index 49d799b..316fe63 100644
--- a/src/bin/pg_dump/pg_restore.c
+++ b/src/bin/pg_dump/pg_restore.c
@@ -77,6 +77,7 @@ main(int argc, char **argv)
 	static int	disable_triggers = 0;
 	static int	no_data_for_failed_tables = 0;
 	static int	outputNoTablespaces = 0;
+	static int	truncate_tables = 0;
 	static int	use_setsessauth = 0;
 	static int	no_security_labels = 0;
 
@@ -119,6 +120,7 @@ main(int argc, char **argv)
 		{"no-tablespaces", no_argument, &outputNoTablespaces, 1},
 		{"role", required_argument, NULL, 2},
 		{"section", required_argument, NULL, 3},
+		{"truncate-tables", no_argument, &truncate_tables, 1},
 		{"use-set-session-authorization", no_argument, &use_setsessauth, 1},
 		{"no-security-labels", no_argument, &no_security_labels, 1},
 
@@ -324,6 +326,7 @@ main(int argc, char **argv)
 	opts->disable_triggers = disable_triggers;
 	opts->noDataForFailedTables = no_data_for_failed_tables;
 	opts->noTablespace = outputNoTablespaces;
+	opts->truncate_tables = truncate_tables;
 	opts->use_setsessauth = use_setsessauth;
 	opts->no_security_labels = no_security_labels;
 
@@ -434,6 +437,7 @@ usage(const char *progname)
 	printf(_("  --no-security-labels         do not restore security labels\n"));
 	printf(_("  --no-tablespaces             do not restore tablespace assignments\n"));
 	printf(_("  --section=SECTION            restore named section (pre-data, data, or post-data)\n"));
+	printf(_("  --truncate-tables            truncate tables before restore\n"));
 	printf(_("  --use-set-session-authorization\n"
 			 "                               use SET SESSION AUTHORIZATION commands instead of\n"
 			 "                               ALTER OWNER commands to set ownership\n"));