Copy schemas/namespaces as a separate sub-command

docs/include/copy-schemas.rst

@@ -0,0 +1,13 @@
+::
+
+   pgcopydb copy schemas: Create all the schemas found in the source database in the target
+   usage: pgcopydb copy schemas  --source ... --target ... [ --table-jobs ... --index-jobs ... ] 
+
+     --source             Postgres URI to the source database
+     --target             Postgres URI to the target database
+     --dir                Work directory to use
+     --filters <filename> Use the filters defined in <filename>
+     --restart            Allow restarting when temp files exist already
+     --resume             Allow resuming operations after a failure
+     --not-consistent     Allow taking a new snapshot on the source database
+

docs/include/copy.rst

@@ -14,4 +14,5 @@
        sequences    Copy the current value from all sequences in database from source to target
        indexes      Create all the indexes found in the source database in the target
        constraints  Create all the constraints found in the source database in the target
+       schemas      Create all the schemas found in the source database in the target
 

docs/include/help.rst

@@ -30,6 +30,7 @@
        sequences    Copy the current value from all sequences in database from source to target
        indexes      Create all the indexes found in the source database in the target
        constraints  Create all the constraints found in the source database in the target
+       schemas      Create all the schemas found in the source database in the target
 
      pgcopydb dump
        schema     Dump source database schema as custom files in work directory

docs/ref/pgcopydb_copy.rst

@@ -198,6 +198,15 @@ is found existing already on the target database.
 
 .. include:: ../include/copy-constraints.rst
 
+pgcopydb copy schemas
+---------------------
+
+pgcopydb copy schemas - Creates all the schemas found in the source database in the target
+
+The command ``pgcopydb copy schemas`` fetches all the CREATE SCHEMA commands from the pre-data section of pg_dump. Ownership and ACLs can also be restored if they pre-exist, or the ``pgcopydb copy roles`` command can be used beforehand.
+
+.. include:: ../include/copy-schemas.rst
+
 Description
 -----------
 

src/bin/pgcopydb/cli_copy.c

@@ -28,6 +28,7 @@ static void cli_copy_sequences(int argc, char **argv);
 static void cli_copy_indexes(int argc, char **argv);
 static void cli_copy_constraints(int argc, char **argv);
 static void cli_copy_blobs(int argc, char **argv);
+static void cli_copy_schemas(int argc, char **argv);
 
 static CommandLine copy_db_command =
 	make_command(
@@ -202,6 +203,21 @@ static CommandLine copy_constraints_command =
 		cli_copy_db_getopts,
 		cli_copy_constraints);
 
+static CommandLine copy_schemas_command =
+	make_command(
+		"schemas",
+		"Create all the schemas found in the source database in the target",
+		" --source ... --target ... [ --table-jobs ... --index-jobs ... ] ",
+		"  --source             Postgres URI to the source database\n"
+		"  --target             Postgres URI to the target database\n"
+		"  --dir                Work directory to use\n"
+		"  --filters <filename> Use the filters defined in <filename>\n"
+		"  --restart            Allow restarting when temp files exist already\n"
+		"  --resume             Allow resuming operations after a failure\n"
+		"  --not-consistent     Allow taking a new snapshot on the source database\n",
+		cli_copy_db_getopts,
+		cli_copy_schemas);
+
 static CommandLine *copy_subcommands[] = {
 	&copy_db_command,
 	&copy_roles_command,
@@ -213,6 +229,7 @@ static CommandLine *copy_subcommands[] = {
 	&copy_sequence_command,
 	&copy_indexes_command,
 	&copy_constraints_command,
+	&copy_schemas_command,
 	NULL
 };
 
@@ -657,3 +674,49 @@ cli_copy_extensions(int argc, char **argv)
 		exit(EXIT_CODE_INTERNAL_ERROR);
 	}
 }
+
+
+/*
+ * cli_copy_schemas implements copying schemas
+ */
+static void
+cli_copy_schemas(int argc, char **argv)
+{
+	CopyDataSpec copySpecs = { 0 };
+
+	(void) cli_copy_prepare_specs(&copySpecs, DATA_SECTION_SCHEMAS);
+
+	/*
+	 * First, we need to open a snapshot that we're going to re-use in all our
+	 * connections to the source database. When the --snapshot option has been
+	 * used, instead of exporting a new snapshot, we can just re-use it.
+	 */
+	if (!copydb_prepare_snapshot(&copySpecs))
+	{
+		/* errors have already been logged */
+		exit(EXIT_CODE_INTERNAL_ERROR);
+	}
+
+	/* fetch schema information from source catalogs, including filtering */
+	if (!copydb_fetch_schema_and_prepare_specs(&copySpecs))
+	{
+		/* errors have already been logged */
+		exit(EXIT_CODE_INTERNAL_ERROR);
+	}
+
+	if (!copydb_dump_source_schema(&copySpecs,
+								   copySpecs.sourceSnapshot.snapshot,
+								   PG_DUMP_SECTION_PRE_DATA))
+	{
+		/* errors have already been logged */
+		exit(EXIT_CODE_INTERNAL_ERROR);
+	}
+
+	/* Now restore the pre-data, but only the schemas */
+	if (!copydb_target_prepare_schema(&copySpecs))
+	{
+		log_error(
+			"Failed to prepare schema on the target database, see above for details");
+		exit(EXIT_CODE_TARGET);
+	}
+}

src/bin/pgcopydb/dump_restore.c

@@ -646,12 +646,35 @@ copydb_write_restore_list(CopyDataSpec *specs, PostgresDumpSection section)
 
 		bool skip = false;
 
+		log_trace("Processing dumpId %d: %s %u %u %s",
+				  item->dumpId,
+				  item->description,
+				  item->catalogOid,
+				  item->objectOid,
+				  item->restoreListName);
+
+		/*
+		 * Skip everything except SCHEMAS when specs->section == DATA_SECTION_SCHEMAS
+		 */
+		if (specs->section == DATA_SECTION_SCHEMAS &&
+			(item->isCompositeTag ?
+			 item->tagType != ARCHIVE_TAG_TYPE_SCHEMA :
+			 item->desc != ARCHIVE_TAG_SCHEMA))
+		{
+			skip = true;
+			log_debug("Skipping non schema %d: %s %u %s",
+					  item->dumpId,
+					  item->description,
+					  item->objectOid,
+					  item->restoreListName);
+		}
+
 		/*
 		 * Skip COMMENT ON EXTENSION when either of the option
 		 * --skip-extensions or --skip-ext-comment has been used.
 		 */
-		if ((specs->skipExtensions ||
-			 specs->skipCommentOnExtension) &&
+		if (!skip && (specs->skipExtensions ||
+					  specs->skipCommentOnExtension) &&
 			item->isCompositeTag &&
 			item->tagKind == ARCHIVE_TAG_KIND_COMMENT &&
 			item->tagType == ARCHIVE_TAG_TYPE_EXTENSION)

tests/extensions/copydb.sh

@@ -31,6 +31,8 @@ EOF
 psql -a -1 ${PGCOPYDB_SOURCE_PGURI_SU} <<EOF
 create extension intarray cascade;
 create extension postgis cascade;
+create schema foo;
+create extension hstore with schema foo cascade;
 EOF
 
 #
@@ -57,6 +59,14 @@ coproc ( pgcopydb snapshot --debug )
 
 sleep 1
 
+# copy the schemas to the target database
+# before we copy the extensions
+pgcopydb copy schemas \
+         --source ${PGCOPYDB_SOURCE_PGURI_SU} \
+         --target ${PGCOPYDB_TARGET_PGURI_SU} \
+         --resume \
+         --debug
+
 # copy the extensions separately, needs superuser (both on source and target)
 pgcopydb list extensions --source ${PGCOPYDB_SOURCE_PGURI_SU}