Bump default version; add upgrade script

Adding a new UDF means adding an upgrade script to augment existing
installations of pg_shard.

Makefile

@@ -25,7 +25,7 @@ else
 endif
 
 EXTENSION = pg_shard
-DATA = pg_shard--1.0.sql
+DATA = pg_shard--1.1.sql pg_shard--1.0--1.1.sql
 
 # Default to 5432 if PGPORT is undefined. Replace placeholders in our tests
 # with actual port number in order to anticipate correct output during tests.

pg_shard--1.0--1.1.sql

@@ -0,0 +1,62 @@
+CREATE FUNCTION partition_column_to_node_string(table_oid oid)
+RETURNS text
+AS 'MODULE_PATHNAME'
+LANGUAGE C;
+
+COMMENT ON FUNCTION partition_column_to_node_string(oid)
+		IS 'return textual form of distributed table''s partition column';
+
+CREATE FUNCTION sync_table_metadata_to_citus(table_name text) RETURNS VOID
+AS $sync_table_metadata_to_citus$
+	DECLARE
+		table_relation_id CONSTANT oid NOT NULL := table_name::regclass::oid;
+		dummy_shard_length CONSTANT bigint := 0;
+	BEGIN
+		-- copy shard placement metadata
+		INSERT INTO pg_dist_shard_placement
+					(shardid,
+					 shardstate,
+					 shardlength,
+					 nodename,
+					 nodeport)
+		SELECT shard_id,
+			   shard_state,
+			   dummy_shard_length,
+			   node_name,
+			   node_port
+		FROM   pgs_distribution_metadata.shard_placement
+		WHERE  shard_id IN (SELECT id
+							FROM   pgs_distribution_metadata.shard
+							WHERE  relation_id = table_relation_id);
+
+		-- copy shard metadata
+		INSERT INTO pg_dist_shard
+					(shardid,
+					 logicalrelid,
+					 shardstorage,
+					 shardminvalue,
+					 shardmaxvalue)
+		SELECT id,
+			   relation_id,
+			   storage,
+			   min_value,
+			   max_value
+		FROM   pgs_distribution_metadata.shard
+		WHERE  relation_id = table_relation_id;
+
+		-- copy partition metadata, which also converts the partition column to
+		-- a node string representation as expected by CitusDB
+		INSERT INTO pg_dist_partition
+					(logicalrelid,
+					 partmethod,
+					 partkey)
+		SELECT relation_id,
+			   partition_method,
+			   partition_column_to_node_string(table_relation_id)
+		FROM   pgs_distribution_metadata.partition
+		WHERE  relation_id = table_relation_id;
+	END;
+$sync_table_metadata_to_citus$ LANGUAGE 'plpgsql';
+
+COMMENT ON FUNCTION sync_table_metadata_to_citus(text)
+		IS 'synchronize a distributed table''s pg_shard metadata to CitusDB';

pg_shard--1.0.sql → pg_shard--1.1.sql

@@ -1,4 +1,4 @@
-/* pg_shard--1.0.sql */
+/* pg_shard--1.1.sql */
 
 -- complain if script is sourced in psql, rather than via CREATE EXTENSION
 \echo Use "CREATE EXTENSION pg_shard" to load this file. \quit

pg_shard.control

@@ -1,5 +1,5 @@
 # pg_shard extension
 comment = 'extension for sharding across remote PostgreSQL servers'
-default_version = '1.0'
+default_version = '1.1'
 module_pathname = '$libdir/pg_shard'
 relocatable = true