add drop_range_partition_expand_next() function

zilder · zilder · commit b1c67ae02349 · 2017-01-25T16:12:06.000+03:00
diff --git a/expected/pathman_basic.out b/expected/pathman_basic.out
@@ -1409,6 +1409,35 @@ SELECT pathman.drop_range_partition('test.num_range_rel_7');
  test.num_range_rel_7
 (1 row)
 
+SELECT pathman.drop_range_partition_expand_next('test.num_range_rel_4');
+ drop_range_partition_expand_next 
+----------------------------------
+ 
+(1 row)
+
+SELECT * FROM pathman.pathman_partition_list WHERE parent = 'test.num_range_rel'::regclass;
+       parent       |      partition       | parttype | partattr | range_min | range_max 
+--------------------+----------------------+----------+----------+-----------+-----------
+ test.num_range_rel | test.num_range_rel_1 |        2 | id       | 0         | 1000
+ test.num_range_rel | test.num_range_rel_2 |        2 | id       | 1000      | 2000
+ test.num_range_rel | test.num_range_rel_3 |        2 | id       | 2000      | 3000
+ test.num_range_rel | test.num_range_rel_6 |        2 | id       | 3000      | 5000
+(4 rows)
+
+SELECT pathman.drop_range_partition_expand_next('test.num_range_rel_6');
+ drop_range_partition_expand_next 
+----------------------------------
+ 
+(1 row)
+
+SELECT * FROM pathman.pathman_partition_list WHERE parent = 'test.num_range_rel'::regclass;
+       parent       |      partition       | parttype | partattr | range_min | range_max 
+--------------------+----------------------+----------+----------+-----------+-----------
+ test.num_range_rel | test.num_range_rel_1 |        2 | id       | 0         | 1000
+ test.num_range_rel | test.num_range_rel_2 |        2 | id       | 1000      | 2000
+ test.num_range_rel | test.num_range_rel_3 |        2 | id       | 2000      | 3000
+(3 rows)
+
 SELECT pathman.append_range_partition('test.range_rel');
  append_range_partition 
 ------------------------
@@ -1711,15 +1740,13 @@ SELECT COUNT(*) FROM ONLY test.hash_rel;
 
 DROP TABLE test.hash_rel CASCADE;
 SELECT pathman.drop_partitions('test.num_range_rel');
-NOTICE:  drop cascades to 4 other objects
+NOTICE:  drop cascades to 3 other objects
 NOTICE:  998 rows copied from test.num_range_rel_1
 NOTICE:  1000 rows copied from test.num_range_rel_2
 NOTICE:  1000 rows copied from test.num_range_rel_3
-NOTICE:  2 rows copied from test.num_range_rel_4
-NOTICE:  0 rows copied from test.num_range_rel_6
  drop_partitions 
 -----------------
-               5
+               3
 (1 row)
 
 DROP TABLE test.num_range_rel CASCADE;
diff --git a/range.sql b/range.sql
@@ -533,68 +533,6 @@ END
 $$
 LANGUAGE plpgsql;
 
-
-/*
- * Merge RANGE partitions
- */
-CREATE OR REPLACE FUNCTION @extschema@.merge_range_partitions(
-	partition1		REGCLASS,
-	partition2		REGCLASS)
-RETURNS VOID AS
-$$
-DECLARE
-	v_parent1		REGCLASS;
-	v_parent2		REGCLASS;
-	v_attname		TEXT;
-	v_part_type		INTEGER;
-	v_atttype		REGTYPE;
-
-BEGIN
-	IF partition1 = partition2 THEN
-		RAISE EXCEPTION 'cannot merge partition with itself';
-	END IF;
-
-	v_parent1 := @extschema@.get_parent_of_partition(partition1);
-	v_parent2 := @extschema@.get_parent_of_partition(partition2);
-
-	/* Acquire data modification locks (prevent further modifications) */
-	PERFORM @extschema@.prevent_relation_modification(partition1);
-	PERFORM @extschema@.prevent_relation_modification(partition2);
-
-	IF v_parent1 != v_parent2 THEN
-		RAISE EXCEPTION 'cannot merge partitions with different parents';
-	END IF;
-
-	/* Acquire lock on parent */
-	PERFORM @extschema@.lock_partitioned_relation(v_parent1);
-
-	SELECT attname, parttype
-	FROM @extschema@.pathman_config
-	WHERE partrel = v_parent1
-	INTO v_attname, v_part_type;
-
-	IF v_attname IS NULL THEN
-		RAISE EXCEPTION 'table "%" is not partitioned', v_parent1::TEXT;
-	END IF;
-
-	/* Check if this is a RANGE partition */
-	IF v_part_type != 2 THEN
-		RAISE EXCEPTION 'specified partitions are not RANGE partitions';
-	END IF;
-
-	v_atttype := @extschema@.get_attribute_type(partition1, v_attname);
-
-	EXECUTE format('SELECT @extschema@.merge_range_partitions_internal($1, $2, $3, NULL::%s)',
-				   @extschema@.get_base_type(v_atttype)::TEXT)
-	USING v_parent1, partition1, partition2;
-
-	/* Tell backend to reload configuration */
-	PERFORM @extschema@.on_update_partitions(v_parent1);
-END
-$$
-LANGUAGE plpgsql;
-
-
 /*
  * Merge multiple partitions. All data will be copied to the first one. The rest
  * of partitions will be dropped
@@ -617,7 +555,6 @@ BEGIN
 END
 $$ LANGUAGE plpgsql;
 
-
 /*
  * Append new partition.
  */
@@ -952,6 +889,19 @@ LANGUAGE plpgsql
 SET pg_pathman.enable_partitionfilter = off; /* ensures that PartitionFilter is OFF */
 
 
+/*
+ * Drops partition and expands the next partition so that it cover dropped
+ * one
+ *
+ * This function was written in order to support Oracle-like ALTER TABLE ...
+ * DROP PARTITION. In Oracle partitions only have upper bound and when
+ * partition is dropped the next one automatically covers freed range
+ */
+CREATE OR REPLACE FUNCTION @extschema@.drop_range_partition_expand_next(relid REGCLASS)
+RETURNS VOID AS 'pg_pathman', 'drop_range_partition_expand_next'
+LANGUAGE C STRICT;
+
+
 /*
  * Attach range partition
  */
diff --git a/sql/pathman_basic.sql b/sql/pathman_basic.sql
@@ -400,6 +400,11 @@ SELECT pathman.prepend_range_partition('test.num_range_rel');
 EXPLAIN (COSTS OFF) SELECT * FROM test.num_range_rel WHERE id < 0;
 SELECT pathman.drop_range_partition('test.num_range_rel_7');
 
+SELECT pathman.drop_range_partition_expand_next('test.num_range_rel_4');
+SELECT * FROM pathman.pathman_partition_list WHERE parent = 'test.num_range_rel'::regclass;
+SELECT pathman.drop_range_partition_expand_next('test.num_range_rel_6');
+SELECT * FROM pathman.pathman_partition_list WHERE parent = 'test.num_range_rel'::regclass;
+
 SELECT pathman.append_range_partition('test.range_rel');
 SELECT pathman.prepend_range_partition('test.range_rel');
 EXPLAIN (COSTS OFF) SELECT * FROM test.range_rel WHERE dt BETWEEN '2014-12-15' AND '2015-01-15';
diff --git a/src/pl_range_funcs.c b/src/pl_range_funcs.c
@@ -59,6 +59,7 @@ PG_FUNCTION_INFO_V1( get_part_range_by_idx );
 PG_FUNCTION_INFO_V1( build_range_condition );
 PG_FUNCTION_INFO_V1( build_sequence_name );
 PG_FUNCTION_INFO_V1( merge_range_partitions );
+PG_FUNCTION_INFO_V1( drop_range_partition_expand_next );
 
 
 /*
@@ -690,3 +691,62 @@ drop_table(Oid relid)
 
 	RemoveRelations(n);
 }
+
+/*
+ * Drops partition and expands the next partition so that it cover dropped
+ * one
+ *
+ * This function was written in order to support Oracle-like ALTER TABLE ...
+ * DROP PARTITION. In Oracle partitions only have upper bound and when
+ * partition is dropped the next one automatically covers freed range
+ */
+Datum
+drop_range_partition_expand_next(PG_FUNCTION_ARGS)
+{
+	PartParentSearch		parent_search;
+	const PartRelationInfo *prel;
+	RangeEntry	   *ranges;
+	Oid				relid = PG_GETARG_OID(0),
+					parent;
+	int				i;
+
+	/* Get parent relid */
+	parent = get_parent_of_partition(relid, &parent_search);
+	if (parent_search != PPS_ENTRY_PART_PARENT)
+		elog(ERROR, "relation \"%s\" is not a partition",
+			 get_rel_name_or_relid(relid));
+
+	prel = get_pathman_relation_info(parent);
+	shout_if_prel_is_invalid(parent, prel, PT_RANGE);
+
+	ranges = PrelGetRangesArray(prel);
+
+	/* Looking for partition in child relations */
+	for (i = 0; i < prel->children_count; i++)
+		if (ranges[i].child_oid == relid)
+			break;
+
+	/*
+	 * It must be in ranges array because we already know that table
+	 * is a partition
+	 */
+	Assert(i < prel->children_count);
+
+	/* If there is next partition then expand it */
+	if (i < prel->children_count - 1)
+	{
+		RangeEntry	   *cur = &ranges[i],
+					   *next = &ranges[i+1];
+
+		recreate_range_constraint(next->child_oid,
+						get_relid_attribute_name(prel->key, prel->attnum),
+						prel->attnum,
+						prel->atttype,
+						&cur->min,
+						&next->max);
+	}
+
+	drop_table(relid);
+
+	PG_RETURN_VOID();	
+}
