Add support for correlated constraints

Allow users to specify a specific column to be used as a correlated constraint using the add_dimension() API. We store such correlated constraints in the dimensions related timescaledb catalog tables. The "dimension" catalog table has been amended by adding a "type" column. This column now explicitly stores the type: open, closed or correlated as appropriate. We create dimension_slice and chunk_constraint entries for chunks which have correlated constraints on them. The dimension slice entry will have -inf/+inf as start/end range initially for a given correlated constraint and the chunk_constraint entry will refer back to this slice entry. This start/end range will be refreshed later. One of the entry points is during compression for now. We can thus store the min/max values for such correlated contraints in these catalog tables at the per-chunk level. Note that correlated constraints do not participate in partitioning of the data. Such a correlated constraint will be used for chunk pruning if the WHERE clause of a SQL query specifies ranges on such a column. A "DROP COLUMN" on a column with a correlated constraint on it ends up removing all relevant entries from the catalog tables. Also a new "remove_dimension" API has been introduced to allow removal of correlated dimension entries from the catalogs.
timescale · May 6, 2024 · 00b31f7 · 00b31f7
1 parent d8057c4
commit 00b31f7
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diff --git a/sql/ddl_api.sql b/sql/ddl_api.sql
@@ -133,7 +133,8 @@ CREATE OR REPLACE FUNCTION @extschema@.add_dimension(
     number_partitions       INTEGER = NULL,
     chunk_time_interval     ANYELEMENT = NULL::BIGINT,
     partitioning_func       REGPROC = NULL,
-    if_not_exists           BOOLEAN = FALSE
+    if_not_exists           BOOLEAN = FALSE,
+    correlated              BOOLEAN = FALSE
 ) RETURNS TABLE(dimension_id INT, schema_name NAME, table_name NAME, column_name NAME, created BOOL)
 AS '@MODULE_PATHNAME@', 'ts_dimension_add' LANGUAGE C VOLATILE;
 
@@ -160,6 +161,24 @@ CREATE OR REPLACE FUNCTION @extschema@.by_range(column_name NAME,
     RETURNS _timescaledb_internal.dimension_info LANGUAGE C
     AS '@MODULE_PATHNAME@', 'ts_range_dimension';
 
+CREATE OR REPLACE FUNCTION @extschema@.by_correlation(column_name NAME)
+    RETURNS _timescaledb_internal.dimension_info LANGUAGE C
+    AS '@MODULE_PATHNAME@', 'ts_correlated_dimension';
+
+-- Remove a dimension on a hypertable. Currently only correlated constraint
+-- dimensions can be removed since the other dimensions will need a data
+-- rewrite which is not implemented
+--
+-- hypertable - OID of the table to remove dimension from
+-- column_name - NAME of the column on which the dimension exists
+-- if_not_exists - If set, and the dimension does not exist, generate a notice instead of an error
+CREATE OR REPLACE FUNCTION @extschema@.remove_dimension(
+    hypertable              REGCLASS,
+    column_name             NAME,
+    if_not_exists           BOOLEAN = FALSE
+) RETURNS TABLE(dimension_id INT, dropped BOOL)
+AS '@MODULE_PATHNAME@', 'ts_dimension_remove' LANGUAGE C VOLATILE;
+
 CREATE OR REPLACE FUNCTION @extschema@.attach_tablespace(
     tablespace NAME,
     hypertable REGCLASS,

diff --git a/sql/pre_install/tables.sql b/sql/pre_install/tables.sql
@@ -100,13 +100,14 @@ CREATE TABLE _timescaledb_catalog.dimension (
   compress_interval_length bigint NULL,
   integer_now_func_schema name NULL,
   integer_now_func name NULL,
+  type  "char",
   -- table constraints
   CONSTRAINT dimension_pkey PRIMARY KEY (id),
   CONSTRAINT dimension_hypertable_id_column_name_key UNIQUE (hypertable_id, column_name),
   CONSTRAINT dimension_check CHECK ((partitioning_func_schema IS NULL AND partitioning_func IS NULL) OR (partitioning_func_schema IS NOT NULL AND partitioning_func IS NOT NULL)),
   CONSTRAINT dimension_check1 CHECK ((num_slices IS NULL AND interval_length IS NOT NULL) OR (num_slices IS NOT NULL AND interval_length IS NULL)),
   CONSTRAINT dimension_check2 CHECK ((integer_now_func_schema IS NULL AND integer_now_func IS NULL) OR (integer_now_func_schema IS NOT NULL AND integer_now_func IS NOT NULL)),
-  CONSTRAINT dimension_interval_length_check CHECK (interval_length IS NULL OR interval_length > 0),
+  CONSTRAINT dimension_interval_length_check CHECK (interval_length IS NULL OR interval_length > 0 OR type = 'C'),
   CONSTRAINT dimension_compress_interval_length_check CHECK (compress_interval_length IS NULL OR compress_interval_length > 0),
   CONSTRAINT dimension_hypertable_id_fkey FOREIGN KEY (hypertable_id) REFERENCES _timescaledb_catalog.hypertable (id) ON DELETE CASCADE
 );

diff --git a/sql/updates/latest-dev.sql b/sql/updates/latest-dev.sql
@@ -438,3 +438,147 @@ BEGIN
   END LOOP;
 END
 $$;
+
+DROP FUNCTION IF EXISTS @extschema@.add_dimension(
+    REGCLASS,
+    NAME,
+    INTEGER,
+    ANYELEMENT,
+    REGPROC,
+    BOOLEAN
+);
+
+CREATE FUNCTION @extschema@.add_dimension(
+    hypertable              REGCLASS,
+    column_name             NAME,
+    number_partitions       INTEGER = NULL,
+    chunk_time_interval     ANYELEMENT = NULL::BIGINT,
+    partitioning_func       REGPROC = NULL,
+    if_not_exists           BOOLEAN = FALSE,
+    correlated              BOOLEAN = FALSE
+) RETURNS TABLE(dimension_id INT, schema_name NAME, table_name NAME, column_name NAME, created BOOL)
+AS '@MODULE_PATHNAME@', 'ts_dimension_add' LANGUAGE C VOLATILE;
+
+CREATE FUNCTION @extschema@.by_correlation(column_name NAME)
+    RETURNS _timescaledb_internal.dimension_info LANGUAGE C
+    AS '@MODULE_PATHNAME@', 'ts_correlated_dimension';
+
+-- Remove a dimension on a hypertable. Currently only correlated constraint
+-- dimensions can be removed since the other dimensions will need a data
+-- rewrite which is not implemented
+--
+-- hypertable - OID of the table to remove dimension from
+-- column_name - NAME of the column on which the dimension exists
+-- if_not_exists - If set, and the dimension does not exist, generate a notice instead of an error
+CREATE FUNCTION @extschema@.remove_dimension(
+    hypertable              REGCLASS,
+    column_name             NAME,
+    if_not_exists           BOOLEAN = FALSE
+) RETURNS TABLE(dimension_id INT, dropped BOOL)
+AS '@MODULE_PATHNAME@', 'ts_dimension_remove' LANGUAGE C VOLATILE;
+
+--
+-- Rebuild the catalog table `_timescaledb_catalog.dimension with type column
+--
+
+CREATE TABLE _timescaledb_internal._tmp_dimension
+AS SELECT * from _timescaledb_catalog.dimension;
+
+CREATE TABLE _timescaledb_internal.tmp_dimension_seq_value AS
+SELECT last_value, is_called FROM _timescaledb_catalog.dimension_id_seq;
+
+--drop foreign keys on dimension table
+ALTER TABLE _timescaledb_catalog.dimension_slice DROP CONSTRAINT
+dimension_slice_dimension_id_fkey;
+
+--drop dependent views
+DROP VIEW IF EXISTS timescaledb_information.chunks;
+DROP VIEW IF EXISTS timescaledb_information.dimensions;
+DROP VIEW IF EXISTS timescaledb_information.hypertable_compression_settings;
+
+ALTER EXTENSION timescaledb DROP TABLE _timescaledb_catalog.dimension;
+ALTER EXTENSION timescaledb DROP SEQUENCE _timescaledb_catalog.dimension_id_seq;
+DROP TABLE _timescaledb_catalog.dimension;
+
+CREATE TABLE _timescaledb_catalog.dimension (
+  id serial NOT NULL ,
+  hypertable_id integer NOT NULL,
+  column_name name NOT NULL,
+  column_type REGTYPE NOT NULL,
+  aligned boolean NOT NULL,
+  -- closed dimensions
+  num_slices smallint NULL,
+  partitioning_func_schema name NULL,
+  partitioning_func name NULL,
+  -- open dimensions (e.g., time)
+  interval_length bigint NULL,
+  -- compress interval is used by rollup procedure during compression
+  -- in order to merge multiple chunks into a single one
+  compress_interval_length bigint NULL,
+  integer_now_func_schema name NULL,
+  integer_now_func name NULL,
+  type "char",
+  -- table constraints
+  CONSTRAINT dimension_pkey PRIMARY KEY (id),
+  CONSTRAINT dimension_hypertable_id_column_name_key UNIQUE (hypertable_id, column_name),
+  CONSTRAINT dimension_check CHECK ((partitioning_func_schema IS NULL AND partitioning_func IS NULL) OR (partitioning_func_schema IS NOT NULL AND partitioning_func IS NOT NULL)),
+  CONSTRAINT dimension_check1 CHECK ((num_slices IS NULL AND interval_length IS NOT NULL) OR (num_slices IS NOT NULL AND interval_length IS NULL)),
+  CONSTRAINT dimension_check2 CHECK ((integer_now_func_schema IS NULL AND integer_now_func IS NULL) OR (integer_now_func_schema IS NOT NULL AND integer_now_func IS NOT NULL)),
+  CONSTRAINT dimension_interval_length_check CHECK (interval_length IS NULL OR interval_length > 0 OR type = 'C'),
+  CONSTRAINT dimension_compress_interval_length_check CHECK (compress_interval_length IS NULL OR compress_interval_length > 0),
+  CONSTRAINT dimension_hypertable_id_fkey FOREIGN KEY (hypertable_id) REFERENCES _timescaledb_catalog.hypertable (id) ON DELETE CASCADE
+);
+
+INSERT INTO _timescaledb_catalog.dimension
+( id, hypertable_id, column_name, column_type,
+  aligned, num_slices, partitioning_func_schema,
+  partitioning_func, interval_length,
+  compress_interval_length,
+  integer_now_func_schema, integer_now_func,
+  type)
+SELECT id, hypertable_id, column_name, column_type,
+  aligned, num_slices, partitioning_func_schema,
+  partitioning_func, interval_length,
+  compress_interval_length,
+  integer_now_func_schema, integer_now_func,
+  CASE WHEN interval_length IS NULL AND num_slices IS NOT NULL THEN
+        'c' -- closed dimension
+       WHEN interval_length IS NOT NULL AND num_slices is NULL THEN
+        'o' -- open dimension
+       ELSE
+        'a' -- any.. This should never happen
+  END as type
+FROM _timescaledb_internal._tmp_dimension;
+
+-- Check that there's no entry with type == 'a'
+DO $$
+DECLARE
+  count_var INTEGER;
+BEGIN
+    SELECT count(*) FROM _timescaledb_catalog.dimension INTO count_var WHERE
+        type = 'a';
+    IF count_var != 0 THEN
+        RAISE EXCEPTION 'invalid dimension entry found!';
+    END IF;
+END
+$$;
+
+ALTER SEQUENCE _timescaledb_catalog.dimension_id_seq OWNED BY _timescaledb_catalog.dimension.id;
+SELECT setval('_timescaledb_catalog.dimension_id_seq', last_value, is_called) FROM _timescaledb_internal.tmp_dimension_seq_value;
+
+SELECT pg_catalog.pg_extension_config_dump('_timescaledb_catalog.dimension', '');
+SELECT pg_catalog.pg_extension_config_dump(pg_get_serial_sequence('_timescaledb_catalog.dimension', 'id'), '');
+
+--add the foreign key constraints
+ALTER TABLE _timescaledb_catalog.dimension_slice ADD CONSTRAINT
+dimension_slice_dimension_id_fkey FOREIGN KEY (dimension_id)
+REFERENCES _timescaledb_catalog.dimension(id) ON DELETE CASCADE;
+
+--cleanup
+DROP TABLE _timescaledb_internal._tmp_dimension;
+DROP TABLE _timescaledb_internal.tmp_dimension_seq_value;
+
+GRANT SELECT ON _timescaledb_catalog.dimension_id_seq TO PUBLIC;
+GRANT SELECT ON _timescaledb_catalog.dimension TO PUBLIC;
+
+-- end recreate _timescaledb_catalog.dimension table --
diff --git a/sql/updates/reverse-dev.sql b/sql/updates/reverse-dev.sql
@@ -288,3 +288,114 @@ UPDATE _timescaledb_config.bgw_job SET scheduled = true WHERE id = 2;
 DELETE FROM _timescaledb_config.bgw_job WHERE id = 3;
 
 DROP PROCEDURE IF EXISTS _timescaledb_functions.cagg_migrate_to_time_bucket(cagg REGCLASS);
+
+DROP FUNCTION IF EXISTS @extschema@.add_dimension(
+    REGCLASS,
+    NAME,
+    INTEGER,
+    ANYELEMENT,
+    REGPROC,
+    BOOLEAN,
+    BOOLEAN
+);
+
+CREATE FUNCTION @extschema@.add_dimension(
+    hypertable              REGCLASS,
+    column_name             NAME,
+    number_partitions       INTEGER = NULL,
+    chunk_time_interval     ANYELEMENT = NULL::BIGINT,
+    partitioning_func       REGPROC = NULL,
+    if_not_exists           BOOLEAN = FALSE
+) RETURNS TABLE(dimension_id INT, schema_name NAME, table_name NAME, column_name NAME, created BOOL)
+AS '@MODULE_PATHNAME@', 'ts_dimension_add' LANGUAGE C VOLATILE;
+
+DROP FUNCTION IF EXISTS @extschema@.by_correlation(
+    NAME
+);
+
+DROP FUNCTION IF EXISTS @extschema@.remove_dimension(
+    REGCLASS,
+    NAME,
+    BOOLEAN
+);
+
+-- Recreate _timescaledb_catalog.dimension table without the type column --
+CREATE TABLE _timescaledb_internal._tmp_dimension
+AS SELECT * from _timescaledb_catalog.dimension;
+
+CREATE TABLE _timescaledb_internal.tmp_dimension_seq_value AS
+SELECT last_value, is_called FROM _timescaledb_catalog.dimension_id_seq;
+
+--drop foreign keys on dimension table
+ALTER TABLE _timescaledb_catalog.dimension_slice DROP CONSTRAINT
+dimension_slice_dimension_id_fkey;
+
+--drop dependent views
+DROP VIEW IF EXISTS timescaledb_information.chunks;
+DROP VIEW IF EXISTS timescaledb_information.dimensions;
+DROP VIEW IF EXISTS timescaledb_information.hypertable_compression_settings;
+
+ALTER EXTENSION timescaledb DROP TABLE _timescaledb_catalog.dimension;
+ALTER EXTENSION timescaledb DROP SEQUENCE _timescaledb_catalog.dimension_id_seq;
+DROP TABLE _timescaledb_catalog.dimension;
+
+CREATE TABLE _timescaledb_catalog.dimension (
+  id serial NOT NULL ,
+  hypertable_id integer NOT NULL,
+  column_name name NOT NULL,
+  column_type REGTYPE NOT NULL,
+  aligned boolean NOT NULL,
+  -- closed dimensions
+  num_slices smallint NULL,
+  partitioning_func_schema name NULL,
+  partitioning_func name NULL,
+  -- open dimensions (e.g., time)
+  interval_length bigint NULL,
+  -- compress interval is used by rollup procedure during compression
+  -- in order to merge multiple chunks into a single one
+  compress_interval_length bigint NULL,
+  integer_now_func_schema name NULL,
+  integer_now_func name NULL,
+  -- table constraints
+  CONSTRAINT dimension_pkey PRIMARY KEY (id),
+  CONSTRAINT dimension_hypertable_id_column_name_key UNIQUE (hypertable_id, column_name),
+  CONSTRAINT dimension_check CHECK ((partitioning_func_schema IS NULL AND partitioning_func IS NULL) OR (partitioning_func_schema IS NOT NULL AND partitioning_func IS NOT NULL)),
+  CONSTRAINT dimension_check1 CHECK ((num_slices IS NULL AND interval_length IS NOT NULL) OR (num_slices IS NOT NULL AND interval_length IS NULL)),
+  CONSTRAINT dimension_check2 CHECK ((integer_now_func_schema IS NULL AND integer_now_func IS NULL) OR (integer_now_func_schema IS NOT NULL AND integer_now_func IS NOT NULL)),
+  CONSTRAINT dimension_interval_length_check CHECK (interval_length IS NULL OR interval_length > 0),
+  CONSTRAINT dimension_compress_interval_length_check CHECK (compress_interval_length IS NULL OR compress_interval_length > 0),
+  CONSTRAINT dimension_hypertable_id_fkey FOREIGN KEY (hypertable_id) REFERENCES _timescaledb_catalog.hypertable (id) ON DELETE CASCADE
+);
+
+INSERT INTO _timescaledb_catalog.dimension
+( id, hypertable_id, column_name, column_type,
+  aligned, num_slices, partitioning_func_schema,
+  partitioning_func, interval_length,
+  compress_interval_length,
+  integer_now_func_schema, integer_now_func)
+SELECT id, hypertable_id, column_name, column_type,
+  aligned, num_slices, partitioning_func_schema,
+  partitioning_func, interval_length,
+  compress_interval_length,
+  integer_now_func_schema, integer_now_func
+FROM _timescaledb_internal._tmp_dimension;
+
+ALTER SEQUENCE _timescaledb_catalog.dimension_id_seq OWNED BY _timescaledb_catalog.dimension.id;
+SELECT setval('_timescaledb_catalog.dimension_id_seq', last_value, is_called) FROM _timescaledb_internal.tmp_dimension_seq_value;
+
+SELECT pg_catalog.pg_extension_config_dump('_timescaledb_catalog.dimension', '');
+SELECT pg_catalog.pg_extension_config_dump(pg_get_serial_sequence('_timescaledb_catalog.dimension', 'id'), '');
+
+--add the foreign key constraints
+ALTER TABLE _timescaledb_catalog.dimension_slice ADD CONSTRAINT
+dimension_slice_dimension_id_fkey FOREIGN KEY (dimension_id)
+REFERENCES _timescaledb_catalog.dimension(id) ON DELETE CASCADE;
+
+--cleanup
+DROP TABLE _timescaledb_internal._tmp_dimension;
+DROP TABLE _timescaledb_internal.tmp_dimension_seq_value;
+
+GRANT SELECT ON _timescaledb_catalog.dimension_id_seq TO PUBLIC;
+GRANT SELECT ON _timescaledb_catalog.dimension TO PUBLIC;
+
+-- end recreate _timescaledb_catalog.dimension table --
diff --git a/src/chunk.c b/src/chunk.c
@@ -841,14 +841,16 @@ chunk_create_object(const Hypertable *ht, Hypercube *cube, const char *schema_na
 					const char *table_name, const char *prefix, int32 chunk_id)
 {
 	const Hyperspace *hs = ht->space;
+	const Hyperspace *ss = ht->correlated_space;
 	Chunk *chunk;
 	const char relkind = RELKIND_RELATION;
 
 	if (NULL == schema_name || schema_name[0] == '\0')
 		schema_name = NameStr(ht->fd.associated_schema_name);
 
 	/* Create a new chunk based on the hypercube */
-	chunk = ts_chunk_create_base(chunk_id, hs->num_dimensions, relkind);
+	chunk =
+		ts_chunk_create_base(chunk_id, hs->num_dimensions + (ss ? ss->num_dimensions : 0), relkind);
 
 	chunk->fd.hypertable_id = hs->hypertable_id;
 	chunk->cube = cube;
@@ -1091,6 +1093,9 @@ chunk_create_from_hypercube_after_lock(const Hypertable *ht, Hypercube *cube,
 													  prefix,
 													  get_next_chunk_id());
 
+	/* Insert any new correlated constraint slices into metadata */
+	ts_correlated_constraints_dimension_slice_insert(ht, chunk);
+
 	chunk_add_constraints(chunk);
 	chunk_insert_into_metadata_after_lock(chunk);
 	chunk_create_table_constraints(ht, chunk);
@@ -3374,8 +3379,17 @@ ts_chunk_set_unordered(Chunk *chunk)
 bool
 ts_chunk_set_partial(Chunk *chunk)
 {
+	Cache *hcache;
+	bool set_status;
+	Hypertable *htable =
+		ts_hypertable_cache_get_cache_and_entry(chunk->hypertable_relid, CACHE_FLAG_NONE, &hcache);
 	Assert(ts_chunk_is_compressed(chunk));
-	return ts_chunk_add_status(chunk, CHUNK_STATUS_COMPRESSED_PARTIAL);
+	set_status = ts_chunk_add_status(chunk, CHUNK_STATUS_COMPRESSED_PARTIAL);
+	/* reset any correlated constraints after the partial uncompressed data */
+	if (htable->correlated_space)
+		ts_correlated_constraints_dimension_slice_calculate_update(htable, chunk, true);
+	ts_cache_release(hcache);
+	return set_status;
 }
 
 /* No inserts, updates, and deletes are permitted on a frozen chunk.
@@ -4733,7 +4747,7 @@ ts_chunk_merge_on_dimension(const Hypertable *ht, Chunk *chunk, const Chunk *mer
 		ts_dimension_slice_insert(new_slice);
 	}
 
-	ts_chunk_constraint_update_slice_id(chunk->fd.id, slice->fd.id, new_slice->fd.id);
+	ts_chunk_constraint_update_slice_id_name(chunk->fd.id, slice->fd.id, new_slice->fd.id, NULL);
 	ChunkConstraints *ccs = ts_chunk_constraints_alloc(1, CurrentMemoryContext);
 	ScanIterator iterator =
 		ts_scan_iterator_create(CHUNK_CONSTRAINT, AccessShareLock, CurrentMemoryContext);