Add table mappings to compression settings

Refactor the compression settings metadata table to include a mapping
from a chunk's relid to its compressed chunk's relid.

Adding this mapping makes compression settings the main metadata table
for compression-related information, while decoupling it from chunk
metadata. This simplifies the code that looks up compression metadata
as it no longer requires first looking up the corresponding compressed
chunk.

The new compression settings is a step towards removing a chunk's
compression table from the chunk metadata. In other words, the
"compressed chunk" will no longer be a chunk, just a relation
associated with the regular chunk via compression settings.

sql/pre_install/tables.sql

@@ -431,7 +431,8 @@ CREATE TABLE _timescaledb_catalog.compression_algorithm (
 );
 
 CREATE TABLE _timescaledb_catalog.compression_settings (
-	relid regclass NOT NULL,
+  relid regclass NOT NULL,
+  compress_relid regclass NULL,
   segmentby text[],
   orderby text[],
   orderby_desc bool[],
@@ -443,6 +444,7 @@ CREATE TABLE _timescaledb_catalog.compression_settings (
 );
 
 SELECT pg_catalog.pg_extension_config_dump('_timescaledb_catalog.compression_settings', '');
+CREATE INDEX compression_settings_compress_relid_idx ON _timescaledb_catalog.compression_settings (compress_relid);
 
 CREATE TABLE _timescaledb_catalog.compression_chunk_size (
   chunk_id integer NOT NULL,

sql/updates/latest-dev.sql

@@ -0,0 +1,55 @@
+-- Update compression settings
+
+CREATE TEMP TABLE tempsettings (LIKE _timescaledb_catalog.compression_settings);
+INSERT INTO tempsettings SELECT * FROM _timescaledb_catalog.compression_settings;
+ALTER EXTENSION timescaledb DROP TABLE _timescaledb_catalog.compression_settings;
+DROP TABLE _timescaledb_catalog.compression_settings CASCADE;
+
+CREATE TABLE _timescaledb_catalog.compression_settings (
+  relid regclass NOT NULL,
+  compress_relid regclass NULL,
+  segmentby text[],
+  orderby text[],
+  orderby_desc bool[],
+  orderby_nullsfirst bool[],
+  CONSTRAINT compression_settings_pkey PRIMARY KEY (relid),
+  CONSTRAINT compression_settings_check_segmentby CHECK (array_ndims(segmentby) = 1),
+  CONSTRAINT compression_settings_check_orderby_null CHECK ((orderby IS NULL AND orderby_desc IS NULL AND orderby_nullsfirst IS NULL) OR (orderby IS NOT NULL AND orderby_desc IS NOT NULL AND orderby_nullsfirst IS NOT NULL)),
+  CONSTRAINT compression_settings_check_orderby_cardinality CHECK (array_ndims(orderby) = 1 AND array_ndims(orderby_desc) = 1 AND array_ndims(orderby_nullsfirst) = 1 AND cardinality(orderby) = cardinality(orderby_desc) AND cardinality(orderby) = cardinality(orderby_nullsfirst))
+);
+
+-- Insert hypertable settings
+INSERT INTO _timescaledb_catalog.compression_settings
+SELECT
+	cs.relid,
+	NULL,
+	cs.segmentby,
+	cs.orderby,
+	cs.orderby_desc,
+	cs.orderby_nullsfirst
+FROM
+	tempsettings cs
+INNER JOIN
+	_timescaledb_catalog.hypertable h ON (cs.relid = format('%I.%I', h.schema_name, h.table_name)::regclass);
+
+-- Insert chunk settings
+INSERT INTO _timescaledb_catalog.compression_settings
+SELECT
+	format('%I.%I', ch2.schema_name, ch2.table_name)::regclass AS relid,
+	cs.relid AS compress_relid,
+	cs.segmentby,
+	cs.orderby,
+	cs.orderby_desc,
+	cs.orderby_nullsfirst
+FROM
+	tempsettings cs
+INNER JOIN
+	_timescaledb_catalog.chunk ch ON (cs.relid = format('%I.%I', ch.schema_name, ch.table_name)::regclass)
+INNER JOIN
+	_timescaledb_catalog.chunk ch2 ON (ch.id = ch2.compressed_chunk_id);
+
+CREATE INDEX compression_settings_compress_relid_idx ON _timescaledb_catalog.compression_settings (compress_relid);
+
+DROP TABLE tempsettings CASCADE; -- not strictly necessary
+GRANT SELECT ON _timescaledb_catalog.compression_settings TO PUBLIC;
+SELECT pg_catalog.pg_extension_config_dump('_timescaledb_catalog.compression_settings', '');

sql/updates/reverse-dev.sql

@@ -0,0 +1,47 @@
+-- Update compression settings
+CREATE TEMP TABLE tempsettings (LIKE _timescaledb_catalog.compression_settings);
+INSERT INTO tempsettings SELECT * FROM _timescaledb_catalog.compression_settings;
+ALTER EXTENSION timescaledb DROP TABLE _timescaledb_catalog.compression_settings;
+DROP TABLE _timescaledb_catalog.compression_settings CASCADE;
+
+CREATE TABLE _timescaledb_catalog.compression_settings (
+  relid regclass NOT NULL,
+  segmentby text[],
+  orderby text[],
+  orderby_desc bool[],
+  orderby_nullsfirst bool[],
+  CONSTRAINT compression_settings_pkey PRIMARY KEY (relid),
+  CONSTRAINT compression_settings_check_segmentby CHECK (array_ndims(segmentby) = 1),
+  CONSTRAINT compression_settings_check_orderby_null CHECK ((orderby IS NULL AND orderby_desc IS NULL AND orderby_nullsfirst IS NULL) OR (orderby IS NOT NULL AND orderby_desc IS NOT NULL AND orderby_nullsfirst IS NOT NULL)),
+  CONSTRAINT compression_settings_check_orderby_cardinality CHECK (array_ndims(orderby) = 1 AND array_ndims(orderby_desc) = 1 AND array_ndims(orderby_nullsfirst) = 1 AND cardinality(orderby) = cardinality(orderby_desc) AND cardinality(orderby) = cardinality(orderby_nullsfirst))
+);
+
+-- Insert hypertable settings
+INSERT INTO _timescaledb_catalog.compression_settings
+SELECT
+	cs.compress_relid,
+	cs.segmentby,
+	cs.orderby,
+	cs.orderby_desc,
+	cs.orderby_nullsfirst
+FROM
+	tempsettings cs
+WHERE
+	cs.compress_relid IS NOT NULL;
+
+-- Insert chunk settings
+INSERT INTO _timescaledb_catalog.compression_settings
+SELECT
+	cs.relid,
+	cs.segmentby,
+	cs.orderby,
+	cs.orderby_desc,
+	cs.orderby_nullsfirst
+FROM
+	tempsettings cs
+WHERE
+	cs.compress_relid IS NULL;
+
+DROP TABLE tempsettings CASCADE;
+GRANT SELECT ON _timescaledb_catalog.compression_settings TO PUBLIC;
+SELECT pg_catalog.pg_extension_config_dump('_timescaledb_catalog.compression_settings', '');

sql/views.sql

@@ -390,8 +390,7 @@ CREATE OR REPLACE VIEW timescaledb_information.chunk_compression_settings AS
 		un.orderby
 	FROM _timescaledb_catalog.hypertable ht
 	INNER JOIN _timescaledb_catalog.chunk ch ON ch.hypertable_id = ht.id
-  INNER JOIN _timescaledb_catalog.chunk ch2 ON ch2.id = ch.compressed_chunk_id
-  LEFT JOIN _timescaledb_catalog.compression_settings s ON format('%I.%I',ch2.schema_name,ch2.table_name)::regclass = s.relid
+ 	INNER JOIN _timescaledb_catalog.compression_settings s ON (format('%I.%I',ch.schema_name,ch.table_name)::regclass = s.relid AND format('%I.%I',ch.schema_name,ch.table_name)::regclass != s.compress_relid)
 	LEFT JOIN LATERAL (
 		SELECT
 			string_agg(

src/chunk.c

@@ -2865,13 +2865,13 @@ chunk_tuple_delete(TupleInfo *ti, DropBehavior behavior, bool preserve_chunk_cat
 	{
 		Chunk *compressed_chunk = ts_chunk_get_by_id(form.compressed_chunk_id, false);
 
-		/* The chunk may have been delete by a CASCADE */
+		/* The chunk may have been deleted by a CASCADE */
 		if (compressed_chunk != NULL)
 		{
 			/* Plain drop without preserving catalog row because this is the compressed
 			 * chunk */
-			ts_compression_settings_delete(compressed_chunk->table_id);
 			ts_chunk_drop(compressed_chunk, behavior, DEBUG1);
+			ts_compression_settings_delete_by_compress_relid(compressed_chunk->table_id);
 		}
 	}
 

src/dimension.c

@@ -18,6 +18,7 @@
 #include <utils/timestamp.h>
 
 #include "compat/compat.h"
+#include "chunk.h"
 #include "cross_module_fn.h"
 #include "debug_point.h"
 #include "dimension.h"

src/process_utility.c

@@ -1916,7 +1916,9 @@ process_rename_column(ProcessUtilityArgs *args, Cache *hcache, Oid relid, Rename
 	 * we don't do anything. */
 	if (ht)
 	{
-		ts_compression_settings_rename_column_hypertable(ht, stmt->subname, stmt->newname);
+		ts_compression_settings_rename_column_recurse(ht->main_table_relid,
+													  stmt->subname,
+													  stmt->newname);
 		add_hypertable_to_process_args(args, ht);
 		dim = ts_hyperspace_get_mutable_dimension_by_name(ht->space,
 														  DIMENSION_TYPE_ANY,
@@ -4276,8 +4278,8 @@ process_drop_table(EventTriggerDropObject *obj)
 
 	Assert(obj->type == EVENT_TRIGGER_DROP_TABLE || obj->type == EVENT_TRIGGER_DROP_FOREIGN_TABLE);
 	ts_hypertable_delete_by_name(table->schema, table->name);
-	ts_chunk_delete_by_name(table->schema, table->name, DROP_RESTRICT);
 	ts_compression_settings_delete(table->relid);
+	ts_chunk_delete_by_name(table->schema, table->name, DROP_RESTRICT);
 }
 
 static void

src/ts_catalog/catalog.c

@@ -237,6 +237,7 @@ static const TableIndexDef catalog_table_index_definitions[_MAX_CATALOG_TABLES]
 		.length =  _MAX_COMPRESSION_SETTINGS_INDEX,
 		.names = (char *[]) {
 			[COMPRESSION_SETTINGS_PKEY] = "compression_settings_pkey",
+			[COMPRESSION_SETTINGS_COMPRESS_RELID_IDX] = "compression_settings_compress_relid_idx",
 		},
 	},
 	[COMPRESSION_CHUNK_SIZE] = {

src/ts_catalog/catalog.h

@@ -1091,6 +1091,7 @@ typedef enum Anum_continuous_aggs_watermark_pkey
 typedef enum Anum_compression_settings
 {
 	Anum_compression_settings_relid = 1,
+	Anum_compression_settings_compress_relid,
 	Anum_compression_settings_segmentby,
 	Anum_compression_settings_orderby,
 	Anum_compression_settings_orderby_desc,
@@ -1103,6 +1104,7 @@ typedef enum Anum_compression_settings
 typedef struct FormData_compression_settings
 {
 	Oid relid;
+	Oid compress_relid;
 	ArrayType *segmentby;
 	ArrayType *orderby;
 	ArrayType *orderby_desc;
@@ -1114,6 +1116,7 @@ typedef FormData_compression_settings *Form_compression_settings;
 enum
 {
 	COMPRESSION_SETTINGS_PKEY = 0,
+	COMPRESSION_SETTINGS_COMPRESS_RELID_IDX,
 	_MAX_COMPRESSION_SETTINGS_INDEX,
 };
 
@@ -1125,6 +1128,15 @@ typedef enum Anum_compression_settings_pkey
 
 #define Natts_compression_chunk_size_pkey (_Anum_compression_chunk_size_pkey_max - 1)
 
+typedef enum Anum_compression_settings_compress_relid_idx
+{
+	Anum_compression_settings_compress_relid_idx_relid = 1,
+	_Anum_compression_settings_compress_relid_idx_max,
+} Anum_compression_settings_compress_relid_idx;
+
+#define Natts_compression_settings_compress_relid_idx                                              \
+	(_Anum_compression_settings_compress_relid_idx_max - 1)
+
 #define COMPRESSION_CHUNK_SIZE_TABLE_NAME "compression_chunk_size"
 typedef enum Anum_compression_chunk_size
 {