Add compression settings view

Add informational view that lists the settings
used while enabling compression on a hypertable.

sql/views.sql

@@ -259,5 +259,28 @@ CREATE OR REPLACE VIEW timescaledb_information.data_node AS
     LEFT OUTER JOIN LATERAL @extschema@.data_node_hypertable_info(CASE WHEN s.node_up THEN s.node_name ELSE NULL END) size ON TRUE
   GROUP BY s.node_name, s.node_up, s.owner, s.options;
 
+---compression parameters information ---
+CREATE VIEW timescaledb_information.compression_settings
+AS
+SELECT
+    ht.schema_name,
+    ht.table_name,
+    segq.attname,
+    segq.segmentby_column_index,
+    segq.orderby_column_index,
+    segq.orderby_asc,
+    segq.orderby_nullsfirst
+FROM
+    _timescaledb_catalog.hypertable_compression segq,
+    _timescaledb_catalog.hypertable ht
+WHERE
+    segq.hypertable_id = ht.id
+    AND ( segq.segmentby_column_index IS NOT NULL
+        OR segq.orderby_column_index IS NOT NULL)
+ORDER BY
+    table_name,
+    segmentby_column_index,
+    orderby_column_index;
+
 GRANT USAGE ON SCHEMA timescaledb_information TO PUBLIC;
 GRANT SELECT ON ALL TABLES IN SCHEMA timescaledb_information TO PUBLIC;

test/expected/pg_dump.out

@@ -535,6 +535,7 @@ WHERE   refclassid = 'pg_catalog.pg_extension'::pg_catalog.regclass AND
         ORDER BY objid::text DESC;
                         objid                        
 -----------------------------------------------------
+ timescaledb_information.compression_settings
  timescaledb_information.data_node
  timescaledb_information.compressed_hypertable_stats
  timescaledb_information.compressed_chunk_stats
@@ -550,7 +551,7 @@ WHERE   refclassid = 'pg_catalog.pg_extension'::pg_catalog.regclass AND
  _timescaledb_internal.bgw_policy_chunk_stats
  _timescaledb_internal.bgw_job_stat
  _timescaledb_catalog.tablespace_id_seq
-(15 rows)
+(16 rows)
 
 -- Make sure we can't run our restoring functions as a normal perm user as that would disable functionality for the whole db
 \c :TEST_DBNAME :ROLE_DEFAULT_PERM_USER

tsl/test/expected/compression.out

@@ -63,6 +63,15 @@ select * from _timescaledb_catalog.hypertable_compression order by hypertable_id
              1 | d       |                        4 |                        |                    2 | t           | f
 (4 rows)
 
+select * from timescaledb_information.compression_settings ;
+ schema_name | table_name | attname | segmentby_column_index | orderby_column_index | orderby_asc | orderby_nullsfirst 
+-------------+------------+---------+------------------------+----------------------+-------------+--------------------
+ public      | foo        | a       |                      1 |                      |             | 
+ public      | foo        | b       |                      2 |                      |             | 
+ public      | foo        | c       |                        |                    1 | f           | t
+ public      | foo        | d       |                        |                    2 | t           | f
+(4 rows)
+
 -- TEST2 compress-chunk for the chunks created earlier --
 select compress_chunk( '_timescaledb_internal._hyper_1_2_chunk');
              compress_chunk             
@@ -1124,6 +1133,32 @@ ERROR:  constraint "fk_table1" requires column "col2" to be a timescaledb.compre
 ALTER TABLE table1 SET (timescaledb.compress, timescaledb.compress_segmentby = 'col1,col2');
 NOTICE:  adding index _compressed_hypertable_23_col1__ts_meta_sequence_num_idx ON _timescaledb_internal._compressed_hypertable_23 USING BTREE(col1, _ts_meta_sequence_num)
 NOTICE:  adding index _compressed_hypertable_23_col2__ts_meta_sequence_num_idx ON _timescaledb_internal._compressed_hypertable_23 USING BTREE(col2, _ts_meta_sequence_num)
+SELECT * FROM timescaledb_information.compression_settings ORDER BY table_name;
+ schema_name |   table_name   |   attname   | segmentby_column_index | orderby_column_index | orderby_asc | orderby_nullsfirst 
+-------------+----------------+-------------+------------------------+----------------------+-------------+--------------------
+ public      | conditions     | location    |                      1 |                      |             | 
+ public      | conditions     | time        |                        |                    1 | t           | f
+ public      | datatype_test  | time        |                        |                    1 | f           | t
+ public      | foo            | a           |                      1 |                      |             | 
+ public      | foo            | b           |                      2 |                      |             | 
+ public      | foo            | c           |                        |                    1 | f           | t
+ public      | foo            | d           |                        |                    2 | t           | f
+ public      | ht5            | time        |                        |                    1 | f           | t
+ public      | hyper          | device_id   |                      1 |                      |             | 
+ public      | hyper          | time        |                        |                    1 | t           | f
+ public      | metrics        | time        |                        |                    1 | f           | t
+ public      | plan_inval     | time        |                        |                    1 | f           | t
+ public      | rescan_test    | id          |                      1 |                      |             | 
+ public      | rescan_test    | t           |                        |                    1 | f           | t
+ public      | table1         | col1        |                      1 |                      |             | 
+ public      | table1         | col2        |                      2 |                      |             | 
+ public      | test_collation | device_id   |                      1 |                      |             | 
+ public      | test_collation | device_id_2 |                      2 |                      |             | 
+ public      | test_collation | val_1       |                        |                    1 | t           | f
+ public      | test_collation | val_2       |                        |                    2 | t           | f
+ public      | test_collation | time        |                        |                    3 | t           | f
+(21 rows)
+
 -- test delete/update on non-compressed tables involving hypertables with compression
 CREATE TABLE uncompressed_ht (
   time timestamptz NOT NULL,

tsl/test/sql/compression.sql

@@ -29,6 +29,7 @@ SET timescaledb.enable_transparent_decompression to OFF;
 select id, schema_name, table_name, compressed, compressed_hypertable_id from
 _timescaledb_catalog.hypertable order by id;
 select * from _timescaledb_catalog.hypertable_compression order by hypertable_id, attname;
+select * from timescaledb_information.compression_settings ;
 
 -- TEST2 compress-chunk for the chunks created earlier --
 select compress_chunk( '_timescaledb_internal._hyper_1_2_chunk');
@@ -451,6 +452,7 @@ SELECT create_hypertable('table1','col1', chunk_time_interval => 10);
 ALTER TABLE table1 SET (timescaledb.compress, timescaledb.compress_segmentby = 'col1');
 -- Listing all fields of the compound key should succeed:
 ALTER TABLE table1 SET (timescaledb.compress, timescaledb.compress_segmentby = 'col1,col2');
+SELECT * FROM timescaledb_information.compression_settings ORDER BY table_name;
 
 -- test delete/update on non-compressed tables involving hypertables with compression
 CREATE TABLE uncompressed_ht (