timescaledb_information.compression_settings

Get information about compression settings for hypertables

Deprecated v2.0.0 Since 1.5.0

This view exists for backwards compatibility. The supported views to retrieve information about compression are:

• timescaledb_information.hypertable_compression_settings
• timescaledb_information.chunk_compression_settings.

Get information about compression-related settings for s. Each row of the view provides information about individual orderby and segmentby columns used by compression.

How you use segmentby is the single most important thing for compression. It affects compresion rates, query performance, and what is compressed or decompressed by mutable compression.

Samples

CREATE TABLE hypertab (a_col integer, b_col integer, c_col integer, d_col integer, e_col integer) WITH (
  tsdb.hypertable,
  tsdb.partition_column = 'a_col',
  tsdb.chunk_interval = '864000000'
);

ALTER TABLE hypertab SET (timescaledb.compress, timescaledb.compress_segmentby = 'a_col,b_col',
  timescaledb.compress_orderby = 'c_col desc, d_col asc nulls last');

SELECT * FROM timescaledb_information.compression_settings WHERE hypertable_name = 'hypertab';

-[ RECORD 1 ]----------+---------
hypertable_schema      | public
hypertable_name        | hypertab
attname                | a_col
segmentby_column_index | 1
orderby_column_index   |
orderby_asc            |
orderby_nullsfirst     |
-[ RECORD 2 ]----------+---------
hypertable_schema      | public
hypertable_name        | hypertab
attname                | b_col
segmentby_column_index | 2
orderby_column_index   |
orderby_asc            |
orderby_nullsfirst     |
-[ RECORD 3 ]----------+---------
hypertable_schema      | public
hypertable_name        | hypertab
attname                | c_col
segmentby_column_index |
orderby_column_index   | 1
orderby_asc            | f
orderby_nullsfirst     | t
-[ RECORD 4 ]----------+---------
hypertable_schema      | public
hypertable_name        | hypertab
attname                | d_col
segmentby_column_index |
orderby_column_index   | 2
orderby_asc            | t
orderby_nullsfirst     | f

The by_range dimension builder is an addition to 2.13.

Returns

Name	Type	Description
hypertable_schema	TEXT	Schema name of the hypertable
hypertable_name	TEXT	Table name of the hypertable
attname	TEXT	Name of the column used in the compression settings
segmentby_column_index	SMALLINT	Position of attname in the compress_segmentby list
orderby_column_index	SMALLINT	Position of attname in the compress_orderby list
orderby_asc	BOOLEAN	True if this is used for order by ASC, False for order by DESC
orderby_nullsfirst	BOOLEAN	True if nulls are ordered first for this column, False if nulls are ordered last