Deprecated
This view exists for backwards compatibility. The supported views to retrieve information about compression are:
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 );
SELECT table_name FROM create_hypertable( 'hypertab' , by_range( 'a_col' , 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.
Available columns
Name Type Description
hypertable_schemaTEXT Schema name of the hypertable hypertable_nameTEXT Table name of the hypertable attnameTEXT Name of the column used in the compression settings segmentby_column_indexSMALLINT Position of attname in the compress_segmentby list orderby_column_indexSMALLINT Position of attname in the compress_orderby list orderby_ascBOOLEAN True if this is used for order by ASC, False for order by DESC orderby_nullsfirstBOOLEAN True if nulls are ordered first for this column, False if nulls are ordered last