Compression overview (Old API, replaced by hypercore)

TimescaleDB API reference for compressing your data. Includes SQL functions for compressing and decompressing chunks, managing compression policies, and getting compression stats

Old API since v2.18.0. Superseded by Hypercore.

Compression functionality is included in .

Before you set up compression, you need to configure the for compression and then set up a compression policy.

Before you set up compression for the first time, read the compression blog post and documentation.

You can also compress s manually, instead of using an automated compression policy to compress s as they age.

Compressed s have the following limitations:

• ROW LEVEL SECURITY is not supported on compressed s.
• Creation of unique constraints on compressed s is not supported. You can add them by disabling compression on the and re-enabling after constraint creation.

Restrictions

In general, compressing a imposes some limitations on the types of data modifications that you can perform on data inside a compressed .

This table shows changes to the compression feature, added in different versions of :

version	Supported data modifications on compressed s
1.5 - 2.0	Data and schema modifications are not supported.
2.1 - 2.2	Schema may be modified on compressed s. Data modification not supported.
2.3	Schema modifications and basic insert of new data is allowed. Deleting, updating and some advanced insert statements are not supported.
2.11	Deleting, updating and advanced insert statements are supported.

In 2.1 and later, you can modify the schema of s that have compressed s. Specifically, you can add columns to and rename existing columns of compressed s.

In v2.3 and later, you can insert data into compressed s and to enable compression policies on distributed s.

In v2.11 and later, you can update and delete compressed data. You can also use advanced insert statements like ON CONFLICT and RETURNING.

Available functions

Configuration

• ALTER TABLE (Compression): change compression settings on a compressed

Policies

• add_compression_policy(): add policy to schedule automatic compression of s
• remove_compression_policy(): remove a compression policy from a

Manual compression

• compress_chunk(): manually compress a given
• decompress_chunk(): decompress a compressed
• recompress_chunk(): recompress a that had new data inserted after compression

Statistics

• chunk_compression_stats(): get compression-related statistics for s
• hypertable_compression_stats(): get statistics related to compression