recompress_chunk.md

api_name	recompress_chunk()
excerpt	Recompress a chunk that had new data inserted after compression
topics	compression
keywords	compression recompression chunks
tags	hypertables
api	license type community function
products	cloud mst self_hosted

import Deprecated2180 from "versionContent/_partials/_deprecated_2_18_0.mdx";

recompress_chunk()

Superseded by convert_to_columnstore(). However, compression APIs are still supported, you do not need to migrate to the hypercore APIs.

Recompresses a compressed chunk that had more data inserted after compression.

recompress_chunk(
    chunk REGCLASS,
    if_not_compressed BOOLEAN = false
)

You can also recompress chunks by running the job associated with your compression policy. recompress_chunk gives you more fine-grained control by allowing you to target a specific chunk.

recompress_chunk is deprecated since $TIMESCALE_DB v2.14 and will be removed in the future. The procedure is now a wrapper which calls compress_chunk instead of it.

recompress_chunk is implemented as an SQL procedure and not a function. Call the procedure with CALL. Don't use a SELECT statement.

recompress_chunk only works on chunks that have previously been compressed. To compress a chunk for the first time, use compress_chunk.

Samples

Recompress the chunk timescaledb_internal._hyper_1_2_chunk:

CALL recompress_chunk('_timescaledb_internal._hyper_1_2_chunk');

Required arguments

Name	Type	Description
chunk	REGCLASS	The chunk to be recompressed. Must include the schema, for example _timescaledb_internal, if it is not in the search path.

Optional arguments

Name	Type	Description
if_not_compressed	BOOLEAN	If true, prints a notice instead of erroring if the chunk is already compressed. Defaults to false.

Troubleshooting

In $TIMESCALE_DB 2.6.0 and above, recompress_chunk is implemented as a procedure. Previously, it was implemented as a function. If you are upgrading to $TIMESCALE_DB 2.6.0 or above, therecompress_chunk function could cause an error. For example, trying to run SELECT recompress_chunk(i.show_chunks, true) FROM... gives the following error:

ERROR:  recompress_chunk(regclass, boolean) is a procedure

To fix the error, use CALL instead of SELECT. You might also need to write a procedure to replace the full functionality in your SELECT statement. For example:

DO $$
DECLARE chunk regclass;
BEGIN
  FOR chunk IN SELECT format('%I.%I', chunk_schema, chunk_name)::regclass
  FROM timescaledb_information.chunks
  WHERE is_compressed = true
  LOOP
    RAISE NOTICE 'Recompressing %', chunk::text;
    CALL recompress_chunk(chunk, true);
  END LOOP;
END
$$;