convert_to_rowstore()

Move a chunk from the columnstore to the rowstore

Since 2.18.0

convert_to_rowstore() replaces decompress_chunk(), deprecated in 2.18.0.

Manually convert a specific chunk in the hypertable columnstore to the rowstore.

If you need to modify or add a lot of data to a chunk in the columnstore, best practice is to stop any jobs moving chunks to the columnstore, convert the chunk back to the rowstore, then modify the data. After the update, convert the chunk to the columnstore and restart the jobs. This workflow is especially useful if you need to backfill old data.

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Samples

To modify or add a lot of data to a chunk:

1. Stop the jobs that are automatically adding chunks to the columnstore

   Retrieve the list of jobs from the timescaledb_information.jobs view to find the job you need to alter_job.

   SELECT alter_job(JOB_ID, scheduled => false);
   

2. Convert a chunk to update back to the rowstore

   CALL convert_to_rowstore('_timescaledb_internal._hyper_2_2_chunk');
   

3. Update the data in the chunk you added to the rowstore

   Best practice is to structure your INSERT statement to include appropriate partition key values, such as the timestamp. TimescaleDB adds the data to the correct chunk:

   INSERT INTO metrics (time, value)
   VALUES ('2025-01-01T00:00:00', 42);
   

4. Convert the updated chunks back to the columnstore

   CALL convert_to_columnstore('_timescaledb_internal._hyper_1_2_chunk');
   

5. Restart the jobs that are automatically converting chunks to the columnstore

   SELECT alter_job(JOB_ID, scheduled => true);
   

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Arguments

The syntax is:

CALL convert_to_rowstore(
    chunk = '<chunk_name>',
    if_columnstore = true | false
);

Name	Type	Default	Required	Description
chunk	REGCLASS	-	✔	Name of the chunk to be moved to the rowstore.
if_columnstore	BOOLEAN	true	✖	Set to false so this call fails with an error rather than a warning if chunk is not in the columnstore

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Returns

This function returns void.