---
title: Create a custom job for automatic tablespace management | Tiger Data Docs
description: Automatically move hypertable chunks between tablespaces with a custom job
---

Moving older data to a different tablespace can help you save on storage costs. TimescaleDB supports automatic tablespace management by providing the `move_chunk` function to move chunks between tablespaces. To schedule the moves automatically, you can write a custom job.

Note

On Tiger Cloud, use [tiered storage](/docs/build/data-management/storage/manage-storage/index.md) which handles this by providing a [tiering policy API](/docs/build/data-management/storage/manage-storage#automate-tiering-with-policies/index.md) to move data to low-cost object storage backed by Amazon S3 and Azure Blob storage.

To implement automatic chunk moving with a job:

1. **Create a procedure to move chunks**

   Create a procedure that moves chunks to a different tablespace if they contain data older than the `lag` parameter.

   ```
   CREATE OR REPLACE PROCEDURE move_chunks (job_id int, config jsonb)
   LANGUAGE PLPGSQL
   AS $$
   DECLARE
      ht REGCLASS;
      lag interval;
      destination_tablespace name;
      index_destination_tablespace name;
      reorder_index REGCLASS;
      chunk REGCLASS;
      tmp_name name;
   BEGIN
      SELECT jsonb_object_field_text (config, 'hypertable')::regclass INTO STRICT ht;
      SELECT jsonb_object_field_text (config, 'lag')::interval INTO STRICT lag;
      SELECT jsonb_object_field_text (config, 'destination_tablespace') INTO STRICT destination_tablespace;
      SELECT jsonb_object_field_text (config, 'index_destination_tablespace') INTO STRICT index_destination_tablespace;
      SELECT jsonb_object_field_text (config, 'reorder_index') INTO STRICT reorder_index;


    IF ht IS NULL OR lag IS NULL OR destination_tablespace IS NULL THEN
      RAISE EXCEPTION 'Config must have hypertable, lag and destination_tablespace';
    END IF;


    IF index_destination_tablespace IS NULL THEN
      index_destination_tablespace := destination_tablespace;
    END IF;


    FOR chunk IN
       SELECT c.oid
       FROM pg_class AS c
         LEFT JOIN pg_tablespace AS t ON (c.reltablespace = t.oid)
         JOIN pg_namespace AS n ON (c.relnamespace = n.oid)
         JOIN (SELECT * FROM show_chunks(ht, older_than => lag) SHOW (oid)) AS chunks ON (chunks.oid::text = n.nspname || '.' || c.relname)
       WHERE t.spcname != destination_tablespace OR t.spcname IS NULL
    LOOP
      RAISE NOTICE 'Moving chunk: %', chunk::text;
      PERFORM move_chunk(
          chunk => chunk,
          destination_tablespace => destination_tablespace,
          index_destination_tablespace => index_destination_tablespace,
          reorder_index => reorder_index
      );
    END LOOP;
   END
   $$;
   ```

2. **Register the job to run daily**

   In the config, set `hypertable` to `metrics` to implement automatic chunk moves on the `metrics` hypertable. Set `lag` to 12 months to move chunks containing data older than 12 months. Set `tablespace` to the destination tablespace.

   ```
   SELECT add_job(
     'move_chunks',
     '1d',
     config => '{"hypertable":"metrics","lag":"12 month","destination_tablespace":"old_chunks"}'
   );
   ```