Timescale automatically supports
INSERTs into compressed chunks. But if you
need to insert a lot of data, for example as part of a bulk backfilling
operation, you should first decompress the chunk. Inserting data into a
compressed chunk is more computationally expensive than inserting data into an
uncompressed chunk. This adds up over a lot of rows.
When compressing your data, you can reduce the amount of storage space for your Timescale instance. But you should always leave some additional storage capacity. This gives you the flexibility to decompress chunks when necessary, for actions such as bulk inserts.
This section describes commands to use for decompressing chunks. You can filter by time to select the chunks you want to decompress. To learn how to backfill data, see the backfilling section.
There are several methods for selecting chunks and decompressing them.
To decompress a single chunk by name, run this command:
<chunk_name> is the name of the chunk you want to decompress.
To decompress a set of chunks based on a time range, you can use the output of
show_chunks to decompress each one:
SELECT decompress_chunk(i)FROM show_chunks('table_name', older_than, newer_than) i;
If you want to use more precise matching constraints, for example space partitioning, you can construct a command like this:
SELECT tableoid::regclass FROM metricsWHERE time = '2000-01-01' AND device_id = 1GROUP BY tableoid;tableoid------------------------------------------_timescaledb_internal._hyper_72_37_chunk
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