An administrator can use tablespaces to manage storage for a hypertable. A tablespace is a location on a file system where database objects (e.g., tables and indexes) are stored. Review the standard PostgreSQL documentation on tablespaces for more information, including how to create tablespaces.
Since a hypertable comprises a number of chunks, each chunk can be
placed in a specific tablespace, allowing the hypertable to grow
across many disks. To this end, TimescaleDB allows
attaching and detaching
tablespaces on a hypertable. When new chunks are created, one of the
hypertable's attached tablespaces is picked by the runtime to store
the chunk's data. Thus, a typical use case is to detach a tablespace
from a hypertable when the tablespace runs out of disk space and
attach a new one that has free space. A hypertable's attached
tablespaces can be viewed with the
A hypertable can be partitioned in multiple dimensions, but only one of the dimensions is used to determine the tablespace assigned to a particular hypertable chunk. If a hypertable has one or more hash-partitioned ("space") dimensions, then the first hash-partitioned dimension is used. Otherwise, the first time dimension is used. This assignment strategy ensures that hash-partitioned hypertables have chunks colocated according to hash partition, as long as the list of tablespaces attached to the hypertable remains the same. Modulo calculation is used to pick a tablespace, so there can be more partitions than tablespaces (e.g., if there are two tablespaces, partition number three uses the first tablespace).
Hypertables that are only time-partitioned add new partitions continuously, and therefore have chunks assigned to tablespaces in a way similar to round-robin.
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