hypertable_columnstore_stats()

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Retrieve compression statistics for the columnstore.

For more information about using hypertables, including chunk size partitioning, see hypertables.

Since TimescaleDB v2.18.0

Samples

To retrieve compression statistics:

Show the compression status of the conditions hypertable:


SELECT * FROM hypertable_columnstore_stats('conditions');

Returns:


-[ RECORD 1 ]------------------+------
total_chunks                   | 4
number_compressed_chunks       | 1
before_compression_table_bytes | 8192
before_compression_index_bytes | 32768
before_compression_toast_bytes | 0
before_compression_total_bytes | 40960
after_compression_table_bytes  | 8192
after_compression_index_bytes  | 32768
after_compression_toast_bytes  | 8192
after_compression_total_bytes  | 49152
node_name                      |

Use pg_size_pretty get the output in a more human friendly format:


SELECT pg_size_pretty(after_compression_total_bytes) as total
  FROM hypertable_columnstore_stats('conditions');

Returns:


-[ RECORD 1 ]--+------
total | 48 kB

Arguments

Name	Type	Description
`hypertable`	REGCLASS	Hypertable to show statistics for

Returns

Column	Type	Description
`total_chunks`	BIGINT	The number of chunks used by the hypertable. Returns `NULL` if `compression_status` == `Uncompressed`.
`number_compressed_chunks`	INTEGER	The number of chunks used by the hypertable that are currently compressed. Returns `NULL` if `compression_status` == `Uncompressed`.
`before_compression_table_bytes`	BIGINT	Size of the heap before compression. Returns `NULL` if `compression_status` == `Uncompressed`.
`before_compression_index_bytes`	BIGINT	Size of all the indexes before compression. Returns `NULL` if `compression_status` == `Uncompressed`.
`before_compression_toast_bytes`	BIGINT	Size the TOAST table before compression. Returns `NULL` if `compression_status` == `Uncompressed`.
`before_compression_total_bytes`	BIGINT	Size of the entire table (`before_compression_table_bytes` + `before_compression_index_bytes` + `before_compression_toast_bytes`) before compression. Returns `NULL` if `compression_status` == `Uncompressed`.
`after_compression_table_bytes`	BIGINT	Size of the heap after compression. Returns `NULL` if `compression_status` == `Uncompressed`.
`after_compression_index_bytes`	BIGINT	Size of all the indexes after compression. Returns `NULL` if `compression_status` == `Uncompressed`.
`after_compression_toast_bytes`	BIGINT	Size the TOAST table after compression. Returns `NULL` if `compression_status` == `Uncompressed`.
`after_compression_total_bytes`	BIGINT	Size of the entire table (`after_compression_table_bytes` + `after_compression_index_bytes` + `after_compression_toast_bytes`) after compression. Returns `NULL` if `compression_status` == `Uncompressed`.
`node_name`	TEXT	nodes on which the hypertable is located, applicable only to distributed hypertables. Returns `NULL` if `compression_status` == `Uncompressed`.

hypertable_columnstore_stats()

Samples

Arguments

Returns

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