hypertable_columnstore_stats.md

api_name	excerpt	topics	keywords	tags	api
hypertable_columnstore_stats()	Get columnstore statistics related to the columnstore	hypercore columnstore	hypercore columnstore hypertables information	statistics size	license type community procedure

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hypertable_columnstore_stats() Community

Retrieve compression statistics for the columnstore.

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

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.