timescaledb_information.chunks

Get metadata about the chunks of hypertables.

This view shows metadata for the chunk’s primary time-based dimension. For information about a hypertable’s secondary dimensions, the dimensions view should be used instead.

If the chunk’s primary dimension is of a time datatype, range_start and range_end are set. Otherwise, if the primary dimension type is integer based, range_start_integer and range_end_integer are set.

Available columns

Name Type Description
hypertable_schema TEXT Schema name of the hypertable
hypertable_name TEXT Table name of the hypertable
chunk_schema TEXT Schema name of the chunk
chunk_name TEXT Name of the chunk
primary_dimension TEXT Name of the column that is the primary dimension
primary_dimension_type REGTYPE Type of the column that is the primary dimension
range_start TIMESTAMP WITH TIME ZONE Start of the range for the chunk’s dimension
range_end TIMESTAMP WITH TIME ZONE End of the range for the chunk’s dimension
range_start_integer BIGINT Start of the range for the chunk’s dimension, if the dimension type is integer based
range_end_integer BIGINT End of the range for the chunk’s dimension, if the dimension type is integer based
is_compressed BOOLEAN Is the data in the chunk compressed? Note that for distributed hypertables, this is the cached compression status of the chunk on the access node. The cached status on the access node and data node is not in sync in some scenarios. For example, if a user compresses or decompresses the chunk on the data node instead of the access node, or sets up compression policies directly on data nodes. Use chunk_compression_stats() function to get real-time compression status for distributed chunks.
chunk_tablespace TEXT Tablespace used by the chunk
data_nodes ARRAY Nodes on which the chunk is replicated. This is applicable only to chunks for distributed hypertables

Sample usage

Get information about the chunks of a hypertable.

2. CREATE TABLESPACE tablespace1 location '/usr/local/pgsql/data1';

4. CREATE TABLE hyper_int (a_col integer, b_col integer, c integer);

6. SELECT table_name from create_hypertable('hyper_int', 'a_col', chunk_time_interval=> 10);

8. CREATE OR REPLACE FUNCTION integer_now_hyper_int() returns int LANGUAGE SQL STABLE as $$ SELECT coalesce(max(a_col), 0) FROM hyper_int $$;

10. SELECT set_integer_now_func('hyper_int', 'integer_now_hyper_int');

12. INSERT INTO hyper_int SELECT generate_series(1,5,1), 10, 50;

14. SELECT attach_tablespace('tablespace1', 'hyper_int');

16. INSERT INTO hyper_int VALUES( 25 , 14 , 20), ( 25, 15, 20), (25, 16, 20);

18. SELECT * FROM timescaledb_information.chunks WHERE hypertable_name = 'hyper_int';

20. -[ RECORD 1 ]----------+----------------------

22. hypertable_schema      | public

24. hypertable_name        | hyper_int

26. chunk_schema           | _timescaledb_internal

28. chunk_name             | _hyper_7_10_chunk

30. primary_dimension      | a_col

32. primary_dimension_type | integer

34. range_start            |

36. range_end              |

38. range_start_integer    | 0

40. range_end_integer      | 10

42. is_compressed          | f

44. chunk_tablespace       |

46. data_nodes             |

48. -[ RECORD 2 ]----------+----------------------

50. hypertable_schema      | public

52. hypertable_name        | hyper_int

54. chunk_schema           | _timescaledb_internal

56. chunk_name             | _hyper_7_11_chunk

58. primary_dimension      | a_col

60. primary_dimension_type | integer

62. range_start            |

64. range_end              |

66. range_start_integer    | 20

68. range_end_integer      | 30

70. is_compressed          | f

72. chunk_tablespace       | tablespace1

74. data_nodes             |