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

NameTypeDescription
hypertable_schemaTEXTSchema name of the hypertable
hypertable_nameTEXTTable name of the hypertable
chunk_schemaTEXTSchema name of the chunk
chunk_nameTEXTName of the chunk
primary_dimensionTEXTName of the column that is the primary dimension
primary_dimension_typeREGTYPEType of the column that is the primary dimension
range_startTIMESTAMP WITH TIME ZONEStart of the range for the chunk’s dimension
range_endTIMESTAMP WITH TIME ZONEEnd of the range for the chunk’s dimension
range_start_integerBIGINTStart of the range for the chunk’s dimension, if the dimension type is integer based
range_end_integerBIGINTEnd of the range for the chunk’s dimension, if the dimension type is integer based
is_compressedBOOLEANIs 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 will not be 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_tablespaceTEXTTablespace used by the chunk
data_nodesARRAYNodes 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.

  1. CREATE TABLESPACE tablespace1 location '/usr/local/pgsql/data1';
  3. CREATE TABLE hyper_int (a_col integer, b_col integer, c integer);
  4. SELECT table_name from create_hypertable('hyper_int', 'a_col', chunk_time_interval=> 10);
  5. CREATE OR REPLACE FUNCTION integer_now_hyper_int() returns int LANGUAGE SQL STABLE as $$ SELECT coalesce(max(a_col), 0) FROM hyper_int $$;
  6. SELECT set_integer_now_func('hyper_int', 'integer_now_hyper_int');
  8. INSERT INTO hyper_int SELECT generate_series(1,5,1), 10, 50;
  10. SELECT attach_tablespace('tablespace1', 'hyper_int');
  11. INSERT INTO hyper_int VALUES( 25 , 14 , 20), ( 25, 15, 20), (25, 16, 20);
  13. SELECT * FROM timescaledb_information.chunks WHERE hypertable_name = 'hyper_int';
  15. -[ RECORD 1 ]----------+----------------------
  16. hypertable_schema      | public
  17. hypertable_name        | hyper_int
  18. chunk_schema           | _timescaledb_internal
  19. chunk_name             | _hyper_7_10_chunk
  20. primary_dimension      | a_col
  21. primary_dimension_type | integer
  22. range_start            | 
  23. range_end              | 
  24. range_start_integer    | 0
  25. range_end_integer      | 10
  26. is_compressed          | f
  27. chunk_tablespace       | 
  28. data_nodes             | 
  29. -[ RECORD 2 ]----------+----------------------
  30. hypertable_schema      | public
  31. hypertable_name        | hyper_int
  32. chunk_schema           | _timescaledb_internal
  33. chunk_name             | _hyper_7_11_chunk
  34. primary_dimension      | a_col
  35. primary_dimension_type | integer
  36. range_start            | 
  37. range_end              | 
  38. range_start_integer    | 20
  39. range_end_integer      | 30
  40. is_compressed          | f
  41. chunk_tablespace       | tablespace1
  42. data_nodes             |