SHOW FUNCTIONS

Description

Returns the list of functions after applying an optional regex pattern. Given number of functions supported by Spark is quite large, this statement in conjunction with describe function may be used to quickly find the function and understand its usage. The LIKE clause is optional and supported only for compatibility with other systems.

Syntax

  1. SHOW [ function_kind ] FUNCTIONS [ { FROM | IN } database_name ] [ LIKE regex_pattern ]

Parameters

  • function_kind

    Specifies the name space of the function to be searched upon. The valid name spaces are :

    • USER - Looks up the function(s) among the user defined functions.
    • SYSTEM - Looks up the function(s) among the system defined functions.
    • ALL - Looks up the function(s) among both user and system defined functions.

  • { FROM | IN } database_name

    Specifies the database name from which functions are listed.

  • regex_pattern

    Specifies a regular expression pattern that is used to filter the results of the statement.

    • Except for * and | character, the pattern works like a regular expression.
    • * alone matches 0 or more characters and | is used to separate multiple different regular expressions, any of which can match.
    • The leading and trailing blanks are trimmed in the input pattern before processing. The pattern match is case-insensitive.

Examples

  1. -- List a system function `trim` by searching both user defined and system
  2. -- defined functions.
  3. SHOW FUNCTIONS trim;
  4. +--------+
  5. |function|
  6. +--------+
  7. |    trim|
  8. +--------+
  10. -- List a system function `concat` by searching system defined functions.
  11. SHOW SYSTEM FUNCTIONS concat;
  12. +--------+
  13. |function|
  14. +--------+
  15. |  concat|
  16. +--------+
  18. -- List a qualified function `max` from database `salesdb`. 
  19. SHOW SYSTEM FUNCTIONS FROM salesdb LIKE 'max';
  20. +--------+
  21. |function|
  22. +--------+
  23. |     max|
  24. +--------+
  26. -- List all functions starting with `t`
  27. SHOW FUNCTIONS LIKE 't*';
  28. +-----------------+
  29. |         function|
  30. +-----------------+
  31. |              tan|
  32. |             tanh|
  33. |        timestamp|
  34. |          tinyint|
  35. |           to_csv|
  36. |          to_date|
  37. |          to_json|
  38. |     to_timestamp|
  39. |to_unix_timestamp|
  40. | to_utc_timestamp|
  41. |        transform|
  42. |   transform_keys|
  43. | transform_values|
  44. |        translate|
  45. |             trim|
  46. |            trunc|
  47. |           typeof|
  48. +-----------------+
  50. -- List all functions starting with `yea` or `windo`
  51. SHOW FUNCTIONS LIKE 'yea*|windo*';
  52. +--------+
  53. |function|
  54. +--------+
  55. |  window|
  56. |    year|
  57. +--------+
  59. -- Use normal regex pattern to list function names that has 4 characters
  60. -- with `t` as the starting character.
  61. SHOW FUNCTIONS LIKE 't[a-z][a-z][a-z]';
  62. +--------+
  63. |function|
  64. +--------+
  65. |    tanh|
  66. |    trim|
  67. +--------+