begriffs open source - ai-pg/blob - full-docs/txt/pglogicalinspect.txt

   1
   2 F.28. pg_logicalinspect — logical decoding components inspection #
   3
   4    F.28.1. Functions
   5    F.28.2. Author
   6
   7    The pg_logicalinspect module provides SQL functions that allow you to
   8    inspect the contents of logical decoding components. It allows the
   9    inspection of serialized logical snapshots of a running PostgreSQL
  10    database cluster, which is useful for debugging or educational
  11    purposes.
  12
  13    By default, use of these functions is restricted to superusers and
  14    members of the pg_read_server_files role. Access may be granted by
  15    superusers to others using GRANT.
  16
  17 F.28.1. Functions #
  18
  19    pg_get_logical_snapshot_meta(filename text) returns record #
  20           Gets logical snapshot metadata about a snapshot file that is
  21           located in the server's pg_logical/snapshots directory. The
  22           filename argument represents the snapshot file name. For
  23           example:
  24
  25 postgres=# SELECT * FROM pg_ls_logicalsnapdir();
  26 -[ RECORD 1 ]+-----------------------
  27 name         | 0-40796E18.snap
  28 size         | 152
  29 modification | 2024-08-14 16:36:32+00
  30
  31 postgres=# SELECT * FROM pg_get_logical_snapshot_meta('0-40796E18.snap');
  32 -[ RECORD 1 ]--------
  33 magic    | 1369563137
  34 checksum | 1028045905
  35 version  | 6
  36
  37 postgres=# SELECT ss.name, meta.* FROM pg_ls_logicalsnapdir() AS ss,
  38 pg_get_logical_snapshot_meta(ss.name) AS meta;
  39 -[ RECORD 1 ]-------------
  40 name     | 0-40796E18.snap
  41 magic    | 1369563137
  42 checksum | 1028045905
  43 version  | 6
  44
  45           If filename does not match a snapshot file, the function raises
  46           an error.
  47
  48    pg_get_logical_snapshot_info(filename text) returns record #
  49           Gets logical snapshot information about a snapshot file that is
  50           located in the server's pg_logical/snapshots directory. The
  51           filename argument represents the snapshot file name. For
  52           example:
  53
  54 postgres=# SELECT * FROM pg_ls_logicalsnapdir();
  55 -[ RECORD 1 ]+-----------------------
  56 name         | 0-40796E18.snap
  57 size         | 152
  58 modification | 2024-08-14 16:36:32+00
  59
  60 postgres=# SELECT * FROM pg_get_logical_snapshot_info('0-40796E18.snap');
  61 -[ RECORD 1 ]------------+-----------
  62 state                    | consistent
  63 xmin                     | 751
  64 xmax                     | 751
  65 start_decoding_at        | 0/40796AF8
  66 two_phase_at             | 0/40796AF8
  67 initial_xmin_horizon     | 0
  68 building_full_snapshot   | f
  69 in_slot_creation         | f
  70 last_serialized_snapshot | 0/0
  71 next_phase_at            | 0
  72 committed_count          | 0
  73 committed_xip            |
  74 catchange_count          | 2
  75 catchange_xip            | {751,752}
  76
  77 postgres=# SELECT ss.name, info.* FROM pg_ls_logicalsnapdir() AS ss,
  78 pg_get_logical_snapshot_info(ss.name) AS info;
  79 -[ RECORD 1 ]------------+----------------
  80 name                     | 0-40796E18.snap
  81 state                    | consistent
  82 xmin                     | 751
  83 xmax                     | 751
  84 start_decoding_at        | 0/40796AF8
  85 two_phase_at             | 0/40796AF8
  86 initial_xmin_horizon     | 0
  87 building_full_snapshot   | f
  88 in_slot_creation         | f
  89 last_serialized_snapshot | 0/0
  90 next_phase_at            | 0
  91 committed_count          | 0
  92 committed_xip            |
  93 catchange_count          | 2
  94 catchange_xip            | {751,752}
  95
  96           If filename does not match a snapshot file, the function raises
  97           an error.
  98
  99 F.28.2. Author #
 100
 101    Bertrand Drouvot <bertranddrouvot.pg@gmail.com>