patroni.postgresql.rewind module

Bases: IntEnum

An enumeration.

CHECK = 2

CHECKPOINT = 1

FAILED = 6

INITIAL = 0

NEED = 3

NOT_NEED = 4

SUCCESS = 5

Bases: object

__checkpoint ( task : CriticalTask , wakeup : Callable [ [ ... ] , Any ] ) → None

__init__ ( postgresql : Postgresql ) → None View on GitHub

_archive_ready_wals ( ) → None View on GitHub

Try to archive WALs that have .ready files just in case archive_mode was not set to ‘always’ before promote, while after it the WALs were recycled on the promoted replica. With this we prevent the entire loss of such WALs and the consequent old leader’s start failure.

_build_archiver_command ( command : str , wal_filename : str ) → str View on GitHub

Replace placeholders in the given archiver command’s template. Applicable for archive_command and restore_command. Can also be used for archive_cleanup_command and recovery_end_command, however %r value is always set to 000000010000000000000001.

_check_timeline_and_lsn ( leader : Leader | RemoteMember ) → None View on GitHub

_conn_kwargs ( member : Leader | RemoteMember , auth : Dict [ str , Any ] ) → Dict [ str , Any ] View on GitHub

_fetch_missing_wal ( restore_command : str , wal_filename : str ) → bool View on GitHub

_find_missing_wal ( data : bytes ) → str | None View on GitHub

_get_checkpoint_end ( timeline : int , lsn : int ) → int View on GitHub

Get the end of checkpoint record from WAL.

Note

The checkpoint record size in WAL depends on postgres major version and platform (memory alignment). Hence, the only reliable way to figure out where it ends, is to read the record from file with the help of pg_waldump and parse the output.

We are trying to read two records, and expect that it will fail to read the second record with message:

fatal: error in WAL record at 0/182E220: invalid record length at 0/182E298: wanted 24, got 0; or

fatal: error in WAL record at 0/182E220: invalid record length at 0/182E298: expected at least 24, got 0

The error message contains information about LSN of the next record, which is exactly where checkpoint ends.

Parameters :

• timeline – the checkpoint timeline from pg_controldata .

• lsn – the checkpoint location as int from pg_controldata .

Returns :

the end of checkpoint record as int or 0 if failed to parse pg_waldump output.

_get_local_timeline_lsn ( ) → Tuple [ bool | None , int | None , int | None ] View on GitHub

_get_local_timeline_lsn_from_controldata ( ) → Tuple [ bool | None , int | None , int | None ] View on GitHub

static _log_primary_history ( history : List [ Tuple [ int , int , str ] ] , i : int ) → None View on GitHub

_maybe_clean_pg_replslot ( ) → None View on GitHub

Clean pg_replslot directory if pg version is less then 11 (pg_rewind deletes $PGDATA/pg_replslot content only since pg11).

property can_rewind : bool View on GitHub

check if pg_rewind executable is there and that pg_controldata indicates we have either wal_log_hints or checksums turned on

property can_rewind_or_reinitialize_allowed : bool View on GitHub

static check_leader_has_run_checkpoint ( conn_kwargs : Dict [ str , Any ] ) → str | None View on GitHub

static check_leader_is_not_in_recovery ( conn_kwargs : Dict [ str , Any ] ) → bool | None View on GitHub

checkpoint_after_promote ( ) → bool View on GitHub

cleanup_archive_status ( ) → None View on GitHub

static configuration_allows_rewind ( data : Dict [ str , str ] ) → bool View on GitHub

property enabled : bool View on GitHub

ensure_checkpoint_after_promote ( wakeup : Callable [ [ ... ] , Any ] ) → None View on GitHub

After promote issue a CHECKPOINT from a new thread and asynchronously check the result. In case if CHECKPOINT failed, just check that timeline in pg_control was updated.

ensure_clean_shutdown ( ) → bool | None View on GitHub

execute ( leader : Leader | RemoteMember ) → bool | None View on GitHub

property executed : bool View on GitHub

property failed : bool View on GitHub

property is_needed : bool View on GitHub

pg_rewind ( conn_kwargs : Dict [ str , Any ] ) → bool View on GitHub

Do pg_rewind.

Note

If pg_rewind doesn’t support --restore-target-wal parameter and exited with non zero code, Patroni will parse stderr/stdout to figure out if it failed due to a missing WAL file and will repeat an attempt after downloading the missing file using restore_command .

Parameters :

conn_kwargs – dict object with connection parameters.

Returns :

True if pg_rewind finished successfully, False otherwise.

read_postmaster_opts ( ) → Dict [ str , str ] View on GitHub

returns the list of option names/values from postgres.opts, Empty dict if read failed or no file

reset_state ( ) → None View on GitHub

rewind_or_reinitialize_needed_and_possible ( leader : Leader | RemoteMember | None ) → bool View on GitHub

property should_remove_data_directory_on_diverged_timelines : bool View on GitHub

single_user_mode ( communicate : Dict [ str , Any ] | None = None , options : Dict [ str , str ] | None = None ) → int | None View on GitHub

run a given command in a single-user mode. If the command is empty - then just start and stop

trigger_check_diverged_lsn ( ) → None View on GitHub