patroni.postgresql package¶
Submodules¶
- patroni.postgresql.bootstrap module
- patroni.postgresql.callback_executor module
- patroni.postgresql.cancellable module
- patroni.postgresql.citus module
- patroni.postgresql.config module
- patroni.postgresql.connection module
- patroni.postgresql.misc module
- patroni.postgresql.postmaster module
- patroni.postgresql.rewind module
- patroni.postgresql.slots module
- patroni.postgresql.sync module
- patroni.postgresql.validator module
Module contents¶
- class patroni.postgresql.Postgresql(config: Dict[str, Any])¶
Bases:
object
- POSTMASTER_START_TIME = 'pg_catalog.pg_postmaster_start_time()'¶
- TL_LSN = "CASE WHEN pg_catalog.pg_is_in_recovery() THEN 0 ELSE ('x' || pg_catalog.substr(pg_catalog.pg_{0}file_name(pg_catalog.pg_current_{0}_{1}()), 1, 8))::bit(32)::int END, CASE WHEN pg_catalog.pg_is_in_recovery() THEN 0 ELSE pg_catalog.pg_{0}_{1}_diff(pg_catalog.pg_current_{0}{2}_{1}(), '0/0')::bigint END, pg_catalog.pg_{0}_{1}_diff(pg_catalog.pg_last_{0}_replay_{1}(), '0/0')::bigint, pg_catalog.pg_{0}_{1}_diff(COALESCE(pg_catalog.pg_last_{0}_receive_{1}(), '0/0'), '0/0')::bigint, pg_catalog.pg_is_in_recovery() AND pg_catalog.pg_is_{0}_replay_paused()"¶
- _checkpoint_locations_from_controldata(data: Dict[str, str]) Optional[Tuple[int, int]] ¶
Get shutdown checkpoint location.
- Parameters
data –
dict
object with values returned by pg_controldata tool.- Returns
a tuple of checkpoint LSN for the cleanly shut down primary, and LSN of prev wal record (SWITCH) if we know that the checkpoint was written to the new WAL file due to the archive_mode=on.
- _do_stop(mode: str, block_callbacks: bool, checkpoint: bool, on_safepoint: Optional[Callable[[...], Any]], on_shutdown: Optional[Callable[[int, int], Any]], before_shutdown: Optional[Callable[[...], Any]], stop_timeout: Optional[int]) Tuple[bool, bool] ¶
- _get_gucs() patroni.collections.CaseInsensitiveSet ¶
Get all available GUCs based on
postgres --describe-config
output.- Returns
all available GUCs in the local Postgres server.
- _pre_promote() bool ¶
Runs a fencing script after the leader lock is acquired but before the replica is promoted. If the script exits with a non-zero code, promotion does not happen and the leader key is removed from DCS.
- _query(sql: str, *params: Any) List[Tuple[Any, ...]] ¶
Execute sql query with params and optionally return results.
- Parameters
sql – SQL statement to execute.
params – parameters to pass.
- Returns
a query response as a list of tuples if there is any.
- Raises
Error
if had issues while executing sql.PostgresConnectionException
: if had issues while connecting to the database.RetryFailedError
: if it was detected that connection/query failed due to PostgreSQL restart.
- _wait_for_connection_close(postmaster: patroni.postgresql.postmaster.PostmasterProcess) None ¶
- static _wal_position(is_primary: bool, wal_position: int, received_location: Optional[int], replayed_location: Optional[int]) int ¶
- property available_gucs: patroni.collections.CaseInsensitiveSet¶
GUCs available in this Postgres server.
- call_nowait(cb_type: patroni.postgresql.callback_executor.CallbackAction) None ¶
pick a callback command and call it without waiting for it to finish
- can_create_replica_without_replication_connection(replica_methods: Optional[List[str]]) bool ¶
go through the replication methods to see if there are ones that does not require a working replication connection.
- check_for_startup() bool ¶
Checks PostgreSQL status and returns if PostgreSQL is in the middle of startup.
- check_startup_state_changed() bool ¶
Checks if PostgreSQL has completed starting up or failed or still starting.
Should only be called when state == ‘starting’
- Returns
True if state was changed from ‘starting’
- checkpoint(connect_kwargs: Optional[Dict[str, Any]] = None, timeout: Optional[float] = None) Optional[str] ¶
- property cluster_info_query: str¶
Returns the monitoring query with a fixed number of fields.
The query text is constructed based on current state in DCS and PostgreSQL version:
function names depend on version. wal/lsn for v10+ and xlog/location for pre v10.
for primary we query timeline_id (extracted from pg_walfile_name()) and pg_current_wal_lsn()
for replicas we query pg_last_wal_receive_lsn(), pg_last_wal_replay_lsn(), and pg_is_wal_replay_paused()
for v9.6+ we query primary_slot_name and primary_conninfo from pg_stat_get_wal_receiver()
for v11+ with permanent logical slots we query from pg_replication_slots and aggregate the result
for standby_leader node running v9.6+ we also query pg_control_checkpoint to fetch timeline_id
if sync replication is enabled we query pg_stat_replication and aggregate the result. In addition to that we get current values of synchronous_commit and synchronous_standby_names GUCs.
If some conditions are not satisfied we simply put static values instead. E.g., NULL, 0, ‘’, and so on.
- connection() Union[connection3, Connection3[Any]] ¶
- controldata() Dict[str, str] ¶
return the contents of pg_controldata, or non-True value if pg_controldata call failed
- ensure_major_version_is_known() bool ¶
Calls configure_server_parameters() if _major_version is not known
- Returns
True if _major_version is set, otherwise False
- follow(member: Optional[Union[patroni.dcs.Leader, patroni.dcs.Member]], role: str = 'replica', timeout: Optional[float] = None, do_reload: bool = False) Optional[bool] ¶
Reconfigure postgres to follow a new member or use different recovery parameters.
Method may call on_role_change callback if role is changing.
- Parameters
member – The member to follow
role – The desired role, normally ‘replica’, but could also be a ‘standby_leader’
timeout – start timeout, how long should the start() method wait for postgres accepting connections
do_reload – indicates that after updating postgresql.conf we just need to do a reload instead of restart
- Returns
True - if restart/reload were successfully performed, False - if restart/reload failed None - if nothing was done or if Postgres is still in starting state after timeout seconds.
- get_major_version() int ¶
Reads major version from PG_VERSION file
- Returns
major PostgreSQL version in integer format or 0 in case of missing file or errors
- get_replication_connection_cursor(host: Optional[str] = None, port: Union[int, str] = 5432, **kwargs: Any) Iterator[Union[cursor, Cursor[Any]]] ¶
- property global_config: Optional[GlobalConfig]¶
- initdb(*args: str, **kwargs: Any) bool ¶
Builds and executes the initdb command.
- Parameters
args – List of arguments to be joined into the initdb command.
kwargs – Keyword arguments to pass to
subprocess.call
.
- Returns
True
if the result ofsubprocess.call`, the exit code, is ``0
.
- is_running() Optional[patroni.postgresql.postmaster.PostmasterProcess] ¶
Returns PostmasterProcess if one is running on the data directory or None. If most recently seen process is running updates the cached process based on pid file.
- latest_checkpoint_location() Optional[int] ¶
Get shutdown checkpoint location.
Note
In case if checkpoint was written to the new WAL file due to the archive_mode=on we return LSN of the previous wal record (SWITCH).
- Returns
checkpoint LSN for the cleanly shut down primary.
- parse_wal_record(timeline: str, lsn: str) Union[Tuple[str, str, str, str], Tuple[None, None, None, None]] ¶
- pg_ctl(cmd: str, *args: str, **kwargs: Any) bool ¶
Builds and executes pg_ctl command
- Returns
!True when return_code == 0, otherwise !False
- pg_isready() str ¶
Runs pg_isready to see if PostgreSQL is accepting connections.
- Returns
‘ok’ if PostgreSQL is up, ‘reject’ if starting up, ‘no_resopnse’ if not up.
- pg_stat_replication() List[Dict[str, Any]] ¶
- Returns
a result set of ‘SELECT * FROM pg_stat_replication’.
- pg_tblspc_realpaths() Dict[str, str] ¶
Returns a dict containing the symlink (key) and target (values) for the tablespaces
- pg_wal_realpath() Dict[str, str] ¶
Returns a dict containing the symlink (key) and target (value) for the wal directory
- pgcommand(cmd: str) str ¶
Return path to the specified PostgreSQL command.
Note
If
postgresql.bin_name.*cmd*
was configured by the user then that binary name is used, otherwise the default binary name cmd is used.- Parameters
cmd – the Postgres binary name to get path to.
- Returns
path to Postgres binary named cmd.
- promote(wait_seconds: int, task: patroni.async_executor.CriticalTask, before_promote: Optional[Callable[[...], Any]] = None) Optional[bool] ¶
- query(sql: str, *params: Any, retry: bool = True) List[Tuple[Any, ...]] ¶
Execute sql query with params and optionally return results.
- Parameters
sql – SQL statement to execute.
params – parameters to pass.
retry – whether the query should be retried upon failure or given up immediately.
- Returns
a query response as a list of tuples if there is any.
- Raises
Error
if had issues while executing sql.PostgresConnectionException
: if had issues while connecting to the database.RetryFailedError
: if it was detected that connection/query failed due to PostgreSQL restart or if retry deadline was exceeded.
- replication_state() Optional[str] ¶
Checks replication state from pg_stat_get_wal_receiver().
Note
Available only since 9.6
- Returns
streaming
,in archive recovery
, orNone
- replication_state_from_parameters(is_primary: bool, receiver_state: Optional[str], restore_command: Optional[str]) Optional[str] ¶
Figure out the replication state from input parameters.
Note
This method could be only called when Postgres is up, running and queries are successfuly executed.
- Is_primary
True is postgres is not running in recovery
- Receiver_state
value from pg_stat_get_wal_receiver.state or None if Postgres is older than 9.6
- Restore_command
value of
restore_command
GUC for PostgreSQL 12+ or postgresql.recovery_conf.restore_command if it is set in Patroni configuration- Returns
None for the primary and for Postgres older than 9.6;
’streaming’ if replica is streaming according to the pg_stat_wal_receiver view;
’in archive recovery’ if replica isn’t streaming and there is a restore_command
- reset_cluster_info_state(cluster: Optional[patroni.dcs.Cluster], nofailover: bool = False, global_config: Optional[GlobalConfig] = None) None ¶
Reset monitoring query cache.
It happens in the beginning of heart-beat loop and on change of synchronous_standby_names.
- Parameters
cluster – currently known cluster state from DCS
nofailover – whether this node could become a new primary. Important when there are logical permanent replication slots because “nofailover” node could do cascading replication and should enable hot_standby_feedback
global_config – last known
GlobalConfig
object
- restart(timeout: Optional[float] = None, task: Optional[patroni.async_executor.CriticalTask] = None, block_callbacks: bool = False, role: Optional[str] = None, before_shutdown: Optional[Callable[[...], Any]] = None, after_start: Optional[Callable[[...], Any]] = None) Optional[bool] ¶
Restarts PostgreSQL.
When timeout parameter is set the call will block either until PostgreSQL has started, failed to start or timeout arrives.
- Returns
True when restart was successful and timeout did not expire when waiting.
- schedule_sanity_checks_after_pause() None ¶
After coming out of pause we have to: 1. configure server parameters if necessary 2. sync replication slots, because it might happen that slots were removed 3. get new ‘Database system identifier’ to make sure that it wasn’t changed
- start(timeout: Optional[float] = None, task: Optional[patroni.async_executor.CriticalTask] = None, block_callbacks: bool = False, role: Optional[str] = None, after_start: Optional[Callable[[...], Any]] = None) Optional[bool] ¶
Start PostgreSQL
Waits for postmaster to open ports or terminate so pg_isready can be used to check startup completion or failure.
- Returns
True if start was initiated and postmaster ports are open, False if start failed, and None if postgres is still starting up
- stop(mode: str = 'fast', block_callbacks: bool = False, checkpoint: Optional[bool] = None, on_safepoint: Optional[Callable[[...], Any]] = None, on_shutdown: Optional[Callable[[int, int], Any]] = None, before_shutdown: Optional[Callable[[...], Any]] = None, stop_timeout: Optional[int] = None) bool ¶
Stop PostgreSQL
Supports a callback when a safepoint is reached. A safepoint is when no user backend can return a successful commit to users. Currently this means we wait for user backends to close. But in the future alternate mechanisms could be added.
- Parameters
on_safepoint – This callback is called when no user backends are running.
on_shutdown – is called when pg_controldata starts reporting Database cluster state: shut down
before_shutdown – is called after running optional CHECKPOINT and before running pg_ctl stop
- property supports_multiple_sync: bool¶
True if Postgres version supports more than one synchronous node.
- Type
returns
- terminate_postmaster(postmaster: patroni.postgresql.postmaster.PostmasterProcess, mode: str, stop_timeout: Optional[int]) Optional[bool] ¶
- terminate_starting_postmaster(postmaster: patroni.postgresql.postmaster.PostmasterProcess) None ¶
Terminates a postmaster that has not yet opened ports or possibly even written a pid file. Blocks until the process goes away.
- wait_for_port_open(postmaster: patroni.postgresql.postmaster.PostmasterProcess, timeout: float) bool ¶
Waits until PostgreSQL opens ports.
- wait_for_startup(timeout: float = 0) Optional[bool] ¶
Waits for PostgreSQL startup to complete or fail.
- Returns
True if start was successful, False otherwise
- patroni.postgresql.null_context()¶