This page describes the database flags that AlloyDB for PostgreSQL uses to enable and manage various service features unique to AlloyDB. For a list of all database flags that AlloyDB supports, see Supported database flags.
Flags marked with Instance restarts mean that AlloyDB restarts an instance whenever you set, remove, or modify this flag on that instance. The flag's value persists for the instance until you modify it again.
alloydb.enable_auto_explain
| Type | boolean
|
| Default | off
|
| Instance restarts | Yes |
Controls the availability of the auto_explain extension in
an AlloyDB instance. Set the parameter to on and restart the
instance.
The auto_explain extension enables
automatic logging of execution plans of slow statements, for troubleshooting and
more. It provides an automated way to perform the functionality of the EXPLAIN
command.
alloydb.enable_pg_bigm
| Type | boolean
|
| Default | off
|
| Instance restarts | Yes |
Controls the availability of the pg_bigm extension in an AlloyDB
instance. Set the parameter to on and restart the instance. Then add the
pg_bigm extension to individual databases in the instance by using the CREATE
EXTENSION command.
The pg_bigm extension provides
full text search capability in PostgreSQL using 2-gram (bigram) indexes for
faster full text searches.
alloydb.enable_pg_cron
| Type | boolean
|
| Default | off
|
| Instance restarts | Yes |
Controls the availability of the pg_cron extension in an AlloyDB
instance. Set the parameter to on and restart the instance. Then add the
pg_cron extension to individual databases in the instance by using the CREATE
EXTENSION command.
The pg_cron extension provides
a simple cron-based job scheduler for PostgreSQL that runs inside the database
as an extension. It uses the same syntax as regular cron, and it lets you
schedule PostgreSQL commands directly from the database.
alloydb.enable_pg_hint_plan
| Type | boolean
|
| Default | off
|
| Instance restarts | Yes |
Controls the availability of the pg_hint_plan extension in
an AlloyDB instance. Set the parameter to on and restart the
instance. Then add the pg_hint_plan extension to individual databases in the
instance by using the CREATE EXTENSION command.
The pg_hint_plan extension
enables you to improve PostgreSQL execution plans using hints, which are simple
descriptions in SQL comments.
alloydb.enable_pg_wait_sampling
| Type | boolean |
| Default | off |
| Instance restarts | Yes |
Enables AlloyDB to collect sampling statistics of wait events.
Set the parameter to on and restart the instance. Then, add the
pg_wait_sampling extension to individual databases in the instance by using
the CREATE EXTENSION command.
The pg_wait_sampling extension
aggregates and summarizes the wait event data. You can query these views to gain
insights into wait times, frequencies, and relative importance of different wait
events.
alloydb.enable_pgaudit
| Type | boolean
|
| Default | off
|
| Instance restarts | Yes |
Controls the availability of the pgaudit extension in an AlloyDB
instance. Set the parameter to on and restart the instance. Then add the
pgaudit extension to individual databases in the instance by using the CREATE
EXTENSION command.
The pgaudit extension provides detailed session
and object audit logging using the standard logging facility provided by
PostgreSQL.
alloydb.enable_pglogical
| Type | boolean
|
| Default | off
|
| Instance restarts | Yes |
Controls the availability of the pglogical extension in
an AlloyDB instance. Set the parameter to on and restart the
instance. Then add the pglogical extension to individual databases in the
instance by using the CREATE EXTENSION command.
The pglogical extension
provides logical streaming replication for PostgreSQL using a publish/subscribe
model.
alloydb.iam_authentication
| Type | boolean
|
| Default | off
|
| Instance restarts | Yes |
Enables the use of Identity and Access Management (IAM) authentication with an AlloyDB instance.
alloydb.logical_decoding
| Type | boolean
|
| Default | off
|
| Instance restarts | Yes |
Enables the PostgreSQL logical decoding infrastructure in an AlloyDB instance.
Logical decoding provides the infrastructure necessary to stream data modifications to external consumers.
alloydb.log_throttling_window
| Type | integer |
| Default | 0 |
| Instance restarts | No |
Controls whether AlloyDB records duplicate log messages received during a specified time window.
If set to a value greater than 0, then AlloyDB starts a
timer that many seconds long whenever it records a log message. If
AlloyDB receives the identical log message before the timer
expires, it does not record the message. After the timer expires,
AlloyDB appends a count of any skipped messages to the
next occurrence of the same log message that it records.
If set to 0, then AlloyDB records all duplicate log
messages.
alloydb.promote_cancel_to_terminate
| Type | boolean |
| Default | off |
| Instance restarts | No |
If set to true, then any query cancellation requests due to issues such as lock timeouts, statement timeouts, and recovery (replay) conflicts that AlloyDB encounters, are promoted to forced backend termination requests.
By promoting the cancellation requests, AlloyDB helps prevent stuck backends from blocking log replay and other backends.
alloydb.pg_shadow_select_role
| Type | string |
| Default | An empty string |
| Instance restarts | No |
Name of the PostgreSQL role that is to be used to grant permission to query the
pg_shadow view.
google_storage.log_replay_throttle_read_transactions
| Type | boolean |
| Default | on |
| Instance restarts | No |
Controls whether lag-based throttling of a read query is enabled on read nodes.
If the parameter is set to on, then the read queries are throttled for up to one minute
when replication lag exceeds one second.