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. Then add the auto_explain
extension to individual databases in the
instance by using the CREATE EXTENSION
command.
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.