Supported database flags

This page lists the database flags that AlloyDB for PostgreSQL supports.

You use database flags for many operations, including adjusting PostgreSQL parameters, adjusting options, and configuring and tuning instances.

For more information about setting database flags in AlloyDB, see Configure an instance's database flags.

For more information about how to use each flag listed in the following table, click the name of the flag.

The table's other columns contain additional information about each flag:

• The Default value column displays the value that AlloyDB sets for this flag in a new instance, unless you specify a different value when creating the instance.

  Standard default indicates that the flag has a default value that's not set by AlloyDB. To learn more, click the flag's name.

• In the Instance restarts column, Yes indicates 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.

• In the Read pool restrictions column, Yes indicates the following restrictions on how you can use the flag:

  • Before setting this flag on your cluster's primary instance, set the flag on each of your cluster's read pool instances.

  • If the primary instance has this flag set, then the value of this flag on any read pool instance must be equal to or greater than the primary instance's value for this flag.

A | C | D | E | F | G | H | I | J | L | M | O | P | R | S | T | V | W

AlloyDB flag	Default value	Instance restarts	Read pool restrictions
alloydb.enable_auto_explain	off	Yes	No
alloydb.enable_pg_bigm	off	Yes	No
alloydb.enable_pg_cron	off	Yes	No
alloydb.enable_pg_hint_plan	off	Yes	No
alloydb.enable_pg_wait_sampling	off	Yes	No
alloydb.enable_pgaudit	off	Yes	No
alloydb.enable_pglogical	off	Yes	No
alloydb.iam_authentication	off	Yes	No
alloydb.logical_decoding	off	Yes	No
alloydb.log_throttling_window	No	No
alloydb.promote_cancel_to_terminate	off	No	No
alloydb.pg_shadow_select_role	An empty string	No	No
auto_explain.log_analyze	Standard default	No	No
auto_explain.log_buffers	Standard default	No	No
auto_explain.log_format	Standard default	No	No
auto_explain.log_level	Standard default	No	No
auto_explain.log_min_duration	Standard default	No	No
auto_explain.log_nested_statements	Standard default	No	No
auto_explain.log_settings	Standard default	No	No
auto_explain.log_timing	Standard default	No	No
auto_explain.log_triggers	Standard default	No	No
auto_explain.log_verbose	Standard default	No	No
auto_explain.log_wal	Standard default	No	No
auto_explain.sample_rate	Standard default	No	No
autovacuum	Standard default	No	No
autovacuum_analyze_scale_factor	Standard default	No	No
autovacuum_analyze_threshold	Standard default	No	No
autovacuum_freeze_max_age	Standard default	Yes	No
autovacuum_max_workers	Standard default	Yes	No
autovacuum_multixact_freeze_max_age	Standard default	Yes	No
autovacuum_naptime	Standard default	No	No
autovacuum_vacuum_cost_delay	Standard default	No	No
autovacuum_vacuum_cost_limit	Standard default	No	No
autovacuum_vacuum_scale_factor	Standard default	No	No
autovacuum_vacuum_threshold	Standard default	No	No
autovacuum_work_mem	Standard default	No	No
checkpoint_completion_target	Standard default	No	No
checkpoint_timeout	Standard default	No	No
checkpoint_warning	Standard default	No	No
commit_delay	Standard default	No	No
commit_siblings	Standard default	No	No
constraint_exclusion	Standard default	No	No
cpu_index_tuple_cost	Standard default	No	No
cpu_operator_cost	Standard default	No	No
cpu_tuple_cost	Standard default	No	No
createrole_self_grant (PostgreSQL 16)	-	No	No
cron.database_name	Standard default	Yes	No
cron.log_min_messages	Standard default	No	No
cron.log_run	Standard default	Yes	No
cron.log_statement	Standard default	Yes	No
cron.max_running_jobs	Standard default	Yes	No
cursor_tuple_fraction	Standard default	No	No
deadlock_timeout	Standard default	No	No
debug_io_direct (PostgreSQL 16)	-	No	No
debug_logical_replication_streaming (PostgreSQL 16)	buffered	No	No
debug_parallel_query (PostgreSQL 16)	off	No	No
default_statistics_target	Standard default	No	No
default_tablespace	Standard default	No	No
default_transaction_deferrable	Standard default	No	No
default_transaction_isolation	Standard default	No	No
effective_cache_size	80% of instance RAM	No	No
enable_bitmapscan	Standard default	No	No
enable_google_adaptive_autovacuum	on	No	No
enable_hashagg	Standard default	No	No
enable_hashjoin	Standard default	No	No
enable_indexonlyscan	Standard default	No	No
enable_indexscan	Standard default	No	No
enable_material	Standard default	No	No
enable_mergejoin	Standard default	No	No
enable_nestloop	Standard default	No	No
enable_presorted_aggregate (PostgreSQL 16)	on	No	No
enable_seqscan	Standard default	No	No
enable_sort	Standard default	No	No
enable_tidscan	Standard default	No	No
force_parallel_mode	Standard default	No	No
from_collapse_limit	Standard default	No	No
geqo	Standard default	No	No
geqo_effort	Standard default	No	No
geqo_generations	Standard default	No	No
geqo_pool_size	Standard default	No	No
geqo_seed	Standard default	No	No
geqo_selection_bias	Standard default	No	No
geqo_threshold	Standard default	No	No
gin_fuzzy_search_limit	Standard default	No	No
gin_pending_list_limit	Standard default	No	No
google_columnar_engine.auto_columnarization_schedule	'EVERY 1 HOUR'	No	No
google_columnar_engine.enable_auto_columnarization	on	No	No
google_columnar_engine.enable_columnar_scan	on	No	No
google_columnar_engine.enable_vectorized_join	No	No
google_columnar_engine.enabled	off	Yes	No
google_columnar_engine.memory_size_in_mb	30% of instance RAM	Yes	No
google_columnar_engine.refresh_threshold_percentage	50	No	No
google_columnar_engine.refresh_threshold_scan_count	5	No	No
google_columnar_engine.relations	An empty string	No	No
google_columnar_engine.vectorized_join_threads	No	No
google_db_advisor.auto_advisor_max_time_in_seconds	1800	No	No
google_db_advisor.auto_advisor_schedule	'EVERY 24 HOURS'	No	No
google_db_advisor.enable_auto_advisor	on	No	No
google_db_advisor.enabled	on	Yes	No
google_db_advisor.max_index_width	2	No	No
google_db_advisor.max_num_indexable_columns	1000	No	No
google_db_advisor.max_statement_length	102400	No	No
google_db_advisor.max_storage_size_in_mb	0	No	No
google_db_advisor.recommendation_max_time_in_seconds	600	No	No
google_db_advisor.recommend_indexes_on_partitions	off	No	No
google_db_advisor.top_k_slowest_statements	100	No	No
google_job_scheduler.maintenance_cpu_percentage	20	No	No
google_job_scheduler.max_parallel_workers_per_job	2	No	No
google_ml_integration.enable_model_support	on	No
google_storage.log_replay_throttle_read_transactions	on	No	No
gss_accept_delegation (PostgreSQL 16)	off	No	No
hot_standby_feedback	on	No	No
icu_validation_level (PostgreSQL 16)	warning	No	No
idle_in_transaction_session_timeout	Standard default	No	No
idle_session_timeout	Standard default	No	No
idle_in_transaction_session_timeout (PostgreSQL 16)	86,400,000	No	No
join_collapse_limit	Standard default	No	No
lock_timeout	Standard default	No	No
log_autovacuum_min_duration	0	No	No
log_checkpoints	Standard default	No	No
log_connections	Standard default	No	No
log_disconnections	Standard default	No	No
log_duration	Standard default	No	No
log_error_verbosity	Standard default	No	No
log_executor_stats	Standard default	No	No
log_hostname	Standard default	No	No
log_line_prefix	Standard default	No	No
log_lock_waits	Standard default	No	No
log_min_duration_statement	Standard default	No	No
log_min_error_statement	Standard default	No	No
log_min_messages	Standard default	No	No
log_parser_stats	Standard default	No	No
log_planner_stats	Standard default	No	No
log_replication_commands	Standard default	No	No
log_statement	Standard default	No	No
log_statement_stats	Standard default	No	No
log_temp_files	0	No	No
maintenance_work_mem	Standard default	No	No
max_connections	1000	Yes	Yes
max_locks_per_transaction	Standard default	Yes	Yes
max_logical_replication_workers	Standard default	Yes	No
max_parallel_apply_workers_per_subscription (PostgreSQL 16)	2	No	No
max_parallel_maintenance_workers	Standard default	No	No
max_parallel_workers	The instance CPU count or 8, whichever is greater	No	No
max_parallel_workers_per_gather	Half of the instance CPU count or 2, whichever is greater	No	No
max_pred_locks_per_page	Standard default	Yes	No
max_pred_locks_per_relation	Standard default	Yes	No
max_pred_locks_per_transaction	Standard default	Yes	No
max_prepared_transactions	Standard default	Yes	Yes
max_replication_slots	60	Yes	No
max_standby_archive_delay	Standard default	No	No
max_standby_streaming_delay	Standard default	No	No
max_sync_workers_per_subscription	Standard default	No	No
max_wal_senders	50	Yes	Yes
max_wal_size	1504	No	No
max_worker_processes	64	Yes	Yes
min_wal_size	Standard default	No	No
old_snapshot_threshold	Standard default	Yes	No
parallel_setup_cost	Standard default	No	No
parallel_tuple_cost	Standard default	No	No
password_encryption	Standard default	No	No
password.enforce_password_does_not_contain_username	OFF	No	No
password.enforce_expiration	OFF	No	No
password.enforce_complexity	OFF	No	No
password.expiration_in_days	90	No	No
password.min_uppercase_letters	0	No	No
password.max_uppercase_letters	1000	No	No
password.min_lowercase_letters	0	No	No
password.max_lowercase_letters	1000	No	No
password.min_numerical_chars	0	No	No
password.max_numerical_chars	1000	No	No
password.min_special_chars	0	No	No
password.max_special_chars	1000	No	No
password.min_pass_length	0	No	No
password.max_pass_length	1000	No	No
password.notify_expiration_in_days	30	No	No
pg_bigm.enable_recheck	Standard default	No	No
pg_bigm.gin_key_limit	Standard default	No	No
pg_bigm.similarity_limit	Standard default	No	No
pg_hint_plan.debug_print	Standard default	No	No
pg_hint_plan.enable_hint	Standard default	No	No
pg_hint_plan.enable_hint_table	Standard default	No	No
pg_hint_plan.message_level	Standard default	No	No
pg_hint_plan.parse_messages	Standard default	No	No
pg_stat_statements.max	Standard default	Yes	No
pg_stat_statements.save	Standard default	No	No
pg_stat_statements.track	Standard default	No	No
pg_stat_statements.track_utility	Standard default	No	No
pgaudit.log	Standard default	No	No
pgaudit.log_catalog	Standard default	No	No
pgaudit.log_client	Standard default	No	No
pgaudit.log_level	Standard default	No	No
pgaudit.log_parameter	Standard default	No	No
pgaudit.log_relation	Standard default	No	No
pgaudit.log_statement_once	Standard default	No	No
pgaudit.role	Standard default	No	No
pglogical.batch_inserts	Standard default	Yes	No
pglogical.conflict_log_level	Standard default	No	No
pglogical.conflict_resolution	Standard default	No	No
pglogical.extra_connection_options	Standard default	No	No
pglogical.synchronous_commit	Standard default	Yes	No
pglogical.use_spi	Standard default	Yes	No
random_page_cost	Standard default	No	No
replacement_sort_tuples	Standard default	No	No
reserved_connections (PostgreSQL 16)	0	Yes	No
scram_iterations (PostgreSQL 16)	4096	No	No
send_abort_for_crash (PostgreSQL 16)	off	No	No
send_abort_for_kill (PostgreSQL 16)	off	No	No
shared_buffers	80% of instance memory	Yes	No
ssl_max_protocol_version	Standard default	No	No
ssl_min_protocol_version	Standard default	No	No
standard_conforming_strings	Standard default	No	No
statement_timeout	Standard default	No	No
synchronize_seqscans	Standard default	No	No
tcp_keepalives_count	5	No	No
tcp_keepalives_idle	300	No	No
tcp_keepalives_interval	60	No	No
temp_buffers	Standard default	No	No
temp_file_limit	Standard default	No	No
trace_notify	Standard default	No	No
trace_recovery_messages	Standard default	No	No
trace_sort	Standard default	No	No
track_activities	Standard default	No	No
track_activity_query_size	Standard default	Yes	No
track_commit_timestamp	Standard default	Yes	No
track_counts	Standard default	No	No
track_functions	Standard default	No	No
track_io_timing	on	No	No
vacuum_buffer_usage_limit (PostgreSQL 16)	256	No	No
vacuum_cost_delay	Standard default	No	No
vacuum_cost_limit	Standard default	No	No
vacuum_freeze_min_age	Standard default	No	No
vacuum_freeze_table_age	Standard default	No	No
vacuum_multixact_freeze_min_age	Standard default	No	No
vacuum_multixact_freeze_table_age	Standard default	No	No
wal_buffers	2048	Yes	No
wal_receiver_timeout	Standard default	No	No
wal_sender_timeout	Standard default	No	No
work_mem	N MB, where N is either 4 or the number of instance vCPUs, whichever is greater	No	No