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 | N | O | P | R | S | T | V | W

AlloyDB flag Default value Instance restarts Read pool restrictions
alloydb.ai_nl_enabled off No No
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.enable_query_plan_patch off No No
alloydb.iam_authentication off Yes No
alloydb.logical_decoding off Yes No
alloydb.log_throttling_window No No
alloydb.promote_cancel_to_terminate on No No
alloydb.pg_shadow_select_role An empty string No No
alloydb.enable_pg_squeeze off No No
allow_alter_system (PostgreSQL 17) on 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_max_threshold (PostgreSQL 18) 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
autovacuum_worker_slots (PostgreSQL 18) Standard default Yes 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
commit_timestamp_buffers (PostgreSQL 17) 0 Yes 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_distinct_reordering (PostgreSQL 18) on No No
enable_google_adaptive_autovacuum on No No
enable_group_by_reordering (PostgreSQL 17) 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_self_join_elimination (PostgreSQL 18) Standard default No No
enable_seqscan Standard default No No
enable_sort Standard default No No
enable_tidscan Standard default No No
event_triggers (PostgreSQL 17) true No Yes
file_copy_method (PostgreSQL 18) 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_virtual_columns_scan off 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_faster_embedding_generation off No No
google_ml_integration.enable_model_support on No No
google_ml_integration.enable_forecasting off No No
google_plan_management.enabled off Yes No
google_plan_management.enable_track_plans on No No
google_plan_management.enable_steer_plans on No 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_replication_slot_timeout Standard default No No
idle_session_timeout Standard default No No
idle_in_transaction_session_timeout (PostgreSQL 16) 86,400,000 No No
io_max_combine_limit (PostgreSQL 18) Standard default Yes No
io_max_concurrency (PostgreSQL 18) Standard default Yes No
io_method (PostgreSQL 18) Sync is the only valid value for Preview Yes 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
The log_duration=on setting might increase log volume under a heavy workload and cause higher query latencies.		 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
The log_statement=all setting might increase log volume under a heavy workload and cause higher query latencies.		 No No
log_statement_stats Standard default No No
log_temp_files 0 No No
log_timezone Standard default No No
maintenance_work_mem Standard default No No
max_active_replication_origins (PostgreSQL 18) Standard default Yes No
max_connections 1000 Yes Yes
max_locks_per_transaction Standard default Yes Yes
max_logical_replication_workers Standard default Yes No
max_notify_queue_pages (PostgreSQL 17) 1048576 Yes Yes
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 50 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
md5_password_warnings (PostgreSQL 18) Standard default No No
min_wal_size Standard default No No
multixact_member_buffers (PostgreSQL 17) 32 Yes No
multixact_offset_buffers (PostgreSQL 17) 32 Yes No
notify_buffers (PostgreSQL 17) 16 Yes No
parameterized_views.enabled off Yes No
parameterized_views.json_results_max_rows 1,000,000 No No
parameterized_views.json_results_max_size 1,048,576 No No
parameterized_views.max_parallel_workers_per_gather -1 No No
parameterized_views.statement_timeout 0 No No
parameterized_views.temp_file_limit -1 No No
parameterized_views.work_mem 0 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
perfsnap.interval 86400 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
serializable_buffers (PostgreSQL 17) 32 Yes No
shared_buffers 80% of instance memory Yes No
scann.enable_preview_features off Yes No
scann.max_background_workers 1 Yes No
scann.maintenance_background_naptime_s 1 minute Yes No
ssl_groups (PostgreSQL 18) Standard default No No
ssl_max_protocol_version Standard default No No
ssl_min_protocol_version Standard default No No
ssl_tls13_ciphers (PostgreSQL 18) Standard default No No
squeeze.worker_autostart Standard default No No
squeeze.worker_role Standard default No No
squeeze.workers_per_database Default value is 1 No No
squeeze.max_xlock_time Default value is 1. Set to any value between 1 and 2147483647 No No
standard_conforming_strings Standard default No No
statement_timeout Standard default No No
subtransaction_buffers (PostgreSQL 17) 0 Yes No
summarize_wal (PostgreSQL 17) off No Yes
sync_replication_slots (PostgreSQL 17) off No Yes
synchronize_seqscans Standard default No No
synchronized_standby_slots (PostgreSQL 17) off No Yes
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
timezone Standard default No No
trace_connection_negotiation (PostgreSQL 17) off Yes 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
transaction_buffers (PostgreSQL 17) 0 Yes No
transaction_timeout (PostgreSQL 17) 0 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_max_eager_freeze_failure_rate (PostgreSQL 18) Standard default No No
vacuum_multixact_freeze_min_age Standard default No No
vacuum_multixact_freeze_table_age Standard default No No
vacuum_truncate (PostgreSQL 18) Standard default No No
wal_buffers The default depends on the number of vCPUs, as shown in the following list:
  • < 8vCPU: 16MB (2048 8k buffers)
  • 8 vCPU: 128MB (16384 8k buffers)
  • 16 vCPU: 256MB (32768 8k buffers)
  • 32 vCPU: 512MB (65536 8k buffers)
  • 64 vCPU: 1GB (131072 8k buffers)
  • 96 vCPU: 1.5GB (196608 8k buffers)
  • 128 vCPU: 2GB (262144 8k buffers)
 Yes No
wal_receiver_timeout Standard default No No
wal_sender_timeout Standard default No No
wal_summary_keep_time (PostgreSQL 17) 10 days No Yes
work_mem N MB, where N is either 4 or the number of instance vCPUs, whichever is greater No No