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

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

    • In the Instance restartscolumn, Yesindicates 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 restrictionscolumn, Yesindicates 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 | 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
    off
    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_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
    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_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_seqscan
    Standard default
    No
    No
    enable_sort
    Standard default
    No
    No
    enable_tidscan
    Standard default
    No
    No
    event_triggers (PostgreSQL 17)
    true
    No
    Yes
    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_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_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
    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
    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_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
    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_max_protocol_version
    Standard default
    No
    No
    ssl_min_protocol_version
    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
    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_multixact_freeze_min_age
    Standard default
    No
    No
    vacuum_multixact_freeze_table_age
    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
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