Configuring database flags

MySQL | PostgreSQL | SQL Server

This page describes how to configure database flags for Cloud SQL, and lists which flags you can set for your instance. You use database flags to adjust MySQL parameters and options, to configure and tune your instance.

In some cases, setting one flag may require that you set another flag to fully enable the desired functionality. For example, to enable slow query logging, you must set both the slow_query_log flag to on and the log_output flag to FILE to make your logs available using the Google Cloud Console Logs Viewer.

When you set, remove, or modify a flag for a database instance, the database might be restarted. The flag value is then persisted for the instance until you remove it. If the instance is the source of a replica, the replica will also restart to align with the current configuration of the instance.

Configuring database flags

Setting a database flag

Console

In the Google Cloud Console, create a new Cloud Console project, or open an existing project by selecting the project name.
Important: You should be aware that some resource identifiers (such as project IDs) might be retained beyond the life of your project. For this reason, avoid storing sensitive information in resource identifiers.
...see naming guidelines
Open the instance and click Edit.
Scroll down to the Flags section.
To set a flag that has not been set on the instance before, click Add item, choose the flag from the drop-down menu, and set its value.
Click Save to save your changes.
Confirm your changes under Flags on the Overview page.

gcloud

Edit the instance:

gcloud sql instances patch [INSTANCE_NAME] --database-flags [FLAG1=VALUE1,FLAG2=VALUE2]

This command will overwrite all database flags previously set. To keep those and add new ones, include the values for all flags you want set on the instance; any flag not specifically included is set to its default value. For flags that do not take a value, specify the flag name followed by an equals sign ("=").

For example, to set the general_log, skip_show_database, and wait_timeout flags, you can use the following command:

gcloud sql instances patch [INSTANCE_NAME] --database-flags \
    general_log=on,skip_show_database=on,wait_timeout=200000

REST

To set a flag for an existing database:

Before using any of the request data below, make the following replacements:

project-id: The project ID
instance-id: The instance ID

HTTP method and URL:

PATCH https://www.googleapis.com/sql/v1beta4/projects/project-id/instances/instance-id

Request JSON body:

{
  "settings":
  {
    "databaseFlags":
    [
      {
        "name": "flag_name",
        "value": "flag_value"
      }
    ]
  }
}

To send your request, expand one of these options:

curl (Linux, macOS, or Cloud Shell)

Note: The command below assumes that you have used either gcloud init or gcloud auth login to authenticate gcloud with your user account. You can check the currently active account by executing gcloud auth list.

Save the request body in a file called request.json, and execute the following command:

curl -X PATCH \
-H "Authorization: Bearer "$(gcloud auth print-access-token) \
-H "Content-Type: application/json; charset=utf-8" \
-d @request.json \
https://www.googleapis.com/sql/v1beta4/projects/project-id/instances/instance-id

PowerShell (Windows)

Save the request body in a file called request.json, and execute the following command:

$cred = gcloud auth print-access-token
$headers = @{ "Authorization" = "Bearer $cred" }

Invoke-WebRequest `
  -Method PATCH `
  -Headers $headers `
  -ContentType: "application/json; charset=utf-8" `
  -InFile request.json `
  -Uri "https://www.googleapis.com/sql/v1beta4/projects/project-id/instances/instance-id" | Select-Object -Expand Content

You should receive a JSON response similar to the following:

Response

{
  "kind": "sql#operation",
  "targetLink": "https://www.googleapis.com/sql/v1beta4/projects/project-id/instances/instance-id",
  "status": "PENDING",
  "user": "user@example.com",
  "insertTime": "2020-01-21T22:43:37.981Z",
  "operationType": "UPDATE",
  "name": "operation-id",
  "targetId": "instance-id",
  "selfLink": "https://www.googleapis.com/sql/v1beta4/projects/project-id/operations/operation-id",
  "targetProject": "project-id"
}

For example, to set the general_log flag for an existing database use:

Before using any of the request data below, make the following replacements:

project-id: The project ID
instance-id: The instance ID

HTTP method and URL:

PATCH https://www.googleapis.com/sql/v1beta4/projects/project-id/instances/instance-id

Request JSON body:

{
  "settings":
  {
    "databaseFlags":
    [
      {
        "name": "general_log",
        "value": "on"
      }
    ]
  }
}

To send your request, expand one of these options:

curl (Linux, macOS, or Cloud Shell)

Save the request body in a file called request.json, and execute the following command:

curl -X PATCH \
-H "Authorization: Bearer "$(gcloud auth print-access-token) \
-H "Content-Type: application/json; charset=utf-8" \
-d @request.json \
https://www.googleapis.com/sql/v1beta4/projects/project-id/instances/instance-id

PowerShell (Windows)

Save the request body in a file called request.json, and execute the following command:

$cred = gcloud auth print-access-token
$headers = @{ "Authorization" = "Bearer $cred" }

Invoke-WebRequest `
  -Method PATCH `
  -Headers $headers `
  -ContentType: "application/json; charset=utf-8" `
  -InFile request.json `
  -Uri "https://www.googleapis.com/sql/v1beta4/projects/project-id/instances/instance-id" | Select-Object -Expand Content

You should receive a JSON response similar to the following:

Response

{
  "kind": "sql#operation",
  "targetLink": "https://www.googleapis.com/sql/v1beta4/projects/project-id/instances/instance-id",
  "status": "PENDING",
  "user": "user@example.com",
  "insertTime": "2020-01-21T22:43:37.981Z",
  "operationType": "UPDATE",
  "name": "operation-id",
  "targetId": "instance-id",
  "selfLink": "https://www.googleapis.com/sql/v1beta4/projects/project-id/operations/operation-id",
  "targetProject": "project-id"
}

If there are existing flags configured for the database, modify the previous command to include them. The PATCH command overwrites the existing flags with the ones specified in the request.

Clearing all flags to their default value

Console

In the Google Cloud Console, create a new Cloud Console project, or open an existing project by selecting the project name.
Important: You should be aware that some resource identifiers (such as project IDs) might be retained beyond the life of your project. For this reason, avoid storing sensitive information in resource identifiers.
...see naming guidelines
Open the instance and click Edit.
Open the Database flags section.
Click the X next to all of the flags shown.
Click Save to save your changes.

gcloud

Clear all flags to their default values on an instance:

gcloud sql instances patch [INSTANCE_NAME] --clear-database-flags

You are prompted to confirm that the instance will be restarted.

REST

To clear all flags for an existing instance:

Before using any of the request data below, make the following replacements:

project-id: The project ID
instance-id: The instance ID

HTTP method and URL:

PATCH https://www.googleapis.com/sql/v1beta4/projects/project-id/instances/instance-id

Request JSON body:

{
  "settings":
  {
    "databaseFlags": []
  }
}

To send your request, expand one of these options:

curl (Linux, macOS, or Cloud Shell)

Save the request body in a file called request.json, and execute the following command:

curl -X PATCH \
-H "Authorization: Bearer "$(gcloud auth print-access-token) \
-H "Content-Type: application/json; charset=utf-8" \
-d @request.json \
https://www.googleapis.com/sql/v1beta4/projects/project-id/instances/instance-id

PowerShell (Windows)

Save the request body in a file called request.json, and execute the following command:

$cred = gcloud auth print-access-token
$headers = @{ "Authorization" = "Bearer $cred" }

Invoke-WebRequest `
  -Method PATCH `
  -Headers $headers `
  -ContentType: "application/json; charset=utf-8" `
  -InFile request.json `
  -Uri "https://www.googleapis.com/sql/v1beta4/projects/project-id/instances/instance-id" | Select-Object -Expand Content

You should receive a JSON response similar to the following:

Response

{
  "kind": "sql#operation",
  "targetLink": "https://www.googleapis.com/sql/v1beta4/projects/project-id/instances/instance-id",
  "status": "PENDING",
  "user": "user@example.com",
  "insertTime": "2020-01-21T22:43:37.981Z",
  "operationType": "UPDATE",
  "name": "operation-id",
  "targetId": "instance-id",
  "selfLink": "https://www.googleapis.com/sql/v1beta4/projects/project-id/operations/operation-id",
  "targetProject": "project-id"
}

Viewing current values of database flags

To view all current values of the MySQL system variables, log into your instance with the mysql client and enter the following statement:

 SHOW VARIABLES;

Note that you can change the value only for supported flags (as listed below).

Determining what database flags have been set for an instance

To see what flags have been set for a Cloud SQL instance:

Console

In the Google Cloud Console, create a new Cloud Console project, or open an existing project by selecting the project name.
Important: You should be aware that some resource identifiers (such as project IDs) might be retained beyond the life of your project. For this reason, avoid storing sensitive information in resource identifiers.
...see naming guidelines
Select the instance to open its Instance Overview page.
The database flags that have been set are listed under the Database flags section.

gcloud

Get the instance state:

gcloud sql instances describe [INSTANCE_NAME]

In the output, database flags are listed under the settings as the collection databaseFlags. For more information about the representation of the flags in the output, see Instances Resource Representation.

REST

To list flags configured for an instance:

Before using any of the request data below, make the following replacements:

project-id: The project ID
instance-id: The instance ID

HTTP method and URL:

GET https://www.googleapis.com/sql/v1beta4/projects/project-id/instances/instance-id

To send your request, expand one of these options:

curl (Linux, macOS, or Cloud Shell)

Execute the following command:

curl -X GET \
-H "Authorization: Bearer "$(gcloud auth print-access-token) \
https://www.googleapis.com/sql/v1beta4/projects/project-id/instances/instance-id

PowerShell (Windows)

Execute the following command:

$cred = gcloud auth print-access-token
$headers = @{ "Authorization" = "Bearer $cred" }

Invoke-WebRequest `
  -Method GET `
  -Headers $headers `
  -Uri "https://www.googleapis.com/sql/v1beta4/projects/project-id/instances/instance-id" | Select-Object -Expand Content

You should receive a JSON response similar to the following:

Response

{
  "settings":
  {
    "authorizedGaeApplications": [],
    "tier": "machine-type",
    "kind": "sql#settings",
    "availabilityType": "REGIONAL",
    "pricingPlan": "PER_USE",
    "replicationType": "SYNCHRONOUS",
    "activationPolicy": "ALWAYS",
    "ipConfiguration":
    {
      "privateNetwork": "projects/project-id/global/networks/default",
      "authorizedNetworks": [],
      "ipv4Enabled": false
    },
    "locationPreference":
    {
      "zone": "zone",
      "kind": "sql#locationPreference"
    },
    "databaseFlags": [
      {
        "name": "general_log",
        "value": "on"
      }
    ],
    "dataDiskType": "PD_SSD",
    "maintenanceWindow":
    {
      "kind": "sql#maintenanceWindow",
      "hour": 0,
      "day": 0
    },
    "backupConfiguration":
    {
      "startTime": "03:00",
      "kind": "sql#backupConfiguration",
      "enabled": true,
      "pointInTimeEnabled": true
    },
    "settingsVersion": "54",
    "storageAutoResizeLimit": "0",
    "storageAutoResize": true,
    "dataDiskSizeGb": "10"
  }
}

In the output, look for the databaseFlags field.

Supported flags

The flags supported in Cloud SQL are the most commonly requested flags for MySQL.

For a given flag, Cloud SQL might support a different range than the corresponding MySQL parameter or option.

The flags apply to all versions of MySQL supported by Cloud SQL except where noted.

A | B | C | D | E | F | G | I | L | M | N | O | P | Q | R | S | T | U | W

Cloud SQL Flag	Type Acceptable Values and Notes	Restart Required?	In Beta?
auto_increment_increment	`integer` `1` ... `65535`	No	No
auto_increment_offset	`integer` `1` ... `65535`	No	No
binlog_cache_size	`integer` `4096` ... `9223372036854775807`	No	Yes
binlog_row_image	`enumeration` `full` (default), `minimal`, or `noblob`	No	No
binlog_stmt_cache_size	`4096` ... `9223372036854775807`	No	Yes
character_set_server	`string` utf8 or utf8mb4 (recommended)	Yes	No
default_time_zone	`string` Specify values as time zone offsets, from `-12:59` to `+13:00`. Leading zeros required. For example, London is in the UTC time zone, which is +00:00 in the supported values for this flag. Named areas, such as 'Europe/London', are not supported by Cloud SQL. Note: Automatic adjustment to daylight saving time is not supported, and you must update this flag manually to account for it.	Yes	No
eq_range_index_dive_limit	`integer` `0` ... `2147483647`	No	No
event_scheduler	`boolean` `on` \| `off` Cannot be set at instance creation time for First Generation instances. Note: Second Generation is replacing First Generation; support for First Generation instances ends January 30, 2020. To upgrade a First Generation instance to Second Generation, see Upgrading a First Generation Instance to Second Generation. If you are using the Event Scheduler, you should configure your instance with an activation policy of ALWAYS to ensure that scheduled events run.	No	No
explicit_defaults_for_timestamp	`boolean` `on` \| `off`	No	No
ft_max_word_len	`integer` `10` ... `252`	Yes	No
ft_min_word_len	`integer` `1` ... `16`	Yes	No
ft_query_expansion_limit	`integer` `0` ... `1000`	Yes	No
general_log	`boolean` `on` \| `off` See the Tips section for more information about general logs.	No	No
group_concat_max_len	`integer` `4` ... `17179869184`	No	No
init_connect	`string`	No	Yes
innodb_adaptive_hash_index	`boolean` `on` \| `off`	No	Yes
innodb_adaptive_hash_index_parts	`integer` `1` ... `512`	Yes	Yes
innodb_adaptive_max_sleep_delay	`integer` `0` ... `1000000`	No	No
innodb_autoinc_lock_mode	`integer` `0` ... `2`	Yes	No
innodb_change_buffer_max_size	`integer` `0` ... `50`	No	Yes
innodb_concurrency_tickets	`integer` `1` ... `4294967295`	No	No
innodb_file_per_table	`boolean` `on` \| `off` See the Tips section for more information about this flag.	No	No
innodb_fill_factor	`integer` `10` ... `100`	No	No
innodb_ft_cache_size	`integer` `1600000` ... `80000000`	Yes	Yes
innodb_ft_enable_diag_print	`boolean` `on` \| `off`	No	No
innodb_ft_enable_stopword	`boolean` `on` \| `off`	No	No
innodb_ft_max_token_size	`integer` `10` ... `252` Supported only in MySQL 5.6 and later versions.	Yes	No
innodb_ft_min_token_size	`integer` `0` ... `16` Supported only in MySQL 5.6 and later versions.	Yes	No
innodb_ft_num_word_optimize	`integer` `1000` ... `10000`	No	No
innodb_ft_result_cache_limit	`integer` `1000000` ... `4294967295`	No	Yes
innodb_ft_server_stopword_table	`string` Supported only in MySQL 5.6 and later versions.	No	No
innodb_ft_sort_pll_degree	`integer` `1` ... `32`	Yes	No
innodb_ft_total_cache_size	`integer` `32000000` ... `1600000000`	Yes	Yes
innodb_ft_user_stopword_table	`string`	No	No
innodb_large_prefix	`boolean` `on` \| `off` Supported only in MySQL 5.5 and 5.6.	No	No
innodb_lock_wait_timeout	`integer` `1` ... `1073741824`	No	No
innodb_log_buffer_size	`integer` `262144` ... `4294967295`	Yes	Yes
innodb_log_file_size	`integer` MySQL 5.6: `1048576` ... `274877906944` MySQL 5.7: `4194304` ... `274877906944`	Yes	Yes
innodb_lru_scan_depth	`integer` `100` ... `9223372036854775807`	No	No
innodb_old_blocks_pct	`integer` `5` ... `95`	No	No
innodb_old_blocks_time	`integer` `0` ... `4294967295`	No	No
innodb_online_alter_log_max_size	`integer` `65536` ... `9223372036854775807`	No	No
innodb_optimize_fulltext_only	`boolean` `on` \| `off`	No	No
innodb_print_all_deadlocks	`boolean` `on` \| `off`	No	No
innodb_random_read_ahead	`boolean` `on` \| `off`	No	No
innodb_read_ahead_threshold	`integer` `0` ... `64`	No	No
innodb_read_io_threads	`integer` `1` ... `64`	Yes	No
innodb_replication_delay	`integer` `0` ... `4294967295`	No	Yes
innodb_rollback_on_timeout	`boolean` `on` \| `off`	Yes	No
innodb_rollback_segments	`integer` `1` ... `128`	No	No
innodb_sort_buffer_size	`integer` `65536` ... `67108864`	Yes	Yes
innodb_stats_auto_recalc	`boolean` `on` \| `off`	No	No
innodb_stats_method	`enumeration` `nulls_equal` \| `nulls_unequal` \| `nulls_ignored`	No	No
innodb_stats_on_metadata	`boolean` `on` \| `off`	No	No
innodb_stats_persistent	`boolean` `on` \| `off`	No	No
innodb_stats_persistent_sample_pages	`integer` `1` ... `9223372036854775807`	No	No
innodb_stats_sample_pages	`integer` `1` ... `9223372036854775807`	No	No
innodb_stats_transient_sample_pages	`integer` `1` ... `9223372036854775807`	No	No
innodb_status_output	`boolean` `on` \| `off`	No	No
innodb_status_output_locks	`boolean` `on` \| `off`	No	No
innodb_strict_mode	`boolean` `on` \| `off`	No	No
innodb_thread_concurrency	`integer` `0` ... `1000`	No	No
innodb_thread_sleep_delay	`integer` `0` ... `1000000`	No	No
innodb_write_io_threads	`integer` `1` ... `64`	Yes	No
interactive_timeout	`integer` `1` ... `31536000`	No	No
join_buffer_size	`integer` `128` ... `9223372036854775807`	No	Yes
local_infile	`boolean` `on` \| `off`	No	No
lock_wait_timeout	`integer` `1` ... `31536000`	No	No
log_bin_trust_function_creators	`boolean` `on` \| `off`	No	No
log_output	`set` `FILE` \| `TABLE` \| `NONE`	No	No
log_queries_not_using_indexes	`boolean` `on` \| `off`	No	No
log_throttle_queries_not_using_indexes	`integer` `0` ... `9223372036854775807`	No	No
long_query_time	`float` `0` ... `30000000` Cloud SQL provides the ability to set this flag to less than 1 if needed. If the `log_queries_not_using_indexes` flag is also enabled, you may see queries with less than the time specified here.	No	No
lower_case_table_names	`integer` `0` or `1` In most cases, the default value of 0 should be used, which makes table and database names case sensitive. If you need to change the value of this flag, make sure that you understand how the change will affect your existing tables and databases.	Yes	No
max_allowed_packet	`integer` `16384` ... `1073741824` This value should be a multiple of 1024, if sql_mode=TRADITIONAL or sql_mode=STRICT_ALL_TABLES.	No	No
max_binlog_size	`integer` `4096` ... `1073741824`	No	Yes
max_connections	`integer` `25` ... `100000`	No	Yes
max_digest_length	`integer` `0` ... `1048576`	Yes	Yes
max_execution_time	`integer` `0` ... `9223372036854775807`	No	No
max_heap_table_size	`integer` `16384` ... `67108864` See the Tips section for more information about this flag.	No	No
max_join_size	`integer` `16` ... `9223372036854775807`	No	No
max_length_for_sort_data	`integer` `4` ... `8388608`	No	No
max_points_in_geometry	`integer` `3` ... `1048576`	No	No
max_prepared_stmt_count	`integer` `0` ... `1048576`	No	No
max_seeks_for_key	`integer` `1` ... `9223372036854775807`	No	No
max_sort_length	`integer` `4` ... `8388608`	No	Yes
max_sp_recursion_depth	`integer` `0` ... `255`	No	Yes
max_user_connections	`integer` `0` ... `4294967295`	No	Yes
max_write_lock_count	`integer` `1` ... `9223372036854775807`	No	No
net_read_timeout	`integer` `30` ... `4294967295`	No	No
net_retry_count	`integer` `10` ... `4294967295`	No	No
net_write_timeout	`integer` `60` ... `4294967295`	No	No
optimizer_prune_level	`integer` `0` ... `1`	No	No
optimizer_search_depth	`integer` `0` ... `62`	No	No
optimizer_trace_max_mem_size	`integer` `0` ... `9223372036854775807`	No	Yes
optimizer_trace_offset	`integer` `-9223372036854775808` ... `9223372036854775807`	No	No
parser_max_mem_size	`integer` `10000000` ... `9223372036854775807`	No	Yes
performance_schema	`boolean` `on` \| `off` (default) See Tips section for more information about performance_schema flags.	Yes	No
performance_schema_accounts_size	`integer` `-1` ... `1048576` See Tips section for more information about performance_schema flags.	Yes	Yes
performance_schema_digests_size	`integer` `-1` ... `1048576` See Tips section for more information about performance_schema flags.	Yes	Yes
performance_schema_events_stages_history_long_size	`integer` `-1` ... `1048576`	Yes	Yes
performance_schema_events_stages_history_size	`integer` `-1` ... `1024` See Tips section for more information about performance_schema flags.	Yes	Yes
performance_schema_events_statements_history_long_size	`integer` `-1` ... `1048576` See Tips section for more information about performance_schema flags.	Yes	Yes
performance_schema_events_statements_history_size	`integer` `-1` ... `1024` See Tips section for more information about performance_schema flags.	Yes	Yes
performance_schema_events_transactions_history_long_size	`integer` `-1` ... `1048576` See Tips section for more information about performance_schema flags.	Yes	Yes
performance_schema_events_transactions_history_size	`integer` `-1` ... `1024` See Tips section for more information about performance_schema flags.	Yes	Yes
performance_schema_events_waits_history_long_size	`integer` `-1` ... `1048576` See Tips section for more information about performance_schema flags.	Yes	Yes
performance_schema_events_waits_history_size	`integer` `-1` ... `1024` See Tips section for more information about performance_schema flags.	Yes	Yes
performance_schema_hosts_size	`integer` `-1` ... `1048576` See Tips section for more information about performance_schema flags.	Yes	Yes
performance_schema_max_cond_classes	`integer` `0` ... `256` See Tips section for more information about performance_schema flags.	Yes	Yes
performance_schema_max_cond_instances	`integer` `-1` ... `1048576` See Tips section for more information about performance_schema flags.	Yes	Yes
performance_schema_max_digest_length	`integer` `0` ... `1048576` See Tips section for more information about performance_schema flags.	Yes	Yes
performance_schema_max_file_classes	`integer` `0` ... `256` See Tips section for more information about performance_schema flags.	Yes	Yes
performance_schema_max_file_handles	`integer` `0` ... `1048576` See Tips section for more information about performance_schema flags.	Yes	Yes
performance_schema_max_file_instances	`integer` `-1` ... `1048576` See Tips section for more information about performance_schema flags.	Yes	Yes
performance_schema_max_index_stat	`integer` `-1` ... `1048576` See Tips section for more information about performance_schema flags.	Yes	Yes
performance_schema_max_memory_classes	`integer` `0` ... `1024` See Tips section for more information about performance_schema flags.	Yes	Yes
performance_schema_max_metadata_locks	`integer` `-1` ... `104857600` See Tips section for more information about performance_schema flags.	Yes	Yes
performance_schema_max_mutex_classes	`integer` `0` ... `256` See Tips section for more information about performance_schema flags.	Yes	Yes
performance_schema_max_mutex_instances	`integer` `-1` ... `104857600` See Tips section for more information about performance_schema flags.	Yes	Yes
performance_schema_max_prepared_statements_instances	`integer` `-1` ... `1048576` See Tips section for more information about performance_schema flags.	Yes	Yes
performance_schema_max_program_instances	`integer` `-1` ... `1048576` See Tips section for more information about performance_schema flags.	Yes	Yes
performance_schema_max_rwlock_classes	`integer` `0` ... `256` See Tips section for more information about performance_schema flags.	Yes	Yes
performance_schema_max_rwlock_instances	`integer` `-1` ... `104857600` See Tips section for more information about performance_schema flags.	Yes	Yes
performance_schema_max_socket_classes	`integer` `0` ... `256` See Tips section for more information about performance_schema flags.	Yes	Yes
performance_schema_max_socket_instances	`integer` `-1` ... `1048576` See Tips section for more information about performance_schema flags.	Yes	Yes
performance_schema_max_sql_text_length	`integer` `0` ... `1048576` See Tips section for more information about performance_schema flags.	Yes	Yes
performance_schema_max_stage_classes	`integer` `0` ... `256` See Tips section for more information about performance_schema flags.	Yes	Yes
performance_schema_max_statement_classes	`integer` `0` ... `256` See Tips section for more information about performance_schema flags.	Yes	Yes
performance_schema_max_statement_stack	`integer` `1` ... `256` See Tips section for more information about performance_schema flags.	Yes	Yes
performance_schema_max_table_handles	`integer` `-1` ... `1048576` See Tips section for more information about performance_schema flags.	Yes	Yes
performance_schema_max_table_instances	`integer` `-1` ... `1048576` See Tips section for more information about performance_schema flags.	Yes	Yes
performance_schema_max_table_lock_stat	`integer` `-1` ... `1048576` See Tips section for more information about performance_schema flags.	Yes	Yes
performance_schema_max_thread_classes	`integer` `0` ... `256` See Tips section for more information about performance_schema flags.	Yes	Yes
performance_schema_max_thread_instances	`integer` `-1` ... `1048576` See Tips section for more information about performance_schema flags.	Yes	Yes
performance_schema_session_connect_attrs_size	`integer` `-1` ... `1048576` See Tips section for more information about performance_schema flags.	Yes	Yes
performance_schema_setup_actors_size	`integer` `-1` ... `1048576` See Tips section for more information about performance_schema flags.	Yes	Yes
performance_schema_setup_objects_size	`integer` `-1` ... `1048576` See Tips section for more information about performance_schema flags.	Yes	Yes
performance_schema_users_size	`integer` `-1` ... `1048576` See Tips section for more information about performance_schema flags.	Yes	Yes
query_alloc_block_size	`integer` `1024` ... `4294967295`	No	Yes
query_cache_limit	`integer` `0` ... `223338299392`	No	No
query_cache_min_res_unit	`integer` `0` ... `9223372036854775807`	No	Yes
query_cache_size	`integer` `0` ... `223338299392` See the Tips section for more information about this flag.	No	No
query_cache_type	`enumeration` `0` ... `2` See the Tips section for more information about this flag.	Yes	No
query_cache_wlock_invalidate	`boolean` `on` \| `off`	No	No
query_prealloc_size	`integer` `8192` ... `9223372036854775807`	No	Yes
range_alloc_block_size	`integer` `4096` ... `4294967295`	No	Yes
range_optimizer_max_mem_size	`integer` `0` ... `9223372036854775807`	No	Yes
read_buffer_size	`integer` `8192` ... `2147483647`	No	Yes
read_only	`boolean` `on` \| `off` Has no effect for replicas.	No	No
read_rnd_buffer_size	`integer` `1` ... `2147483647`	No	Yes
show_compatibility_56	`boolean` `on` \| `off` Supported only in MySQL 5.7.	No	No
skip_show_database	`flag` `on` \| `off`	Yes	No
slow_query_log	`boolean` `on` \| `off` See the Tips section for more information on slow query logs.	No	No
sort_buffer_size	`integer` `32768` ... `9223372036854775807`	No	Yes
sql_mode	`string` See the Server SQL Modes in the MySQL documentation for allowed values, including combined modes such as `ANSI`. `NO_DIR_IN_CREATE` is not supported.	Yes	No
stored_program_cache	`integer` `16` ... `524288`	No	Yes
table_definition_cache	`integer` `400` ... `524288`	No	Yes
table_open_cache	`integer` `1` ... `524288`	No	Yes
table_open_cache_instances	`integer` `1` ... `64`	Yes	Yes
thread_cache_size	`integer` `0` ... `16384`	No	Yes
thread_stack	`integer` `131072` ... `9223372036854775807`	Yes	Yes
tmp_table_size	`integer` `1024` ... `67108864` See the Tips section for more information about this flag.	No	No
transaction_alloc_block_size	`integer` `1024` ... `131072`	No	Yes
transaction_isolation	`enumeration` `READ-UNCOMMITTED` \| `READ-COMMITTED` \| `REPEATABLE-READ` \| `SERIALIZABLE`	Yes	Yes
transaction_prealloc_size	`integer` `1024` ... `131072`	No	Yes
updatable_views_with_limit	`integer` `0` ... `1`	No	No
wait_timeout	`integer` `1` ... `31536000`	No	No

Tips for working with flags

general_log, slow_query_log

To make your general or slow query logs available, enable the corresponding flag and set the log_output flag to FILE. This makes the log output available using the Logs Viewer in the Google Cloud Console. Note that Google Cloud's operations suite logging charges apply.

If log_output is set to NONE, you will not be able to access the logs. If you set log_output to TABLE, the log output is placed in a table in your database. If this table becomes large, it can affect instance restart time or cause the instance to lose its SLA coverage; for this reason, the TABLE option is not recommended. If needed, you can truncate your log tables by using the API. For more information, see the instances.truncateLog reference page.

For First Generation instances, a very large mysql.general_log or mysql.slow_log table can cause connections to hang after a restart of the instance. To avoid this problem, the general_log and/or slow_query_log settings are ignored on restart if the log size grows to be larger than 128 Mb. For this reason, for First Generation instances, we recommend enabling the flag only temporarily or keeping the table small by periodically truncating it. If needed, INSERT ... SELECT can be used to preserve the contents of the mysql.general_log table.

innodb_file_per_table

This flag is set to OFF by default for MySQL 5.5; for all later MySQL versions, the default value is ON.

max_heap_table_size, tmp_table_size

Exhausting the available instance memory can occur when you set tmp_table_size and max_heap_table_size too high for the number of concurrent queries the instance processes. Exhausting the memory will result in an instance crash and restart.

Some values for these flags can cause your instance to lose its SLA coverage. Learn more. For more information about working with these flags, see How MySQL Uses Internal Temporary Tables and The MEMORY Storage Engine.

performance_schema*

You must use the API to change the value of this flag. It cannot be enabled on instances with a tier size smaller than db-n1-standard-8 or db-n1-highmem-4. If this flag is enabled, you cannot change your tier to a size that does not support this flag; you must first disable this flag. Not supported for First Generation instances.

query_cache_size, query_cache_type

Some values for these flags can cause your instance to lose its SLA coverage. Learn more.

Flags managed by Cloud SQL

Cloud SQL adjusts certain system flags depending on the instance tier. You cannot adjust these values.

Cloud SQL Flag	Values and Notes
innodb_buffer_pool_instances	See the buffer pool instances section below for more information about this flag.
innodb_buffer_pool_size	See the buffer pool size section below for more information about this flag.

innodb_buffer_pool_instances

1 for f1-micro, g1-small and n1-standard-1.
2 for n1-standard-2.
4 for n1-standard-4 and n1-highmem-2.
8 for all other tiers.

innodb_buffer_pool_size

approximate sizes.

~ 1.5 GB for f1-micro, g1-small and n1-standard-1.
~ 4 GB for n1-standard-2.
~ 11 GB for n1-standard-4.
~ 22 GB for n1-standard-8.
~ 46 GB for n1-standard-16.
~ 92 GB for n1-standard-32.
~ 186 GB for n1-standard-64.
~ 10 GB for n1-highmem-2.
~ 20 GB for n1-highmem-4.
~ 40 GB for n1-highmem-8.
~ 80 GB for n1-highmem-16.
~ 160 GB for n1-highmem-32.
~ 320 GB for n1-highmem-64.

What's next

Learn more about MySQL system variables.
Learn more about Operational Guidelines.