Configuring database flags

This page describes how to configure database flags for Cloud SQL, and lists the flags that you can set for your instance. You use database flags for many operations, including adjusting MySQL parameters, adjusting options, and configuring and tuning an 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, and the instance is restarted, the replica is also restarted to align with the current configuration of the instance.

Configuring database flags

Setting a database flag

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

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

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

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

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

$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://sqladmin.googleapis.com/sql/v1beta4/projects/project-id/instances/instance-id" | Select-Object -Expand Content

{
  "kind": "sql#operation",
  "targetLink": "https://sqladmin.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://sqladmin.googleapis.com/sql/v1beta4/projects/project-id/operations/operation-id",
  "targetProject": "project-id"
}

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

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

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

$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://sqladmin.googleapis.com/sql/v1beta4/projects/project-id/instances/instance-id" | Select-Object -Expand Content

{
  "kind": "sql#operation",
  "targetLink": "https://sqladmin.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://sqladmin.googleapis.com/sql/v1beta4/projects/project-id/operations/operation-id",
  "targetProject": "project-id"
}

Clearing all flags to their default value

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

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

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

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

$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://sqladmin.googleapis.com/sql/v1beta4/projects/project-id/instances/instance-id" | Select-Object -Expand Content

{
  "kind": "sql#operation",
  "targetLink": "https://sqladmin.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://sqladmin.googleapis.com/sql/v1beta4/projects/project-id/operations/operation-id",
  "targetProject": "project-id"
}

Viewing current values of database flags

 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:

gcloud sql instances describe [INSTANCE_NAME]

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

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

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

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

{
  "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,
      "binaryLogEnabled": true
    },
    "settingsVersion": "54",
    "storageAutoResizeLimit": "0",
    "storageAutoResize": true,
    "dataDiskSizeGb": "10"
  }
}

Supported flags

The flags supported in Cloud SQL are the most commonly requested flags for MySQL. Flags not mentioned below are not supported.

For a given flag, Cloud SQL might support a different range from 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

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. To minimize instance storage cost, general and slow query logs on the instance disk will be rotated when the log file is older than 24 hours (and no changes have been made within that duration) or greater than 100MB in size. Old log files will be automatically deleted after the rotation.

If log_output is set to NONE, you will be unable 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.

expire_logs_days, binlog_expire_logs_seconds

If you enable point-in-time recovery, the expiration period of your binary logs will be determined by the lesser of your transaction log retention period and the value of this flag. For more information, see the transaction log retention page.

innodb_buffer_pool_size

The value of the innodb_buffer_pool_size is the size in bytes of the buffer pool. You cannot enable this flag on instances that have fewer than 3,840 MiB of RAM.

This flag is not configurable for shared-core machine types (f1_micro and g1_small). Changing this flag on MySQL 5.6 requires a restart.

In Cloud SQL, the default, minimum allowable, and maximum allowable values of the innodb_buffer_pool_size flag depend on the instance's memory. These values can be roughly calculated as a percentage of the instance's RAM. By default, the value of this flag is typically set close to the maximum allowable value. The maximum allowable allocation percentage increases with instance size. The minimum allowable value is usually about 20% of the instance's RAM.

Approximate values for this flag:

Instance RAM Range	Min %	Default %	Max %
0 - 4.0GB of RAM		~34%
4.0GB - 7.5GB	~20%	~34%	~34%
7.5GB - 12GB	~20%	~52%	~52%
12GB - 24GB	~20%	~67%	~67%
24GB and above	~20%	~72%	~72%

Your exact values may vary. To calculate the current value for your instance, you can run the query:

  show global variables like 'innodb_buffer_pool_size'
  

For reference, the minimum allowable, default, and maximum allowable values are provided for the predefined machine types below.

Predefined machine type	Instance RAM (GB)	Min (GB) (% of total)	Default (GB) (% of total)	Max (GB) (% of total)
f1-micro	0.6	-	0.053	-
g1-small	1.7	-	0.625	-
db-custom-1-3840	3.75	0.875 (23%)	1.375 (37%)	1.375 (37%)
db-custom-2-7680	7.5	1.5 (20%)	4 (53%)	4 (53%)
db-custom-4-15360	15	3 (20%)	10.5 (70%)	10.5 (70%)
db-custom-8-30720	30	6 (20%)	22 (73%)	22 (73%)
db-custom-16-61440	60	12 (20%)	44 (73%)	44 (73%)
db-custom-32-122880	120	24 (20%)	87 (73%)	87 (73%)
db-custom-64-245760	240	48 (20%)	173 (72%)	173 (72%)
db-custom-96-368640	360	72 (20%)	260 (72%)	260 (72%)
db-custom-2-13312	13	3 (23%)	9 (69%)	9 (69%)
db-custom-4-26624	26	6 (23%)	19 (73%)	19 (73%)
db-custom-8-53248	52	11 (21%)	38 (73%)	38 (73%)
db-custom-16-106496	104	21 (20%)	75 (72%)	75 (72%)
db-custom-32-212992	208	42 (20%)	150 (72%)	150 (72%)
db-custom-64-425984	416	84 (20%)	300 (72%)	300 (72%)
db-custom-96-638976	624	125 (20%)	450 (72%)	450 (72%)

Flags managed by Cloud SQL

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

innodb_buffer_pool_instances

• 1 for db-f1-micro and db-g1-small.
• 1 if RAM < 7.5 GB.
• 2 if 7.5 GB <= RAM < 13 GB.
• 4 if 13 GB <= RAM < 26 GB.
• 8 if RAM >= 26 GB.

Troubleshooting

Click the links in the table for details:

Enabling a flag crashes the instance

After enabling a flag the instances loop between panicking and crashing.

The issue might be

Setting the max_connections flag value too high causes this error.

Things to try

Contact customer support to request a flag removal followed by a hard drain. This forces the instance to restart on a different host with a fresh configuration without the undesired flag or setting.

Time zone doesn't automatically change

The time zone didn't automatically change for daylight savings time.

The issue might be

Automated time zone changes are not supported in Cloud SQL and must be done manually, and not by string but by time zone offset value.

Things to try

Edit the instance to change the default_time_zone flag. Named areas are not supported. For example: Europe/LondonLondon is in the UTC time zone, which would be a supported value of +00:00 for the default_time_zone flag.

Bad syntax for dict arg

You see the error message Bad syntax for dict arg when trying to set a flag.

The issue might be

Complex parameter values, such as comma-separated lists, require special treatment when used with gcloud commands.

Things to try

Use the gcloud --flags-file parameter, which specifies a YAML or JSON file containing a --flag:value dictionary useful for complex flag values.

What's next

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