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MySQL | PostgreSQL | SQL Server
This page describes how to manage databases with a high number of simultaneous
client connections and a high number of database connection threads. Thisrecommenderis calledReconfigure connection settings.
Every day, this recommender analyzes metrics for the following:
The peak number of database connections by tracking the value of
themax_used_connectionsflag. If the maximum number of connections since
the server restarted is 80% of the valuemax_connections,Reconfigure
connection settingsrecommends that you increase the value ofmax_connections.
The number of new database connection threads compared to the number of
existing database connection threads. If more than 50% of connections result
in new threads instead of reusing cached ones, or if the value ofthread_cache_sizeis set to 0, thenReconfigure connection settingsrecommends that you increase the value ofthread_cache_size.
GET https://recommender.googleapis.com/v1/projects/PROJECT_ID/locations/LOCATION/recommenders/google.cloudsql.instance.PerformanceRecommender/recommendations
Replace the following:
PROJECT_ID: your project ID
LOCATION: a region where your instances are located, such asus-central1
View insights and detailed recommendations
To view insights and detailed recommendations, follow these steps:
Console
Do one of the following:
On thePerformance Recommendationspage, click thePerformance
recommendationscard and then clickReconfigure connection settings.
The recommendation panel appears, which contains insights and detailed
recommendations for the instance.
On theInstancespage, clickReconfigure connection settings.
The list of instances displays only those instances for which the
recommendation applies.
GET https://recommender.googleapis.com/v1/projects/PROJECT_ID/locations/LOCATION/insightTypes/google.cloudsql.instance.PerformanceInsight/insights
Replace the following:
PROJECT_ID: your project ID
LOCATION: a region where your instances are located, such asus-central1
Apply the recommendation
To implement this recommendation, do one of the following:
To apply the recommendation for the connection thread cache size, do one of
the following:
If the value ofthread_cache_sizeis set to 0, then enable the thread
cache by setting this flag to a value greater than 0.
If the value ofthread_cache_sizeis greater than 0, then increase the
value of this flag.thread_cache_sizeshould be equivalent to the average
number of connections to the database. Increase the value ofthread_cache_sizeif the number of new threads is higher than the current
setting.
To apply the database connection recommendation, increase the value of themax_connectionsflag. The recommendation is updated daily, so after you
increase the value of this flag, wait for 24 hours before checking the recommendation again. For more information on
increasing the value ofmax_connections, seeMaximum concurrent connections.
[[["Easy to understand","easyToUnderstand","thumb-up"],["Solved my problem","solvedMyProblem","thumb-up"],["Other","otherUp","thumb-up"]],[["Hard to understand","hardToUnderstand","thumb-down"],["Incorrect information or sample code","incorrectInformationOrSampleCode","thumb-down"],["Missing the information/samples I need","missingTheInformationSamplesINeed","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-09-03 UTC."],[],[],null,["# Reconfigure connection settings\n\n\u003cbr /\u003e\n\nMySQL \\| PostgreSQL \\| SQL Server\n\n\u003cbr /\u003e\n\n|\n| **Preview**\n|\n|\n| This feature is subject to the \"Pre-GA Offerings Terms\" in the General Service Terms section\n| of the [Service Specific Terms](/terms/service-terms#1).\n|\n| You can process personal data for this feature as outlined in the\n| [Cloud Data Processing\n| Addendum](/terms/data-processing-addendum), subject to the obligations and restrictions described in the agreement under\n| which you access Google Cloud.\n|\n| Pre-GA features are available \"as is\" and might have limited support.\n|\n| For more information, see the\n| [launch stage descriptions](/products#product-launch-stages).\n\nThis page describes how to manage databases with a high number of simultaneous\nclient connections and a high number of database connection threads. This\n[recommender](/recommender/docs/recommenders) is called\n**Reconfigure connection settings**.\n\nEvery day, this recommender analyzes metrics for the following:\n\n- The peak number of database connections by tracking the value of\n the `max_used_connections` flag. If the maximum number of connections since\n the server restarted is 80% of the value `max_connections`, **Reconfigure\n connection settings** recommends that you increase the value of\n `max_connections` .\n\n For more information on increasing the value of `max_connections`, see\n [Maximum concurrent connections](/sql/docs/quotas#maximum_concurrent_connections).\n- The number of new database connection threads compared to the number of\n existing database connection threads. If more than 50% of connections result\n in new threads instead of reusing cached ones, or if the value of\n `thread_cache_size` is set to 0, then **Reconfigure connection settings**\n recommends that you increase the value of `thread_cache_size`.\n\n For more information on increasing the value of `max_connections`, see\n [Optimize high CPU utilization in instances](/sql/docs/mysql/optimize-cpu-usage).\n This feature is in [Preview](/products#product-launch-stages).\n\nPricing\n-------\n\nThe **Reconfigure connection settings** recommender is in the *Standard*\n[Recommender pricing tier](/recommender/pricing).\n\nBefore you begin\n----------------\n\n[Enable the Recommender API](/recommender/docs/enabling).\n\n### Required roles and permissions\n\nTo get the permissions to view and work with insights and recommendations,\nensure that you have the required [Identity and Access Management (IAM) roles](/sql/docs/mysql/project-access-control#roles).\n\nFor more information about IAM roles, see [IAM basic and predefined roles reference](/iam/docs/understanding-roles) and [Manage access to projects, folders, and organizations](/iam/docs/granting-changing-revoking-access).\n\n\u003cbr /\u003e\n\nList the recommendations\n------------------------\n\nTo list the recommendations, follow these steps: \n\n### Console\n\nTo list recommendations about instance performance, follow these steps:\n\n1. Go to the **Cloud SQL Instances** page.\n\n[Go to Cloud SQL Instances](https://console.cloud.google.com/sql/instances)\n\n1. On the **Improve instance health by investigating issues and acting on\n recommendations** banner, click **Expand Details**.\n\nAlternatively, follow these steps:\n\n1. Go to the **Recommendation Hub** . See also [Find and apply recommendations with the Recommendations](/recommender/docs/recommendation-hub/identify-configuration-problems).\n\n [Go to the Recommendation Hub](https://console.cloud.google.com/home/recommendations/)\n2. In the **All recommendations** card, click **Performance** .\n\n### gcloud\n\nRun the [`gcloud recommender recommendations list`](/sdk/gcloud/reference/recommender/recommendations/list) command as follows: \n\n```\ngcloud recommender recommendations list \\\n--project=PROJECT_ID \\\n--location=LOCATION \\\n--recommender=google.cloudsql.instance.PerformanceRecommender \\\n--filter=recommenderSubtype=MYSQL_RECONFIG_CONNECTIONS\n```\n\nReplace the following:\n\n- \u003cvar translate=\"no\"\u003ePROJECT_ID\u003c/var\u003e: your project ID\n- \u003cvar translate=\"no\"\u003eLOCATION\u003c/var\u003e: a region where your instances are located, such as `us-central1`\n\n### API\n\nCall the [`recommendations.list`](/recommender/docs/reference/rest/v1/projects.locations.recommenders.recommendations/list) method as follows: \n\n```\nGET https://recommender.googleapis.com/v1/projects/PROJECT_ID/locations/LOCATION/recommenders/google.cloudsql.instance.PerformanceRecommender/recommendations\n```\n\nReplace the following:\n\n- \u003cvar translate=\"no\"\u003ePROJECT_ID\u003c/var\u003e: your project ID\n- \u003cvar translate=\"no\"\u003eLOCATION\u003c/var\u003e: a region where your instances are located, such as `us-central1`\n\nView insights and detailed recommendations\n------------------------------------------\n\nTo view insights and detailed recommendations, follow these steps: \n\n### Console\n\nDo one of the following:\n\n- On the **Performance Recommendations** page, click the **Performance\n recommendations** card and then click **Reconfigure connection settings**.\n The recommendation panel appears, which contains insights and detailed\n recommendations for the instance.\n\n- On the **Instances** page, click **Reconfigure connection settings**.\n The list of instances displays only those instances for which the\n recommendation applies.\n\n### gcloud\n\nRun the [`gcloud recommender insights list`](/sdk/gcloud/reference/recommender/insights/list) command as follows: \n\n```\n\ngcloud recommender insights list \\\n--project=PROJECT_ID \\\n--location=LOCATION \\\n--insight-type=google.cloudsql.instance.PerformanceInsight \\\n--filter=insightSubtype=INSIGHT_SUBTYPE\n\n```\n\nReplace the following:\n\n- \u003cvar translate=\"no\"\u003ePROJECT_ID\u003c/var\u003e: your project ID\n- \u003cvar translate=\"no\"\u003eLOCATION\u003c/var\u003e: a region where your instances are located, such as `us-central1`\n- \u003cvar translate=\"no\"\u003eINSIGHT_SUBTYPE\u003c/var\u003e: set this parameter to one of the following:\n - `MYSQL_HIGH_NUMER_OF_CONNECTIONS`: display insights for the number of database connections for your instance\n - `MYSQL_HIGH_THREAD_CACHE_MISS_RATE`: display insights for the number of new database connection threads without using the thread cache for your instance\n\n### API\n\nCall the [`insights.list`](/recommender/docs/reference/rest/v1/projects.locations.insightTypes.insights/list) method as follows: \n\n```\n\nGET https://recommender.googleapis.com/v1/projects/PROJECT_ID/locations/LOCATION/insightTypes/google.cloudsql.instance.PerformanceInsight/insights\n\n```\n\nReplace the following:\n\n- \u003cvar translate=\"no\"\u003ePROJECT_ID\u003c/var\u003e: your project ID\n- \u003cvar translate=\"no\"\u003eLOCATION\u003c/var\u003e: a region where your instances are located, such as `us-central1`\n\nApply the recommendation\n------------------------\n\nTo implement this recommendation, do one of the following:\n\n- To apply the recommendation for the connection thread cache size, do one of\n the following:\n\n - If the value of `thread_cache_size` is set to 0, then enable the thread\n cache by setting this flag to a value greater than 0.\n\n - If the value of `thread_cache_size` is greater than 0, then increase the\n value of this flag. `thread_cache_size` should be equivalent to the average\n number of connections to the database. Increase the value of\n `thread_cache_size` if the number of new threads is higher than the current\n setting.\n\n- To apply the database connection recommendation, increase the value of the\n `max_connections` flag. The recommendation is updated daily, so after you\n increase the value of this flag, wait for 24 hours before checking the recommendation again. For more information on\n increasing the value of `max_connections`, see [Maximum concurrent connections](/sql/docs/quotas#maximum_concurrent_connections).\n\n| **Note:** Increasing `thread_cache_size` and `max_connections` requires more memory. After increasing these flags, monitor the memory usage.\n\nWhat's next\n-----------\n\n- [Google Cloud recommenders](/recommender/docs/recommenders)"]]
