Review Cloud SQL SQL Server connection limits

Description

If SQL Server user connections is lower than the concurrency a workload needs, new connections can be rejected. An explicit limit can also be an intentional overload control; 1000 is not inherently an incorrect value.

0 selects dynamic adjustment up to 32767, not unlimited connections. Instance resources and application constraints still limit actual capacity.

Potential impact

An overly low limit can block legitimate requests and administrative access.
Raising the limit without capacity planning can increase resource use and latency.

Remediation

Choose user connections after reviewing concurrent usage, connection pools and instance capacity. Use 0 when dynamic adjustment is appropriate, and plan the required restart.
Load-test legitimate connection capacity and overload controls, and monitor connection failures and resource usage.

Examples

These excerpts compare part of the instance settings. Use a supported engine version and SQL Server machine type, and supply var.sql_server_tier and omitted required inputs. Changing this flag does not require the engine-version change shown in the examples.

Before

hcl

resource "google_sql_database_instance" "db" {
  name             = "sqlserver-instance"
  database_version = "SQLSERVER_2017_EXPRESS"
  region           = "us-central1"

  settings {
    database_flags {
      name  = "user connections"
      value = "1000"
    }
  }
}

After

hcl

resource "google_sql_database_instance" "db" {
  name             = "sqlserver-instance"
  database_version = "SQLSERVER_2019_STANDARD"
  region           = "us-central1"

  settings {
    tier = var.sql_server_tier

    database_flags {
      name  = "user connections"
      value = "0"
    }
  }
}

Explanation:

Before: The connection limit is 1000. Assess whether it matches workload and capacity needs.
After: 0 selects dynamic adjustment. It does not provide unlimited connections or resources.