This document explains how to review and optimize a Cloud SQL for SQL Server instance if that instance is identifiedby the underprovisioned instance recommender as having high memory consumption.

SQL Server memory

SQL Server memory can be divided into the following:

• Caches
• Fixed memory
• SQL Server overhead
• In-Memory online transactional processing (OLTP)

Caches

These are objects on a disk that can be reloaded, such as database pages and stored procedures. As a result, the SQL Server can grow and shrink these objects based on memory utilization. Caches include buffer pools and plan caches.

Fixed memory

Fixed memory can grow and shrink. It only shrinks when not in use; for example, when the number of connections drops or the number of queries executing decreases. It's different from caches. If there is not enough fixed memory, SQL Server can run out of memory. Fixed memory includes connection memory and memory grants.

SQL Server overhead

SQL Server overhead includes threads and stacks.

In-Memory OLTP

In-Memory OLTP includes In-Memory tables and In-Memory filegroups.

The memory consumption by SQL Server is controlled by settingmaximum server memory andmemory.memory.limitmb. Thememory.memory.limitmb parameter is set by Cloud SQL automatically.

To learn more aboutmemory.memory.limitmb, see theMicrosoft documentation.

Memory optimization options

To determine if an instance needs more memory tuning, do the following:

• Check the value of themax server memory (mb) flag.

  We recommend you let Cloud SQL manage the value of this flag. If you must manually manage this value, use themax_server_memory (mb) usage formula outlined onBest practices to help prevent SQL Server from consuming all memory.

  For more information, seeSpecial flags.

• Monitor thePage life expectancy flag.

  Page life expectancy indicates the amount of time, in seconds, that the oldest page stays in the buffer pool. This value should be more than 300 as recommended by Microsoft. If it consistently falls under 300, it could be an indication that the instance is facing high memory utilization. Run the following query to monitorPage life expectancy.

  SELECT[object_name],[counter_name],[cntr_value]FROMsys.dm_os_performance_countersWHERE[object_name]LIKE'%Manager%'AND[counter_name]='Page life expectancy'

• Check theMemory Grants Pending flag.

  Memory Grants Pending specifies the total number of processes waiting for a workspace memory grant. Run the following query to checkMemory Grants Pending. If this query consistently shows grants pending, then it indicates high memory utilization. You can reduce it by querying the database waits and tuning any statement that's waiting on memory.

  SELECT@@SERVERNAMEAS[ServerName],RTRIM([object_name])AS[ObjectName],cntr_valueAS[MemoryGrantsPending]FROMsys.dm_os_performance_countersWITH(NOLOCK)WHERE[object_name]LIKEN'%Memory Manager%'--HandlesnamedinstancesANDcounter_name=N'Memory Grants Pending'

What's next

• Google Cloud recommenders