Database Reference
In-Depth Information
Table 2-2.
Main Ring Buffers Associated with Memory
Ring Buffer
Ring_buffer_type
Use
Resource Monitor
RING_BUFFER_
RESOURCE_MONITOR
As memory allocation changes, notifications of this change are
recorded here. This information can be useful for identifying external
memory pressure.
Out Of Memory
RING_BUFFER_OOM
When you get out-of-memory issues, they are recorded here so you
can tell what kind of memory action failed.
Memory Broker
RING_BUFFER_
MEMORY_BROKER
As the memory internal to SQL Server drops, a low memory
notification will force processes to release memory for the buffer.
These notifications are recorded here, making this a useful measure
for when internal memory pressure occurs.
Buffer Pool
RING_BUFFER_
BUFFER_POOL
Notifications of when the buffer pool itself is running out of memory
are recorded here. This is just a general indication of memory pressure.
There are other ring buffers available, but they are not applicable to memory allocation issues.
Sys.dm_db_xtp_table_memory_stats
To see the memory in use by the tables and indexes that you created in-memory, you can query this DMV. The output
measures the memory allocated and memory used for the tables and indexes. It outputs only the object_id, so you'll
need to also query the system view sys.objects to get the names of tables or indexes. This DMV outputs for the database
you are currently connected to when querying.
Sys.dm_xtp_system_memory_consumers
This DMV shows system structures that are used to manage the internals of the in-memory engine. It's not something
you should normally have to deal with, but when troubleshooting memory issues, it's good to understand if you're
dealing directly with something occurring within the system or just the amount of data that you've loaded into
memory. The principal measures you'd be looking for here are the allocated and used bytes shown for each of the
management structures.
Memory Bottleneck Resolutions
When there is high stress on memory, indicated by a large number of hard page faults, you can resolve a memory
bottleneck using the flowchart shown in Figure
2-6
.
