Reserved Memory Allocation Waits And Trace Flag 834

Joe Obbish has another post looking at sub-optimal columnstore index performance:

It is possible to see a scalability bottleneck in the form of high average wait time for the RESERVED_MEMORY_ALLOCATION_EXT wait if a highly concurrent workload is run on a server that consumes memory with batch mode operators. I believe that the severity of the bottleneck depends on unknown factors in the server’s initial memory state and the rate of memory actually used by queries to run batch mode operations. This blog post shares a reproduction of the issue along with a call to action.

If you use clustered columnstore indexes, check out Joe’s User Voice entry.

Related Posts

Wait Stats Related To Columnstore Indexes

Niko Neugebauer has some documentation on important wait stats around columnstore: I split the known wait types into the following distinct groups: – Batch Execution Mode (HTBUILD, HTDELETE, HTMEMO, HTREINIT, HTREPARTITION, PWAIT_QRY_BPMEMORY, BPSORT) – Columnstore Indexes (ROWGROUP_VERSION, ROWGROUP_OP_STATS, SHARED_DELTASTORE_CREATION, COLUMNSTORE_BUILD_THROTTLE, COLUMNSTORE_MIGRATION_BACKGROUND_TASK, COLUMNSTORE_COLUMNDATASET_SESSION_LIST) With an appearance in the next SQL Server version of the Batch Execution Mode for the RowStore […]

Read More

Columnstore And Merge Replication

Niko Neugebauer tests whether merge replicated tables can use columnstore indexes: Adding this table to the publication will end up with the following, self-explaining error message, being very clear that the Clustered Columnstore Indexes are not supported for the Merge Replication[.] There is no surprise here, as the same Clustered Columnstore Indexes are not supported […]

Read More

Categories

March 2018
MTWTFSS
« Feb Apr »
 1234
567891011
12131415161718
19202122232425
262728293031