I'm using [vColumnstoreDensity]
to monitor the health of my columnstore indexes.
I've noticed that I've got one index that looks strange.
As far as my understanding goes, the columnstore index will fill a rowgroup before starting the next rowgroup. For best index performance, fuller row groups are better.
Having said all of this, I have one table that I'm having trouble understanding. Even after an index rebuild using the largest resource class (to give the maximum amount of memory possible to the build process) the [vColumnstoreDensity]
view still shows this index as being spread across many partially full rowgroups.
COMPRESSED_rowgroup_count
4936
COMPRESSED_rowgroup_rows
2693512978
COMPRESSED_rowgroup_rows_MIN
468
COMPRESSED_rowgroup_rows_MAX
739443
COMPRESSED_rowgroup_rows_AVG
545687
Edit:
This is a clustered columnstore index.
ALTER INDEX CCI_name ON Table REORGANIZE WITH (COMPRESS_ALL_ROW_GROUPS = ON)
followed byALTER INDEX CCI_name ON Table REORGANIZE
– John Eisbrener Jun 19 '17 at 15:15