How to determine the data usage across a Virtuoso instance.

There are times when a variety of DBMS activities (e.g., automated content crawling) can lead to increase in database size, without the instance operator being fully aware of such activities and their consequences.

Run the following statement:

	SELECT TOP 20 * FROM sys_index_space_stats ORDER BY iss_pages DESC;

Query result:
ISS_KEY_TABLE ISS_KEY_NAME ISS_KEY_ID            ISS_NROWS       ISS_ROW_BYTES ISS_BLOB_PAGES ISS_ROW_PAGES ISS_PAGES
 WS.WS.SYS_DAV_RES         WS.WS.SYS_DAV_RE..    492   630627	   437635794     501049         57521         558570
 DB.DBA.RDF_QUAD           DB.DBA.RDF_QUAD       487   25134153  321502272     0	            49779         49779
 DB.DBA.RDF_QUAD           RDF_QUAD_POGS         489   14749814  307163163     0	            47191         47191
 WS.WS.SYS_DAV_RES....     DB.DBA.RDF_OBJ        501   1139934   160445830     10748          21478         32226
 WS.WS.SYS_DAV_RES         WS.WS.SYS_DAV_RE..    729   432       307124	       28840          97            28937
 DB.DBA.RDF_IRI            DB.DBA.RDF_IRI        485   4378779   138542078     0	            22479         22479
 DB.DBA.RDF_IRI            DB_DBA_RDF_IRI_UN..   486   4259557   139496730     0	            20187         20187
......