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A pseudo table containing one row for every index in your database. This table represents data related to the index histogram. It is currently almost an exact subset of
INDEXSTATISTICS with the exception of
FieldCount, but this is subject to change in the future.
Caution: Client applications should never contain code that accesses
SYSTEM pseudo tables as they are subject to, and furthermore likely to, change from release to release.
|OBJECTID||integer||The ID for the database object|
|CATALOGID||bigint||The catalog ID for the database object|
|HISTOGRAMID||string||The ID for the histogram, unique to the table|
|FIELDCOUNT||integer||The number of fields in the index|
|MAXRESOLUTION||integer||The maximum number of histogram buckets. Index histograms are one of the most important parts of index statistics. By default, the number of histogram buckets created is 10 for Version 1 statistics and 256 for Version 2 statistics. Raising this number (see
In the following example, we are referencing the table
SCORING created by SQL QuickStart (see Running the SQL QuickStart). This table has a primary key,
SCORING..PRIMARY_KEY, which is defined over five columns.
SELECT s.tablename, s.indexname, h.fieldcount, h.maxresolution as MAXRES, h.histogramid as HIST, h.objectid as OBJ, h.catalogid as CAT FROM system.indexstatistics s, system.indexhistograms h WHERE s.tablename='SCORING' and s.objectid = h.objectid and s.catalogid = h.catalogid ORDER BY s.tablename, s.indexname; TABLENAME INDEXNAME FIELDCOUNT MAXRES HIST OBJ CAT ---------- -------------------- ----------- ------ ---- --- --- SCORING SCORING..PRIMARY_KEY 5 10 5 1 78