SQL/MX 2.x Reference Manual (H06.04+)

Metadata Tables
HP NonStop SQL/MX Reference Manual—540440-003
10-72
HISTOGRAMS Table
HISTOGRAMS Table
The SQL/MX HISTOGRAMS table describes columns, interval count, total number of
rows and number of unique rows, and the low and high values of column distribution
for a table:
File name:
catalog.schema.SQLMX
_tablename
File name:
\node.$vol.ZZMXTEMP.tablename
Size limits:
Because files are always format 2,
the temporary table is limited to 1
TB or the amount of available
space on each volume.
Size limits:
File format is determined by format of the
base table’s primary partition.
If it is format 1, the temporary table is
limited to 2 GB.
If it is format 2, the temporary table is
limited to 1 TB or the amount of available
space on the disk volume.
Column Name Data Type Description
*1 TABLE_UID LARGEINT The UID of the table for which this histogram is
generated.
*2 HISTOGRAM_ID INT UNSIGNED System-generated ID for the histogram. Each
HISTOGRAM_ID has a corresponding ID in the
HISTOGRAM_INTERVALS table.
*3 COL_POSITION INT Column position in a column group for which the
histogram is generated.
4 COLUMN_NUMBER INT Table column number for which this histogram is
generated.
5 COLCOUNT INT Number of columns in the column group.
6 INTERVAL_COUNT SMALLINT Number of intervals in the histogram. If the
value is n, there are n+1 corresponding rows in
the HISTOGRAM_INTERVALS table with the
same HISTOGRAM_ID.
7 ROWCOUNT LARGEINT Total number of rows in the table.
8 TOTAL_UEC LARGEINT Total number of unique entries in the table.
9 STATS_TIME TIMESTAMP(0) Start time of statistics generation, expressed as
Greenwich mean time.
10 LOW_VALUE VARCHAR(250)
CHARACTER
SET UCS2
Low value of column distribution (for the entire
table).
11 HIGH_VALUE VARCHAR(250)
CHARACTER
SET UCS2
High value of column distribution (for the entire
table).
* Indicates primary key
SQL/MX Objects SQL/MP Objects