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

Metadata Tables
HP NonStop SQL/MX Reference Manual—540440-003
10-74
HISTOGRM Table
HISTOGRM Table
The SQL/MP HISTOGRM table is a user table registered in the catalog of the primary
partition of the table specified in the UPDATE STATISTICS statement that created the
histogram tables. It describes columns, interval count, total number of rows and unique
rows, and the low and high values of column distribution for the table for which the
histogram is created.
Caution. HISTOGRM is an SQL/MP user table with the security of the user who runs the
UPDATE STATISTICS command on the user tables of a particular SQL/MP catalog. It does not
have the same protection as the SQL/MP catalog tables, which can be modified by licensed
processes only. As such, system users who have write access to the table could enter invalid
data, which could affect the performance or operation of NonStop SQL/MX. Therefore, you
should secure access to the HISTOGRM table to a restricted group of users.
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 HISTINTS table.
*3 COL_POSITION INT Column position in a column group for which
the histogram is generated. For example,
columns in the group (a, b, c) have the
corresponding positions of 0, 1, and 2.
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 HISTINTS 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(500) Low value of column distribution (for the
entire table).
11 HIGH_VALUE VARCHAR(500) High value of column distribution (for the
entire table).
* Indicates primary key