SQL/MX 2.x Query Guide (G06.24+, H06.03+)

Operators and Operator Groups
HP NonStop SQL/MX Query Guide—523728-003
7-42
SAMPLE Operator
SAMPLE Operator
Data Mining Group
The SAMPLE operator occurs as a result of a sample clause in a query.
The SAMPLE operator has one child node. The description field for this operator
contains:
For more information about data mining, see the SQL/MX Data Mining Guide.
The example of the SAMPLE operator is based on:
SELECT * FROM starter SAMPLE RANDOM 10 PERCENT;
sampled_columns: Sampled_column(indexcol(CAT.SCH.STARTER.A))
balance_expression: randomSelection
sample_type: RANDOM
SEQUENCE Operator
Data Mining Group
The SEQUENCE operator occurs as a result of a SEQUENCE BY clause in the query.
The SEQUENCE operator has one child node. The description field for this operator
contains:
Token Followed by ... Data Type
sampled_columns List of column references representing the
outputs of the sample operator. Indicates
that the column has been sampled.
expr(text)
balance_expression Expression representing the sampling
expression. A simple random selection, but
could be more complex if the sample clause
contains a balance clause.
expr(text)
sample_type Indicates the type of sampling being
performed. Possible values are RANDOM,
PERIODIC, FIRST, and CLUSTER.
text
required_order Specified order keys for a sample operation. expr(text)
Token Followed by ... Data Type
required_order List of column references specifying the
ordering required by the SEQUENCE operator.
Obtained from a list of columns specified in the
SEQUENCE BY clause.
expr(text)