Neoview Query Guide (R2.2)

The PACK operator has one child. The description field for this operator contains:
Data TypeToken DescriptionToken
integerA sequential number assigned to the fragment. 0 is always master
executor and 1 is reserved for the Explain plan. Numbers 2 to n will
be ESP or DAM fragments.
fragment_id
integerThe fragment_id for the parent fragment of the current fragment.
Value is (none) for master executor.
parent_frag
textmaster, ESP, or DAMfragment_type
expr(text)Expression used to pack values of a row into a packed rowpack_expr
SAMPLE Operator
The SAMPLE operator occurs as a result of a sample clause in a query.
The SAMPLE operator has one child operator. The description field for this operator contains:
Data TypeToken DescriptionToken
integerA sequential number assigned to the fragment. 0 is always master
executor and 1 is reserved for the Explain plan. Numbers 2 to n
will be ESP or DAM fragments.
fragment_id
integerThe fragment_id for the parent fragment of the current fragment.
Value is (none) for master executor.
parent_frag
textmaster, ESP, or DAMfragment_type
expr(text)List of column references representing the outputs of the sample
operator. Indicates that the column has been sampled.
sampled_columns
expr(text)Expression representing the sampling expression. A simple random
selection, but could be more complex if the sample clause contains
a balance clause.
balance_expression
textIndication of the type of sampling being performed. Possible values
are RANDOM, PERIODIC, FIRST, and CLUSTER.
sample_type
expr(text)Specified order keys for a sample operation.required_order
Understanding Joins 65