Neoview Query Guide (R2.3, R2.4, R2.5)

Data TypeToken DescriptionToken
expr(text)Expression of the aggregate functionaggregates
expr(text)Expression of the HAVING clauseselection_predicates
expr(text)Expression of the grouping columnsgrouping_columns
HASH_PARTIAL_GROUPBY_LEAF Operator
The HASH_PARTIAL_GROUPBY_LEAF operator executes a partial group by operation as close
to where the data is read as is cost effective. This strategy reduces the amount of data that must
be relocated for a query. When executed in DAM, the HASH_PARTIAL_GROUPBY_LEAF is
limited to a small amount of memory. Any group that does not fit in memory is passed on
ungrouped, with the full grouping occurring at the HASH_PARTIAL_GROUPBY_ROOT. If the
HASH_PARTIAL_GROUPBY_LEAF is not executed in DAM, more memory is available, and
all rows are grouped. The groups from multiple processes are then rolled up in the
HASH_PARTIAL_GROUPBY_ROOT.
The operator must always be accompanied by a HASH_PARTIAL_GROUPBY_ROOT operator
above it in the tree, which finalizes the query.
The HASH_PARTIAL_GROUPBY_LEAF 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)Expression of the grouping columnsgrouping_columns
expr(text)Expression of the aggregate functionaggregates
expr(text)Expression of the HAVING clauseselection_predicates
HASH_PARTIAL_GROUPBY_ROOT Operator
The HASH_PARTIAL_GROUPBY_ROOT operator works together as a pair with the
HASH_PARTIAL_GROUPBY_LEAF operator. The HASH_PARTIAL_GROUPBY_ROOT operator
finalizes the group by at the ESP level. See “HASH_PARTIAL_GROUPBY_LEAF Operator”
(page 46).
The HASH_PARTIAL_GROUPBY_ROOT 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)Expression of the grouping columnsgrouping_columns
46 Query Plan Operators