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

Data TypeToken DescriptionToken
textName of join method: hashjoin_method
text1 for Type1 or 2 for Type2, depending on parallel join algorithmparallel_join_type
expr(text)Expression of the join predicatehash_join_predicate
expr(text)Expression of the join predicate, specified in the ON clause. Used for
semi and outer joins.
join_predicate
expr(text)Expression of the WHERE clause that is not included in a
hash_join_predicate or one of the child scans
selection_predicates
The difference between join_predicate and hash_join_predicate tokens is that the former are the
non-equijoin predicates. The latter are equijoin predicates that you use to help build and probe
the hash table.
LEFT_HYBRID_HASH_JOIN Operator
The LEFT_HYBRID_HASH_JOIN operator returns an unmatched outer row even when it does
not find a match in the inner table. Null values are supplied for the missing inner rows. The
LEFT_HYBRID_HASH_JOIN operator differs from the HYBRID_HASH_JOIN only when it does
not find a match in the inner table. See “HYBRID_HASH_JOIN Operator” (page 29).
The LEFT_HYBRID_HASH_JOIN operator has two child operators. 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
textLeft joinjoin_type
textName of join method: hashjoin_method
text1 for Type1 or 2 for Type2, depending on parallel join algorithmparallel_join_type
expr(text)Expression of the join predicatehash_join_predicate
expr(text)Expression of the join predicate, specified in the ON clause. Used for semi
and outer joins.
join_predicate
expr(text)Expression of the WHERE clause that is not included in a
hash_join_predicate or one of the child scans
selection_predicates
Ordered Joins
ORDERED_HASH_JOIN Operator
The ORDERED_HASH_JOIN operator joins the data from two child tables. This operator preserves
the order of the outer table and does not overflow to disk. It creates a hash table from the inner
table, joins the outer table by hashing each outer row, and looks for matches in the hash table.
The reuse feature enables reuse of the hash table for subsequent requests within the same query.
This operator is chosen only if the inner table is small enough to fit in memory. Equijoins are
supported by this operator.
This operator supports equijoins and cross-products.
Operators and Description Fields 31