Neoview Query Guide (R2.2)

LEFT_ORDERED_HASH_JOIN Operator
The LEFT_ORDERED_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_ORDERED_HASH_JOIN operator differs from the LEFT_HYBRID_HASH_JOIN in that
it preserves the order of the outer table and does not overflow to disk. In addition, 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.
The LEFT_ORDERED_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)List of values that cause the hash table to be rebuilt when values changereuse_comparison_values
expr(text)Expression of the join predicatejoin_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
ORDER_CROSS_PRODUCT
The ORDER_CROSS_PRODUCT operator forms a cross product of the data from two child tables.
This operator preserves the order of both the outer and inner tables and does not overflow to
disk. This operator is chosen only if the inner table is small enough to fit in memory, and no join
or selection predicates exist. Used only for joining dimension tables in a star schema.
The ORDER_CROSS_PRODUCT 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
textInner or natural joinjoin_type
textName of join method: hashjoin_method
text1 for Type1 or 2 for Type2, depending on parallel join algorithmparallel_join_type
46 Query Plan Operators