SQL/MX 3.2.1 Query Guide (H06.26+, J06.15+)

SQL/MX Operators
HP NonStop SQL/MX Release 3.2.1 Query Guide—663851-003
7-30
INDEX_SCAN Operator
The following is an example of the HYBRID_HASH_SEMI_JOIN operator:
prepare TestQuery31 from
select * from TAB1
where TAB1.col1 in (select col2 from TAB2 where TAB2.col1 < 10);
DESCRIPTION
fragment_id ............ 0
parent_frag ............ (none)
fragment_type .......... master
join_type .............. inner semi
join_method ............ hash
hash_join_predicate .... (DETCAT.DETSCH.TAB1.COL1 =
DETCAT.DETSCH.TAB2.COL2)
INDEX_SCAN Operator
DAM Subset Group
The INDEX_SCAN operator scans the index built on the key columns. The node
description contains details about how a certain access path is scanned, such as
lock_mode and scan_direction.
The INDEX_SCAN operator has no child nodes. The description field for this operator
contains the following:
Token Followed by ... Data Type
fragment_id A sequential number assigned to the fragment. 0
is always the master executor and 1 is reserved
for the EXPLAIN plan. Numbers 2 to n will be
ESP or DAM fragments.
integer
parent_frag The fragment_id for the parent of the current
fragment. The value is (none) for the master
executor.
integer
fragment_type Master, ESP, or DP2. text
olt_optimization Indicates whether an optimization for short,
simple operations is used. Value is used if this
optimization is used. Its value is used or not
used.
text
olt_opt_lean Indicates for short, simple operations whether a
further optimization that reduces the physical
size of the plan is used. Its value is used or not
used.
text
key_columns Columns used as the primary key. expr(text)
begin_key Expression of the begin key predicates. expr(text)
end_key Expression of the end key predicates. expr(text)
scan_type INDEX_SCAN followed by table or index name. text
TP663851.fm Page 30 Wednesday, January 30, 2013 5:37 PM