SQL/MP Query Guide

Analyzing Query Performance
HP NonStop SQL/MP Query Guide—524488-003
6-63
Key-Sequenced Merge Join With Executor
Aggregates
Example 6-38. EXPLAIN Plan for Key-Sequenced Merge Join With Executor
Aggregates
<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
Query plan 1
SQL request : Select
<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
---------------------------------------------------------------------------
Plan step 1
---------------------------------------------------------------------------
Operation 1.0 : Scan
Table : \SQL1.$DATA2.WISCREG.TENKTUP2
with correlation name TENKTUP2
Access type : Record locks, stable access
Lock mode : Chosen by the system
Column processing : Requires retrieval of 1 out of 16 columns
Access path 1 : Alternate \SQL1.$DATA2.WISCREG.TKTUP2I, index
only, sequential cache
SBB for reads : Virtual
Begin key pred. : None
End key pred. : None
Index selectivity : Expect to examine 100% of rows from index
Index pred. : None
Base table pred. : None
Executor pred. : None
Executor aggr. : Computed for each group
COUNT ( * )
Table selectivity : Expect to select 100% of rows from table
Expected row count: 74666 rows after the scan
Operation cost : 2187
---------------------------------------------------------------------------
Plan step 2 : Perform an Inner Join
Join strategy : Key-Sequenced Merge Join
Plan Forced : Join Method forced by user directive
Characteristic : Joins a row resulting from plan step 1
---------------------------------------------------------------------------
Operation 2.0 : Scan
Table : \SQL1.$DATA2.WISCREG.TENKTUP1
with correlation name TENKTUP1
Access type : Record locks, stable access
Lock mode : Chosen by the system
Column processing : Requires retrieval of 1 out of 16 columns
Access path 1 : Alternate \SQL1.$DATA2.WISCREG.TKTUP1I, unique,
index only, sequential cache
SBB for reads : Virtual
Begin key pred. : TENKTUP1.UNIQUE1 = TENKTUP2.UNIQUE1
End key pred. : None
Index selectivity : Expect to examine 0.0013% of rows from index
Index pred. : None
Base table pred. : None
Executor pred. : None
Table selectivity : Expect to select 0.0013% of rows from table
Expected row count: 74704 rows after the join
Operation cost : 1
Total cost : 4389