SQL/MP Query Guide

Analyzing Query Performance
HP NonStop SQL/MP Query Guide—524488-003
6-56
Parallel Execution of Nested Inner Join
Parallel Execution of Nested Inner Join
This example and the following merged join example both use the query from
Example 6-32 on page 6-49, but each uses a different CONTROL TABLE directive:
CONTROL TABLE * JOIN METHOD NESTED;
EXPLAIN
SELECT *
FROM TENKTUP1 A, TENKTUP2 B
WHERE A.TENPCT = B.TENPCT ;
Example 6-35. EXPLAIN Plan for Nested Inner Join (page 1 of 2)
<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
Query plan 1 : Will utilize parallel execution
SQL request : Select
<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
---------------------------------------------------------------------------
Plan step 1
Each operation is performed in parallel for this step
Each ESP will read one of the following partitions:
\SQL1.$DATA3 \SQL1.$DATA4 \SQL1.$DATA2
The ESP's will be started in the cpu's numbered
0 2 3
---------------------------------------------------------------------------
Operation 1.0 : Scan
Table : \SQL1.$DATA2.WISCREG.TENKTUP2
with correlation name B
Access type : Record locks, stable access
Lock mode : Chosen by the system
Column processing : Requires retrieval of 16 out of 16 columns
Access path 1 : Primary, partitioned, sequential cache
SBB for reads : Virtual
Begin key pred. : None
End key pred. : None
Index selectivity : Expect to examine 100% of rows from table
Index pred. : None
Base table pred. : None
Executor pred. : None
Table selectivity : Expect to select 100% of rows from table
Expected row count: 74666 rows after the scan
Operation cost : 2276