Introduction to NonStop SQL/MP

Parallel Execution
NonStop SQL Architecture
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Figure 3-7. Parallel Execution of a Query Using an Aggregate Function
Application
Server Process
SQL Master Executor
Volume
Containing
Partition 1
Volume
Containing
Partition 2
Volume
Containing
Partition 3
Volume
Containing
Partition 4
014
Data Access
Manager
COUNT COUNT COUNT COUNT
EMPLOYEE Table
SUM of COUNTs
Master executor
computes final
aggregate result.
Data access
managers
compute
partial aggregate
results.
Data Access
Manager
Data Access
Manager
Data Access
Manager
ESPs manage
separate tasks.
ESP
(SQL Executor)
File System
ESP
(SQL Executor)
File System
ESP
(SQL Executor)
File System
ESP
(SQL Executor)
File System
If a table is not partitioned or partitioned in a way that does not facilitate parallel
execution for this query, the optimizer can request the executor to repartition
(reorganize) a copy of the data at run time. During repartitioning, NonStop SQL/MP
distributes the data over a set of temporary partitions using a hash algorithm. A
separate ESP then processes the data in each temporary partition.
NonStop SQL/MP can also repartition data in tables and indexes participating in a
join. The master executor and ESPs use the repartitioned data to perform a parallel
join operation.