Intraquery Parallelism
It is about
executing a single query in parallel using multiple processors or disks. This can
be done by dividing the data into many smaller units and execute the query on
those smaller tables. We have so many queries which are complex and consume
more time and resources. For example, consider the query given below;
SELECT
* FROM Email ORDER BY Start_Date;
This query
will sort the records of Email table
in ascending order on the attribute Start_Date. Assume that the Email
table has 10000 records. To sort the table we need at least 10000 comparisons of
Salary attribute values, if the query is executed in single processor. If the
same query is executed in several processors simultaneously, we can finish
sorting in lesser time. For example, if 10000 records are distributed equally
into 10 processors, 1000 each, then every processor can sort 1000 records in
lesser time, later it can be combined/merged using other algorithms to produce
final sorted result.
In Intraquery
Parallelism, we have two types;