SQL Server - concepts of query parallelism - Feb 27, 2010 at
11:50 AM by Shuchi Gauri
Explain the concepts and capabilities of query parallelism.
SQL Server has the capability to process queries in parallel to optimize query
execution and index operations for machines that have more than one
microprocessor. This allows operations to be completed quickly and efficiently.
SQL Server looks for queries/index operations that benefit from parallel
execution while query optimization. For such queries, it inserts exchange
operators into query execution plan to prepare the query for parallel
execution. This operator provides process management, data redistribution and
flow control.
A parallel execution plan can use more than a single thread which is determined
at query plan execution initialization and is known by complexity of the plan
and the degree of parallelism. Degree of parallelism determines number of
microprocessors that are being used, it can be changed by using sp_configure
stored procedure.
SQL Server - concepts of query parallelism - May 05, 2009 at
22:00 PM by Rajmeet Ghai
Explain the concepts and capabilities of query parallelism.
Parallelism is the process of executing queries in parallel to increase
performance.
Parallelism can be either inter query parallelism or intra query parallelism. In
the former, the database accepts queries from multiple applications at the same
time. Intra query parallelism is execution of the same query in parts. Parallel
queries are most commonly used in decision support systems and data
warehousing.
SQL Server - concepts of query parallelism - June 21, 2009 at
09:00 AM by Amit Satpute
Explain the concepts and capabilities of query parallelism.
Types of query parallelism:
1. Interquery parallelism:
-
Database can accept queries from multiple applications at the same time.
-
Each query runs independently of the others and at the same time.
2. Intraquery parallelism
-
Simultaneous processing of parts of a single query using intrapartition
parallelism, interpartition parallelism, or both.
a) Intrapartition parallelism
-
Query is broken into multiple parts.
b) Interpartition parallelism
-
Query is broken into multiple parts across multiple partitions of a partitioned
database, on one machine or multiple machines.
-
The query is run in parallel.
Also read
SQL INTERSECT allows combining results of two or more select queries. If a
record exists in one query and not in the other, it will be omitted from the
INTERSECT results..............
SQL EXISTS: If the subquery returns at least one row the EXISTS condition is
considered "to be met"...............
Answer - Restricting query result means
return of required rows instead of all rows of the table. This helps in
reducing network traffic......
Answer - Distributed Query is a query which can retrieve data
from multiple data sources including distributed data........
Answer - SQL Server English Query helps to build applications
that can accept query.....
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