Reducing run times by breaking a problem into parts that can be completed by separate execution paths simultaneously.

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6
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2answers
14k views

Using multiple cores for single MySQL queries on Debian

I am running a MySQL server for tests on a VM (VMWare) with Debian as guest OS. The guest has four emulated CPU cores, so I set thread_concurrency to four. I am doing expensive joins on large tables, ...
11
votes
2answers
12k views

Need to understand parallel query execution error

Today we experienced a degradation in performance on our production sql server. Durring the time this occurred we logged several "The query processor could not start the necessary thread resources ...
31
votes
4answers
17k views

Can a single PostgreSQL query use multiple cores?

In recent versions of PostgreSQL, can we share a query between two or more cores to get a performance boost? Or should we get faster cores?
9
votes
5answers
6k views

Parallelism Best Practices

What are the best practices with setting parallelism in general? I know that SQL Server defaults to 0 to use all available processors, but in what instance would you want to change this default ...
7
votes
6answers
9k views

CXPACKET Waits performance tune for SQL Server 2008

I have a SQL Server 2008 query that is working on millions of records. The query is w/in a proc that is run nightly by a job. The query can take a full day to run when I first put it on the server, ...
6
votes
1answer
86 views

Parallel option performing worse on cluster

I'm trying out oracles parallel option on a cluster and surprisingly I am getting worse results with the parallel option. I was expecting some improvement with the parallel option but certainly not ...
7
votes
3answers
2k views

Dealing with CXPACKET waits - setting cost threshold for parallelism

As a follow-up to my previous question on perf troubleshooting a Sharepoint site, I was wondering if I could do something about the CXPACKET waits. I know the knee-jerk solution is to turn off all ...
5
votes
1answer
201 views

What is the minimum required compatibility level to use parallel SELECT INTO?

What is the minimum required compatibility level to use parallel SELECT INTO in SQL Server 2014?
4
votes
2answers
1k views

A query submitted from different applications has differing DOP

I have a query which selects from multiple views and is fairly I/O heavy. If I execute this query using Management Studio it uses parallelism across most of the 16 CPUs and completes in under 10 ...
1
vote
1answer
297 views

How is parallelism threshold (seconds) used if query CPU cost is actually unitless

How does the optimizer decide whether or not to use parallelism when the parallelism threshold is specified in seconds (on specific hardware, see below) but the estimated CPU costs are supposedly ...