Reducing run times by breaking a problem into parts that can be completed by separate execution paths simultaneously.
3
votes
0answers
26 views
PLSQL : DBMS Jobs - parallelization?
I am looping over a cursor and executing a stored procedure; how do I parallelize this process through dbms.jobs?
for rec in select column from table1
loop
execute stored_procedure( rec.column );
end ...
1
vote
1answer
25 views
MySQL: parallel restores at same time from backup files?
Slightly related to this question, but for MySQL: Would it be possible/wise to execute 2 parallel restores from a single backup?
Is it possible/wise to do a parallel restore of two independent ...
2
votes
0answers
95 views
Are the following statements concerning sys.dm_exec_requests true?
Parallel plans mean that cpu_time can be greater than total_elapsed time.
Therefore, per-query wait time is not possible to determine accurately from DMVs on servers with more than one CPU thread.
...
4
votes
1answer
308 views
Executing SPs in parallel (maybe with a cursor) [closed]
We have an 3rd party accounting system that runs on SQL Server 2008 R2. To insert invoices into this accounting system, we have to use the API that comes with it (which is just a set of encrypted ...
0
votes
1answer
28 views
Oracle scheduler max_jobs_Slave_processes is set to null, how many will be allocated?
Executing the following query against my database:
select value
from dba_scheduler_global_attribute
where attribute_name='MAX_JOB_SLAVE_PROCESSES';
yields a value of NULL. My question is what ...
3
votes
1answer
112 views
SQL Server parallelism issue
I am rather new to SQL Server administrations, I am running an SSIS that never ends...
A) looking at the processes using
SELECT r.*, t.text
FROM sys.dm_exec_requests r
CROSS APPLY ...
4
votes
3answers
383 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 ...
2
votes
2answers
255 views
Parallel Statistics Update
In SQL Server 2008 or later, is UPDATE STATISTICS WITH FULLSCAN a single threaded operation or it can use parallelism? How about update statistics with default sampling - can it use parallelism? I ...
1
vote
1answer
172 views
What is the “Data partitioned, Shared-Nothing, Parallel Database” solution for PostgreSQL ?
I was looking for a open source parallel database solution. It seems Postgres-XC is a viable solution. However, I don't need the replication. In this case, is there any better solution towards read ...
1
vote
2answers
448 views
Is problem with parallelism more common today than before? And what issues can arise from paralellism?
This is a very general question so I don't give much specific information. I am more interested in parallelism and its possible drawbacks. Generally I am all for parallelism as something useful and ...
9
votes
3answers
1k views
Why is an aggregate query significantly faster with a GROUP BY clause than without one?
I'm just curious why an aggregate query runs so much faster with a GROUP BY clause than without one.
For example, this query takes almost 10 seconds to run
SELECT MIN(CreatedDate)
FROM MyTable
WHERE ...
4
votes
2answers
3k 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, ...
2
votes
1answer
2k views
In Oracle, if parallel_max_servers is set to be significantly less than the DOP can the explain plan be sub-optimal?
For tables that have DEGREE DEFAULT, the degree of parallelism (DOP) is calculated by Oracle using number of CPUs and number of threads per CPU amongst other things. As I understand it, when costing ...
4
votes
4answers
3k 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, ...
5
votes
4answers
2k 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 ...
