question on parallelism
does postgres have this capability? specifically local intrapartition?
http://pic.dhe.ibm.com/infocenter/db2luw/v10r5/topic/com.ibm.db2.luw.admin.partition.doc/doc/c0004557.html
sorry for all the newbie pg questions...
--
personal Signature
------------------------------------------------------------------------
Andrew McIntyre
amcintyre@m-m.com <mailto:amcintyre@m-m.com>
http://www.mindspring.com/~amcintyr/resume.htm
<http://www.mindspring.com/%7Eamcintyr/resume.htm>
------------------------------------------------------------------------
On Wed, Jan 1, 2014 at 7:35 PM, Andrew McIntyre <amcintyre@m-m.com> wrote:
does postgres have this capability? specifically local intrapartition?
Nope. Here's a quick breakdown of what is done in parallel and what is
done sequentially in PostgreSQL.
Separate queries run in parallel, and can piggy back on eachother's
sequential scans. In essence all of the work that is done in parallelism
affects parallel queries.
There is no intra-query parallelism however. This means that partitioning
doesn't generally help here (although sequential scans on the same
partition by different queries can run in parallel with good results, a
single query cannot run several scans on different partitions in parallel).
If you need this sort of feature you are going to either need to go to a
related product (like Postgres-XC) or you are going to need to have some
other layer that can do the parallelism.
Best Wishes,
Chris Travers
sorry for all the newbie pg questions...
--
------------------------------
Andrew McIntyre
amcintyre@m-m.com
http://www.mindspring.com/~amcintyr/resume.htm
------------------------------
--
Best Wishes,
Chris Travers
Efficito: Hosted Accounting and ERP. Robust and Flexible. No vendor
lock-in.
http://www.efficito.com/learn_more.shtml
On Thu, Jan 2, 2014 at 2:29 PM, Chris Travers <chris.travers@gmail.com> wrote:
On Wed, Jan 1, 2014 at 7:35 PM, Andrew McIntyre <amcintyre@m-m.com> wrote:
does postgres have this capability? specifically local intrapartition?
Nope. Here's a quick breakdown of what is done in parallel and what is done
sequentially in PostgreSQL.Separate queries run in parallel, and can piggy back on eachother's
sequential scans. In essence all of the work that is done in parallelism
affects parallel queries.There is no intra-query parallelism however. This means that partitioning
doesn't generally help here (although sequential scans on the same partition
by different queries can run in parallel with good results, a single query
cannot run several scans on different partitions in parallel).If you need this sort of feature you are going to either need to go to a
related product (like Postgres-XC) or you are going to need to have some
other layer that can do the parallelism.
In the case of XC, it is worth noting that a query can take advantage
of parallelism on a sequential scan only roughly for sharded tables.
In the case of replicated table, query is usually simply pushed to one
singke remote node, making the scan occur on this single node.
Regards,
--
Michael
--
Sent via pgsql-general mailing list (pgsql-general@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-general