Please take our Survey
logo       

Choosing A Webhost:
A web hosting service is a type of Internet hosting service that allows individuals and organizations to provide their own website accessible via the World Wide Web. Web hosts are companies that provide space on a server they own for use by their clients as well as providing Internet connectivity, typically in a data center. Web hosts can also provide data center space and connectivity to the Internet for servers they do not own to be located in their data center, called colocation. more...

Re: query optimization differs between view and explicit: msg#00311

db.postgresql.performance

Subject: Re: query optimization differs between view and explicit


rkh@csb-dev=> create view v1 as
select distinct on (AH.p2gblataln_id) AH.p2gblataln_id,H.pseq_id,min(H.pstart) as
"pstart",
max(H.pstop) as "pstop",A.ident,(A.ident/Q.len::float*100)::int as "pct_ident",
sum(H.pstop-H.pstart+1) as "aln_length",H.genasm_id,H.chr,H.plus_strand,min(H.gstart) as
"gstart",
max(H.gstop) as "gstop"
from p2gblathsp H
join p2gblatalnhsp AH on H.p2gblathsp_id=AH.p2gblathsp_id
join p2gblataln A on AH.p2gblataln_id=A.p2gblataln_id
join pseq Q on H.pseq_id=Q.pseq_id
group by
AH.p2gblataln_id,H.pseq_id,H.genasm_id,H.chr,H.plus_strand,A.ident,Q.len;
CREATE VIEW
Time: 103.041 ms

What happens if you make it a function:

CREATE FUNCTION f1() RETURNS ... AS '
select distinct on (AH.p2gblataln_id) AH.p2gblataln_id,H.pseq_id,min(H.pstart) as "pstart",
max(H.pstop) as "pstop",A.ident,(A.ident/Q.len::float*100)::int as "pct_ident",
sum(H.pstop-H.pstart+1) as "aln_length",H.genasm_id,H.chr,H.plus_strand,min(H.gstart) as "gstart",
max(H.gstop) as "gstop"
from p2gblathsp H
join p2gblatalnhsp AH on H.p2gblathsp_id=AH.p2gblathsp_id
join p2gblataln A on AH.p2gblataln_id=A.p2gblataln_id
join pseq Q on H.pseq_id=Q.pseq_id
where H.pseq_id=76
group by AH.p2gblataln_id,H.pseq_id,H.genasm_id,H.chr,H.plus_strand,A.ident,Q.len
' LANGUAGE SQL;

I suspect that will be even faster than the normal (non-view) query.

Chris

---------------------------(end of broadcast)---------------------------
TIP 1: subscribe and unsubscribe commands go to majordomo@xxxxxxxxxxxxxx



<Prev in Thread] Current Thread [Next in Thread>
Google Custom Search

Recently Viewed:
qnx.openqnx.dev...    gcc.libstdc++.c...    solaris.opensol...    information-ret...    misc.misterhous...    web.catalyst.ge...    apache.webservi...    redhat.release....    hardware.lirc/2...    kernel.autofs/2...    technology.sust...    linux.vdr/2003-...    editors.lyx.gen...    org.user-groups...    netbsd.devel.pk...    xdg.devel/2004-...    version-control...    jakarta.slide.d...    debian.packages...    creativecommons...    ports.ppc.embed...    bug-tracking.bu...   
Home | blog view | USPTO Patent Archive | advertise | OSDir is an inevitable website. super tiny logo

Free Magazines

Cisco News
Receive a free quarterly e-newsletter with exclusive articles on how Cisco IT uses its own products and solutions to enable the business.
subscribe

Systems Management News, the newspaper for IT systems administration and data center managers! Each issue of Systems Management News is chock-full of news and analysis to help you understand what's happening in your field.
subscribe

The Enterprise Newsweekly eWeek is the essential technology information source for builders of e-business.
subscribe

Oracle Magazine Oracle Magazine contains technology strategy articles, sample code, tips, Oracle and partner news, how to articles for developers and DBAs, and more. Oracle (NASDAQ: ORCL) is the world's largest enterprise software company.
subscribe

Total Telecom Total Telecom is "The Economist of the communications industry".
subscribe