July 6, 2008 05:52pm pdt

1. adrpo 24,265
2. ivanovn 21,940
3. earthman2 21,510
4. gheist 10,260
5. drazen_n... 9,400
6. lesouef 5,900
7. TomasHelgi 5,625
8. grant300 5,300
9. rokov 4,500
10. fridom 4,000
11. tusharka... 3,900
12. sanjooz 3,800
13. ee_rlee 3,750
14. mark_wills 3,600
15. hernst42 3,500
15. hielo 3,500

1. earthman2 428,643
2. ivanovn 89,577
3. gheist 84,279
4. m1tk4 62,382
5. adrpo 43,659
6. rjkimble 31,347
7. grant300 28,122
8. ravenpl 20,699
9. GGuzdziol 16,660
10. fridom 13,000
11. TomasHelgi 11,125
12. drazen_n... 9,400
13. Ghitza 7,600
14. angelIII 7,000
15. ldbkutty 6,730

02.26.2008 at 03:51PM PST, ID: 23195522

	[x] Attachment Details

[x]

The Solution Rating System

With so many solutions, how can you tell which solutions are most likely to help you and which ones are not? To provide you with a tool to use, we rate our solutions based on various elements that most accurately determine if a solution is a quality solution. To explain what factors affect the solution rating, here are the elements we take into consideration when formulating our solution rating.

The Grade of the Solution
The Zone Rank of the Expert Providing the Solution
The Number of Author and Expert Comments
The Number of Experts Contributing
The Feedback of the Community

Your Input Matters
Because of the way the system is set up, the most important variable in this equation is you. As a member of Experts Exchange, you are able to cast your vote on the quality of the solutions in regard to how complete, accurate, helpful and easy to understand each solution is. When you provide your feedback, each rating is adjusted accordingly. So, if you see a solution that has a poor rating that you think is a good solution, let us know by rating it. As you do, the rating will be adjusted and will become more accurate for other members of our site.

If you have any suggestions that you would like to make for our rating system, please ask a question in the Suggestions Zone of Community Support.

Thank you!

7.6

Return multiple select as a single recordset

Zones: PostgreSQL Database, Databases Miscellaneous

Tags: postgres, function, sql, select, view

Hi Folks,

I currently have an outrageously complex query consisting of many nested subqueries and convoluted joins in order to produce a recordset of about a half a dozen rows.

This query is currently taking way too long (more than 30 seconds each time) and I am certain that I can do better if I run just half a dozen independent queries.

I'm thinking that I could write some kind of function containing those 6 queries, and then send that back to the source as a single recordset. Does postgres function work this way?

if so, is there a guide with some samples somewhere I can look at?

If not, what alternatives do I have?

Many thanks in advance, and regards, Mike.

Start your free trial to view this solution

Question Stats

Zone: Database

Question Asked By: meverest

Solution Provided By: jimpen

Participating Experts: 3

Solution Grade: B

Translate:

Loading Advertisement...

Microsoft

Internet Protocols
Applications

Development
OS

Hardware
Windows Security

Apple

Operating Systems
Hardware

Programming
Networking

Software

Internet

Search Engines
File Sharing
WebTrends / Stats
Spy / Ad Blockers

Web Browsers
New Net Users
Web Development
Chat / IM

Anti Spam
Web Servers
Anti-Virus
Email Clients

Gamers

Tips
Online / MMORPG
Puzzle
Emulators

Action / Adventure
Role Playing
Consoles
Game Programming

Strategy
Sports
Misc
Computer Games

Digital Living

Hardware
New Net Users
New Users

Software
Digital Music
Gaming World

Home Security
Apple
Networking Hardware

Virus & Spyware

Vulnerabilities
IDS
Encryption
Anti-Virus

Operating Systems Security
Software Firewalls
WebApplications
Cell Phones

Operating Systems
Internet
Hardware Firewalls

Hardware

Handhelds / PDAs
Displays / Monitors
Components
Networking Hardware

Peripherals
Laptops/Notebooks
Storage
Servers

Desktops
New Users
Misc
Apple

Software

System Utilities
Industry Specific
Network Management
Photos / Graphics
Page Layout
VMWare
Misc
Web Development

OS
CYGWIN
Voice Recognition
Message Queue
Quality Assurance
Security
Firewalls
MultiMedia Applications

Development
Database
Office / Productivity
Business Management
OS/2 Apps
Server Software
Internet / Email

ITPro

OS
Storage
Encryption
Operating Systems Security
Apple Hardware
Laptops & Notebooks
Servers
Networking Hardware
Peripherals

Devices
Displays / Monitors
WebTrends / Stats
Search Engines
Firewalls
WebApplications
IDS
Vulnerabilities
Email Clients

File Sharing
Spy / Ad Blockers
Web Browsers
Web Servers
Networking
Anti-Virus
Chat / IM
Anti Spam

Developer

Web Servers
Web Browsers
Game Programming
Dev Tools
Industry Specific
Office / Productivity

Database
CYGWIN
Web Development
Search Engines
File Sharing
WebTrends / Stats

Programming
Content Management
Application Servers
Protocols

Storage

Removable Backup Media
Storage Technology
Servers

Grid
Remote Access
Backup / Restore

Misc
Hard Drives

Miscellaneous
Security
Development
Linux
VMWare

MainFrame OS
Unix
Apple
OS / 2
AS / 400

BeOS
Microsoft
VMS / OpenVMS

Database

Oracle
Miscellaneous
MySQL
Software
Sybase
Contact Management
PostgreSQL
Data Manipulation
Clarion
InterSystems Cache

Siebel
MUMPS
OLAP
SQLBase
SAS
GIS & GPS
4GL
Berkeley DB
DB2
Informix

Interbase / Firebird
FoxPro
Reporting
LDAP
Filemaker Pro
MS SQL Server
dBase
MS Access

Security

Misc
Web Browsers
Software Firewalls
Operating Systems Security
File Sharing

Spy / Ad Blockers
Vulnerabilities
WebApplications
IDS
Anti-Virus

Encryption
Anti Spam
Email Clients
VPN
Chat / IM

Programming

Editors IDEs
Installation
Handhelds / PDAs
Multimedia Programming
System / Kernel

Algorithms
Game
Signal Processing
Project Management
Open Source

Database
Misc
Languages
Processor Platforms
Theory

Web Development

Scripting
Blogs
Web Servers
Software
Search Engines
Web Graphics
Images

Internet Marketing
Images and Photos
Components
Document Imaging
Web Languages/Standards
Illustration
WebApplications

Fonts
WebTrends / Stats
Authoring
Digital Camera Software
Miscellaneous

Networking

Protocols
Apple Networking
Network Management
Message Queue
Application Servers
Content Management
File Servers
Email Servers
Misc
Java Editors & IDEs

Wireless
Networking Hardware
Backup / Restore
System Utilities
ISPs & Hosting
Web Servers
Storage Technology
Removable Backup Media
Servers
Broadband

Grid
OS / 2
Novell Netware
Unix Networking
Windows Networking
Security
Telecommunications
Operating Systems
Linux Networking

Other

Community Advisor
Lounge
Community Support
New Net Users

Philosophy / Religion
Math / Science
Miscellaneous
URLs

Expert Lounge
Politics
Puzzles / Riddles

Community Support

Suggestions
New to EE
New Topics
Community Advisor

CleanUp
Announcements
General

Feedback
Input
EE Bugs

02.27.2008 at 06:21AM PST, ID: 20994118

Rank: Guru

jimpen:

Never having used PostgreSQL, but the UNION queries are pretty standard among various SQL. How about something like this.

                       
             SELECT OtherFldName1 AS FldName1, OtherFldName2 AS FldName2, ......
FROM TableA
WHERE Sun <> 'Moon'
UNION
SELECT ThatFldName1 AS FldName1, ThatFldName2 AS FldName2, ......
FROM TableB
WHERE Stars <> 'Sky'

Open in New Window

Accepted Solution

02.28.2008 at 12:38AM PST, ID: 21002103

Rank: Wizard

earthman2:

look in the postgresql documentation for set returning functions.

The steps are to create a type that the function will contain ie tmp_stocuri
declare a record say r of row type.
loop
return next r
end loop
return

eg heres one i wrote earlier.

create or replace function xxxx() returns setof tmp_stocuri as $$
declare
r tmp_stocuri%ROWTYPE;
begin
FOR r IN SELECT * FROM tmp_stocuri LOOP
begin
insert into desttable( id, mac, serie, nr, agent, socasig, an, cod ) values r.id, r.mac, r.serie, r.nr, r.agent, r.socasig, r.an, r.cod ;
exception when unique_violation then
return next r;
exception when others then
null;
end;
end loop;
return;
end;
$$ language plpgsql

Assisted Solution

02.28.2008 at 01:10PM PST, ID: 21008109

Rank: Master

grant300:

Your best bet is, as you suggested, to break a complex query up into a string of smaller, simpler pieces. That give the optimizer half a chance to figure out what it really needs to do and gives you half a chance at tuning each piece.

Generally, the approach I use (in several different databases, not just PostgreSQL) is to break off the first chunk of the query and stuff it's results into a temp table using SELECT/INTO. Then I use the temp table from the first section as the driving table for the next hunk of query work and create another temp table. In your case, you might wind up with 5 temp tables if your guess at the number of chunks is correct. The final query actually returns the result set.

If you need to hide the stored procedure call in a SELECT statement because of limitations in your environment, you can create it as a function that returns a record set but, to be honest, it is simpler and easier in most cases just to invoke the proc and be done.

Regards,
Bill

Assisted Solution

02.28.2008 at 02:58PM PST, ID: 21009133

meverest:

Thanks, yes - temp table is what I have been thinking about now.

Do you have a sample of this kind of thing that I can use as a starting point?

Regards, Mike.

02.28.2008 at 02:59PM PST, ID: 21009141

meverest:

oh! I didn't notice the previous comments until after I posted my last!

Thanks to all - I'll have a play with this now :)

Cheers!

02.29.2008 at 03:28AM PST, ID: 21012357

meverest:

Thanks everyone,

I've ended up migrating my databases to some new hardware, and I'm completely gobsmacked what a HUGE improvement that's made to all my queries - just goes to show what a bit of extra RAM and cpu ticks can do...

So I'll have a bit of time to properly investigate these pointers.

Now I'll have to work out how to score all these excellent comments.

Regards, Mike.

jimpen

02.29.2008 at 06:05AM PST, ID: 21013222

Glad to be of assistance. May all your days get brighter and brighter.

20080236-EE-VQP-29 / EE_QW_2_20070628