Using an index will only work for certain types of selects - for equality, or string 'starting with'. They won't work for string 'containing' or string 'finishing with'.
Ed -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Les Hewkin Sent: 14 December 2009 11:44 To: U2 Users List Subject: Re: [U2] SELECTs on FILEs Hi, a good trick to speed selects like this up is to add an index to the ID....try it and see what happens to your selects.... Cheers Les Sherlock Hewkin Project Manager, Group Financial Systems, I.T. Department T 01604 592289, M 07917 856195 -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Brian Whitehorn Sent: 14 December 2009 00:33 To: 'U2 Users List' Subject: Re: [U2] SELECTs on FILEs Not sure about UD, but on UV this would result in a filescan: >SELECT CUSTOMER WITH @ID = "AAA]" EXPLAIN Optimizing query block 0 Tuple restriction: F0 MATCHES ''AAA'...' Driver source: CUSTOMER Access method: file scan UniVerse/SQL: Press any key to continue or 'Q' to quit 0 record(s) selected to SELECT list #0. HTH, Regards, Brian. -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Dan McGrath Sent: Monday, 14 December 2009 11:15 AM To: U2 Users List Subject: [U2] SELECTs on FILEs Hi all, Just a quick question on SELECTs for UD. I was under the impression that performing a wildcard SELECT with @ID would only result the key section of a FILE been read. Eg, SELECT MYFILE WITH @ID = "prefix]" Is this incorrect? Does it actually result in the entire FILE being read into memory to complete this SELECT? Regards, Dan ######################################################################## #### ############### The information transmitted in this message and attachments (if any) is intended only for the person or entity to which it is addressed. The message may contain confidential and/or privileged material. Any review, retransmission, dissemination or other use of or taking of any action in reliance upon this information by persons or entities other than the intended recipient is prohibited. If you received this in error, please contact the sender and delete the material from any computer. The intended recipient of this e-mail may only use, reproduce, disclose or distribute the information contained in this e-mail and any attached files with the permission of IMB. ######################################################################## #### ############### _______________________________________________ U2-Users mailing list [email protected] http://listserver.u2ug.org/mailman/listinfo/u2-users -- Message protected by DealerGuard: e-mail anti-virus, anti-spam and content filtering. http://www.pentanasolutions.com Click here to report this message as spam: https://login.mailguard.com.au/report/1ySixwy6Eo/3i2V58ugRT0g7JgXdX3Hyi/ 8.65 3 _______________________________________________ U2-Users mailing list [email protected] http://listserver.u2ug.org/mailman/listinfo/u2-users <html> <head> <meta http-equiv="Content-type" content="text/html; charset=UTF-8"> </head> <body> <P style="MARGIN-TOP: 0pt; MARGIN-BOTTOM: 0pt"><SPAN style="FONT-SIZE: 8.2pt; FONT-FAMILY: 'MS Sans Serif'">This e-mail and any attachments are confidential and intended solely for the use of the addressee only. If you have received this message in error, you must not copy, distribute or disclose the contents; please notify the sender immediately and delete the message. </SPAN></P> <P style="MARGIN-TOP: 0pt; MARGIN-BOTTOM: 0pt"><SPAN style="FONT-SIZE: 8.2pt; FONT-FAMILY: 'MS Sans Serif'">This message is attributed to the sender and may not necessarily reflect the view of Travis Perkins plc or its subsidiaries (Travis Perkins). Agreements binding Travis Perkins may not be concluded by means of e-mail communication. </SPAN></P> <P style="MARGIN-TOP: 0pt; MARGIN-BOTTOM: 0pt"><SPAN style="FONT-SIZE: 8.2pt; FONT-FAMILY: 'MS Sans Serif'">E-mail transmissions are not secure and Travis Perkins accepts no responsibility for changes made to this message after it was sent. Whilst steps have been taken to ensure that this message is virus free, Travis Perkins accepts no liability for infection and recommends that you scan this e-mail and any attachments. </SPAN></P> <P style="MARGIN-TOP: 0pt; MARGIN-BOTTOM: 0pt"><SPAN style="FONT-SIZE: 8.2pt; FONT-FAMILY: 'MS Sans Serif'">Part of Travis Perkins plc. Registered Office: Lodge Way House, Lodge Way, Harlestone Road, Northampton, NN5 7UG. </SPAN></P> </BODY> </HTML> _______________________________________________ U2-Users mailing list [email protected] http://listserver.u2ug.org/mailman/listinfo/u2-users ------------------------------------------------------------------------------------------- Please remember to recycle wherever possible. Reduce, reuse, recycle, think do you need to print this e-mail? ------------------------------------------------------------------------------------------- This e-mail and any attachment(s), is confidential and may be legally privileged. It is intended solely for the addressee. If you are not the addressee, dissemination, copying or use of this e-mail or any of its content is prohibited and may be unlawful. If you are not the intended recipient please inform the sender immediately and destroy the e-mail, any attachment(s) and any copies. All liability for viruses is excluded to the fullest extent permitted by law. It is your responsibility to scan or otherwise check this email and any attachment(s). Unless otherwise stated (i) views expressed in this message are those of the individual sender (ii) no contract may be construed by this e-mail. Emails may be monitored and you are taken to consent to this monitoring. Civica Services Limited, Company No. 02374268; Civica UK Limited, Company No. 01628868 Both companies are registered in England and Wales and each has its registered office at 2 Burston Road, Putney, London, SW15 6AR. ------------------------------------------------------------------------------------------- _______________________________________________ U2-Users mailing list [email protected] http://listserver.u2ug.org/mailman/listinfo/u2-users
