As always, test any change. And, if it ain't broke, don't fix it. The key (pun intended) here is to understand how the parenthesis interact with efficiency. Sometimes I use parenthesis to force use of the better index for a particular query, by effectively ruling out the less efficient index.
Case in point is a large table with index on custid and enterdate. When I am querying for a range of entrydate's I parenthesize the custid part of the where clause WHERE (CustID) = .vCustID This is because some customer have a huge number of entries, so the date range will least frequently bog the query down. Dennis -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Tom Frederick Sent: Tuesday, May 18, 2010 9:20 AM To: RBASE-L Mailing List Subject: [RBASE-L] - RE: Expressions, Spaces, and Performance Dennis, Thanks for that one. I have always used parenthesis around variables to make them easy to stand out. Time to change. Tom Frederick Elm City Center 1314 W Walnut Jacksonville, IL 62650 O - 217-245-9504 F- 217-245-2350 Email - [email protected] -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Dennis McGrath Sent: Tuesday, May 18, 2010 8:55 AM To: RBASE-L Mailing List Subject: [RBASE-L] - RE: Expressions, Spaces, and Performance What will speed up your query is to remove the parenthesis around the variable. Both of these syntaxes prevent using the index on ZID from being used. WHERE ZID = (.vZID) WHERE (ZID) = .vZID This should be faster WHERE ZID = .vZID Dennis McGrath -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Emmitt Dove Sent: Sunday, May 16, 2010 3:50 PM To: RBASE-L Mailing List Subject: [RBASE-L] - RE: Expressions, Spaces, and Performance Tom, Short answer: no, parsing the two formattings of your SELECT should make no practical difference to how fast R:BASE runs. Emmitt Dove Manager, Converting Applications Development Evergreen Packaging, Inc. [email protected] (203) 214-5683 m (203) 643-8022 o (203) 643-8086 f [email protected] -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Tom Frederick Sent: Sunday, May 16, 2010 14:39 To: RBASE-L Mailing List Subject: [RBASE-L] - Expressions, Spaces, and Performance This seems like a pretty elementary question but does the structure of how an expression is set up have any significant effect on performance? When writing expressions, I tend to write out all words and align/box items in a consistent format that makes it easy for others to read as in the first example below. That includes me 6 months later. We are doing more wireless connections and some concern has popped up that the extra spaces/letters would effect performance speed as simply more info to process. As time has gone by my EEPs have gone from simple 20 liners to over some with well over 300 lines as we put more controls in. Have not seen any difference on the LAN, but the wireless field laptops are not the fastest machines. Using latest V8 and doing a complete jump to v9 in the next week. SELECT + Item1, Item2, ThirdThing, NumberFour + INTO + aItem1 INDICATOR a1, + aItem2 INDICATOR a2, + aThirdThing INDICATOR a3, + aNumberFour INDICATOR a4 FROM Z_MHA_Summary WHERE ZID = (.vZID) Compared to SEL Item1, Item2, ThirdThing, NumberFour INTO + aItem1 IND a1, + aItem2 IND a2, + aThirdThing IND a3, + aNumberFour IND a4 FROM Z_MHA_Summary WHERE ZID = (.vZID) Tom Frederick Jacksonville, IL
