First off, don't do that. REPLACE (or better, UPDATE) once. Especially in high network traffic situations, the amount of time it takes to assemble a field and value list to issue one:
UPDATE TableName SET &lcSetFieldsToValues WHERE FilterCriteria saves an enormous amount of I/O and CPU cycles: one lock, one transaction, one row re-write, one set of reindexes. Second, in VFP, all indexes have to be evaluated, as there's no backlink to which fields are used in which expressions. Indexes are defined at the table level, not the row, so can have multiple field names, functions (UPPER() or DELETED(), for example), concatentations or just random stuff. <OldWarStory> I once worked on an app where the original developer thought it would be a "clever" idea to define index expressions as UDFs. Yes, it's possible. In his UDFs, he would switch work areas, open tables if not already opened, look up values, and then return the value, cleaning up work areas and tables as he went. For every index definition for every record. A reindex with more than a couple hundred records brought the entire system to its knees. </OldWarStory> On Wed, Jan 24, 2018 at 1:29 PM, <[email protected]> wrote: > > I understand that ADDing and DELETEing records updated all indexes; I would > think the UPDATEs--regardless of what fields updated--would cause index > updates for every indexed field on every update as well. > I don't know if it actually caused *UPDATES* but I think VFP would have to go through each index expression and test to see if the value had changed. Perhaps they'd skip the write if it was unchanged. Other database engines do this differently -- Ted Roche Ted Roche & Associates, LLC http://www.tedroche.com _______________________________________________ Post Messages to: [email protected] Subscription Maintenance: http://mail.leafe.com/mailman/listinfo/profox OT-free version of this list: http://mail.leafe.com/mailman/listinfo/profoxtech Searchable Archive: http://leafe.com/archives/search/profox This message: http://leafe.com/archives/byMID/profox/cacw6n4vqfjixaq93golmpma3j8ld8_1magxrjqf3ganwngc...@mail.gmail.com ** All postings, unless explicitly stated otherwise, are the opinions of the author, and do not constitute legal or medical advice. This statement is added to the messages for those lawyers who are too stupid to see the obvious.
