On Wed, Jul 16, 2014 at 5:01 PM, Fernando D. Bozzo <fdbo...@gmail.com> wrote:
> The index for DELETED() is only justifiable if deleted records are more > than 20% of the total records of the DBF. > I hadn't heard that figure quoted before. This was discussed years ago in the magazines, including a great series by Mac Rubel and a wonderful article by our host Ed Leafe. In concept, the idea of having deleted tags was to avoid forcing the query engine to have to read the entire physical table in order to deterine which records applied to the result set. On very large sets, avoiding a lot of unnecessary reads would result in significant speedup. However, it depends on so many factors: network latency, bandwidth and saturation, disk(s) speed and seek time, amount of fragmentation, how much of the table is already cached, size of the table, block size and so forth. The most important point to remember is this: you must test your technique on your data, on your network, under the real workload that the application will experience. Otherwise, we are all just speculating. > Not always the "full optimize" is the best option, and sometimes it takes > more time than without this index. > True! -- Ted Roche Ted Roche & Associates, LLC http://www.tedroche.com --- StripMime Report -- processed MIME parts --- multipart/alternative text/plain (text body -- kept) text/html --- _______________________________________________ Post Messages to: ProFox@leafe.com 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/cacw6n4tf7eku97kx+pshnagphua1trxoy+9ustq0bfnha4v...@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.
