Thank you M. Hipp ! I feel that WAL is rarely used now.
It is difficult to get opinions / feedback on this feature. And for users of database servers (MySQL, Postgres, etc.). It is impossible to have a reliable database without a server. You think SQLite can handle a website / web app that has 1000 readers per day, including 200 to 300 who will write regularly? Olivier Vidal Le 3 nov. 2011 à 18:44, Richard Hipp a écrit : > On Thu, Nov 3, 2011 at 12:13 PM, Simon Slavin <slav...@bigfraud.org> wrote: > >> >> If I start getting contention issues (locks failing because of too many >> concurrent attempts at access) then I'll look into using some PRAGMAs, >> possibly switching to WAL. >> >> > Several points: > > (1) You only have to set WAL mode once for the database. The database > remembers that it is in WAL mode and all subsequent opens bring it back up > in WAL mode again (until you deliberately change it out of WAL mode.) You > do *not* have to set WAL mode every time you open the database file. > > (2) WAL really does give better concurrency since it allows other processes > to continue reading while a single process is writing to the database. In > rollback mode you can have one writer *or* multiple readers. In WAL mode > you can have one writer *and* multiple readers. On a busy system, or in a > system with long-running transactions, the difference can be significant. > > (3) Transactions commit a lot faster with WAL. Depending on your app, you > might see a measurable performance improvement just by switching to WAL. > > (4) WAL mode is much more resistant to corruption following a power failure > that occurs soon after the disk drive lied and said that content was > committed to oxide when in fact it was still in a volatile track buffer. > And pretty much all consumer-grade disk drives tell such lies these days. > > -- > D. Richard Hipp > d...@sqlite.org > _______________________________________________ > sqlite-users mailing list > sqlite-users@sqlite.org > http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users _______________________________________________ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
