> > a normal DB where writing does not happen often I would suggest a SSD... > but anything with a very active read/write cycle is best avoided
If you were to quantify this, would you say that "active" starts at once per second, many times per second, once a min or...? On Mon, Mar 3, 2014 at 3:47 PM, RSmith <rsm...@rsweb.co.za> wrote: > > On 2014/03/03 23:11, romtek wrote: > >> Simon, does a real disk have to be a rotating hard disk? Is there problem >> with SSDs as far as SQLite is concerned? >> > > No, what Simon is trying to point out is simply that the write performance > experienced by L. Wood might be because journal writes might be synced to > hard disk (in rotating disk cases anyway) and as such cause delays all > throughout the transaction even if they are not holding up the final > commit. Not because this is in error or wrong in any way, simply as trying > to explain why he sees the performance spread he sees. > > Other reasons might be excessively large binds causing the cache to spill > or simply have memory writes taking so long that it seems to cause > inter-transaction delays, although if that were the case one would expect > the final commit to take a lot longer even. > > My money is still on the specific pragmas used which might be forcing > syncs or non-ACID operation. We would need to have the DB schema and the > typical query to really test why it works the way it works in his case. > > > One note on SSD's, they pose no physical problem to SQLite, and in fact > works magically fast, but having a DB which read/write a LOT of data on > them is not really great since the repeated read-write cycle of specific > data areas tire down the typical NAND flash that makes up the SSD, even > though modern SSDs may use MLC NAND or have firmware that tries to exercise > every bit in memory equally so as to spread the write operations to avoid > one piece of disk-memory dying quickly. Eventually though, when all bits of > memory experienced upwards of 500K write operations (which is quite a > while), it will fail... but you will have lots of warning. A read-only DB > on an SSD drive cannot be beaten... even a normal DB where writing does not > happen often I would suggest a SSD... but anything with a very active > read/write cycle is best avoided - or at a minimum backed up by a good old > rotating magnetic platter drive. > > > _______________________________________________ > 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
