Alex Katebi <[EMAIL PROTECTED]> wrote: > Do I need to enable shared cache mode plus read uncommitted option?
You only have one connection (one call to sqlite3_open), right? Then it doesn't matter. "Shared" only makes a difference if there are at least two connections to share between. > Also you mentioned earlier: > "(but you will experience "dirty reads" with all the attendant > problems)." > > What is a dirty read? What problems does it cause? Dirty read is another term for read uncommitted. Your select statement may see changes made to the database while the statement is still active. This is especially "interesting" if you have a query that may scan the same table several times. For example: select * from table1 where exists (select * from table2 where table2.value = table1.value); Suppose you have two records in table1 both having value=1 - let's call them A and B. Looking at the statement, one would think that, regardless of what's in table2, it should always return both A and B, or neither. So, you step through the statement above. For each record in table1, it scans table2 in search of a matching record. At some point, a call to sqlite3_step returns record A. Then you run another statement that deletes one and only record from table2 that had value=1. A subsequent sqlite3_step call won't find record B anymore. So you get A but not B, which may be surprising. Igor Tandetnik _______________________________________________ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
