On Tue, Jun 11, 2013 at 9:08 AM, Igor Tandetnik <i...@tandetnik.org> wrote:
> On 6/11/2013 9:01 AM, Simon Slavin wrote: > >> The only time that _prepare() will use a lot of memory is when it has to >> generate a temporary index because you have not created a table index >> suitable for the WHERE and ORDER BY clauses. >> > > I'm pretty sure this would happen on the first _step(), not on _prepare(). > Prepare is always nearly instantaneous. > Correct. Think of sqlite3_prepare() as the compiler that converts your SQL program into machine language (really byte-code in the case of SQLite). sqlite3_step() runs your program up to the next breakpoint, which is the spot in which the first row of output is computed, or until the program exits. SQLITE_ROW is returned if it hits a breakpoint and SQLITE_DONE is returned on exit. Creating of temporary indices happen when the program is run, not when it is compiled. That means it happens during sqlite3_step(). sqlite3_prepare() == running the compiler sqlite3_step() == running the compiled binary NB: There are some PRAGMA statements that cheat and take effect during the compilation step. But all "regular" SQL statements obey the rules above. -- D. Richard Hipp d...@sqlite.org _______________________________________________ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
