On Thu, Jan 19, 2012 at 7:51 AM, John Elrick <[email protected]>wrote:
> Interesting:
>
> 1. There are no database schema changes occurring after the system is fully
> initialized
> 2. There are no ATTACHed databases (we checked that earlier)
> 3. There are no calls to VACUUM
> 4. As far as I am aware, there are no changes to any callbacks after the
> system is fully initialized.
>
> I believe your earlier note is pointing us in the right direction.
> Examining my call stacks, it appears that the query is being reparsed on
> every call to step. The question is, why? Did any of these conditions
> change between 3.6.17 and 3.7.9? Maybe we are doing something that is
> unintentionally triggering the re-parse which did not do so in the earlier
> version.
>
>
Also: Changing a bound parameter on the right-hand side of a LIKE or GLOB
operator forces a reprepare of that one statement, so that the query
optimizer can determine if the new value meets certain criteria for
optimization.
Try setting a breakpoint on sqlite3ExpirePreparedStatements() to see what
you find. Also, on these lines to check for statement expiration due to
variable rebinding:
http://www.sqlite.org/src/artifact/3662b6a468a2?ln=1024
http://www.sqlite.org/src/artifact/3662b6a468a2?ln=129
> On Thu, Jan 19, 2012 at 7:45 AM, Richard Hipp <[email protected]> wrote:
>
> > On Thu, Jan 19, 2012 at 7:41 AM, John Elrick <[email protected]
> > >wrote:
> >
> > > Question:
> > >
> > > If a query has already been prepared with sqlite3_prepare_v2, why would
> > > sqlite3_step need to call sqlite3Prepare, which in turn calls
> > > sqlite3RunParser?
> > >
> >
> > Because the database schema changed. Or because you ran ATTACH or
> VACUUM,
> > either of which could potential change the bytecode necessary to run the
> > statement. Or, because you changed the authorization callback.
> >
> >
> >
> > > _______________________________________________
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> > > [email protected]
> > > http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
> > >
> >
> >
> >
> > --
> > D. Richard Hipp
> > [email protected]
> > _______________________________________________
> > sqlite-users mailing list
> > [email protected]
> > http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
> >
>
>
>
> --
> John Elrick
> Fenestra Technologies
> 540-868-1377
> _______________________________________________
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>
--
D. Richard Hipp
[email protected]
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