=back
+=head1 ROADMAP
+
+Some maintainer musings on the current state of SQL generation within DBIC as
+of Oct 2015
+
+=head2 Folding of most (or all) of L<SQL::Abstract (SQLA)|SQL::Abstract> into DBIC
+
+The rise of complex prefetch use, and the general streamlining of result
+parsing within DBIC ended up pushing the actual SQL generation to the forefront
+of many casual performance profiles. While the idea behind SQLA's API is sound,
+the actual implementation is terribly inefficient (once again bumping into the
+ridiculously high overhead of perl function calls).
+
+Given that SQLA has a B<very> distinct life on its own, and is used within an
+order of magnitude more projects compared to DBIC, it is prudent to B<not>
+disturb the current call chains within SQLA itself. Instead in the near future
+an effort will be undertaken to seek a more thorough decoupling of DBIC SQL
+generation from reliance on SQLA, possibly to a point where B<DBIC will no
+longer depend on SQLA> at all.
+
+B<The L<SQL::Abstract> library itself will continue being maintained> although
+it is not likely to gain many extra features, notably dialect support, at least
+not within the base C<SQL::Abstract> namespace.
+
+This work (if undertaken) will take into consideration the following
+constraints:
+
+=over
+
+=item Main API compatibility
+
+The object returned by C<< $schema->storage->sqlmaker >> needs to be able to
+satisfy most of the basic tests found in the current-at-the-time SQLA dist.
+While things like L<case|SQL::Abstract/case> or L<logic|SQL::Abstract/logic>
+or even worse L<convert|SQL::Abstract/convert> will definitely remain
+unsupported, the rest of the tests should pass (within reason).
+
+=item Ability to plug back an SQL::Abstract (or derivative)
+
+During the initial work on L<Data::Query> the test suite of DBIC turned out to
+be an invaluable asset to iron out hard-to-reason-about corner cases. In
+addition the test suite is much more vast and intricate than the tests of SQLA
+itself. This state of affairs is way too valuable to sacrifice in order to gain
+faster SQL generation. Thus a compile-time-ENV-check will be introduced along
+with an extra CI configuration to ensure that DBIC is used with an off-the-CPAN
+SQLA and that it continues to flawlessly run its entire test suite. While this
+will undoubtedly complicate the implementation of the better performing SQL
+generator, it will preserve both the usability of the test suite for external
+projects and will keep L<SQL::Abstract> from regressions in the future.
+
+=back
+
+Aside from these constraints it is becoming more and more practical to simply
+stop using SQLA in day-to-day production deployments of DBIC. The flexibility
+of the internals is simply not worth the performance cost.
+
+=head2 Relationship to L<Data::Query (DQ)|Data::Query>
+
+When initial work on DQ was taking place, the tools in L<::Storage::DBIHacks
- |http://github.com/dbsrgits/dbix-class/blob/current/blead/lib/DBIx/Class/Storage/DBIHacks.pm>
++|http://github.com/dbsrgits/dbix-class/blob/master/lib/DBIx/Class/Storage/DBIHacks.pm>
+were only beginning to take shape, and it wasn't clear how important they will
+become further down the road. In fact the I<regexing all over the place> was
+considered an ugly stop-gap, and even a couple of highly entertaining talks
+were given to that effect. As the use-cases of DBIC were progressing, and
+evidence for the importance of supporting arbitrary SQL was mounting, it became
+clearer that DBIC itself would not really benefit in any way from an
+integration with DQ, but on the contrary is likely to lose functionality while
+the corners of the brand new DQ codebase are sanded off.
+
+The current status of DBIC/DQ integration is that the only benefit is for DQ by
+having access to the very extensive "early adopter" test suite, in the same
+manner as early DBIC benefitted tremendously from usurping the Class::DBI test
+suite. As far as the DBIC user-base - there are no immediate practical upsides
+to DQ integration, neither in terms of API nor in performance.
+
+So (as described higher up) the DBIC development effort will in the foreseable
+future ignore the existence of DQ, and will continue optimizing the preexisting
+SQLA-based solution, potentially "organically growing" its own compatible
+implementation. Also (again, as described higher up) the ability to plug a
+separate SQLA-compatible class providing the necessary surface API will remain
+possible, and will be protected at all costs in order to continue providing DQ
+access to the test cases of DBIC.
+
+In the short term, after one more pass over the ResultSet internals is
+undertaken I<real soon now (tm)>, and before the SQLA/SQLMaker integration
+takes place, the preexisting DQ-based branches will be pulled/modified/rebased
+to get up-to-date with the current state of the codebase, which changed very
+substantially since the last migration effort, especially in the SQL
+classification meta-parsing codepath.
+
=cut
use base qw/
projects / dbsrgits/DBIx-Class.git / commitdiff