X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=lib%2FDBIx%2FClass%2FSQLMaker.pm;h=9b140c172c371776e1cd395126123ed64e545262;hb=02562a2092543488bba4ccd98c39abca72560555;hp=791e4fc4782ca5e683c3cadf4b221f77161a32a8;hpb=1efc866d8235ddd640d956352d59036a1cd3bbd7;p=dbsrgits%2FDBIx-Class.git diff --git a/lib/DBIx/Class/SQLMaker.pm b/lib/DBIx/Class/SQLMaker.pm index 791e4fc..9b140c1 100644 --- a/lib/DBIx/Class/SQLMaker.pm +++ b/lib/DBIx/Class/SQLMaker.pm @@ -9,13 +9,13 @@ DBIx::Class::SQLMaker - An SQL::Abstract-based SQL maker class =head1 DESCRIPTION -This module is a subclass of L and includes a number of -DBIC-specific workarounds, not yet suitable for inclusion into the +This module is currently a subclass of L and includes a number of +DBIC-specific extensions/workarounds, not suitable for inclusion into the L core. It also provides all (and more than) the functionality of L, see L for more info. -Currently the enhancements to L are: +Currently the enhancements over L are: =over @@ -25,10 +25,102 @@ Currently the enhancements to L are: =item * C/C support (via extensions to the order_by parameter) +=item * A rudimentary multicolumn IN operator + =item * Support of C<...FOR UPDATE> type of select statement modifiers =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 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 distinct life on its own, and is used within an +order of magnitude more projects compared to DBIC, it is prudent to B +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 at all. + +B 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 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 or L +or even worse L 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 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 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 + +When initial work on DQ was taking place, the tools in L<::Storage::DBIHacks +|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 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, 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/ @@ -38,8 +130,9 @@ use base qw/ /; use mro 'c3'; -use Sub::Name 'subname'; use DBIx::Class::Carp; +use DBIx::Class::_Util 'set_subname'; +use SQL::Abstract 'is_literal_value'; use namespace::clean; __PACKAGE__->mk_group_accessors (simple => qw/quote_char name_sep limit_dialect/); @@ -69,12 +162,12 @@ BEGIN { # that use DBIx::Class::Carp/DBIx::Class::Exception instead of plain Carp no warnings qw/redefine/; - *SQL::Abstract::belch = subname 'SQL::Abstract::belch' => sub (@) { + *SQL::Abstract::belch = set_subname 'SQL::Abstract::belch' => sub (@) { my($func) = (caller(1))[3]; carp "[$func] Warning: ", @_; }; - *SQL::Abstract::puke = subname 'SQL::Abstract::puke' => sub (@) { + *SQL::Abstract::puke = set_subname 'SQL::Abstract::puke' => sub (@) { my($func) = (caller(1))[3]; __PACKAGE__->throw_exception("[$func] Fatal: " . join ('', @_)); }; @@ -99,7 +192,7 @@ sub _assert_bindval_matches_bindtype () { 1 }; # poor man's de-qualifier sub _quote { - $_[0]->next::method( ( $_[0]{_dequalify_idents} and ! ref $_[1] ) + $_[0]->next::method( ( $_[0]{_dequalify_idents} and defined $_[1] and ! ref $_[1] ) ? $_[1] =~ / ([^\.]+) $ /x : $_[1] ); @@ -117,18 +210,38 @@ sub _where_op_NEST { sub select { my ($self, $table, $fields, $where, $rs_attrs, $limit, $offset) = @_; + ($fields, @{$self->{select_bind}}) = length ref $fields + ? $self->_recurse_fields( $fields ) + : $self->_quote( $fields ) + ; - ($fields, @{$self->{select_bind}}) = $self->_recurse_fields($fields); + # Override the default behavior of SQL::Abstract - SELECT * makes + # no sense in the context of DBIC (and has resulted in several + # tricky debugging sessions in the past) + not length $fields + and +# FIXME - some day we need to enable this, but too many things break +# ( notably S::L ) +# # Random value selected by a fair roll of dice +# # In seriousness - this has to be a number, as it is much more +# # palatable to random engines in a SELECT list +# $fields = 42 +# and + carp_unique ( + "ResultSets with an empty selection are deprecated (you almost certainly " + . "did not mean to do that): if this is indeed your intent you must " + . "explicitly supply \\'*' to your search()" + ); if (defined $offset) { $self->throw_exception('A supplied offset must be a non-negative integer') - if ( $offset =~ /\D/ or $offset < 0 ); + if ( $offset =~ /[^0-9]/ or $offset < 0 ); } $offset ||= 0; if (defined $limit) { $self->throw_exception('A supplied limit must be a positive integer') - if ( $limit =~ /\D/ or $limit <= 0 ); + if ( $limit =~ /[^0-9]/ or $limit <= 0 ); } elsif ($offset) { $limit = $self->__max_int; @@ -146,8 +259,9 @@ sub select { if( $limiter = $self->can ('emulate_limit') ) { carp_unique( 'Support for the legacy emulate_limit() mechanism inherited from ' - . 'SQL::Abstract::Limit has been deprecated, and will be removed when ' - . 'DBIC transitions to Data::Query. If your code uses this type of ' + . 'SQL::Abstract::Limit has been deprecated, and will be removed at ' + . 'some future point, as it gets in the way of architectural and/or ' + . 'performance advances within DBIC. If your code uses this type of ' . 'limit specification please file an RT and provide the source of ' . 'your emulate_limit() implementation, so an acceptable upgrade-path ' . 'can be devised' @@ -211,9 +325,9 @@ sub insert { # optimized due to hotttnesss # my ($self, $table, $data, $options) = @_; - # SQLA will emit INSERT INTO $table ( ) VALUES ( ) + # FIXME SQLA will emit INSERT INTO $table ( ) VALUES ( ) # which is sadly understood only by MySQL. Change default behavior here, - # until SQLA2 comes with proper dialect support + # until we fold the extra pieces into SQLMaker properly if (! $_[2] or (ref $_[2] eq 'HASH' and !keys %{$_[2]} ) ) { my @bind; my $sql = sprintf( @@ -234,20 +348,31 @@ sub insert { sub _recurse_fields { my ($self, $fields) = @_; - my $ref = ref $fields; - return $self->_quote($fields) unless $ref; - return $$fields if $ref eq 'SCALAR'; - - if ($ref eq 'ARRAY') { - my (@select, @bind); - for my $field (@$fields) { - my ($select, @new_bind) = $self->_recurse_fields($field); - push @select, $select; - push @bind, @new_bind; - } + + if( not length ref $fields ) { + return $self->_quote( $fields ); + } + + elsif( my $lit = is_literal_value( $fields ) ) { + return @$lit + } + + elsif( ref $fields eq 'ARRAY' ) { + my (@select, @bind, @bind_fragment); + + ( + ( $select[ $#select + 1 ], @bind_fragment ) = length ref $_ + ? $self->_recurse_fields( $_ ) + : $self->_quote( $_ ) + ), + ( push @bind, @bind_fragment ) + for @$fields; + return (join(', ', @select), @bind); } - elsif ($ref eq 'HASH') { + + # FIXME - really crappy handling of functions + elsif ( ref $fields eq 'HASH') { my %hash = %$fields; # shallow copy my $as = delete $hash{-as}; # if supplied @@ -255,34 +380,41 @@ sub _recurse_fields { my ($func, $rhs, @toomany) = %hash; # there should be only one pair - if (@toomany) { - $self->throw_exception( "Malformed select argument - too many keys in hash: " . join (',', keys %$fields ) ); - } - - if (lc ($func) eq 'distinct' && ref $rhs eq 'ARRAY' && @$rhs > 1) { - $self->throw_exception ( - 'The select => { distinct => ... } syntax is not supported for multiple columns.' - .' Instead please use { group_by => [ qw/' . (join ' ', @$rhs) . '/ ] }' - .' or { select => [ qw/' . (join ' ', @$rhs) . '/ ], distinct => 1 }' - ); - } - - my ($rhs_sql, @rhs_bind) = $self->_recurse_fields($rhs); - my $select = sprintf ('%s( %s )%s', - $self->_sqlcase($func), - $rhs_sql, - $as - ? sprintf (' %s %s', $self->_sqlcase('as'), $self->_quote ($as) ) - : '' + $self->throw_exception( + "Malformed select argument - too many keys in hash: " . join (',', keys %$fields ) + ) if @toomany; + + $self->throw_exception ( + 'The select => { distinct => ... } syntax is not supported for multiple columns.' + .' Instead please use { group_by => [ qw/' . (join ' ', @$rhs) . '/ ] }' + .' or { select => [ qw/' . (join ' ', @$rhs) . '/ ], distinct => 1 }' + ) if ( + lc ($func) eq 'distinct' + and + ref $rhs eq 'ARRAY' + and + @$rhs > 1 ); - return ($select, @rhs_bind); - } - elsif ( $ref eq 'REF' and ref($$fields) eq 'ARRAY' ) { - return @{$$fields}; + my ($rhs_sql, @rhs_bind) = length ref $rhs + ? $self->_recurse_fields($rhs) + : $self->_quote($rhs) + ; + + return( + sprintf( '%s( %s )%s', + $self->_sqlcase($func), + $rhs_sql, + $as + ? sprintf (' %s %s', $self->_sqlcase('as'), $self->_quote ($as) ) + : '' + ), + @rhs_bind + ); } + else { - $self->throw_exception( $ref . qq{ unexpected in _recurse_fields()} ); + $self->throw_exception( ref($fields) . ' unexpected in _recurse_fields()' ); } } @@ -294,26 +426,36 @@ sub _recurse_fields { # things in the SQLA space need to have more info about the $rs they # create SQL for. The alternative would be to keep expanding the # signature of _select with more and more positional parameters, which -# is just gross. All hail SQLA2! +# is just gross. +# +# FIXME - this will have to transition out to a subclass when the effort +# of folding the SQLA machinery into SQLMaker takes place sub _parse_rs_attrs { my ($self, $arg) = @_; my $sql = ''; + my @sqlbind; - if ($arg->{group_by}) { - if ( my ($group_sql, @group_bind) = $self->_recurse_fields($arg->{group_by}) ) { - $sql .= $self->_sqlcase(' group by ') . $group_sql; - push @{$self->{group_bind}}, @group_bind; - } + if ( + $arg->{group_by} + and + @sqlbind = $self->_recurse_fields($arg->{group_by}) + ) { + $sql .= $self->_sqlcase(' group by ') . shift @sqlbind; + push @{$self->{group_bind}}, @sqlbind; } - if (defined $arg->{having}) { - my ($frag, @bind) = $self->_recurse_where($arg->{having}); - push(@{$self->{having_bind}}, @bind); - $sql .= $self->_sqlcase(' having ') . $frag; + if ( + $arg->{having} + and + @sqlbind = $self->_recurse_where($arg->{having}) + ) { + $sql .= $self->_sqlcase(' having ') . shift @sqlbind; + push(@{$self->{having_bind}}, @sqlbind); } - if (defined $arg->{order_by}) { + if ($arg->{order_by}) { + # unlike the 2 above, _order_by injects into @{...bind...} for us $sql .= $self->_order_by ($arg->{order_by}); } @@ -324,14 +466,18 @@ sub _order_by { my ($self, $arg) = @_; # check that we are not called in legacy mode (order_by as 4th argument) - if (ref $arg eq 'HASH' and not grep { $_ =~ /^-(?:desc|asc)/i } keys %$arg ) { - return $self->_parse_rs_attrs ($arg); - } - else { - my ($sql, @bind) = $self->next::method($arg); - push @{$self->{order_bind}}, @bind; - return $sql; - } + ( + ref $arg eq 'HASH' + and + not grep { $_ =~ /^-(?:desc|asc)/i } keys %$arg + ) + ? $self->_parse_rs_attrs ($arg) + : do { + my ($sql, @bind) = $self->next::method($arg); + push @{$self->{order_bind}}, @bind; + $sql; # RV + } + ; } sub _split_order_chunk { @@ -484,9 +630,14 @@ sub _join_condition { return $self->_recurse_where($cond); } -# This is hideously ugly, but SQLA does not understand multicol IN expressions -# FIXME TEMPORARY - DQ should have native syntax for this -# moved here to raise API questions +# !!! EXPERIMENTAL API !!! WILL CHANGE !!! +# +# This is rather odd, but vanilla SQLA does not have support for multicolumn IN +# expressions +# Currently has only one callsite in ResultSet, body moved into this subclass +# of SQLA to raise API questions like: +# - how do we convey a list of idents...? +# - can binds reside on lhs? # # !!! EXPERIMENTAL API !!! WILL CHANGE !!! sub _where_op_multicolumn_in { @@ -533,14 +684,17 @@ sub _where_op_multicolumn_in { \[ join( ' IN ', shift @$$lhs, shift @$$rhs ), @$$lhs, @$$rhs ]; } -1; +=head1 FURTHER QUESTIONS? -=head1 AUTHORS +Check the list of L. -See L. +=head1 COPYRIGHT AND LICENSE -=head1 LICENSE - -You may distribute this code under the same terms as Perl itself. +This module is free software L +by the L. You can +redistribute it and/or modify it under the same terms as the +L. =cut + +1;