DBIx::Class::Storage::DBIHacks;
#
-# This module contains code that should never have seen the light of day,
-# does not belong in the Storage, or is otherwise unfit for public
-# display. The arrival of SQLA2 should immediately obsolete 90% of this
+# This module contains code supporting a battery of special cases and tests for
+# many corner cases pushing the envelope of what DBIC can do. When work on
+# these utilities began in mid 2009 (51a296b402c) it wasn't immediately obvious
+# that these pieces, despite their misleading on-first-sighe-flakiness, will
+# become part of the generic query rewriting machinery of DBIC, allowing it to
+# both generate and process queries representing incredibly complex sets with
+# reasonable efficiency.
+#
+# Now (end of 2015), more than 6 years later the routines in this class have
+# stabilized enough, and are meticulously covered with tests, to a point where
+# an effort to formalize them into user-facing APIs might be worthwhile.
+#
+# An implementor working on publicizing and/or replacing the routines with a
+# more modern SQL generation framework should keep in mind that pretty much all
+# existing tests are constructed on the basis of real-world code used in
+# production somewhere.
+#
+# Please hack on this responsibly ;)
#
use strict;
use base 'DBIx::Class::Storage';
use mro 'c3';
-use List::Util 'first';
use Scalar::Util 'blessed';
-use DBIx::Class::_Util qw(UNRESOLVABLE_CONDITION serialize);
+use DBIx::Class::_Util qw(UNRESOLVABLE_CONDITION serialize dump_value);
use SQL::Abstract qw(is_plain_value is_literal_value);
use DBIx::Class::Carp;
use namespace::clean;
$self->_use_join_optimizer
);
- my $orig_aliastypes = $self->_resolve_aliastypes_from_select_args($attrs);
+ my $orig_aliastypes =
+ $attrs->{_precalculated_aliastypes}
+ ||
+ $self->_resolve_aliastypes_from_select_args($attrs)
+ ;
my $new_aliastypes = { %$orig_aliastypes };
push @{$inner_attrs->{as}}, $attrs->{as}[$i];
}
- # We will need to fetch all native columns in the inner subquery, which may
+ my $inner_aliastypes = $self->_resolve_aliastypes_from_select_args($inner_attrs);
+
+ # In the inner subq we will need to fetch *only* native columns which may
# be a part of an *outer* join condition, or an order_by (which needs to be
# preserved outside), or wheres. In other words everything but the inner
# selector
# We can not just fetch everything because a potential has_many restricting
# join collapse *will not work* on heavy data types.
- my $connecting_aliastypes = $self->_resolve_aliastypes_from_select_args({
- %$inner_attrs,
- select => [],
- });
- for (sort map { keys %{$_->{-seen_columns}||{}} } map { values %$_ } values %$connecting_aliastypes) {
+ # essentially a map of all non-selecting seen columns
+ # the sort is there for a nicer select list
+ for (
+ sort
+ map
+ { keys %{$_->{-seen_columns}||{}} }
+ map
+ { values %{$inner_aliastypes->{$_}} }
+ grep
+ { $_ ne 'selecting' }
+ keys %$inner_aliastypes
+ ) {
my $ci = $colinfo->{$_} or next;
if (
$ci->{-source_alias} eq $root_alias
local $self->{_use_join_optimizer} = 1;
# throw away multijoins since we def. do not care about those inside the subquery
- ($inner_attrs->{from}, my $inner_aliastypes) = $self->_prune_unused_joins ({
- %$inner_attrs, _force_prune_multiplying_joins => 1
+ # $inner_aliastypes *will* be redefined at this point
+ ($inner_attrs->{from}, $inner_aliastypes ) = $self->_prune_unused_joins ({
+ %$inner_attrs,
+ _force_prune_multiplying_joins => 1,
+ _precalculated_aliastypes => $inner_aliastypes,
});
# uh-oh a multiplier (which is not us) left in, this is a problem for limits
) {
push @outer_from, $j
}
- elsif (first { $_->{$alias} } @outer_nonselecting_chains ) {
+ elsif (grep { $_->{$alias} } @outer_nonselecting_chains ) {
push @outer_from, $j;
$may_need_outer_group_by ||= $outer_aliastypes->{multiplying}{$alias} ? 1 : 0;
}
});
}
- # This is totally horrific - the {where} ends up in both the inner and outer query
- # Unfortunately not much can be done until SQLA2 introspection arrives, and even
- # then if where conditions apply to the *right* side of the prefetch, you may have
- # to both filter the inner select (e.g. to apply a limit) and then have to re-filter
- # the outer select to exclude joins you didn't want in the first place
+ # FIXME: The {where} ends up in both the inner and outer query, i.e. *twice*
+ #
+ # This is rather horrific, and while we currently *do* have enough
+ # introspection tooling available to attempt a stab at properly deciding
+ # whether or not to include the where condition on the outside, the
+ # machinery is still too slow to apply it here.
+ # Thus for the time being we do not attempt any sanitation of the where
+ # clause and just pass it through on both sides of the subquery. This *will*
+ # be addressed at a later stage, most likely after folding the SQL generator
+ # into SQLMaker proper
#
# OTOH it can be seen as a plus: <ash> (notes that this query would make a DBA cry ;)
+ #
return $outer_attrs;
}
+# This is probably the ickiest, yet most relied upon part of the codebase:
+# this is the place where we take arbitrary SQL input and break it into its
+# constituent parts, making sure we know which *sources* are used in what
+# *capacity* ( selecting / restricting / grouping / ordering / joining, etc )
+# Although the method is pretty horrific, the worst thing that can happen is
+# for a classification failure, which in turn will result in a vocal exception,
+# and will lead to a relatively prompt fix.
+# The code has been slowly improving and is covered with a formiddable battery
+# of tests, so can be considered "reliably stable" at this point (Oct 2015).
+#
+# A note to implementors attempting to "replace" this - keep in mind that while
+# there are multiple optimization avenues, the actual "scan literal elements"
+# part *MAY NEVER BE REMOVED*, even if it is limited only ot the (future) AST
+# nodes that are deemed opaque (i.e. contain literal expressions). The use of
+# blackbox literals is at this point firmly a user-facing API, and is one of
+# *the* reasons DBIC remains as flexible as it is. In other words, when working
+# on this keep in mind that the following is widespread and *encouraged* way
+# of using DBIC in the wild when push comes to shove:
+#
+# $rs->search( {}, {
+# select => \[ $random, @stuff],
+# from => \[ $random, @stuff ],
+# where => \[ $random, @stuff ],
+# group_by => \[ $random, @stuff ],
+# order_by => \[ $random, @stuff ],
+# } )
#
-# I KNOW THIS SUCKS! GET SQLA2 OUT THE DOOR SO THIS CAN DIE!
+# Various incarnations of the above are reflected in many of the tests. If one
+# gets to fail, you get to fix it. A "this is crazy, nobody does that" is not
+# acceptable going forward.
#
-# Due to a lack of SQLA2 we fall back to crude scans of all the
-# select/where/order/group attributes, in order to determine what
-# aliases are needed to fulfill the query. This information is used
-# throughout the code to prune unnecessary JOINs from the queries
-# in an attempt to reduce the execution time.
-# Although the method is pretty horrific, the worst thing that can
-# happen is for it to fail due to some scalar SQL, which in turn will
-# result in a vocal exception.
sub _resolve_aliastypes_from_select_args {
my ( $self, $attrs ) = @_;
],
};
+ # we will be bulk-scanning anyway - pieces will not matter in that case,
+ # thus join everything up
# throw away empty-string chunks, and make sure no binds snuck in
# note that we operate over @{$to_scan->{$type}}, hence the
# semi-mindbending ... map ... for values ...
- ( $_ = [ map {
+ ( $_ = join ' ', map {
- (not $_) ? ()
- : (length ref $_) ? (require Data::Dumper::Concise && $self->throw_exception(
- "Unexpected ref in scan-plan: " . Data::Dumper::Concise::Dumper($_)
- ))
- : $_
+ ( ! defined $_ ) ? ()
+ : ( length ref $_ ) ? $self->throw_exception(
+ "Unexpected ref in scan-plan: " . dump_value $_
+ )
+ : ( $_ =~ /^\s*$/ ) ? ()
+ : $_
- } @$_ ] ) for values %$to_scan;
+ } @$_ ) for values %$to_scan;
# throw away empty to-scan's
(
- @{$to_scan->{$_}}
+ length $to_scan->{$_}
or
delete $to_scan->{$_}
) for keys %$to_scan;
+
+ # these will be used for matching in the loop below
+ my $all_aliases = join ' | ', map { quotemeta $_ } keys %$alias_list;
+ my $fq_col_re = qr/
+ $lquote ( $all_aliases ) $rquote $sep (?: $lquote ([^$rquote]+) $rquote )?
+ |
+ \b ( $all_aliases ) \. ( [^\s\)\($rquote]+ )?
+ /x;
+
+
+ my $all_unq_columns = join ' | ',
+ map
+ { quotemeta $_ }
+ grep
+ # using a regex here shows up on profiles, boggle
+ { index( $_, '.') < 0 }
+ keys %$colinfo
+ ;
+ my $unq_col_re = $all_unq_columns
+ ? qr/
+ $lquote ( $all_unq_columns ) $rquote
+ |
+ (?: \A | \s ) ( $all_unq_columns ) (?: \s | \z )
+ /x
+ : undef
+ ;
+
+
# the actual scan, per type
for my $type (keys %$to_scan) {
- # first see if we have any exact matches (qualified or unqualified)
- for my $piece (@{$to_scan->{$type}}) {
- if ($colinfo->{$piece} and my $alias = $colinfo->{$piece}{-source_alias}) {
- $aliases_by_type->{$type}{$alias} ||= { -parents => $alias_list->{$alias}{-join_path}||[] };
- $aliases_by_type->{$type}{$alias}{-seen_columns}{$colinfo->{$piece}{-fq_colname}} = $piece;
- }
- }
-
- # we will be bulk-scanning anyway - pieces will not matter in that case
- # (unlike in the direct-equivalence above)
- my $scan_string = join ' ', @{$to_scan->{$type}};
# now loop through all fully qualified columns and get the corresponding
# alias (should work even if they are in scalarrefs)
- for my $alias (keys %$alias_list) {
- my $al_re = qr/
- $lquote $alias $rquote $sep (?: $lquote ([^$rquote]+) $rquote )?
- |
- \b $alias \. ([^\s\)\($rquote]+)?
- /x;
-
- if (my @matches = $scan_string =~ /$al_re/g) {
- $aliases_by_type->{$type}{$alias} ||= { -parents => $alias_list->{$alias}{-join_path}||[] };
- $aliases_by_type->{$type}{$alias}{-seen_columns}{"$alias.$_"} = "$alias.$_"
- for grep { defined $_ } @matches;
+ #
+ # The regex captures in multiples of 4, with one of the two pairs being
+ # undef. There may be a *lot* of matches, hence the convoluted loop
+ my @matches = $to_scan->{$type} =~ /$fq_col_re/g;
+ my $i = 0;
+ while( $i < $#matches ) {
+
+ if (
+ defined $matches[$i]
+ ) {
+ $aliases_by_type->{$type}{$matches[$i]} ||= { -parents => $alias_list->{$matches[$i]}{-join_path}||[] };
+
+ $aliases_by_type->{$type}{$matches[$i]}{-seen_columns}{"$matches[$i].$matches[$i+1]"} = "$matches[$i].$matches[$i+1]"
+ if defined $matches[$i+1];
+
+ $i += 2;
}
- }
- # now loop through unqualified column names, and try to locate them within
- # the chunks
- for my $col (keys %$colinfo) {
- next if $col =~ / \. /x; # if column is qualified it was caught by the above
+ $i += 2;
+ }
- my $col_re = qr/ $lquote ($col) $rquote /x;
- if ( my @matches = $scan_string =~ /$col_re/g) {
- my $alias = $colinfo->{$col}{-source_alias};
- $aliases_by_type->{$type}{$alias} ||= { -parents => $alias_list->{$alias}{-join_path}||[] };
- $aliases_by_type->{$type}{$alias}{-seen_columns}{"$alias.$_"} = $_
- for grep { defined $_ } @matches;
- }
+ # now loop through unqualified column names, and try to locate them within
+ # the chunks, if there are any unqualified columns in the 1st place
+ next unless $unq_col_re;
+
+ # The regex captures in multiples of 2, one of the two being undef
+ for ( $to_scan->{$type} =~ /$unq_col_re/g ) {
+ defined $_ or next;
+ my $alias = $colinfo->{$_}{-source_alias} or next;
+ $aliases_by_type->{$type}{$alias} ||= { -parents => $alias_list->{$alias}{-join_path}||[] };
+ $aliases_by_type->{$type}{$alias}{-seen_columns}{"$alias.$_"} = $_
}
}
+
# Add any non-left joins to the restriction list (such joins are indeed restrictions)
(
$_->{-alias}
$aliases_by_type->{restricting}{ $_->{-alias} } = { -parents => $_->{-join_path}||[] }
) for values %$alias_list;
+
# final cleanup
(
keys %{$aliases_by_type->{$_}}
delete $aliases_by_type->{$_}
) for keys %$aliases_by_type;
+
$aliases_by_type;
}
# of the external order and convert them to MIN(X) for ASC or MAX(X)
# for DESC, and group_by the root columns. The end result should be
# exactly what we expect
+ #
- # FIXME - this code is a joke, will need to be completely rewritten in
- # the DQ branch. But I need to push a POC here, otherwise the
- # pesky tests won't pass
- # wrap any part of the order_by that "responds" to an ordering alias
- # into a MIN/MAX
+ # both populated on the first loop over $o_idx
$sql_maker ||= $self->sql_maker;
$order_chunks ||= [
map { ref $_ eq 'ARRAY' ? $_ : [ $_ ] } $sql_maker->_order_by_chunks($attrs->{order_by})
];
+ # FIXME: MIN/MAX can't handle NULLS FIRST/LAST
my ($chunk, $is_desc) = $sql_maker->_split_order_chunk($order_chunks->[$o_idx][0]);
+ # we reached that far - wrap any part of the order_by that "responded"
+ # to an ordering alias into a MIN/MAX
$new_order_by[$o_idx] = \[
sprintf( '%s( %s )%s',
- ($is_desc ? 'MAX' : 'MIN'),
+ $self->_minmax_operator_for_datatype($chunk_ci->{data_type}, $is_desc),
$chunk,
($is_desc ? ' DESC' : ''),
),
);
}
+sub _minmax_operator_for_datatype {
+ #my ($self, $datatype, $want_max) = @_;
+
+ $_[2] ? 'MAX' : 'MIN';
+}
+
sub _resolve_ident_sources {
my ($self, $ident) = @_;
return {} if $colnames and ! @$colnames;
- my $alias2src = $self->_resolve_ident_sources($ident);
+ my $sources = $self->_resolve_ident_sources($ident);
+
+ $_ = { rsrc => $_, colinfos => $_->columns_info }
+ for values %$sources;
my (%seen_cols, @auto_colnames);
# compile a global list of column names, to be able to properly
# disambiguate unqualified column names (if at all possible)
- for my $alias (keys %$alias2src) {
- my $rsrc = $alias2src->{$alias};
- for my $colname ($rsrc->columns) {
- push @{$seen_cols{$colname}}, $alias;
- push @auto_colnames, "$alias.$colname" unless $colnames;
- }
+ for my $alias (keys %$sources) {
+ (
+ ++$seen_cols{$_}{$alias}
+ and
+ ! $colnames
+ and
+ push @auto_colnames, "$alias.$_"
+ ) for keys %{ $sources->{$alias}{colinfos} };
}
$colnames ||= [
@auto_colnames,
- grep { @{$seen_cols{$_}} == 1 } (keys %seen_cols),
+ ( grep { keys %{$seen_cols{$_}} == 1 } keys %seen_cols ),
];
- my (%return, $colinfos);
- foreach my $col (@$colnames) {
- my ($source_alias, $colname) = $col =~ m/^ (?: ([^\.]+) \. )? (.+) $/x;
-
- # if the column was seen exactly once - we know which rsrc it came from
- $source_alias ||= $seen_cols{$colname}[0]
- if ($seen_cols{$colname} and @{$seen_cols{$colname}} == 1);
+ my %return;
+ for (@$colnames) {
+ my ($colname, $source_alias) = reverse split /\./, $_;
- next unless $source_alias;
+ my $assumed_alias =
+ $source_alias
+ ||
+ # if the column was seen exactly once - we know which rsrc it came from
+ (
+ $seen_cols{$colname}
+ and
+ keys %{$seen_cols{$colname}} == 1
+ and
+ ( %{$seen_cols{$colname}} )[0]
+ )
+ ||
+ next
+ ;
- my $rsrc = $alias2src->{$source_alias}
- or next;
+ $self->throw_exception(
+ "No such column '$colname' on source " . $sources->{$assumed_alias}{rsrc}->source_name
+ ) unless $seen_cols{$colname}{$assumed_alias};
- $return{$col} = {
- %{
- ( $colinfos->{$source_alias} ||= $rsrc->columns_info )->{$colname}
- ||
- $self->throw_exception(
- "No such column '$colname' on source " . $rsrc->source_name
- );
- },
- -result_source => $rsrc,
- -source_alias => $source_alias,
- -fq_colname => $col eq $colname ? "$source_alias.$col" : $col,
+ $return{$_} = {
+ %{ $sources->{$assumed_alias}{colinfos}{$colname} },
+ -result_source => $sources->{$assumed_alias}{rsrc},
+ -source_alias => $assumed_alias,
+ -fq_colname => "$assumed_alias.$colname",
-colname => $colname,
};
- $return{"$source_alias.$colname"} = $return{$col} if $col eq $colname;
+ $return{"$assumed_alias.$colname"} = $return{$_}
+ unless $source_alias;
}
return \%return;
# resultset {where} stacks
#
# FIXME - while relatively robust, this is still imperfect, one of the first
-# things to tackle with DQ
+# things to tackle when we get access to a formalized AST. Note that this code
+# is covered by a *ridiculous* amount of tests, so starting with porting this
+# code would be a rather good exercise
sub _collapse_cond {
my ($self, $where, $where_is_anded_array) = @_;
for (sort keys %$chunk) {
# Match SQLA 1.79 behavior
- if ($_ eq '') {
+ unless( length $_ ) {
is_literal_value($chunk->{$_})
? carp 'Hash-pairs consisting of an empty string with a literal are deprecated, use -and => [ $literal ] instead'
: $self->throw_exception("Supplying an empty left hand side argument is not supported in hash-pairs")
# Match SQLA 1.79 behavior
$self->throw_exception("Supplying an empty left hand side argument is not supported in array-pairs")
- if $where_is_anded_array and (! defined $chunk or $chunk eq '');
+ if $where_is_anded_array and (! defined $chunk or ! length $chunk);
push @pairs, $chunk, shift @pieces;
}
while (@$pairs) {
my ($lhs, $rhs) = splice @$pairs, 0, 2;
- if ($lhs eq '') {
+ if (! length $lhs) {
push @conds, $self->_collapse_cond($rhs);
}
elsif ( $lhs =~ /^\-and$/i ) {
# extra sanity check
if (keys %$p > 1) {
- require Data::Dumper::Concise;
local $Data::Dumper::Deepcopy = 1;
$self->throw_exception(
"Internal error: unexpected collapse unroll:"
- . Data::Dumper::Concise::Dumper { in => { $lhs => $rhs }, out => $p }
+ . dump_value { in => { $lhs => $rhs }, out => $p }
);
}
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