package #hide from PAUSE
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
#
use strict;
use warnings;
use base 'DBIx::Class::Storage';
use mro 'c3';
use List::Util 'first';
use Scalar::Util 'blessed';
use Sub::Name 'subname';
use namespace::clean;
#
# This code will remove non-selecting/non-restricting joins from
# {from} specs, aiding the RDBMS query optimizer
#
sub _prune_unused_joins {
my ($self, $attrs) = @_;
# only standard {from} specs are supported, and we could be disabled in general
return ($attrs->{from}, {}) unless (
ref $attrs->{from} eq 'ARRAY'
and
@{$attrs->{from}} > 1
and
ref $attrs->{from}[0] eq 'HASH'
and
ref $attrs->{from}[1] eq 'ARRAY'
and
$self->_use_join_optimizer
);
my $orig_aliastypes = $self->_resolve_aliastypes_from_select_args($attrs);
my $new_aliastypes = { %$orig_aliastypes };
# we will be recreating this entirely
my @reclassify = 'joining';
# a grouped set will not be affected by amount of rows. Thus any
# purely multiplicator classifications can go
# (will be reintroduced below if needed by something else)
push @reclassify, qw(multiplying premultiplied)
if $attrs->{_force_prune_multiplying_joins} or $attrs->{group_by};
# nuke what will be recalculated
delete @{$new_aliastypes}{@reclassify};
my @newfrom = $attrs->{from}[0]; # FROM head is always present
# recalculate what we need once the multipliers are potentially gone
# ignore premultiplies, since they do not add any value to anything
my %need_joins;
for ( @{$new_aliastypes}{grep { $_ ne 'premultiplied' } keys %$new_aliastypes }) {
# add all requested aliases
$need_joins{$_} = 1 for keys %$_;
# add all their parents (as per joinpath which is an AoH { table => alias })
$need_joins{$_} = 1 for map { values %$_ } map { @{$_->{-parents}} } values %$_;
}
for my $j (@{$attrs->{from}}[1..$#{$attrs->{from}}]) {
push @newfrom, $j if (
(! defined $j->[0]{-alias}) # legacy crap
||
$need_joins{$j->[0]{-alias}}
);
}
# we have a new set of joiners - for everything we nuked pull the classification
# off the original stack
for my $ctype (@reclassify) {
$new_aliastypes->{$ctype} = { map
{ $need_joins{$_} ? ( $_ => $orig_aliastypes->{$ctype}{$_} ) : () }
keys %{$orig_aliastypes->{$ctype}}
}
}
return ( \@newfrom, $new_aliastypes );
}
#
# This is the code producing joined subqueries like:
# SELECT me.*, other.* FROM ( SELECT me.* FROM ... ) JOIN other ON ...
#
sub _adjust_select_args_for_complex_prefetch {
my ($self, $attrs) = @_;
$self->throw_exception ('Complex prefetches are not supported on resultsets with a custom from attribute') unless (
ref $attrs->{from} eq 'ARRAY'
and
@{$attrs->{from}} > 1
and
ref $attrs->{from}[0] eq 'HASH'
and
ref $attrs->{from}[1] eq 'ARRAY'
);
my $root_alias = $attrs->{alias};
# generate inner/outer attribute lists, remove stuff that doesn't apply
my $outer_attrs = { %$attrs };
delete @{$outer_attrs}{qw(from bind rows offset group_by _grouped_by_distinct having)};
my $inner_attrs = { %$attrs };
delete @{$inner_attrs}{qw(for collapse select as _related_results_construction)};
# there is no point of ordering the insides if there is no limit
delete $inner_attrs->{order_by} if (
delete $inner_attrs->{_order_is_artificial}
or
! $inner_attrs->{rows}
);
# generate the inner/outer select lists
# for inside we consider only stuff *not* brought in by the prefetch
# on the outside we substitute any function for its alias
$outer_attrs->{select} = [ @{$attrs->{select}} ];
my ($root_node, $root_node_offset);
for my $i (0 .. $#{$inner_attrs->{from}}) {
my $node = $inner_attrs->{from}[$i];
my $h = (ref $node eq 'HASH') ? $node
: (ref $node eq 'ARRAY' and ref $node->[0] eq 'HASH') ? $node->[0]
: next
;
if ( ($h->{-alias}||'') eq $root_alias and $h->{-rsrc} ) {
$root_node = $h;
$root_node_offset = $i;
last;
}
}
$self->throw_exception ('Complex prefetches are not supported on resultsets with a custom from attribute')
unless $root_node;
# use the heavy duty resolver to take care of aliased/nonaliased naming
my $colinfo = $self->_resolve_column_info($inner_attrs->{from});
my $selected_root_columns;
for my $i (0 .. $#{$outer_attrs->{select}}) {
my $sel = $outer_attrs->{select}->[$i];
next if (
$colinfo->{$sel} and $colinfo->{$sel}{-source_alias} ne $root_alias
);
if (ref $sel eq 'HASH' ) {
$sel->{-as} ||= $attrs->{as}[$i];
$outer_attrs->{select}->[$i] = join ('.', $root_alias, ($sel->{-as} || "inner_column_$i") );
}
elsif (! ref $sel and my $ci = $colinfo->{$sel}) {
$selected_root_columns->{$ci->{-colname}} = 1;
}
push @{$inner_attrs->{select}}, $sel;
push @{$inner_attrs->{as}}, $attrs->{as}[$i];
}
# We will need to fetch all native columns in the inner subquery, 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) {
my $ci = $colinfo->{$_} or next;
if (
$ci->{-source_alias} eq $root_alias
and
! $selected_root_columns->{$ci->{-colname}}++
) {
# adding it to both to keep limits not supporting dark selectors happy
push @{$inner_attrs->{select}}, $ci->{-fq_colname};
push @{$inner_attrs->{as}}, $ci->{-fq_colname};
}
}
# construct the inner {from} and lock it in a subquery
# we need to prune first, because this will determine if we need a group_by below
# throw away all non-selecting, non-restricting multijoins
# (since we def. do not care about multiplication of the contents of the subquery)
my $inner_subq = do {
# must use it here regardless of user requests (vastly gentler on optimizer)
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
});
# uh-oh a multiplier (which is not us) left in, this is a problem for limits
# we will need to add a group_by to collapse the resultset for proper counts
if (
grep { $_ ne $root_alias } keys %{ $inner_aliastypes->{multiplying} || {} }
and
# if there are user-supplied groups - assume user knows wtf they are up to
( ! $inner_aliastypes->{grouping} or $inner_attrs->{_grouped_by_distinct} )
) {
my $cur_sel = { map { $_ => 1 } @{$inner_attrs->{select}} };
# *possibly* supplement the main selection with pks if not already
# there, as they will have to be a part of the group_by to collapse
# things properly
my $inner_select_with_extras;
my @pks = map { "$root_alias.$_" } $root_node->{-rsrc}->primary_columns
or $self->throw_exception( sprintf
'Unable to perform complex limited prefetch off %s without declared primary key',
$root_node->{-rsrc}->source_name,
);
for my $col (@pks) {
push @{ $inner_select_with_extras ||= [ @{$inner_attrs->{select}} ] }, $col
unless $cur_sel->{$col}++;
}
($inner_attrs->{group_by}, $inner_attrs->{order_by}) = $self->_group_over_selection({
%$inner_attrs,
$inner_select_with_extras ? ( select => $inner_select_with_extras ) : (),
_aliastypes => $inner_aliastypes,
});
}
# we already optimized $inner_attrs->{from} above
# and already local()ized
$self->{_use_join_optimizer} = 0;
# generate the subquery
$self->_select_args_to_query (
@{$inner_attrs}{qw(from select where)},
$inner_attrs,
);
};
# Generate the outer from - this is relatively easy (really just replace
# the join slot with the subquery), with a major caveat - we can not
# join anything that is non-selecting (not part of the prefetch), but at
# the same time is a multi-type relationship, as it will explode the result.
#
# There are two possibilities here
# - either the join is non-restricting, in which case we simply throw it away
# - it is part of the restrictions, in which case we need to collapse the outer
# result by tackling yet another group_by to the outside of the query
# work on a shallow copy
my @orig_from = @{$attrs->{from}};
$outer_attrs->{from} = \ my @outer_from;
# we may not be the head
if ($root_node_offset) {
# first generate the outer_from, up to the substitution point
@outer_from = splice @orig_from, 0, $root_node_offset;
# substitute the subq at the right spot
push @outer_from, [
{
-alias => $root_alias,
-rsrc => $root_node->{-rsrc},
$root_alias => $inner_subq,
},
# preserve attrs from what is now the head of the from after the splice
@{$orig_from[0]}[1 .. $#{$orig_from[0]}],
];
}
else {
@outer_from = {
-alias => $root_alias,
-rsrc => $root_node->{-rsrc},
$root_alias => $inner_subq,
};
}
shift @orig_from; # what we just replaced above
# scan the *remaining* from spec against different attributes, and see which joins are needed
# in what role
my $outer_aliastypes = $outer_attrs->{_aliastypes} =
$self->_resolve_aliastypes_from_select_args({ %$outer_attrs, from => \@orig_from });
# unroll parents
my ($outer_select_chain, @outer_nonselecting_chains) = map { +{
map { $_ => 1 } map { values %$_} map { @{$_->{-parents}} } values %{ $outer_aliastypes->{$_} || {} }
} } qw/selecting restricting grouping ordering/;
# see what's left - throw away if not selecting/restricting
my $may_need_outer_group_by;
while (my $j = shift @orig_from) {
my $alias = $j->[0]{-alias};
if (
$outer_select_chain->{$alias}
) {
push @outer_from, $j
}
elsif (first { $_->{$alias} } @outer_nonselecting_chains ) {
push @outer_from, $j;
$may_need_outer_group_by ||= $outer_aliastypes->{multiplying}{$alias} ? 1 : 0;
}
}
# also throw in a synthetic group_by if a non-selecting multiplier,
# to guard against cross-join explosions
# the logic is somewhat fragile, but relies on the idea that if a user supplied
# a group by on their own - they know what they were doing
if ( $may_need_outer_group_by and $attrs->{_grouped_by_distinct} ) {
($outer_attrs->{group_by}, $outer_attrs->{order_by}) = $self->_group_over_selection ({
%$outer_attrs,
from => \@outer_from,
});
}
# 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
#
# OTOH it can be seen as a plus: <ash> (notes that this query would make a DBA cry ;)
return $outer_attrs;
}
#
# I KNOW THIS SUCKS! GET SQLA2 OUT THE DOOR SO THIS CAN DIE!
#
# 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 ) = @_;
$self->throw_exception ('Unable to analyze custom {from}')
if ref $attrs->{from} ne 'ARRAY';
# what we will return
my $aliases_by_type;
# see what aliases are there to work with
# and record who is a multiplier and who is premultiplied
my $alias_list;
for my $node (@{$attrs->{from}}) {
my $j = $node;
$j = $j->[0] if ref $j eq 'ARRAY';
my $al = $j->{-alias}
or next;
$alias_list->{$al} = $j;
$aliases_by_type->{multiplying}{$al} ||= { -parents => $j->{-join_path}||[] }
# not array == {from} head == can't be multiplying
if ref($node) eq 'ARRAY' and ! $j->{-is_single};
$aliases_by_type->{premultiplied}{$al} ||= { -parents => $j->{-join_path}||[] }
# parts of the path that are not us but are multiplying
if grep { $aliases_by_type->{multiplying}{$_} }
grep { $_ ne $al }
map { values %$_ }
@{ $j->{-join_path}||[] }
}
# get a column to source/alias map (including unambiguous unqualified ones)
my $colinfo = $self->_resolve_column_info ($attrs->{from});
# set up a botched SQLA
my $sql_maker = $self->sql_maker;
# these are throw away results, do not pollute the bind stack
local $sql_maker->{select_bind};
local $sql_maker->{where_bind};
local $sql_maker->{group_bind};
local $sql_maker->{having_bind};
local $sql_maker->{from_bind};
# we can't scan properly without any quoting (\b doesn't cut it
# everywhere), so unless there is proper quoting set - use our
# own weird impossible character.
# Also in the case of no quoting, we need to explicitly disable
# name_sep, otherwise sorry nasty legacy syntax like
# { 'count(foo.id)' => { '>' => 3 } } will stop working >:(
local $sql_maker->{quote_char} = $sql_maker->{quote_char};
local $sql_maker->{name_sep} = $sql_maker->{name_sep};
unless (defined $sql_maker->{quote_char} and length $sql_maker->{quote_char}) {
$sql_maker->{quote_char} = ["\x00", "\xFF"];
# if we don't unset it we screw up retarded but unfortunately working
# 'MAX(foo.bar)' => { '>', 3 }
$sql_maker->{name_sep} = '';
}
my ($lquote, $rquote, $sep) = map { quotemeta $_ } ($sql_maker->_quote_chars, $sql_maker->name_sep);
# generate sql chunks
my $to_scan = {
restricting => [
$sql_maker->_recurse_where ($attrs->{where}),
$sql_maker->_parse_rs_attrs ({ having => $attrs->{having} }),
],
grouping => [
$sql_maker->_parse_rs_attrs ({ group_by => $attrs->{group_by} }),
],
joining => [
$sql_maker->_recurse_from (
ref $attrs->{from}[0] eq 'ARRAY' ? $attrs->{from}[0][0] : $attrs->{from}[0],
@{$attrs->{from}}[1 .. $#{$attrs->{from}}],
),
],
selecting => [
map { $sql_maker->_recurse_fields($_) } @{$attrs->{select}},
],
ordering => [
map { $_->[0] } $self->_extract_order_criteria ($attrs->{order_by}, $sql_maker),
],
};
# throw away empty chunks and all 2-value arrayrefs: the thinking is that these are
# bind value specs left in by the sloppy renderer above. It is ok to do this
# at this point, since we are going to end up rewriting this crap anyway
for my $v (values %$to_scan) {
my @nv;
for (@$v) {
next if (
! defined $_
or
(
ref $_ eq 'ARRAY'
and
( @$_ == 0 or @$_ == 2 )
)
);
if (ref $_) {
require Data::Dumper::Concise;
$self->throw_exception("Unexpected ref in scan-plan: " . Data::Dumper::Concise::Dumper($v) );
}
push @nv, $_;
}
$v = \@nv;
}
# kill all selectors which look like a proper subquery
# this is a sucky heuristic *BUT* - if we get it wrong the query will simply
# fail to run, so we are relatively safe
$to_scan->{selecting} = [ grep {
$_ !~ / \A \s* \( \s* SELECT \s+ .+? \s+ FROM \s+ .+? \) \s* \z /xsi
} @{ $to_scan->{selecting} || [] } ];
# first see if we have any exact matches (qualified or unqualified)
for my $type (keys %$to_scan) {
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;
}
}
}
# 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;
for my $type (keys %$to_scan) {
for my $piece (@{$to_scan->{$type}}) {
if (my @matches = $piece =~ /$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;
}
}
}
}
# 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
my $col_re = qr/ $lquote ($col) $rquote /x;
for my $type (keys %$to_scan) {
for my $piece (@{$to_scan->{$type}}) {
if ( my @matches = $piece =~ /$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;
}
}
}
}
# Add any non-left joins to the restriction list (such joins are indeed restrictions)
for my $j (values %$alias_list) {
my $alias = $j->{-alias} or next;
$aliases_by_type->{restricting}{$alias} ||= { -parents => $j->{-join_path}||[] } if (
(not $j->{-join_type})
or
($j->{-join_type} !~ /^left (?: \s+ outer)? $/xi)
);
}
for (keys %$aliases_by_type) {
delete $aliases_by_type->{$_} unless keys %{$aliases_by_type->{$_}};
}
return $aliases_by_type;
}
# This is the engine behind { distinct => 1 } and the general
# complex prefetch grouper
sub _group_over_selection {
my ($self, $attrs) = @_;
my $colinfos = $self->_resolve_column_info ($attrs->{from});
my (@group_by, %group_index);
# the logic is: if it is a { func => val } we assume an aggregate,
# otherwise if \'...' or \[...] we assume the user knows what is
# going on thus group over it
for (@{$attrs->{select}}) {
if (! ref($_) or ref ($_) ne 'HASH' ) {
push @group_by, $_;
$group_index{$_}++;
if ($colinfos->{$_} and $_ !~ /\./ ) {
# add a fully qualified version as well
$group_index{"$colinfos->{$_}{-source_alias}.$_"}++;
}
}
}
my @order_by = $self->_extract_order_criteria($attrs->{order_by})
or return (\@group_by, $attrs->{order_by});
# add any order_by parts that are not already present in the group_by
# to maintain SQL cross-compatibility and general sanity
#
# also in case the original selection is *not* unique, or in case part
# of the ORDER BY refers to a multiplier - we will need to replace the
# skipped order_by elements with their MIN/MAX equivalents as to maintain
# the proper overall order without polluting the group criteria (and
# possibly changing the outcome entirely)
my ($leftovers, $sql_maker, @new_order_by, $order_chunks, $aliastypes);
my $group_already_unique = $self->_columns_comprise_identifying_set($colinfos, \@group_by);
for my $o_idx (0 .. $#order_by) {
# if the chunk is already a min/max function - there is nothing left to touch
next if $order_by[$o_idx][0] =~ /^ (?: min | max ) \s* \( .+ \) $/ix;
# only consider real columns (for functions the user got to do an explicit group_by)
my $chunk_ci;
if (
@{$order_by[$o_idx]} != 1
or
# only declare an unknown *plain* identifier as "leftover" if we are called with
# aliastypes to examine. If there are none - we are still in _resolve_attrs, and
# can just assume the user knows what they want
( ! ( $chunk_ci = $colinfos->{$order_by[$o_idx][0]} ) and $attrs->{_aliastypes} )
) {
push @$leftovers, $order_by[$o_idx][0];
}
next unless $chunk_ci;
# no duplication of group criteria
next if $group_index{$chunk_ci->{-fq_colname}};
$aliastypes ||= (
$attrs->{_aliastypes}
or
$self->_resolve_aliastypes_from_select_args({
from => $attrs->{from},
order_by => $attrs->{order_by},
})
) if $group_already_unique;
# check that we are not ordering by a multiplier (if a check is requested at all)
if (
$group_already_unique
and
! $aliastypes->{multiplying}{$chunk_ci->{-source_alias}}
and
! $aliastypes->{premultiplied}{$chunk_ci->{-source_alias}}
) {
push @group_by, $chunk_ci->{-fq_colname};
$group_index{$chunk_ci->{-fq_colname}}++
}
else {
# We need to order by external columns without adding them to the group
# (eiehter a non-unique selection, or a multi-external)
#
# This doesn't really make sense in SQL, however from DBICs point
# of view is rather valid (e.g. order the leftmost objects by whatever
# criteria and get the offset/rows many). There is a way around
# this however in SQL - we simply tae the direction of each piece
# 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
$sql_maker ||= $self->sql_maker;
$order_chunks ||= [
map { ref $_ eq 'ARRAY' ? $_ : [ $_ ] } $sql_maker->_order_by_chunks($attrs->{order_by})
];
my ($chunk, $is_desc) = $sql_maker->_split_order_chunk($order_chunks->[$o_idx][0]);
$new_order_by[$o_idx] = \[
sprintf( '%s( %s )%s',
($is_desc ? 'MAX' : 'MIN'),
$chunk,
($is_desc ? ' DESC' : ''),
),
@ {$order_chunks->[$o_idx]} [ 1 .. $#{$order_chunks->[$o_idx]} ]
];
}
}
$self->throw_exception ( sprintf
'A required group_by clause could not be constructed automatically due to a complex '
. 'order_by criteria (%s). Either order_by columns only (no functions) or construct a suitable '
. 'group_by by hand',
join ', ', map { "'$_'" } @$leftovers,
) if $leftovers;
# recreate the untouched order parts
if (@new_order_by) {
$new_order_by[$_] ||= \ $order_chunks->[$_] for ( 0 .. $#$order_chunks );
}
return (
\@group_by,
(@new_order_by ? \@new_order_by : $attrs->{order_by} ), # same ref as original == unchanged
);
}
sub _resolve_ident_sources {
my ($self, $ident) = @_;
my $alias2source = {};
# the reason this is so contrived is that $ident may be a {from}
# structure, specifying multiple tables to join
if ( blessed $ident && $ident->isa("DBIx::Class::ResultSource") ) {
# this is compat mode for insert/update/delete which do not deal with aliases
$alias2source->{me} = $ident;
}
elsif (ref $ident eq 'ARRAY') {
for (@$ident) {
my $tabinfo;
if (ref $_ eq 'HASH') {
$tabinfo = $_;
}
if (ref $_ eq 'ARRAY' and ref $_->[0] eq 'HASH') {
$tabinfo = $_->[0];
}
$alias2source->{$tabinfo->{-alias}} = $tabinfo->{-rsrc}
if ($tabinfo->{-rsrc});
}
}
return $alias2source;
}
# Takes $ident, \@column_names
#
# returns { $column_name => \%column_info, ... }
# also note: this adds -result_source => $rsrc to the column info
#
# If no columns_names are supplied returns info about *all* columns
# for all sources
sub _resolve_column_info {
my ($self, $ident, $colnames) = @_;
my $alias2src = $self->_resolve_ident_sources($ident);
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;
}
}
$colnames ||= [
@auto_colnames,
grep { @{$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);
next unless $source_alias;
my $rsrc = $alias2src->{$source_alias}
or next;
$return{$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,
-colname => $colname,
};
$return{"$source_alias.$colname"} = $return{$col} if $col eq $colname;
}
return \%return;
}
# The DBIC relationship chaining implementation is pretty simple - every
# new related_relationship is pushed onto the {from} stack, and the {select}
# window simply slides further in. This means that when we count somewhere
# in the middle, we got to make sure that everything in the join chain is an
# actual inner join, otherwise the count will come back with unpredictable
# results (a resultset may be generated with _some_ rows regardless of if
# the relation which the $rs currently selects has rows or not). E.g.
# $artist_rs->cds->count - normally generates:
# SELECT COUNT( * ) FROM artist me LEFT JOIN cd cds ON cds.artist = me.artistid
# which actually returns the number of artists * (number of cds || 1)
#
# So what we do here is crawl {from}, determine if the current alias is at
# the top of the stack, and if not - make sure the chain is inner-joined down
# to the root.
#
sub _inner_join_to_node {
my ($self, $from, $alias) = @_;
# subqueries and other oddness are naturally not supported
return $from if (
ref $from ne 'ARRAY'
||
@$from <= 1
||
ref $from->[0] ne 'HASH'
||
! $from->[0]{-alias}
||
$from->[0]{-alias} eq $alias # this last bit means $alias is the head of $from - nothing to do
);
# find the current $alias in the $from structure
my $switch_branch;
JOINSCAN:
for my $j (@{$from}[1 .. $#$from]) {
if ($j->[0]{-alias} eq $alias) {
$switch_branch = $j->[0]{-join_path};
last JOINSCAN;
}
}
# something else went quite wrong
return $from unless $switch_branch;
# So it looks like we will have to switch some stuff around.
# local() is useless here as we will be leaving the scope
# anyway, and deep cloning is just too fucking expensive
# So replace the first hashref in the node arrayref manually
my @new_from = ($from->[0]);
my $sw_idx = { map { (values %$_), 1 } @$switch_branch }; #there's one k/v per join-path
for my $j (@{$from}[1 .. $#$from]) {
my $jalias = $j->[0]{-alias};
if ($sw_idx->{$jalias}) {
my %attrs = %{$j->[0]};
delete $attrs{-join_type};
push @new_from, [
\%attrs,
@{$j}[ 1 .. $#$j ],
];
}
else {
push @new_from, $j;
}
}
return \@new_from;
}
sub _extract_order_criteria {
my ($self, $order_by, $sql_maker) = @_;
my $parser = sub {
my ($sql_maker, $order_by, $orig_quote_chars) = @_;
return scalar $sql_maker->_order_by_chunks ($order_by)
unless wantarray;
my ($lq, $rq, $sep) = map { quotemeta($_) } (
($orig_quote_chars ? @$orig_quote_chars : $sql_maker->_quote_chars),
$sql_maker->name_sep
);
my @chunks;
for ($sql_maker->_order_by_chunks ($order_by) ) {
my $chunk = ref $_ ? [ @$_ ] : [ $_ ];
($chunk->[0]) = $sql_maker->_split_order_chunk($chunk->[0]);
# order criteria may have come back pre-quoted (literals and whatnot)
# this is fragile, but the best we can currently do
$chunk->[0] =~ s/^ $lq (.+?) $rq $sep $lq (.+?) $rq $/"$1.$2"/xe
or $chunk->[0] =~ s/^ $lq (.+) $rq $/$1/x;
push @chunks, $chunk;
}
return @chunks;
};
if ($sql_maker) {
return $parser->($sql_maker, $order_by);
}
else {
$sql_maker = $self->sql_maker;
# pass these in to deal with literals coming from
# the user or the deep guts of prefetch
my $orig_quote_chars = [$sql_maker->_quote_chars];
local $sql_maker->{quote_char};
return $parser->($sql_maker, $order_by, $orig_quote_chars);
}
}
sub _order_by_is_stable {
my ($self, $ident, $order_by, $where) = @_;
my @cols = (
(map { $_->[0] } $self->_extract_order_criteria($order_by)),
$where ? @{$self->_extract_fixed_condition_columns($where)} :(),
) or return undef;
my $colinfo = $self->_resolve_column_info($ident, \@cols);
return keys %$colinfo
? $self->_columns_comprise_identifying_set( $colinfo, \@cols )
: undef
;
}
sub _columns_comprise_identifying_set {
my ($self, $colinfo, $columns) = @_;
my $cols_per_src;
$cols_per_src -> {$_->{-source_alias}} -> {$_->{-colname}} = $_
for grep { defined $_ } @{$colinfo}{@$columns};
for (values %$cols_per_src) {
my $src = (values %$_)[0]->{-result_source};
return 1 if $src->_identifying_column_set($_);
}
return undef;
}
# this is almost identical to the above, except it accepts only
# a single rsrc, and will succeed only if the first portion of the order
# by is stable.
# returns that portion as a colinfo hashref on success
sub _main_source_order_by_portion_is_stable {
my ($self, $main_rsrc, $order_by, $where) = @_;
die "Huh... I expect a blessed result_source..."
if ref($main_rsrc) eq 'ARRAY';
my @ord_cols = map
{ $_->[0] }
( $self->_extract_order_criteria($order_by) )
;
return unless @ord_cols;
my $colinfos = $self->_resolve_column_info($main_rsrc);
for (0 .. $#ord_cols) {
if (
! $colinfos->{$ord_cols[$_]}
or
$colinfos->{$ord_cols[$_]}{-result_source} != $main_rsrc
) {
$#ord_cols = $_ - 1;
last;
}
}
# we just truncated it above
return unless @ord_cols;
my $order_portion_ci = { map {
$colinfos->{$_}{-colname} => $colinfos->{$_},
$colinfos->{$_}{-fq_colname} => $colinfos->{$_},
} @ord_cols };
# since all we check here are the start of the order_by belonging to the
# top level $rsrc, a present identifying set will mean that the resultset
# is ordered by its leftmost table in a stable manner
#
# RV of _identifying_column_set contains unqualified names only
my $unqualified_idset = $main_rsrc->_identifying_column_set({
( $where ? %{
$self->_resolve_column_info(
$main_rsrc, $self->_extract_fixed_condition_columns($where)
)
} : () ),
%$order_portion_ci
}) or return;
my $ret_info;
my %unqualified_idcols_from_order = map {
$order_portion_ci->{$_} ? ( $_ => $order_portion_ci->{$_} ) : ()
} @$unqualified_idset;
# extra optimization - cut the order_by at the end of the identifying set
# (just in case the user was stupid and overlooked the obvious)
for my $i (0 .. $#ord_cols) {
my $col = $ord_cols[$i];
my $unqualified_colname = $order_portion_ci->{$col}{-colname};
$ret_info->{$col} = { %{$order_portion_ci->{$col}}, -idx_in_order_subset => $i };
delete $unqualified_idcols_from_order{$ret_info->{$col}{-colname}};
# we didn't reach the end of the identifying portion yet
return $ret_info unless keys %unqualified_idcols_from_order;
}
die 'How did we get here...';
}
# returns an arrayref of column names which *definitely* have some
# sort of non-nullable equality requested in the given condition
# specification. This is used to figure out if a resultset is
# constrained to a column which is part of a unique constraint,
# which in turn allows us to better predict how ordering will behave
# etc.
#
# this is a rudimentary, incomplete, and error-prone extractor
# however this is OK - it is conservative, and if we can not find
# something that is in fact there - the stack will recover gracefully
# Also - DQ and the mst it rode in on will save us all RSN!!!
sub _extract_fixed_condition_columns {
my ($self, $where) = @_;
return unless ref $where eq 'HASH';
my @cols;
for my $lhs (keys %$where) {
if ($lhs =~ /^\-and$/i) {
push @cols, ref $where->{$lhs} eq 'ARRAY'
? ( map { @{ $self->_extract_fixed_condition_columns($_) } } @{$where->{$lhs}} )
: @{ $self->_extract_fixed_condition_columns($where->{$lhs}) }
;
}
elsif ($lhs !~ /^\-/) {
my $val = $where->{$lhs};
push @cols, $lhs if (defined $val and (
! ref $val
or
(ref $val eq 'HASH' and keys %$val == 1 and defined $val->{'='})
));
}
}
return \@cols;
}
1;