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 $self = shift;
my ($from, $select, $where, $attrs) = @_;
return $from unless $self->_use_join_optimizer;
if (ref $from ne 'ARRAY' || ref $from->[0] ne 'HASH' || ref $from->[1] ne 'ARRAY') {
return $from; # only standard {from} specs are supported
}
my $aliastypes = $self->_resolve_aliastypes_from_select_args(@_);
my $orig_joins = delete $aliastypes->{joining};
my $orig_multiplying = $aliastypes->{multiplying};
# a grouped set will not be affected by amount of rows. Thus any
# {multiplying} joins can go
delete $aliastypes->{multiplying}
if $attrs->{_force_prune_multiplying_joins} or $attrs->{group_by};
my @newfrom = $from->[0]; # FROM head is always present
my %need_joins;
for (values %$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 $j (@{$from}[1..$#$from]) {
push @newfrom, $j if (
(! defined $j->[0]{-alias}) # legacy crap
||
$need_joins{$j->[0]{-alias}}
);
}
return ( \@newfrom, {
multiplying => { map { $need_joins{$_} ? ($_ => $orig_multiplying->{$_}) : () } keys %$orig_multiplying },
%$aliastypes,
joining => { map { $_ => $orig_joins->{$_} } keys %need_joins },
} );
}
#
# 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, $from, $select, $where, $attrs) = @_;
$self->throw_exception ('Complex prefetches are not supported on resultsets with a custom from attribute')
if (ref $from ne 'ARRAY' || ref $from->[0] ne 'HASH' || ref $from->[1] ne '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(where bind rows offset group_by _grouped_by_distinct having)};
my $inner_attrs = { %$attrs };
delete @{$inner_attrs}{qw(from 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
my $outer_select = [ @$select ];
my $inner_select;
my ($root_node, $root_node_offset);
for my $i (0 .. $#$from) {
my $node = $from->[$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 = $self->_resolve_column_info($from);
my $selected_root_columns;
for my $i (0 .. $#$outer_select) {
my $sel = $outer_select->[$i];
next if (
$colinfo->{$sel} and $colinfo->{$sel}{-source_alias} ne $root_alias
);
if (ref $sel eq 'HASH' ) {
$sel->{-as} ||= $attrs->{as}[$i];
$outer_select->[$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_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)
# 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(
$from,
[],
$where,
$inner_attrs
);
for (sort map { keys %{$_->{-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_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 those inside the subquery)
my $inner_subq = do {
# must use it here regardless of user requests
local $self->{_use_join_optimizer} = 1;
# throw away multijoins since we def. do not care about those inside the subquery
my ($inner_from, $inner_aliastypes) = $self->_prune_unused_joins ($from, $inner_select, $where, {
%$inner_attrs, _force_prune_multiplying_joins => 1
});
# uh-oh a multiplier (which is not us) left in, this is a problem
if (
$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} )
and
my @multipliers = grep { $_ ne $root_alias } keys %{$inner_aliastypes->{multiplying}}
) {
# if none of the multipliers came from an order_by (guaranteed to have been combined
# with a limit) - easy - just slap a group_by to simulate a collape and be on our way
if (
! $inner_aliastypes->{ordering}
or
! first { $inner_aliastypes->{ordering}{$_} } @multipliers
) {
my $unprocessed_order_chunks;
($inner_attrs->{group_by}, $unprocessed_order_chunks) = $self->_group_over_selection ({
%$inner_attrs,
from => $inner_from,
select => $inner_select,
});
$self->throw_exception (
'A required group_by clause could not be constructed automatically due to a complex '
. 'order_by criteria. Either order_by columns only (no functions) or construct a suitable '
. 'group_by by hand'
) if $unprocessed_order_chunks;
}
else {
# We need to order by external columns and group at the same time
# so we can calculate the proper limit
# This doesn't really make sense in SQL, however from DBICs point
# of view is rather valid (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 foreign 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
# supplement the main selection with pks if not already there,
# as they will have to be a part of the group_by to colapse
# things properly
my $cur_sel = { map { $_ => 1 } @$inner_select };
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, $col
unless $cur_sel->{$col}++;
}
# wrap any part of the order_by that "responds" to an ordering alias
# into a MIN/MAX
# 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
my $sql_maker = $self->sql_maker;
my ($lquote, $rquote, $sep) = map { quotemeta $_ } ($sql_maker->_quote_chars, $sql_maker->name_sep);
my $own_re = qr/ $lquote \Q$root_alias\E $rquote $sep | \b \Q$root_alias\E $sep /x;
my @order_chunks = map { ref $_ eq 'ARRAY' ? $_ : [ $_ ] } $sql_maker->_order_by_chunks($attrs->{order_by});
my @new_order = map { \$_ } @order_chunks;
my $inner_columns_info = $self->_resolve_column_info($inner_from);
# loop through and replace stuff that is not "ours" with a min/max func
# everything is a literal at this point, since we are likely properly
# quoted and stuff
for my $i (0 .. $#new_order) {
my $chunk = $order_chunks[$i][0];
# skip ourselves
next if $chunk =~ $own_re;
($chunk, my $is_desc) = $sql_maker->_split_order_chunk($chunk);
# maybe our own unqualified column
my $ord_bit = (
$lquote and $sep and $chunk =~ /^ $lquote ([^$sep]+) $rquote $/x
) ? $1 : $chunk;
next if (
$ord_bit
and
$inner_columns_info->{$ord_bit}
and
$inner_columns_info->{$ord_bit}{-source_alias} eq $root_alias
);
$new_order[$i] = \[
sprintf(
'%s(%s)%s',
($is_desc ? 'MAX' : 'MIN'),
$chunk,
($is_desc ? ' DESC' : ''),
),
@ {$order_chunks[$i]} [ 1 .. $#{$order_chunks[$i]} ]
];
}
$inner_attrs->{order_by} = \@new_order;
# do not care about leftovers here - it will be all the functions
# we just created
($inner_attrs->{group_by}) = $self->_group_over_selection ({
%$inner_attrs,
from => $inner_from,
select => $inner_select,
});
}
}
# we already optimized $inner_from above
# and already local()ized
$self->{_use_join_optimizer} = 0;
# generate the subquery
$self->_select_args_to_query (
$inner_from,
$inner_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
$from = [ @$from ];
my @outer_from;
# we may not be the head
if ($root_node_offset) {
# first generate the outer_from, up and including the substitution point
@outer_from = splice @$from, 0, $root_node_offset;
push @outer_from, [
{
-alias => $root_alias,
-rsrc => $root_node->{-rsrc},
$root_alias => $inner_subq,
},
@{$from->[0]}[1 .. $#{$from->[0]}],
];
}
else {
@outer_from = {
-alias => $root_alias,
-rsrc => $root_node->{-rsrc},
$root_alias => $inner_subq,
};
}
shift @$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( $from, $outer_select, $where, $outer_attrs );
# unroll parents
my ($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
# also throw in a group_by if a non-selecting multiplier,
# to guard against cross-join explosions
my $need_outer_group_by;
while (my $j = shift @$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;
$need_outer_group_by ||= $outer_aliastypes->{multiplying}{$alias} ? 1 : 0;
}
}
if ( $need_outer_group_by and $attrs->{_grouped_by_distinct} ) {
my $unprocessed_order_chunks;
($outer_attrs->{group_by}, $unprocessed_order_chunks) = $self->_group_over_selection ({
%$outer_attrs,
from => \@outer_from,
select => $outer_select,
});
$self->throw_exception (
'A required group_by clause could not be constructed automatically due to a complex '
. 'order_by criteria. Either order_by columns only (no functions) or construct a suitable '
. 'group_by by hand'
) if $unprocessed_order_chunks;
}
# 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 didin'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_from, $outer_select, $where, $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 neded 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, $from, $select, $where, $attrs ) = @_;
$self->throw_exception ('Unable to analyze custom {from}')
if ref $from ne 'ARRAY';
# what we will return
my $aliases_by_type;
# see what aliases are there to work with
my $alias_list;
for (@$from) {
my $j = $_;
$j = $j->[0] if ref $j eq 'ARRAY';
my $al = $j->{-alias}
or next;
$alias_list->{$al} = $j;
$aliases_by_type->{multiplying}{$al} ||= { -parents => $j->{-join_path}||[] } if (
# not array == {from} head == can't be multiplying
( ref($_) eq 'ARRAY' and ! $j->{-is_single} )
or
# a parent of ours is already a multiplier
( grep { $aliases_by_type->{multiplying}{$_} } @{ $j->{-join_path}||[] } )
);
}
# get a column to source/alias map (including unambiguous unqualified ones)
my $colinfo = $self->_resolve_column_info ($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 => [
$sql_maker->_recurse_where ($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 $from->[0] eq 'ARRAY' ? $from->[0][0] : $from->[0],
@{$from}[1 .. $#$from],
),
],
selecting => [
$sql_maker->_recurse_fields ($select),
],
ordering => [
map { $_->[0] } $self->_extract_order_criteria ($attrs->{order_by}, $sql_maker),
],
};
# throw away empty chunks
$_ = [ map { $_ || () } @$_ ] for values %$to_scan;
# 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 $aliases_by_type;
}
# This is the engine behind { distinct => 1 }
sub _group_over_selection {
my ($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->{$_}{-source_alias}.$_"}++;
}
}
}
# add any order_by parts *from the main source* that are not already
# present in the group_by
# we need to be careful not to add any named functions/aggregates
# i.e. order_by => [ ... { count => 'foo' } ... ]
my @leftovers;
for ($self->_extract_order_criteria($attrs->{order_by})) {
# only consider real columns (for functions the user got to do an explicit group_by)
if (@$_ != 1) {
push @leftovers, $_;
next;
}
my $chunk = $_->[0];
if (
!$colinfos->{$chunk}
or
$colinfos->{$chunk}{-source_alias} ne $attrs->{alias}
) {
push @leftovers, $_;
next;
}
$chunk = $colinfos->{$chunk}{-fq_colname};
push @group_by, $chunk unless $group_index{$chunk}++;
}
return wantarray
? (\@group_by, (@leftovers ? \@leftovers : undef) )
: \@group_by
;
}
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 $colinfo = $self->_resolve_column_info($ident, [
(map { $_->[0] } $self->_extract_order_criteria($order_by)),
$where ? @{$self->_extract_fixed_condition_columns($where)} :(),
]);
return undef unless keys %$colinfo;
my $cols_per_src;
$cols_per_src->{$_->{-source_alias}}{$_->{-colname}} = $_ for values %$colinfo;
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 $ret_info unless keys %unqualified_idcols_from_order;
}
die 'How did we get here...';
}
# returns an arrayref of column names which *definitely* have som
# sort of non-nullable equality requested in the given condition
# specification. This is used to figure out if a resultset is
# constrained to a column which is part of a unique constraint,
# which in turn allows us to better predict how ordering will behave
# etc.
#
# this is a rudimentary, incomplete, and error-prone extractor
# however this is OK - it is conservative, and if we can not find
# something that is in fact there - the stack will recover gracefully
# Also - DQ and the mst it rode in on will save us all RSN!!!
sub _extract_fixed_condition_columns {
my ($self, $where, $nested) = @_;
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 { $self->_extract_fixed_condition_columns($_, 1) } @{$where->{$lhs}} )
: $self->_extract_fixed_condition_columns($where->{$lhs}, 1)
;
}
elsif ($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 $nested ? @cols : \@cols;
}
1;