X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?p=dbsrgits%2FDBIx-Class.git;a=blobdiff_plain;f=lib%2FDBIx%2FClass%2FSQLAHacks.pm;h=d2dc16edc58e57e759a0bad3ddf449923aad261d;hp=40bc7a3ee4a1a64eac8a85ef7deec59a3d0eacb1;hb=75f025cf247e75869dcdfe46b37e24d4e0b15e8b;hpb=7ad315356c82a425365b88b6146617485897a4a0 diff --git a/lib/DBIx/Class/SQLAHacks.pm b/lib/DBIx/Class/SQLAHacks.pm index 40bc7a3..d2dc16e 100644 --- a/lib/DBIx/Class/SQLAHacks.pm +++ b/lib/DBIx/Class/SQLAHacks.pm @@ -48,29 +48,25 @@ sub new { # !!! THIS IS ALSO HORRIFIC !!! /me ashamed # -# generate inner/outer select lists for various limit dialects +# Generates inner/outer select lists for various limit dialects # which result in one or more subqueries (e.g. RNO, Top, RowNum) # Any non-root-table columns need to have their table qualifier # turned into a column alias (otherwise names in subqueries clash # and/or lose their source table) # -# returns inner/outer strings of SQL QUOTED selectors with aliases +# Returns inner/outer strings of SQL QUOTED selectors with aliases # (to be used in whatever select statement), and an alias index hashref # of QUOTED SEL => QUOTED ALIAS pairs (to maybe be used for string-subst -# higher up) -# -# If the $scan_order option is supplied, it signals that the limit dialect -# needs to order the outer side of the query, which in turn means that the -# inner select needs to bring out columns used in implicit (non-selected) -# orders, and the order condition itself needs to be realiased to the proper -# names in the outer query. -# -# In this case ($scan_order os true) we also return a hashref (order doesn't -# matter) of QUOTED EXTRA-SEL => QUOTED ALIAS pairs, which is a list of extra -# selectors that do *not* exist in the original select list +# higher up). +# If an order_by is supplied, the inner select needs to bring out columns +# used in implicit (non-selected) orders, and the order condition itself +# needs to be realiased to the proper names in the outer query. Thus we +# also return a hashref (order doesn't matter) of QUOTED EXTRA-SEL => +# QUOTED ALIAS pairs, which is a list of extra selectors that do *not* +# exist in the original select list sub _subqueried_limit_attrs { - my ($self, $rs_attrs, $scan_order) = @_; + my ($self, $rs_attrs) = @_; croak 'Limit dialect implementation usable only in the context of DBIC (missing $rs_attrs)' unless ref ($rs_attrs) eq 'HASH'; @@ -104,10 +100,12 @@ sub _subqueried_limit_attrs { $in_sel_index->{$sql_sel}++; $in_sel_index->{$self->_quote ($sql_alias)}++ if $sql_alias; -# this *may* turn out to be necessary, not sure yet -# my ($sql_unqualified_sel) = $sql_sel =~ / $re_sep (.+) $/x -# if ! ref $s; -# $in_sel_index->{$sql_unqualified_sel}++; + # record unqualified versions too, so we do not have + # to reselect the same column twice (in qualified and + # unqualified form) + if (! ref $s && $sql_sel =~ / $re_sep (.+) $/x) { + $in_sel_index->{$1}++; + } } @@ -130,20 +128,20 @@ sub _subqueried_limit_attrs { } } + # see if the order gives us anything my %extra_order_sel; - if ($scan_order) { - for my $chunk ($self->_order_by_chunks ($rs_attrs->{order_by})) { - # order with bind - $chunk = $chunk->[0] if (ref $chunk) eq 'ARRAY'; - $chunk =~ s/\s+ (?: ASC|DESC ) \s* $//ix; + for my $chunk ($self->_order_by_chunks ($rs_attrs->{order_by})) { + # order with bind + $chunk = $chunk->[0] if (ref $chunk) eq 'ARRAY'; + $chunk =~ s/\s+ (?: ASC|DESC ) \s* $//ix; - next if $in_sel_index->{$chunk}; + next if $in_sel_index->{$chunk}; - $extra_order_sel{$chunk} ||= $self->_quote ( - 'ORDER__BY__' . scalar keys %extra_order_sel - ); - } + $extra_order_sel{$chunk} ||= $self->_quote ( + 'ORDER__BY__' . scalar keys %extra_order_sel + ); } + return ( (map { join (', ', @$_ ) } ( \@in_sel, @@ -163,9 +161,8 @@ sub _RowNumberOver { or croak "Unrecognizable SELECT: $sql"; # get selectors, and scan the order_by (if any) - my ($in_sel, $out_sel, $alias_map, $extra_order_sel) = $self->_subqueried_limit_attrs ( - $rs_attrs, 'scan_order_by', - ); + my ($in_sel, $out_sel, $alias_map, $extra_order_sel) + = $self->_subqueried_limit_attrs ( $rs_attrs ); # make up an order if none exists my $requested_order = (delete $rs_attrs->{order_by}) || $self->_rno_default_order; @@ -207,7 +204,7 @@ SELECT $out_sel FROM ( SELECT $mid_sel, ROW_NUMBER() OVER( $rno_ord ) AS $idx_name FROM ( SELECT $in_sel ${sql}${group_having} ) $qalias -) $qalias WHERE $idx_name BETWEEN %d AND %d +) $qalias WHERE $idx_name BETWEEN %u AND %u EOS @@ -229,10 +226,10 @@ sub _SkipFirst { return sprintf ('SELECT %s%s%s%s', $offset - ? sprintf ('SKIP %d ', $offset) + ? sprintf ('SKIP %u ', $offset) : '' , - sprintf ('FIRST %d ', $rows), + sprintf ('FIRST %u ', $rows), $sql, $self->_parse_rs_attrs ($rs_attrs), ); @@ -246,9 +243,9 @@ sub _FirstSkip { or croak "Unrecognizable SELECT: $sql"; return sprintf ('SELECT %s%s%s%s', - sprintf ('FIRST %d ', $rows), + sprintf ('FIRST %u ', $rows), $offset - ? sprintf ('SKIP %d ', $offset) + ? sprintf ('SKIP %u ', $offset) : '' , $sql, @@ -276,7 +273,7 @@ SELECT $outsel FROM ( SELECT $outsel, ROWNUM $idx_name FROM ( SELECT $insel ${sql}${order_group_having} ) $qalias -) $qalias WHERE $idx_name BETWEEN %d AND %d +) $qalias WHERE $idx_name BETWEEN %u AND %u EOS @@ -294,7 +291,7 @@ sub _Top { # get selectors my ($in_sel, $out_sel, $alias_map, $extra_order_sel) - = $self->_subqueried_limit_attrs ($rs_attrs, 'outer_order_by'); + = $self->_subqueried_limit_attrs ($rs_attrs); my $requested_order = delete $rs_attrs->{order_by}; @@ -359,7 +356,7 @@ sub _Top { my $quoted_rs_alias = $self->_quote ($rs_attrs->{alias}); - $sql = sprintf ('SELECT TOP %d %s %s %s %s', + $sql = sprintf ('SELECT TOP %u %s %s %s %s', $rows + ($offset||0), $in_sel, $sql, @@ -367,7 +364,7 @@ sub _Top { $order_by_inner, ); - $sql = sprintf ('SELECT TOP %d %s FROM ( %s ) %s %s', + $sql = sprintf ('SELECT TOP %u %s FROM ( %s ) %s %s', $rows, $mid_sel, $sql, @@ -375,7 +372,7 @@ sub _Top { $order_by_reversed, ) if $offset; - $sql = sprintf ('SELECT TOP %d %s FROM ( %s ) %s %s', + $sql = sprintf ('SELECT TOP %u %s FROM ( %s ) %s %s', $rows, $out_sel, $sql, @@ -383,6 +380,112 @@ sub _Top { $order_by_requested, ) if ( ($offset && $order_by_requested) || ($mid_sel ne $out_sel) ); + $sql =~ s/\s*\n\s*/ /g; # easier to read in the debugger + return $sql; +} + +# This is the most evil limit "dialect" (more of a hack) for *really* +# stupid databases. It works by ordering the set by some unique column, +# and calculating amount of rows that have a less-er value (thus +# emulating a RowNum-like index). Of course this implies the set can +# only be ordered by a single unique columns. +sub _GenericSubQ { + my ($self, $sql, $rs_attrs, $rows, $offset) = @_; + + my $root_rsrc = $rs_attrs->{_rsroot_source_handle}->resolve; + my $root_tbl_name = $root_rsrc->name; + + # mangle the input sql as we will be replacing the selector + $sql =~ s/^ \s* SELECT \s+ .+? \s+ (?= \b FROM \b )//ix + or croak "Unrecognizable SELECT: $sql"; + + my ($order_by, @rest) = do { + local $self->{quote_char}; + $self->_order_by_chunks ($rs_attrs->{order_by}) + }; + + unless ( + $order_by + && + ! @rest + && + ( ! ref $order_by + || + ( ref $order_by eq 'ARRAY' and @$order_by == 1 ) + ) + ) { + croak ( + 'Generic Subquery Limit does not work on resultsets without an order, or resultsets ' + . 'with complex order criteria (multicolumn and/or functions). Provide a single, ' + . 'unique-column order criteria.' + ); + } + + ($order_by) = @$order_by if ref $order_by; + + $order_by =~ s/\s+ ( ASC|DESC ) \s* $//ix; + my $direction = lc ($1 || 'asc'); + + my ($unq_sort_col) = $order_by =~ /(?:^|\.)([^\.]+)$/; + + my $inf = $root_rsrc->storage->_resolve_column_info ( + $rs_attrs->{from}, [$order_by, $unq_sort_col] + ); + + my $ord_colinfo = $inf->{$order_by} || croak "Unable to determine source of order-criteria '$order_by'"; + + if ($ord_colinfo->{-result_source}->name ne $root_tbl_name) { + croak "Generic Subquery Limit order criteria can be only based on the root-source '" + . $root_rsrc->source_name . "' (aliased as '$rs_attrs->{alias}')"; + } + + # make sure order column is qualified + $order_by = "$rs_attrs->{alias}.$order_by" + unless $order_by =~ /^$rs_attrs->{alias}\./; + + my $is_u; + my $ucs = { $root_rsrc->unique_constraints }; + for (values %$ucs ) { + if (@$_ == 1 && "$rs_attrs->{alias}.$_->[0]" eq $order_by) { + $is_u++; + last; + } + } + croak "Generic Subquery Limit order criteria column '$order_by' must be unique (no unique constraint found)" + unless $is_u; + + my ($in_sel, $out_sel, $alias_map, $extra_order_sel) + = $self->_subqueried_limit_attrs ($rs_attrs); + + my $cmp_op = $direction eq 'desc' ? '>' : '<'; + my $count_tbl_alias = 'rownum__emulation'; + + my $order_group_having = $self->_parse_rs_attrs($rs_attrs); + + # add the order supplement (if any) as this is what will be used for the outer WHERE + $in_sel .= ", $_" for keys %{$extra_order_sel||{}}; + + $sql = sprintf (<_quote ($_) } ( + $rs_attrs->{alias}, + $root_tbl_name, + $count_tbl_alias, + "$count_tbl_alias.$unq_sort_col", + $order_by, + )), + $offset + ? sprintf ('BETWEEN %u AND %u', $offset, $offset + $rows - 1) + : sprintf ('< %u', $rows ) + , + ); + + $sql =~ s/\s*\n\s*/ /g; # easier to read in the debugger return $sql; }