X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=lib%2FDBIx%2FClass%2FSQLMaker%2FLimitDialects.pm;h=5af94879910b09ba90d794e8f5853040d56df421;hb=cecf64bc6850edb1c2ad4af03d51aee022326921;hp=723001d4aa6e594f471e1d6c30294d24d50f4957;hpb=d9672fb94b70dac86a6d4fed7ad46a48c5ee4527;p=dbsrgits%2FDBIx-Class.git diff --git a/lib/DBIx/Class/SQLMaker/LimitDialects.pm b/lib/DBIx/Class/SQLMaker/LimitDialects.pm index 723001d..5af9487 100644 --- a/lib/DBIx/Class/SQLMaker/LimitDialects.pm +++ b/lib/DBIx/Class/SQLMaker/LimitDialects.pm @@ -3,81 +3,19 @@ package DBIx::Class::SQLMaker::LimitDialects; use warnings; use strict; -use Carp::Clan qw/^DBIx::Class|^SQL::Abstract|^Try::Tiny/; use List::Util 'first'; use namespace::clean; -# FIXME -# This dialect has not been ported to the subquery-realiasing code -# that all other subquerying dialects are using. It is very possible -# that this dialect is entirely unnecessary - it is currently only -# used by ::Storage::DBI::ODBC::DB2_400_SQL which *should* be able to -# just subclass ::Storage::DBI::DB2 and use the already rewritten -# RowNumberOver. However nobody has access to this specific database -# engine, thus keeping legacy code as-is -# IF someone ever manages to test DB2-AS/400 with RNO, all the code -# in this block should go on to meet its maker -{ - sub _FetchFirst { - my ( $self, $sql, $order, $rows, $offset ) = @_; - - my $last = $rows + $offset; - - my ( $order_by_up, $order_by_down ) = $self->_order_directions( $order ); - - $sql = " - SELECT * FROM ( - SELECT * FROM ( - $sql - $order_by_up - FETCH FIRST $last ROWS ONLY - ) foo - $order_by_down - FETCH FIRST $rows ROWS ONLY - ) bar - $order_by_up - "; - - return $sql; - } - - sub _order_directions { - my ( $self, $order ) = @_; - - return unless $order; - - my $ref = ref $order; - - my @order; - - CASE: { - @order = @$order, last CASE if $ref eq 'ARRAY'; - @order = ( $order ), last CASE unless $ref; - @order = ( $$order ), last CASE if $ref eq 'SCALAR'; - croak __PACKAGE__ . ": Unsupported data struct $ref for ORDER BY"; - } - - my ( $order_by_up, $order_by_down ); - - foreach my $spec ( @order ) - { - my @spec = split ' ', $spec; - croak( "bad column order spec: $spec" ) if @spec > 2; - push( @spec, 'ASC' ) unless @spec == 2; - my ( $col, $up ) = @spec; # or maybe down - $up = uc( $up ); - croak( "bad direction: $up" ) unless $up =~ /^(?:ASC|DESC)$/; - $order_by_up .= ", $col $up"; - my $down = $up eq 'ASC' ? 'DESC' : 'ASC'; - $order_by_down .= ", $col $down"; - } - - s/^,/ORDER BY/ for ( $order_by_up, $order_by_down ); - - return $order_by_up, $order_by_down; - } +# constants are used not only here, but also in comparison tests +sub __rows_bindtype () { + +{ sqlt_datatype => 'integer' } +} +sub __offset_bindtype () { + +{ sqlt_datatype => 'integer' } +} +sub __total_bindtype () { + +{ sqlt_datatype => 'integer' } } -### end-of-FIXME =head1 NAME @@ -103,8 +41,6 @@ names. Currently the provided dialects are: -=cut - =head2 LimitOffset SELECT ... LIMIT $limit OFFSET $offset @@ -113,9 +49,13 @@ Supported by B and B =cut sub _LimitOffset { - my ( $self, $sql, $order, $rows, $offset ) = @_; - $sql .= $self->_order_by( $order ) . " LIMIT $rows"; - $sql .= " OFFSET $offset" if +$offset; + my ( $self, $sql, $rs_attrs, $rows, $offset ) = @_; + $sql .= $self->_parse_rs_attrs( $rs_attrs ) . " LIMIT ?"; + push @{$self->{limit_bind}}, [ $self->__rows_bindtype => $rows ]; + if ($offset) { + $sql .= " OFFSET ?"; + push @{$self->{limit_bind}}, [ $self->__offset_bindtype => $offset ]; + } return $sql; } @@ -127,10 +67,15 @@ Supported by B and any L based DBD =cut sub _LimitXY { - my ( $self, $sql, $order, $rows, $offset ) = @_; - $sql .= $self->_order_by( $order ) . " LIMIT "; - $sql .= "$offset, " if +$offset; - $sql .= $rows; + my ( $self, $sql, $rs_attrs, $rows, $offset ) = @_; + $sql .= $self->_parse_rs_attrs( $rs_attrs ) . " LIMIT "; + if ($offset) { + $sql .= '?, '; + push @{$self->{limit_bind}}, [ $self->__offset_bindtype => $offset ]; + } + $sql .= '?'; + push @{$self->{limit_bind}}, [ $self->__rows_bindtype => $rows ]; + return $sql; } @@ -150,36 +95,29 @@ B<< MSSQL >= 2005 >>. sub _RowNumberOver { my ($self, $sql, $rs_attrs, $rows, $offset ) = @_; - # 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: $sql"; - # get selectors, and scan the order_by (if any) - my ($in_sel, $out_sel, $alias_map, $extra_order_sel) - = $self->_subqueried_limit_attrs ( $rs_attrs ); + my $sq_attrs = $self->_subqueried_limit_attrs ( $sql, $rs_attrs ); # make up an order if none exists my $requested_order = (delete $rs_attrs->{order_by}) || $self->_rno_default_order; my $rno_ord = $self->_order_by ($requested_order); # this is the order supplement magic - my $mid_sel = $out_sel; - if ($extra_order_sel) { + my $mid_sel = $sq_attrs->{selection_outer}; + if (my $extra_order_sel = $sq_attrs->{order_supplement}) { for my $extra_col (sort { $extra_order_sel->{$a} cmp $extra_order_sel->{$b} } keys %$extra_order_sel ) { - $in_sel .= sprintf (', %s AS %s', + $sq_attrs->{selection_inner} .= sprintf (', %s AS %s', $extra_col, $extra_order_sel->{$extra_col}, ); - - $mid_sel .= ', ' . $extra_order_sel->{$extra_col}; } } # and this is order re-alias magic - for ($extra_order_sel, $alias_map) { + for ($sq_attrs->{order_supplement}, $sq_attrs->{outer_renames}) { for my $col (keys %$_) { my $re_col = quotemeta ($col); $rno_ord =~ s/$re_col/$_->{$col}/; @@ -192,18 +130,18 @@ sub _RowNumberOver { my $qalias = $self->_quote ($rs_attrs->{alias}); my $idx_name = $self->_quote ('rno__row__index'); - $sql = sprintf (<{limit_bind}}, [ $self->__offset_bindtype => $offset + 1], [ $self->__total_bindtype => $offset + $rows ]; -SELECT $out_sel FROM ( + return <{selection_outer} FROM ( SELECT $mid_sel, ROW_NUMBER() OVER( $rno_ord ) AS $idx_name FROM ( - SELECT $in_sel ${sql}${group_having} + SELECT $sq_attrs->{selection_inner} $sq_attrs->{query_leftover}${group_having} ) $qalias -) $qalias WHERE $idx_name BETWEEN %u AND %u +) $qalias WHERE $idx_name >= ? AND $idx_name <= ? EOS - $sql =~ s/\s*\n\s*/ /g; # easier to read in the debugger - return $sql; } # some databases are happy with OVER (), some need OVER (ORDER BY (SELECT (1)) ) @@ -223,14 +161,20 @@ sub _SkipFirst { my ($self, $sql, $rs_attrs, $rows, $offset) = @_; $sql =~ s/^ \s* SELECT \s+ //ix - or croak "Unrecognizable SELECT: $sql"; + or $self->throw_exception("Unrecognizable SELECT: $sql"); return sprintf ('SELECT %s%s%s%s', $offset - ? sprintf ('SKIP %u ', $offset) + ? do { + push @{$self->{pre_select_bind}}, [ $self->__offset_bindtype => $offset]; + 'SKIP ? ' + } : '' , - sprintf ('FIRST %u ', $rows), + do { + push @{$self->{pre_select_bind}}, [ $self->__rows_bindtype => $rows ]; + 'FIRST ? ' + }, $sql, $self->_parse_rs_attrs ($rs_attrs), ); @@ -248,12 +192,18 @@ sub _FirstSkip { my ($self, $sql, $rs_attrs, $rows, $offset) = @_; $sql =~ s/^ \s* SELECT \s+ //ix - or croak "Unrecognizable SELECT: $sql"; + or $self->throw_exception("Unrecognizable SELECT: $sql"); return sprintf ('SELECT %s%s%s%s', - sprintf ('FIRST %u ', $rows), + do { + push @{$self->{pre_select_bind}}, [ $self->__rows_bindtype => $rows ]; + 'FIRST ? ' + }, $offset - ? sprintf ('SKIP %u ', $offset) + ? do { + push @{$self->{pre_select_bind}}, [ $self->__offset_bindtype => $offset]; + 'SKIP ? ' + } : '' , $sql, @@ -261,179 +211,301 @@ sub _FirstSkip { ); } + =head2 RowNum +Depending on the resultset attributes one of: + SELECT * FROM ( SELECT *, ROWNUM rownum__index FROM ( SELECT ... ) WHERE ROWNUM <= ($limit+$offset) ) WHERE rownum__index >= ($offset+1) +or + + SELECT * FROM ( + SELECT *, ROWNUM rownum__index FROM ( + SELECT ... + ) + ) WHERE rownum__index BETWEEN ($offset+1) AND ($limit+$offset) + +or + + SELECT * FROM ( + SELECT ... + ) WHERE ROWNUM <= ($limit+1) + Supported by B. =cut sub _RowNum { my ( $self, $sql, $rs_attrs, $rows, $offset ) = @_; - # 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: $sql"; - - my ($insel, $outsel) = $self->_subqueried_limit_attrs ($rs_attrs); + my $sq_attrs = $self->_subqueried_limit_attrs ($sql, $rs_attrs); my $qalias = $self->_quote ($rs_attrs->{alias}); my $idx_name = $self->_quote ('rownum__index'); my $order_group_having = $self->_parse_rs_attrs($rs_attrs); - if ($offset) { - $sql = sprintf (<{limit_bind}}, [ $self->__rows_bindtype => $rows ]; -SELECT $outsel FROM ( - SELECT $outsel, ROWNUM $idx_name FROM ( - SELECT $insel ${sql}${order_group_having} - ) $qalias WHERE ROWNUM <= %u -) $qalias WHERE $idx_name >= %u + return <{selection_outer} FROM ( + SELECT $sq_attrs->{selection_inner} $sq_attrs->{query_leftover}${order_group_having} +) $qalias WHERE ROWNUM <= ? +EOS + } + # + # There are two ways to limit in Oracle, one vastly faster than the other + # on large resultsets: https://decipherinfosys.wordpress.com/2007/08/09/paging-and-countstopkey-optimization/ + # However Oracle is retarded and does not preserve stable ROWNUM() values + # when called twice in the same scope. Therefore unless the resultset is + # ordered by a unique set of columns, it is not safe to use the faster + # method, and the slower BETWEEN query is used instead + # + # FIXME - this is quite expensive, and does not perform caching of any sort + # as soon as some of the DQ work becomes viable consider switching this + # over + if ( + $rs_attrs->{order_by} + and + $rs_attrs->{_rsroot_rsrc}->storage->_order_by_is_stable( + $rs_attrs->{from}, $rs_attrs->{order_by} + ) + ) { + push @{$self->{limit_bind}}, [ $self->__total_bindtype => $offset + $rows ], [ $self->__offset_bindtype => $offset + 1 ]; + + return <{selection_outer} FROM ( + SELECT $sq_attrs->{selection_outer}, ROWNUM $idx_name FROM ( + SELECT $sq_attrs->{selection_inner} $sq_attrs->{query_leftover}${order_group_having} + ) $qalias WHERE ROWNUM <= ? +) $qalias WHERE $idx_name >= ? EOS } else { - $sql = sprintf (<{limit_bind}}, [ $self->__offset_bindtype => $offset + 1 ], [ $self->__total_bindtype => $offset + $rows ]; + return <{selection_outer} FROM ( + SELECT $sq_attrs->{selection_outer}, ROWNUM $idx_name FROM ( + SELECT $sq_attrs->{selection_inner} $sq_attrs->{query_leftover}${order_group_having} + ) $qalias +) $qalias WHERE $idx_name BETWEEN ? AND ? EOS } - - $sql =~ s/\s*\n\s*/ /g; # easier to read in the debugger - return $sql; } -=head2 Top - - SELECT * FROM - - SELECT TOP $limit FROM ( - SELECT TOP $limit FROM ( - SELECT TOP ($limit+$offset) ... - ) ORDER BY $reversed_original_order - ) ORDER BY $original_order - -Unreliable Top-based implementation, supported by B<< MSSQL < 2005 >>. - -=head3 CAVEAT - -Due to its implementation, this limit dialect returns B -when $limit+$offset > total amount of rows in the resultset. - -=cut -sub _Top { - my ( $self, $sql, $rs_attrs, $rows, $offset ) = @_; - - # 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"; +# used by _Top and _FetchFirst below +sub _prep_for_skimming_limit { + my ( $self, $sql, $rs_attrs ) = @_; # get selectors - my ($in_sel, $out_sel, $alias_map, $extra_order_sel) - = $self->_subqueried_limit_attrs ($rs_attrs); + my $sq_attrs = $self->_subqueried_limit_attrs ($sql, $rs_attrs); my $requested_order = delete $rs_attrs->{order_by}; + $sq_attrs->{order_by_requested} = $self->_order_by ($requested_order); + $sq_attrs->{grpby_having} = $self->_parse_rs_attrs ($rs_attrs); + + # make up an order unless supplied or sanity check what we are given + my $inner_order; + if ($sq_attrs->{order_by_requested}) { + $self->throw_exception ( + 'Unable to safely perform "skimming type" limit with supplied unstable order criteria' + ) unless $rs_attrs->{_rsroot_rsrc}->schema->storage->_order_by_is_stable( + $rs_attrs->{from}, + $requested_order + ); - my $order_by_requested = $self->_order_by ($requested_order); - - # make up an order unless supplied - my $inner_order = ($order_by_requested - ? $requested_order - : [ map - { join ('', $rs_attrs->{alias}, $self->{name_sep}||'.', $_ ) } - ( $rs_attrs->{_rsroot_source_handle}->resolve->_pri_cols ) - ] - ); - - my ($order_by_inner, $order_by_reversed); + $inner_order = $requested_order; + } + else { + $inner_order = [ map + { "$rs_attrs->{alias}.$_" } + ( @{ + $rs_attrs->{_rsroot_rsrc}->_identifying_column_set + || + $self->throw_exception(sprintf( + 'Unable to auto-construct stable order criteria for "skimming type" limit ' + . "dialect based on source '%s'", $rs_attrs->{_rsroot_rsrc}->name) ); + } ) + ]; + } # localise as we already have all the bind values we need - { - local $self->{order_bind}; - $order_by_inner = $self->_order_by ($inner_order); + local $self->{order_bind}; - my @out_chunks; - for my $ch ($self->_order_by_chunks ($inner_order)) { - $ch = $ch->[0] if ref $ch eq 'ARRAY'; + $sq_attrs->{order_by_inner} = $self->_order_by ($inner_order); - $ch =~ s/\s+ ( ASC|DESC ) \s* $//ix; - my $dir = uc ($1||'ASC'); + my @out_chunks; + for my $ch ($self->_order_by_chunks ($inner_order)) { + $ch = $ch->[0] if ref $ch eq 'ARRAY'; - push @out_chunks, \join (' ', $ch, $dir eq 'ASC' ? 'DESC' : 'ASC' ); - } + $ch =~ s/\s+ ( ASC|DESC ) \s* $//ix; + my $dir = uc ($1||'ASC'); - $order_by_reversed = $self->_order_by (\@out_chunks); + push @out_chunks, \join (' ', $ch, $dir eq 'ASC' ? 'DESC' : 'ASC' ); } + $sq_attrs->{quoted_rs_alias} = $self->_quote ($rs_attrs->{alias}); + $sq_attrs->{order_by_middle} = $self->_order_by (\@out_chunks); + $sq_attrs->{selection_middle} = $sq_attrs->{selection_outer}; + # this is the order supplement magic - my $mid_sel = $out_sel; - if ($extra_order_sel) { + if (my $extra_order_sel = $sq_attrs->{order_supplement}) { for my $extra_col (sort { $extra_order_sel->{$a} cmp $extra_order_sel->{$b} } keys %$extra_order_sel ) { - $in_sel .= sprintf (', %s AS %s', + $sq_attrs->{selection_inner} .= sprintf (', %s AS %s', $extra_col, $extra_order_sel->{$extra_col}, ); - $mid_sel .= ', ' . $extra_order_sel->{$extra_col}; + $sq_attrs->{selection_middle} .= ', ' . $extra_order_sel->{$extra_col}; } - # since whatever order bindvals there are, they will be realiased - # and need to show up in front of the entire initial inner subquery - # Unshift *from_bind* to make this happen (horrible, horrible, but - # we don't have another mechanism yet) - unshift @{$self->{from_bind}}, @{$self->{order_bind}}; + # Whatever order bindvals there are, they will be realiased and + # reselected, and need to show up at end of the initial inner select + push @{$self->{select_bind}}, @{$self->{order_bind}}; + + # if this is a part of something bigger, we need to add back all + # the extra order_by's, as they may be relied upon by the outside + # of a prefetch or something + if ($rs_attrs->{_is_internal_subuery}) { + $sq_attrs->{selection_outer} .= sprintf ", $extra_order_sel->{$_} AS $_" + for sort + { $extra_order_sel->{$a} cmp $extra_order_sel->{$b} } + grep { $_ !~ /[^\w\-]/ } # ignore functions + keys %$extra_order_sel + ; + } } # and this is order re-alias magic - for my $map ($extra_order_sel, $alias_map) { - for my $col (keys %$map) { + for my $map ($sq_attrs->{order_supplement}, $sq_attrs->{outer_renames}) { + for my $col (sort { $map->{$a} cmp $map->{$b} } keys %{$map||{}}) { my $re_col = quotemeta ($col); $_ =~ s/$re_col/$map->{$col}/ - for ($order_by_reversed, $order_by_requested); + for ($sq_attrs->{order_by_middle}, $sq_attrs->{order_by_requested}); } } - # generate the rest of the sql - my $grpby_having = $self->_parse_rs_attrs ($rs_attrs); + $sq_attrs; +} + +=head2 Top + + SELECT * FROM - my $quoted_rs_alias = $self->_quote ($rs_attrs->{alias}); + SELECT TOP $limit FROM ( + SELECT TOP $limit FROM ( + SELECT TOP ($limit+$offset) ... + ) ORDER BY $reversed_original_order + ) ORDER BY $original_order + +Unreliable Top-based implementation, supported by B<< MSSQL < 2005 >>. + +=head3 CAVEAT + +Due to its implementation, this limit dialect returns B +when $limit+$offset > total amount of rows in the resultset. + +=cut + +sub _Top { + my ( $self, $sql, $rs_attrs, $rows, $offset ) = @_; + + my $lim = $self->_prep_for_skimming_limit($sql, $rs_attrs); $sql = sprintf ('SELECT TOP %u %s %s %s %s', $rows + ($offset||0), - $in_sel, - $sql, - $grpby_having, - $order_by_inner, + $lim->{selection_inner}, + $lim->{query_leftover}, + $lim->{grpby_having}, + $lim->{order_by_inner}, ); $sql = sprintf ('SELECT TOP %u %s FROM ( %s ) %s %s', $rows, - $mid_sel, + $lim->{selection_middle}, $sql, - $quoted_rs_alias, - $order_by_reversed, + $lim->{quoted_rs_alias}, + $lim->{order_by_middle}, ) if $offset; $sql = sprintf ('SELECT TOP %u %s FROM ( %s ) %s %s', $rows, - $out_sel, + $lim->{selection_outer}, + $sql, + $lim->{quoted_rs_alias}, + $lim->{order_by_requested}, + ) if $offset and ( + $lim->{order_by_requested} or $lim->{selection_middle} ne $lim->{selection_outer} + ); + + return $sql; +} + +=head2 FetchFirst + + SELECT * FROM + ( + SELECT * FROM ( + SELECT * FROM ( + SELECT * FROM ... + ) ORDER BY $reversed_original_order + FETCH FIRST $limit ROWS ONLY + ) ORDER BY $original_order + FETCH FIRST $limit ROWS ONLY + ) + +Unreliable FetchFirst-based implementation, supported by B<< IBM DB2 <= V5R3 >>. + +=head3 CAVEAT + +Due to its implementation, this limit dialect returns B +when $limit+$offset > total amount of rows in the resultset. + +=cut + +sub _FetchFirst { + my ( $self, $sql, $rs_attrs, $rows, $offset ) = @_; + + my $lim = $self->_prep_for_skimming_limit($sql, $rs_attrs); + + $sql = sprintf ('SELECT %s %s %s %s FETCH FIRST %u ROWS ONLY', + $lim->{selection_inner}, + $lim->{query_leftover}, + $lim->{grpby_having}, + $lim->{order_by_inner}, + $rows + ($offset||0), + ); + + $sql = sprintf ('SELECT %s FROM ( %s ) %s %s FETCH FIRST %u ROWS ONLY', + $lim->{selection_middle}, + $sql, + $lim->{quoted_rs_alias}, + $lim->{order_by_middle}, + $rows, + ) if $offset; + + + $sql = sprintf ('SELECT %s FROM ( %s ) %s %s FETCH FIRST %u ROWS ONLY', + $lim->{selection_outer}, $sql, - $quoted_rs_alias, - $order_by_requested, - ) if ( ($offset && $order_by_requested) || ($mid_sel ne $out_sel) ); + $lim->{quoted_rs_alias}, + $lim->{order_by_requested}, + $rows, + ) if $offset and ( + $lim->{order_by_requested} or $lim->{selection_middle} ne $lim->{selection_outer} + ); - $sql =~ s/\s*\n\s*/ /g; # easier to read in the debugger return $sql; } @@ -449,6 +521,7 @@ If no $offset is supplied the limit is simply performed as: Otherwise we fall back to L =cut + sub _RowCountOrGenericSubQ { my $self = shift; my ($sql, $rs_attrs, $rows, $offset) = @_; @@ -484,70 +557,34 @@ Currently used by B, due to lack of any other option. sub _GenericSubQ { my ($self, $sql, $rs_attrs, $rows, $offset) = @_; - my $root_rsrc = $rs_attrs->{_rsroot_source_handle}->resolve; + my $root_rsrc = $rs_attrs->{_rsroot_rsrc}; 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 { + my ($first_order_by) = 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; + map { ref $_ ? $_->[0] : $_ } $self->_order_by_chunks ($rs_attrs->{order_by}) + } or $self->throw_exception ( + 'Generic Subquery Limit does not work on resultsets without an order. Provide a single, ' + . 'unique-column order criteria.' + ); - $order_by =~ s/\s+ ( ASC|DESC ) \s* $//ix; + $first_order_by =~ s/\s+ ( ASC|DESC ) \s* $//ix; my $direction = lc ($1 || 'asc'); - my ($unq_sort_col) = $order_by =~ /(?:^|\.)([^\.]+)$/; + my ($first_ord_alias, $first_ord_col) = $first_order_by =~ /^ (?: ([^\.]+) \. )? ([^\.]+) $/x; - my $inf = $root_rsrc->storage->_resolve_column_info ( - $rs_attrs->{from}, [$order_by, $unq_sort_col] - ); + $self->throw_exception(sprintf + "Generic Subquery Limit order criteria can be only based on the root-source '%s'" + . " (aliased as '%s')", $root_rsrc->source_name, $rs_attrs->{alias}, + ) if ($first_ord_alias and $first_ord_alias ne $rs_attrs->{alias}); - my $ord_colinfo = $inf->{$order_by} || croak "Unable to determine source of order-criteria '$order_by'"; + $first_ord_alias ||= $rs_attrs->{alias}; - if ($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}')"; - } + $self->throw_exception( + "Generic Subquery Limit first order criteria '$first_ord_col' must be unique" + ) unless $root_rsrc->_identifying_column_set([$first_ord_col]); - # 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 $sq_attrs = $self->_subqueried_limit_attrs ($sql, $rs_attrs); my $cmp_op = $direction eq 'desc' ? '>' : '<'; my $count_tbl_alias = 'rownum__emulation'; @@ -555,32 +592,42 @@ sub _GenericSubQ { my $order_sql = $self->_order_by (delete $rs_attrs->{order_by}); my $group_having_sql = $self->_parse_rs_attrs($rs_attrs); + my $in_sel = $sq_attrs->{selection_inner}; + # add the order supplement (if any) as this is what will be used for the outer WHERE - $in_sel .= ", $_" for keys %{$extra_order_sel||{}}; + $in_sel .= ", $_" for keys %{$sq_attrs->{order_supplement}}; + + my $rownum_cond; + if ($offset) { + $rownum_cond = 'BETWEEN ? AND ?'; - $sql = sprintf (<{limit_bind}}, + [ $self->__offset_bindtype => $offset ], + [ $self->__total_bindtype => $offset + $rows - 1] + ; + } + else { + $rownum_cond = '< ?'; + + push @{$self->{limit_bind}}, + [ $self->__rows_bindtype => $rows ] + ; + } + + return sprintf (" +SELECT $sq_attrs->{selection_outer} FROM ( - SELECT $in_sel ${sql}${group_having_sql} + SELECT $in_sel $sq_attrs->{query_leftover}${group_having_sql} ) %s -WHERE ( SELECT COUNT(*) FROM %s %s WHERE %s $cmp_op %s ) %s +WHERE ( SELECT COUNT(*) FROM %s %s WHERE %s $cmp_op %s ) $rownum_cond $order_sql -EOS - ( map { $self->_quote ($_) } ( - $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; + ", map { $self->_quote ($_) } ( + $rs_attrs->{alias}, + $root_tbl_name, + $count_tbl_alias, + "$count_tbl_alias.$first_ord_col", + "$first_ord_alias.$first_ord_col", + )); } @@ -592,10 +639,10 @@ EOS # turned into a column alias (otherwise names in subqueries clash # and/or lose their source table) # -# Returns inner/outer strings of SQL QUOTED selectors with aliases -# (to be used in whatever select statement), and an alias index hashref -# of QUOTED SEL => QUOTED ALIAS pairs (to maybe be used for string-subst -# higher up). +# Returns mangled proto-sql, inner/outer strings of SQL QUOTED selectors +# with aliases (to be used in whatever select statement), and an alias +# index hashref of QUOTED SEL => QUOTED ALIAS pairs (to maybe be used +# for string-subst higher up). # If an order_by is supplied, the inner select needs to bring out columns # used in implicit (non-selected) orders, and the order condition itself # needs to be realiased to the proper names in the outer query. Thus we @@ -603,15 +650,25 @@ EOS # QUOTED ALIAS pairs, which is a list of extra selectors that do *not* # exist in the original select list sub _subqueried_limit_attrs { - my ($self, $rs_attrs) = @_; + my ($self, $proto_sql, $rs_attrs) = @_; - croak 'Limit dialect implementation usable only in the context of DBIC (missing $rs_attrs)' - unless ref ($rs_attrs) eq 'HASH'; + $self->throw_exception( + 'Limit dialect implementation usable only in the context of DBIC (missing $rs_attrs)' + ) unless ref ($rs_attrs) eq 'HASH'; - my ($re_sep, $re_alias) = map { quotemeta $_ } ( - $self->name_sep || '.', - $rs_attrs->{alias}, - ); + # mangle the input sql as we will be replacing the selector entirely + unless ( + $rs_attrs->{_selector_sql} + and + $proto_sql =~ s/^ \s* SELECT \s* \Q$rs_attrs->{_selector_sql}//ix + ) { + $self->throw_exception("Unrecognizable SELECT: $proto_sql"); + } + + my ($re_sep, $re_alias) = map { quotemeta $_ } ( $self->{name_sep}, $rs_attrs->{alias} ); + + # insulate from the multiple _recurse_fields calls below + local $self->{select_bind}; # correlate select and as, build selection index my (@sel, $in_sel_index); @@ -623,13 +680,16 @@ sub _subqueried_limit_attrs { push @sel, { sql => $sql_sel, - unquoted_sql => do { local $self->{quote_char}; $self->_recurse_fields ($s) }, + unquoted_sql => do { + local $self->{quote_char}; + $self->_recurse_fields ($s); + }, as => $sql_alias || $rs_attrs->{as}[$i] || - croak "Select argument $i ($s) without corresponding 'as'" + $self->throw_exception("Select argument $i ($s) without corresponding 'as'") , }; @@ -649,23 +709,27 @@ sub _subqueried_limit_attrs { # unless we are dealing with the current source alias # (which will transcend the subqueries as it is necessary # for possible further chaining) - my (@in_sel, @out_sel, %renamed); + my ($sel, $renamed); for my $node (@sel) { - if (first { $_ =~ / (?{as}, $node->{unquoted_sql}) ) { + if ( + $node->{as} =~ / (?{unquoted_sql} =~ / (?{as} = $self->_unqualify_colname($node->{as}); my $quoted_as = $self->_quote($node->{as}); - push @in_sel, sprintf '%s AS %s', $node->{sql}, $quoted_as; - push @out_sel, $quoted_as; - $renamed{$node->{sql}} = $quoted_as; + push @{$sel->{inner}}, sprintf '%s AS %s', $node->{sql}, $quoted_as; + push @{$sel->{outer}}, $quoted_as; + $renamed->{$node->{sql}} = $quoted_as; } else { - push @in_sel, $node->{sql}; - push @out_sel, $self->_quote ($node->{as}); + push @{$sel->{inner}}, $node->{sql}; + push @{$sel->{outer}}, $self->_quote ($node->{as}); } } # see if the order gives us anything - my %extra_order_sel; + my $extra_order_sel; for my $chunk ($self->_order_by_chunks ($rs_attrs->{order_by})) { # order with bind $chunk = $chunk->[0] if (ref $chunk) eq 'ARRAY'; @@ -673,25 +737,22 @@ sub _subqueried_limit_attrs { 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, - \@out_sel) - ), - \%renamed, - keys %extra_order_sel ? \%extra_order_sel : (), - ); + return { + query_leftover => $proto_sql, + (map {( "selection_$_" => join (', ', @{$sel->{$_}} ) )} keys %$sel ), + outer_renames => $renamed, + order_supplement => $extra_order_sel, + }; } sub _unqualify_colname { my ($self, $fqcn) = @_; - my $re_sep = quotemeta($self->name_sep || '.'); - $fqcn =~ s/ $re_sep /__/xg; + $fqcn =~ s/ \. /__/xg; return $fqcn; }