X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=lib%2FDBIx%2FClass%2FSQLMaker%2FLimitDialects.pm;h=6bb7b9282f7964b74e300f5892a6f4b3a6e7192f;hb=7cec43565df63cdbf6320721c7d7c33cb6ce6e96;hp=00f7cb57d85ee896941a77f00b3b425760fd2ff0;hpb=70c288086248e5a4008490df22a56632341f2473;p=dbsrgits%2FDBIx-Class.git diff --git a/lib/DBIx/Class/SQLMaker/LimitDialects.pm b/lib/DBIx/Class/SQLMaker/LimitDialects.pm index 00f7cb5..6bb7b92 100644 --- a/lib/DBIx/Class/SQLMaker/LimitDialects.pm +++ b/lib/DBIx/Class/SQLMaker/LimitDialects.pm @@ -6,77 +6,16 @@ use strict; 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'; - $self->throw_exception(__PACKAGE__ . ": Unsupported data struct $ref for ORDER BY"); - } - - my ( $order_by_up, $order_by_down ); - - foreach my $spec ( @order ) - { - my @spec = split ' ', $spec; - $self->throw_exception("bad column order spec: $spec") if @spec > 2; - push( @spec, 'ASC' ) unless @spec == 2; - my ( $col, $up ) = @spec; # or maybe down - $up = uc( $up ); - $self->throw_exception("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 @@ -102,8 +41,6 @@ names. Currently the provided dialects are: -=cut - =head2 LimitOffset SELECT ... LIMIT $limit OFFSET $offset @@ -112,9 +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; } @@ -126,10 +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 $sql; } @@ -149,13 +95,9 @@ B<< MSSQL >= 2005 >>. sub _RowNumberOver { my ($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 $self->throw_exception("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 ( $rs_attrs ); + my ($stripped_sql, $in_sel, $out_sel, $alias_map, $extra_order_sel) + = $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; @@ -191,17 +133,18 @@ 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 ]; + + return <= ? AND $idx_name <= ? EOS - return $sql; } # some databases are happy with OVER (), some need OVER (ORDER BY (SELECT (1)) ) @@ -225,10 +168,16 @@ sub _SkipFirst { 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), ); @@ -249,9 +198,15 @@ sub _FirstSkip { 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 ? ' + } : '' , $sql, @@ -259,90 +214,110 @@ sub _FirstSkip { ); } + =head2 RowNum +Depending on the resultset attributes one of: + SELECT * FROM ( SELECT *, ROWNUM rownum__index FROM ( SELECT ... ) WHERE ROWNUM <= ($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 $self->throw_exception("Unrecognizable SELECT: $sql"); - - my ($insel, $outsel) = $self->_subqueried_limit_attrs ($rs_attrs); + my ($stripped_sql, $insel, $outsel) = $self->_subqueried_limit_attrs ($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) { + # + # 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} + ) + ) { + # if offset is 0 (first page) the we can skip a subquery + if (! $offset) { + push @{$self->{limit_bind}}, [ $self->__rows_bindtype => $rows ]; - $sql = sprintf (<{limit_bind}}, [ $self->__total_bindtype => $offset + $rows ], [ $self->__offset_bindtype => $offset + 1 ]; + return <= %u - + SELECT $insel ${stripped_sql}${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 <>. - -=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 $self->throw_exception("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 (%r, $alias_map, $extra_order_sel); + ($r{inner_sql}, $r{in_sel}, $r{out_sel}, $alias_map, $extra_order_sel) + = $self->_subqueried_limit_attrs ($sql, $rs_attrs); my $requested_order = delete $rs_attrs->{order_by}; - - my $order_by_requested = $self->_order_by ($requested_order); + $r{order_by_requested} = $self->_order_by ($requested_order); # make up an order unless supplied - my $inner_order = ($order_by_requested + my $inner_order = ($r{order_by_requested} ? $requested_order : [ map { "$rs_attrs->{alias}.$_" } @@ -350,12 +325,10 @@ sub _Top { ] ); - my ($order_by_inner, $order_by_reversed); - # localise as we already have all the bind values we need { local $self->{order_bind}; - $order_by_inner = $self->_order_by ($inner_order); + $r{order_by_inner} = $self->_order_by ($inner_order); my @out_chunks; for my $ch ($self->_order_by_chunks ($inner_order)) { @@ -367,29 +340,27 @@ sub _Top { push @out_chunks, \join (' ', $ch, $dir eq 'ASC' ? 'DESC' : 'ASC' ); } - $order_by_reversed = $self->_order_by (\@out_chunks); + $r{order_by_reversed} = $self->_order_by (\@out_chunks); } # this is the order supplement magic - my $mid_sel = $out_sel; + $r{mid_sel} = $r{out_sel}; if ($extra_order_sel) { for my $extra_col (sort { $extra_order_sel->{$a} cmp $extra_order_sel->{$b} } keys %$extra_order_sel ) { - $in_sel .= sprintf (', %s AS %s', + $r{in_sel} .= sprintf (', %s AS %s', $extra_col, $extra_order_sel->{$extra_col}, ); - $mid_sel .= ', ' . $extra_order_sel->{$extra_col}; + $r{mid_sel} .= ', ' . $extra_order_sel->{$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* the selector bind stack to make this happen (horrible, - # horrible, but we don't have another mechanism yet) - unshift @{$self->{select_bind}}, @{$self->{order_bind}}; + # Whatever order bindvals there are, they will be realiased and + # need to show up in front of the entire initial inner subquery + push @{$self->{pre_select_bind}}, @{$self->{order_bind}}; } # and this is order re-alias magic @@ -397,38 +368,119 @@ sub _Top { for my $col (keys %$map) { my $re_col = quotemeta ($col); $_ =~ s/$re_col/$map->{$col}/ - for ($order_by_reversed, $order_by_requested); + for ($r{order_by_reversed}, $r{order_by_requested}); } } # generate the rest of the sql - my $grpby_having = $self->_parse_rs_attrs ($rs_attrs); + $r{grpby_having} = $self->_parse_rs_attrs ($rs_attrs); - my $quoted_rs_alias = $self->_quote ($rs_attrs->{alias}); + $r{quoted_rs_alias} = $self->_quote ($rs_attrs->{alias}); + + \%r; +} + +=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 ) = @_; + + my %l = %{ $self->_prep_for_skimming_limit($sql, $rs_attrs) }; $sql = sprintf ('SELECT TOP %u %s %s %s %s', $rows + ($offset||0), - $in_sel, - $sql, - $grpby_having, - $order_by_inner, + $l{in_sel}, + $l{inner_sql}, + $l{grpby_having}, + $l{order_by_inner}, ); $sql = sprintf ('SELECT TOP %u %s FROM ( %s ) %s %s', $rows, - $mid_sel, + $l{mid_sel}, $sql, - $quoted_rs_alias, - $order_by_reversed, + $l{quoted_rs_alias}, + $l{order_by_reversed}, ) if $offset; $sql = sprintf ('SELECT TOP %u %s FROM ( %s ) %s %s', $rows, - $out_sel, + $l{out_sel}, $sql, - $quoted_rs_alias, - $order_by_requested, - ) if ( ($offset && $order_by_requested) || ($mid_sel ne $out_sel) ); + $l{quoted_rs_alias}, + $l{order_by_requested}, + ) if ( ($offset && $l{order_by_requested}) || ($l{mid_sel} ne $l{out_sel}) ); + + 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 %l = %{ $self->_prep_for_skimming_limit($sql, $rs_attrs) }; + + $sql = sprintf ('SELECT %s %s %s %s FETCH FIRST %u ROWS ONLY', + $l{in_sel}, + $l{inner_sql}, + $l{grpby_having}, + $l{order_by_inner}, + $rows + ($offset||0), + ); + + $sql = sprintf ('SELECT %s FROM ( %s ) %s %s FETCH FIRST %u ROWS ONLY', + $l{mid_sel}, + $sql, + $l{quoted_rs_alias}, + $l{order_by_reversed}, + $rows, + ) if $offset; + + $sql = sprintf ('SELECT %s FROM ( %s ) %s %s FETCH FIRST %u ROWS ONLY', + $l{out_sel}, + $sql, + $l{quoted_rs_alias}, + $l{order_by_requested}, + $rows, + ) if ( ($offset && $l{order_by_requested}) || ($l{mid_sel} ne $l{out_sel}) ); return $sql; } @@ -445,6 +497,7 @@ 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) = @_; @@ -483,10 +536,6 @@ sub _GenericSubQ { 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 $self->throw_exception("Unrecognizable SELECT: $sql"); - my ($order_by, @rest) = do { local $self->{quote_char}; $self->_order_by_chunks ($rs_attrs->{order_by}) @@ -545,8 +594,8 @@ sub _GenericSubQ { "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 ($stripped_sql, $in_sel, $out_sel, $alias_map, $extra_order_sel) + = $self->_subqueried_limit_attrs ($sql, $rs_attrs); my $cmp_op = $direction eq 'desc' ? '>' : '<'; my $count_tbl_alias = 'rownum__emulation'; @@ -557,28 +606,37 @@ sub _GenericSubQ { # 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 (<{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 $out_sel FROM ( - SELECT $in_sel ${sql}${group_having_sql} + SELECT $in_sel ${stripped_sql}${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 ) - , - ); - - return $sql; + ", map { $self->_quote ($_) } ( + $rs_attrs->{alias}, + $root_tbl_name, + $count_tbl_alias, + "$count_tbl_alias.$unq_sort_col", + $order_by, + )); } @@ -590,10 +648,10 @@ EOS # turned into a column alias (otherwise names in subqueries clash # and/or lose their source table) # -# Returns inner/outer strings of SQL QUOTED selectors with aliases -# (to be used in whatever select statement), and an alias index hashref -# of QUOTED SEL => QUOTED ALIAS pairs (to maybe be used for string-subst -# higher up). +# Returns mangled proto-sql, inner/outer strings of SQL QUOTED selectors +# with aliases (to be used in whatever select statement), and an alias +# index hashref of QUOTED SEL => QUOTED ALIAS pairs (to maybe be used +# for string-subst higher up). # If an order_by is supplied, the inner select needs to bring out columns # used in implicit (non-selected) orders, and the order condition itself # needs to be realiased to the proper names in the outer query. Thus we @@ -601,14 +659,26 @@ EOS # QUOTED ALIAS pairs, which is a list of extra selectors that do *not* # exist in the original select list sub _subqueried_limit_attrs { - my ($self, $rs_attrs) = @_; + my ($self, $proto_sql, $rs_attrs) = @_; $self->throw_exception( 'Limit dialect implementation usable only in the context of DBIC (missing $rs_attrs)' ) unless ref ($rs_attrs) eq 'HASH'; + # 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); for my $i (0 .. $#{$rs_attrs->{select}}) { @@ -619,7 +689,10 @@ 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 || @@ -663,7 +736,6 @@ sub _subqueried_limit_attrs { push @out_sel, $self->_quote ($node->{as}); } } - # see if the order gives us anything my %extra_order_sel; for my $chunk ($self->_order_by_chunks ($rs_attrs->{order_by})) { @@ -679,6 +751,7 @@ sub _subqueried_limit_attrs { } return ( + $proto_sql, (map { join (', ', @$_ ) } ( \@in_sel, \@out_sel)