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
Currently the provided dialects are:
-=cut
-
=head2 LimitOffset
SELECT ... LIMIT $limit OFFSET $offset
=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;
}
=head2 LimitXY
- SELECT ... LIMIT $offset $limit
+ SELECT ... LIMIT $offset, $limit
Supported by B<MySQL> and any L<SQL::Statement> 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 $sql;
}
sub _RowNumberOver {
my ($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;
+
+ # the order binds (if any) will need to go at the end of the entire inner select
+ local $self->{order_bind};
my $rno_ord = $self->_order_by ($requested_order);
+ push @{$self->{select_bind}}, @{$self->{order_bind}};
# 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 my $col (keys %$_) {
+ for my $map ($sq_attrs->{order_supplement}, $sq_attrs->{outer_renames}) {
+ for my $col (sort { (length $b) <=> (length $a) } keys %{$map||{}} ) {
my $re_col = quotemeta ($col);
- $rno_ord =~ s/$re_col/$_->{$col}/;
+ $rno_ord =~ s/$re_col/$map->{$col}/;
}
}
my $qalias = $self->_quote ($rs_attrs->{alias});
my $idx_name = $self->_quote ('rno__row__index');
- $sql = sprintf (<<EOS, $offset + 1, $offset + $rows, );
+ push @{$self->{limit_bind}}, [ $self->__offset_bindtype => $offset + 1], [ $self->__total_bindtype => $offset + $rows ];
-SELECT $out_sel FROM (
+ return <<EOS;
+
+SELECT $sq_attrs->{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
- return $sql;
}
# some databases are happy with OVER (), some need OVER (ORDER BY (SELECT (1)) )
SELECT SKIP $offset FIRST $limit * FROM ...
-Suported by B<Informix>, almost like LimitOffset. According to
+Supported by B<Informix>, almost like LimitOffset. According to
L<SQL::Abstract::Limit> C<... SKIP $offset LIMIT $limit ...> is also supported.
=cut
my ($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),
);
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 ? '
+ }
: ''
,
$sql,
);
}
+
=head2 RowNum
+Depending on the resultset attributes one of:
+
SELECT * FROM (
- SELECT *, ROWNUM rownum__index FROM (
+ SELECT *, ROWNUM AS rownum__index FROM (
SELECT ...
) WHERE ROWNUM <= ($limit+$offset)
) WHERE rownum__index >= ($offset+1)
+or
+
+ SELECT * FROM (
+ SELECT *, ROWNUM AS rownum__index FROM (
+ SELECT ...
+ )
+ ) WHERE rownum__index BETWEEN ($offset+1) AND ($limit+$offset)
+
+or
+
+ SELECT * FROM (
+ SELECT ...
+ ) WHERE ROWNUM <= ($limit+1)
+
Supported by B<Oracle>.
=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 (<<EOS, $offset + $rows, $offset + 1 );
+ # if no offset (e.g. first page) - we can skip one of the subqueries
+ if (! $offset) {
+ push @{$self->{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 <<EOS;
+SELECT $sq_attrs->{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 SQLA-inlining work becomes viable consider adding
+ # some rudimentary caching support
+ if (
+ $rs_attrs->{order_by}
+ and
+ $rs_attrs->{result_source}->schema->storage->_order_by_is_stable(
+ @{$rs_attrs}{qw/from order_by where/}
+ )
+ ) {
+ push @{$self->{limit_bind}}, [ $self->__total_bindtype => $offset + $rows ], [ $self->__offset_bindtype => $offset + 1 ];
+
+ return <<EOS;
+SELECT $sq_attrs->{selection_outer} FROM (
+ SELECT $sq_attrs->{selection_outer}, ROWNUM AS $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 (<<EOS, $rows );
-
- SELECT $outsel FROM (
- SELECT $insel ${sql}${order_group_having}
- ) $qalias WHERE ROWNUM <= %u
+ push @{$self->{limit_bind}}, [ $self->__offset_bindtype => $offset + 1 ], [ $self->__total_bindtype => $offset + $rows ];
+ return <<EOS;
+SELECT $sq_attrs->{selection_outer} FROM (
+ SELECT $sq_attrs->{selection_outer}, ROWNUM AS $idx_name FROM (
+ SELECT $sq_attrs->{selection_inner} $sq_attrs->{query_leftover}${order_group_having}
+ ) $qalias
+) $qalias WHERE $idx_name BETWEEN ? AND ?
EOS
}
-
- 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<incorrect results>
-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);
- my $order_by_requested = $self->_order_by ($requested_order);
+ # without an offset things are easy
+ if (! $rs_attrs->{offset}) {
+ $sq_attrs->{order_by_inner} = $sq_attrs->{order_by_requested};
+ }
+ else {
+ $sq_attrs->{quoted_rs_alias} = $self->_quote ($rs_attrs->{alias});
- # make up an order unless supplied
- my $inner_order = ($order_by_requested
- ? $requested_order
- : [ map
- { "$rs_attrs->{alias}.$_" }
- ( $rs_attrs->{_rsroot_source_handle}->resolve->_pri_cols )
- ]
- );
+ # localise as we already have all the bind values we need
+ local $self->{order_bind};
- my ($order_by_inner, $order_by_reversed);
+ # 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->{result_source}->schema->storage->_order_by_is_stable(
+ $rs_attrs->{from},
+ $requested_order,
+ $rs_attrs->{where},
+ ));
+
+ $inner_order = $requested_order;
+ }
+ else {
+ $inner_order = [ map
+ { "$rs_attrs->{alias}.$_" }
+ ( @{
+ $rs_attrs->{result_source}->_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->{result_source}->name) );
+ } )
+ ];
+ }
- # localise as we already have all the bind values we need
- {
- local $self->{order_bind};
- $order_by_inner = $self->_order_by ($inner_order);
+ $sq_attrs->{order_by_inner} = $self->_order_by ($inner_order);
my @out_chunks;
for my $ch ($self->_order_by_chunks ($inner_order)) {
$ch = $ch->[0] if ref $ch eq 'ARRAY';
- $ch =~ s/\s+ ( ASC|DESC ) \s* $//ix;
- my $dir = uc ($1||'ASC');
+ ($ch, my $is_desc) = $self->_split_order_chunk($ch);
+
+ # !NOTE! outside chunks come in reverse order ( !$is_desc )
+ push @out_chunks, { ($is_desc ? '-asc' : '-desc') => \$ch };
+ }
- push @out_chunks, \join (' ', $ch, $dir eq 'ASC' ? 'DESC' : 'ASC' );
+ $sq_attrs->{order_by_middle} = $self->_order_by (\@out_chunks);
+
+ # this is the order supplement magic
+ $sq_attrs->{selection_middle} = $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
+ ) {
+ $sq_attrs->{selection_inner} .= sprintf (', %s AS %s',
+ $extra_col,
+ $extra_order_sel->{$extra_col},
+ );
+
+ $sq_attrs->{selection_middle} .= ', ' . $extra_order_sel->{$extra_col};
+ }
+
+ # 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}};
}
- $order_by_reversed = $self->_order_by (\@out_chunks);
+ # and this is order re-alias magic
+ for my $map ($sq_attrs->{order_supplement}, $sq_attrs->{outer_renames}) {
+ for my $col (sort { (length $b) <=> (length $a) } keys %{$map||{}}) {
+ my $re_col = quotemeta ($col);
+ $_ =~ s/$re_col/$map->{$col}/
+ for ($sq_attrs->{order_by_middle}, $sq_attrs->{order_by_requested});
+ }
+ }
}
- # this is the order supplement magic
- my $mid_sel = $out_sel;
- if ($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',
- $extra_col,
- $extra_order_sel->{$extra_col},
- );
+ $sq_attrs;
+}
- $mid_sel .= ', ' . $extra_order_sel->{$extra_col};
- }
+=head2 Top
- # 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}};
- }
+ SELECT * FROM
- # and this is order re-alias magic
- for my $map ($extra_order_sel, $alias_map) {
- for my $col (keys %$map) {
- my $re_col = quotemeta ($col);
- $_ =~ s/$re_col/$map->{$col}/
- for ($order_by_reversed, $order_by_requested);
- }
- }
+ 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<incorrect results>
+when $limit+$offset > total amount of rows in the resultset.
+
+=cut
- # generate the rest of the sql
- my $grpby_having = $self->_parse_rs_attrs ($rs_attrs);
+sub _Top {
+ my ( $self, $sql, $rs_attrs, $rows, $offset ) = @_;
- my $quoted_rs_alias = $self->_quote ($rs_attrs->{alias});
+ 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,
+ $offset ? $lim->{selection_inner} : $lim->{selection_original},
+ $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,
+ $sql = sprintf ('SELECT %s FROM ( %s ) %s %s',
+ $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},
+ ) if $offset and (
+ $lim->{order_by_requested} or $lim->{selection_middle} ne $lim->{selection_outer}
+ );
return $sql;
}
-=head2 RowCountOrGenericSubQ
+=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
+ )
-This is not exactly a limit dialect, but more of a proxy for B<Sybase ASE>.
-If no $offset is supplied the limit is simply performed as:
+Unreliable FetchFirst-based implementation, supported by B<< IBM DB2 <= V5R3 >>.
- SET ROWCOUNT $limit
- SELECT ...
- SET ROWCOUNT 0
+=head3 CAVEAT
-Otherwise we fall back to L</GenericSubQ>
+Due to its implementation, this limit dialect returns B<incorrect results>
+when $limit+$offset > total amount of rows in the resultset.
=cut
-sub _RowCountOrGenericSubQ {
- my $self = shift;
- my ($sql, $rs_attrs, $rows, $offset) = @_;
- return $self->_GenericSubQ(@_) if $offset;
+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',
+ $offset ? $lim->{selection_inner} : $lim->{selection_original},
+ $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',
+ $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 sprintf <<"EOF", $rows, $sql;
-SET ROWCOUNT %d
-%s
-SET ROWCOUNT 0
-EOF
+ return $sql;
}
=head2 GenericSubQ
databases. It works by ordering the set by some unique column, and calculating
the amount of rows that have a less-er value (thus emulating a L</RowNum>-like
index). Of course this implies the set can only be ordered by a single unique
-column. Also note that this technique can be and often is B<excruciatingly
-slow>.
+column.
+
+Also note that this technique can be and often is B<excruciatingly slow>. You
+may have much better luck using L<DBIx::Class::ResultSet/software_limit>
+instead.
Currently used by B<Sybase ASE>, due to lack of any other option.
sub _GenericSubQ {
my ($self, $sql, $rs_attrs, $rows, $offset) = @_;
- my $root_rsrc = $rs_attrs->{_rsroot_source_handle}->resolve;
- my $root_tbl_name = $root_rsrc->name;
+ my $main_rsrc = $rs_attrs->{result_source};
- # 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";
+ # Explicitly require an order_by
+ # GenSubQ is slow enough as it is, just emulating things
+ # like in other cases is not wise - make the user work
+ # to shoot their DBA in the foot
+ $self->throw_exception (
+ 'Generic Subquery Limit does not work on resultsets without an order. Provide a stable, '
+ . 'main-table-based order criteria.'
+ ) unless $rs_attrs->{order_by};
- my ($order_by, @rest) = do {
+ my $usable_order_colinfo = $main_rsrc->schema->storage->_extract_colinfo_of_stable_main_source_order_by_portion(
+ $rs_attrs
+ );
+
+ $self->throw_exception(
+ 'Generic Subquery Limit can not work with order criteria based on sources other than the main one'
+ ) if (
+ ! keys %{$usable_order_colinfo||{}}
+ or
+ grep
+ { $_->{-source_alias} ne $rs_attrs->{alias} }
+ (values %$usable_order_colinfo)
+ );
+
+###
+###
+### we need to know the directions after we figured out the above - reextract *again*
+### this is eyebleed - trying to get it to work at first
+ my $supplied_order = delete $rs_attrs->{order_by};
+
+ my @order_bits = do {
local $self->{quote_char};
- $self->_order_by_chunks ($rs_attrs->{order_by})
+ local $self->{order_bind};
+ map { ref $_ ? $_->[0] : $_ } $self->_order_by_chunks ($supplied_order)
};
- 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.'
- );
+ # truncate to what we'll use
+ $#order_bits = ( (keys %$usable_order_colinfo) - 1 );
+
+ # @order_bits likely will come back quoted (due to how the prefetch
+ # rewriter operates
+ # Hence supplement the column_info lookup table with quoted versions
+ if ($self->quote_char) {
+ $usable_order_colinfo->{$self->_quote($_)} = $usable_order_colinfo->{$_}
+ for keys %$usable_order_colinfo;
}
- ($order_by) = @$order_by if ref $order_by;
+# calculate the condition
+ my $count_tbl_alias = 'rownum__emulation';
+ my $main_alias = $rs_attrs->{alias};
+ my $main_tbl_name = $main_rsrc->name;
+
+ my (@unqualified_names, @qualified_names, @is_desc, @new_order_by);
- $order_by =~ s/\s+ ( ASC|DESC ) \s* $//ix;
- my $direction = lc ($1 || 'asc');
+ for my $bit (@order_bits) {
- my ($unq_sort_col) = $order_by =~ /(?:^|\.)([^\.]+)$/;
+ ($bit, my $is_desc) = $self->_split_order_chunk($bit);
- my $inf = $root_rsrc->storage->_resolve_column_info (
- $rs_attrs->{from}, [$order_by, $unq_sort_col]
- );
+ push @is_desc, $is_desc;
+ push @unqualified_names, $usable_order_colinfo->{$bit}{-colname};
+ push @qualified_names, $usable_order_colinfo->{$bit}{-fq_colname};
+
+ push @new_order_by, { ($is_desc ? '-desc' : '-asc') => $usable_order_colinfo->{$bit}{-fq_colname} };
+ };
- my $ord_colinfo = $inf->{$order_by} || croak "Unable to determine source of order-criteria '$order_by'";
+ my (@where_cond, @skip_colpair_stack);
+ for my $i (0 .. $#order_bits) {
+ my $ci = $usable_order_colinfo->{$order_bits[$i]};
+
+ my ($subq_col, $main_col) = map { "$_.$ci->{-colname}" } ($count_tbl_alias, $main_alias);
+ my $cur_cond = { $subq_col => { ($is_desc[$i] ? '>' : '<') => { -ident => $main_col } } };
+
+ push @skip_colpair_stack, [
+ { $main_col => { -ident => $subq_col } },
+ ];
+
+ # we can trust the nullability flag because
+ # we already used it during _id_col_set resolution
+ #
+ if ($ci->{is_nullable}) {
+ push @{$skip_colpair_stack[-1]}, { $main_col => undef, $subq_col=> undef };
+
+ $cur_cond = [
+ {
+ ($is_desc[$i] ? $subq_col : $main_col) => { '!=', undef },
+ ($is_desc[$i] ? $main_col : $subq_col) => undef,
+ },
+ {
+ $subq_col => { '!=', undef },
+ $main_col => { '!=', undef },
+ -and => $cur_cond,
+ },
+ ];
+ }
- if ($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}')";
+ push @where_cond, { '-and', => [ @skip_colpair_stack[0..$i-1], $cur_cond ] };
}
- # make sure order column is qualified
- $order_by = "$rs_attrs->{alias}.$order_by"
- unless $order_by =~ /^$rs_attrs->{alias}\./;
+# reuse the sqlmaker WHERE, this will not be returning binds
+ my $counted_where = do {
+ local $self->{where_bind};
+ $self->where(\@where_cond);
+ };
- my $is_u;
- my $ucs = { $root_rsrc->unique_constraints };
- for (values %$ucs ) {
- if (@$_ == 1 && "$rs_attrs->{alias}.$_->[0]" eq $order_by) {
- $is_u++;
- last;
- }
+# construct the rownum condition by hand
+ my $rownum_cond;
+ if ($offset) {
+ $rownum_cond = 'BETWEEN ? AND ?';
+ push @{$self->{limit_bind}},
+ [ $self->__offset_bindtype => $offset ],
+ [ $self->__total_bindtype => $offset + $rows - 1]
+ ;
+ }
+ else {
+ $rownum_cond = '< ?';
+ push @{$self->{limit_bind}},
+ [ $self->__rows_bindtype => $rows ]
+ ;
}
- croak "Generic Subquery Limit order criteria column '$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);
+# and what we will order by inside
+ my $inner_order_sql = do {
+ local $self->{order_bind};
- my $cmp_op = $direction eq 'desc' ? '>' : '<';
- my $count_tbl_alias = 'rownum__emulation';
+ my $s = $self->_order_by (\@new_order_by);
- my $order_sql = $self->_order_by (delete $rs_attrs->{order_by});
- my $group_having_sql = $self->_parse_rs_attrs($rs_attrs);
+ $self->throw_exception('Inner gensubq order may not contain binds... something went wrong')
+ if @{$self->{order_bind}};
+
+ $s;
+ };
+
+### resume originally scheduled programming
+###
+###
+
+ # we need to supply the order for the supplements to be properly calculated
+ my $sq_attrs = $self->_subqueried_limit_attrs (
+ $sql, { %$rs_attrs, order_by => \@new_order_by }
+ );
+
+ 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 .= ", $_" for sort keys %{$sq_attrs->{order_supplement}};
+
+ my $group_having_sql = $self->_parse_rs_attrs($rs_attrs);
- $sql = sprintf (<<EOS,
-SELECT $out_sel
+
+ 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 $cmp_op %s ) %s
-$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;
+WHERE ( SELECT COUNT(*) FROM %s %s $counted_where ) $rownum_cond
+$inner_order_sql
+ ", map { $self->_quote ($_) } (
+ $rs_attrs->{alias},
+ $main_tbl_name,
+ $count_tbl_alias,
+ ));
}
#
# Generates inner/outer select lists for various limit dialects
# which result in one or more subqueries (e.g. RNO, Top, RowNum)
-# Any non-root-table columns need to have their table qualifier
+# Any non-main-table columns need to have their table qualifier
# turned into a column alias (otherwise names in subqueries clash
# and/or lose their source table)
#
-# Returns inner/outer strings of SQL QUOTED selectors with aliases
-# (to be used in whatever select statement), and an alias index hashref
-# of QUOTED SEL => QUOTED ALIAS pairs (to maybe be used for string-subst
-# higher up).
+# Returns mangled proto-sql, inner/outer strings of SQL QUOTED selectors
+# with aliases (to be used in whatever select statement), and an alias
+# index hashref of QUOTED SEL => QUOTED ALIAS pairs (to maybe be used
+# for string-subst higher up).
# If an order_by is supplied, the inner select needs to bring out columns
# used in implicit (non-selected) orders, and the order condition itself
# needs to be realiased to the proper names in the outer query. Thus we
# QUOTED ALIAS pairs, which is a list of extra selectors that do *not*
# exist in the original select list
sub _subqueried_limit_attrs {
- my ($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';
- croak '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} );
for my $i (0 .. $#{$rs_attrs->{select}}) {
my $s = $rs_attrs->{select}[$i];
- my $sql_sel = $self->_recurse_fields ($s);
my $sql_alias = (ref $s) eq 'HASH' ? $s->{-as} : undef;
+ my ($sql_sel) = length ref $s
+ # we throw away the @bind here deliberately
+ ? $self->_recurse_fields( $s )
+ : $self->_quote( $s )
+ ;
+
push @sel, {
+ arg => $s,
sql => $sql_sel,
- unquoted_sql => do { local $self->{quote_char}; $self->_recurse_fields ($s) },
+ unquoted_sql => ( length ref $s
+ ? do {
+ local $self->{quote_char};
+ ($self->_recurse_fields ($s))[0]; # ignore binds again
+ }
+ : $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'")
,
};
- $in_sel_index->{$sql_sel}++;
+ # anything with a placeholder in it needs re-selection
+ $in_sel_index->{$sql_sel}++ unless $sql_sel =~ / (?: ^ | \W ) \? (?: \W | $ ) /x;
+
$in_sel_index->{$self->_quote ($sql_alias)}++ if $sql_alias;
# record unqualified versions too, so we do not have
# unless we are dealing with the current source alias
# (which will transcend the subqueries as it is necessary
# for possible further chaining)
- my (@in_sel, @out_sel, %renamed);
+ # same for anything we do not recognize
+ my ($sel, $renamed);
for my $node (@sel) {
+ push @{$sel->{original}}, $node->{sql};
+
if (
+ ! $in_sel_index->{$node->{sql}}
+ or
$node->{as} =~ / (?<! ^ $re_alias ) \. /x
or
$node->{unquoted_sql} =~ / (?<! ^ $re_alias ) $re_sep /x
) {
$node->{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 (ref $node->{arg} ? $node->{as} : $node->{arg});
}
}
# 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';
- $chunk =~ s/\s+ (?: ASC|DESC ) \s* $//ix;
+ ($chunk) = $self->_split_order_chunk($chunk);
next if $in_sel_index->{$chunk};
- $extra_order_sel{$chunk} ||= $self->_quote (
- 'ORDER__BY__' . scalar keys %extra_order_sel
+ $extra_order_sel->{$chunk} ||= $self->_quote (
+ 'ORDER__BY__' . sprintf '%03d', scalar keys %{$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 {
return $fqcn;
}
-1;
-
-=head1 AUTHORS
+=head1 FURTHER QUESTIONS?
-See L<DBIx::Class/CONTRIBUTORS>.
+Check the list of L<additional DBIC resources|DBIx::Class/GETTING HELP/SUPPORT>.
-=head1 LICENSE
+=head1 COPYRIGHT AND LICENSE
-You may distribute this code under the same terms as Perl itself.
+This module is free software L<copyright|DBIx::Class/COPYRIGHT AND LICENSE>
+by the L<DBIx::Class (DBIC) authors|DBIx::Class/AUTHORS>. You can
+redistribute it and/or modify it under the same terms as the
+L<DBIx::Class library|DBIx::Class/COPYRIGHT AND LICENSE>.
=cut
+
+1;
projects / dbsrgits/DBIx-Class.git / blobdiff