Slightly golf ::ResultSource::DESTROY and several weaken() calls
[dbsrgits/DBIx-Class-Historic.git] / lib / DBIx / Class / SQLMaker / LimitDialects.pm
CommitLineData
d5dedbd6 1package DBIx::Class::SQLMaker::LimitDialects;
7fca91be 2
3use warnings;
4use strict;
5
fcb7fcbb 6# constants are used not only here, but also in comparison tests
7sub __rows_bindtype () {
8 +{ sqlt_datatype => 'integer' }
9}
10sub __offset_bindtype () {
11 +{ sqlt_datatype => 'integer' }
12}
13sub __total_bindtype () {
14 +{ sqlt_datatype => 'integer' }
15}
16
d5dedbd6 17=head1 NAME
18
19DBIx::Class::SQLMaker::LimitDialects - SQL::Abstract::Limit-like functionality for DBIx::Class::SQLMaker
20
21=head1 DESCRIPTION
22
23This module replicates a lot of the functionality originally found in
24L<SQL::Abstract::Limit>. While simple limits would work as-is, the more
25complex dialects that require e.g. subqueries could not be reliably
26implemented without taking full advantage of the metadata locked within
27L<DBIx::Class::ResultSource> classes. After reimplementation of close to
2880% of the L<SQL::Abstract::Limit> functionality it was deemed more
29practical to simply make an independent DBIx::Class-specific limit-dialect
30provider.
31
32=head1 SQL LIMIT DIALECTS
33
34Note that the actual implementations listed below never use C<*> literally.
35Instead proper re-aliasing of selectors and order criteria is done, so that
36the limit dialect are safe to use on joined resultsets with clashing column
37names.
38
39Currently the provided dialects are:
40
d5dedbd6 41=head2 LimitOffset
42
43 SELECT ... LIMIT $limit OFFSET $offset
44
45Supported by B<PostgreSQL> and B<SQLite>
46
47=cut
7fca91be 48sub _LimitOffset {
fcb7fcbb 49 my ( $self, $sql, $rs_attrs, $rows, $offset ) = @_;
50 $sql .= $self->_parse_rs_attrs( $rs_attrs ) . " LIMIT ?";
51 push @{$self->{limit_bind}}, [ $self->__rows_bindtype => $rows ];
52 if ($offset) {
53 $sql .= " OFFSET ?";
54 push @{$self->{limit_bind}}, [ $self->__offset_bindtype => $offset ];
55 }
7fca91be 56 return $sql;
57}
58
d5dedbd6 59=head2 LimitXY
60
f4c649f8 61 SELECT ... LIMIT $offset, $limit
d5dedbd6 62
63Supported by B<MySQL> and any L<SQL::Statement> based DBD
64
65=cut
7fca91be 66sub _LimitXY {
fcb7fcbb 67 my ( $self, $sql, $rs_attrs, $rows, $offset ) = @_;
68 $sql .= $self->_parse_rs_attrs( $rs_attrs ) . " LIMIT ";
69 if ($offset) {
70 $sql .= '?, ';
71 push @{$self->{limit_bind}}, [ $self->__offset_bindtype => $offset ];
72 }
73 $sql .= '?';
74 push @{$self->{limit_bind}}, [ $self->__rows_bindtype => $rows ];
75
7fca91be 76 return $sql;
77}
d5dedbd6 78
79=head2 RowNumberOver
80
81 SELECT * FROM (
82 SELECT *, ROW_NUMBER() OVER( ORDER BY ... ) AS RNO__ROW__INDEX FROM (
83 SELECT ...
84 )
85 ) WHERE RNO__ROW__INDEX BETWEEN ($offset+1) AND ($limit+$offset)
86
87
88ANSI standard Limit/Offset implementation. Supported by B<DB2> and
89B<< MSSQL >= 2005 >>.
90
91=cut
7fca91be 92sub _RowNumberOver {
93 my ($self, $sql, $rs_attrs, $rows, $offset ) = @_;
94
7fca91be 95 # get selectors, and scan the order_by (if any)
cecf64bc 96 my $sq_attrs = $self->_subqueried_limit_attrs ( $sql, $rs_attrs );
7fca91be 97
98 # make up an order if none exists
99 my $requested_order = (delete $rs_attrs->{order_by}) || $self->_rno_default_order;
ebc5c60a 100
101 # the order binds (if any) will need to go at the end of the entire inner select
102 local $self->{order_bind};
7fca91be 103 my $rno_ord = $self->_order_by ($requested_order);
ebc5c60a 104 push @{$self->{select_bind}}, @{$self->{order_bind}};
7fca91be 105
106 # this is the order supplement magic
cecf64bc 107 my $mid_sel = $sq_attrs->{selection_outer};
108 if (my $extra_order_sel = $sq_attrs->{order_supplement}) {
7fca91be 109 for my $extra_col (sort
110 { $extra_order_sel->{$a} cmp $extra_order_sel->{$b} }
111 keys %$extra_order_sel
112 ) {
cecf64bc 113 $sq_attrs->{selection_inner} .= sprintf (', %s AS %s',
7fca91be 114 $extra_col,
115 $extra_order_sel->{$extra_col},
116 );
7fca91be 117 }
118 }
119
120 # and this is order re-alias magic
833733fe 121 for my $map ($sq_attrs->{order_supplement}, $sq_attrs->{outer_renames}) {
122 for my $col (sort { (length $b) <=> (length $a) } keys %{$map||{}} ) {
7fca91be 123 my $re_col = quotemeta ($col);
833733fe 124 $rno_ord =~ s/$re_col/$map->{$col}/;
7fca91be 125 }
126 }
127
128 # whatever is left of the order_by (only where is processed at this point)
129 my $group_having = $self->_parse_rs_attrs($rs_attrs);
130
131 my $qalias = $self->_quote ($rs_attrs->{alias});
132 my $idx_name = $self->_quote ('rno__row__index');
133
69d3c270 134 push @{$self->{limit_bind}}, [ $self->__offset_bindtype => $offset + 1], [ $self->__total_bindtype => $offset + $rows ];
135
136 return <<EOS;
7fca91be 137
cecf64bc 138SELECT $sq_attrs->{selection_outer} FROM (
7fca91be 139 SELECT $mid_sel, ROW_NUMBER() OVER( $rno_ord ) AS $idx_name FROM (
cecf64bc 140 SELECT $sq_attrs->{selection_inner} $sq_attrs->{query_leftover}${group_having}
7fca91be 141 ) $qalias
fcb7fcbb 142) $qalias WHERE $idx_name >= ? AND $idx_name <= ?
7fca91be 143
144EOS
145
7fca91be 146}
147
148# some databases are happy with OVER (), some need OVER (ORDER BY (SELECT (1)) )
149sub _rno_default_order {
150 return undef;
151}
152
d5dedbd6 153=head2 SkipFirst
154
155 SELECT SKIP $offset FIRST $limit * FROM ...
156
4b0a90fd 157Supported by B<Informix>, almost like LimitOffset. According to
d5dedbd6 158L<SQL::Abstract::Limit> C<... SKIP $offset LIMIT $limit ...> is also supported.
159
160=cut
7fca91be 161sub _SkipFirst {
162 my ($self, $sql, $rs_attrs, $rows, $offset) = @_;
163
164 $sql =~ s/^ \s* SELECT \s+ //ix
70c28808 165 or $self->throw_exception("Unrecognizable SELECT: $sql");
7fca91be 166
167 return sprintf ('SELECT %s%s%s%s',
168 $offset
fcb7fcbb 169 ? do {
8b31f62e 170 push @{$self->{pre_select_bind}}, [ $self->__offset_bindtype => $offset];
fcb7fcbb 171 'SKIP ? '
172 }
7fca91be 173 : ''
174 ,
fcb7fcbb 175 do {
8b31f62e 176 push @{$self->{pre_select_bind}}, [ $self->__rows_bindtype => $rows ];
fcb7fcbb 177 'FIRST ? '
178 },
7fca91be 179 $sql,
180 $self->_parse_rs_attrs ($rs_attrs),
181 );
182}
183
d5dedbd6 184=head2 FirstSkip
185
186 SELECT FIRST $limit SKIP $offset * FROM ...
187
188Supported by B<Firebird/Interbase>, reverse of SkipFirst. According to
189L<SQL::Abstract::Limit> C<... ROWS $limit TO $offset ...> is also supported.
190
191=cut
7fca91be 192sub _FirstSkip {
193 my ($self, $sql, $rs_attrs, $rows, $offset) = @_;
194
195 $sql =~ s/^ \s* SELECT \s+ //ix
70c28808 196 or $self->throw_exception("Unrecognizable SELECT: $sql");
7fca91be 197
198 return sprintf ('SELECT %s%s%s%s',
fcb7fcbb 199 do {
8b31f62e 200 push @{$self->{pre_select_bind}}, [ $self->__rows_bindtype => $rows ];
fcb7fcbb 201 'FIRST ? '
202 },
7fca91be 203 $offset
fcb7fcbb 204 ? do {
8b31f62e 205 push @{$self->{pre_select_bind}}, [ $self->__offset_bindtype => $offset];
fcb7fcbb 206 'SKIP ? '
207 }
7fca91be 208 : ''
209 ,
210 $sql,
211 $self->_parse_rs_attrs ($rs_attrs),
212 );
213}
214
6a6394f1 215
d5dedbd6 216=head2 RowNum
217
6a6394f1 218Depending on the resultset attributes one of:
219
d5dedbd6 220 SELECT * FROM (
b775fa8e 221 SELECT *, ROWNUM AS rownum__index FROM (
d5dedbd6 222 SELECT ...
d9672fb9 223 ) WHERE ROWNUM <= ($limit+$offset)
224 ) WHERE rownum__index >= ($offset+1)
d5dedbd6 225
6a6394f1 226or
227
228 SELECT * FROM (
b775fa8e 229 SELECT *, ROWNUM AS rownum__index FROM (
6a6394f1 230 SELECT ...
231 )
232 ) WHERE rownum__index BETWEEN ($offset+1) AND ($limit+$offset)
233
234or
235
236 SELECT * FROM (
237 SELECT ...
238 ) WHERE ROWNUM <= ($limit+1)
239
d5dedbd6 240Supported by B<Oracle>.
241
242=cut
7fca91be 243sub _RowNum {
244 my ( $self, $sql, $rs_attrs, $rows, $offset ) = @_;
245
cecf64bc 246 my $sq_attrs = $self->_subqueried_limit_attrs ($sql, $rs_attrs);
7fca91be 247
248 my $qalias = $self->_quote ($rs_attrs->{alias});
249 my $idx_name = $self->_quote ('rownum__index');
250 my $order_group_having = $self->_parse_rs_attrs($rs_attrs);
251
cccd1876 252
253 # if no offset (e.g. first page) - we can skip one of the subqueries
254 if (! $offset) {
255 push @{$self->{limit_bind}}, [ $self->__rows_bindtype => $rows ];
256
257 return <<EOS;
cecf64bc 258SELECT $sq_attrs->{selection_outer} FROM (
259 SELECT $sq_attrs->{selection_inner} $sq_attrs->{query_leftover}${order_group_having}
cccd1876 260) $qalias WHERE ROWNUM <= ?
261EOS
262 }
263
6a6394f1 264 #
265 # There are two ways to limit in Oracle, one vastly faster than the other
266 # on large resultsets: https://decipherinfosys.wordpress.com/2007/08/09/paging-and-countstopkey-optimization/
267 # However Oracle is retarded and does not preserve stable ROWNUM() values
268 # when called twice in the same scope. Therefore unless the resultset is
269 # ordered by a unique set of columns, it is not safe to use the faster
270 # method, and the slower BETWEEN query is used instead
271 #
7cec4356 272 # FIXME - this is quite expensive, and does not perform caching of any sort
07fadea8 273 # as soon as some of the SQLA-inlining work becomes viable consider adding
274 # some rudimentary caching support
7cec4356 275 if (
276 $rs_attrs->{order_by}
277 and
9cc3585d 278 $rs_attrs->{result_source}->storage->_order_by_is_stable(
5f11e54f 279 @{$rs_attrs}{qw/from order_by where/}
7cec4356 280 )
281 ) {
cccd1876 282 push @{$self->{limit_bind}}, [ $self->__total_bindtype => $offset + $rows ], [ $self->__offset_bindtype => $offset + 1 ];
6a6394f1 283
cccd1876 284 return <<EOS;
cecf64bc 285SELECT $sq_attrs->{selection_outer} FROM (
b775fa8e 286 SELECT $sq_attrs->{selection_outer}, ROWNUM AS $idx_name FROM (
cecf64bc 287 SELECT $sq_attrs->{selection_inner} $sq_attrs->{query_leftover}${order_group_having}
fcb7fcbb 288 ) $qalias WHERE ROWNUM <= ?
289) $qalias WHERE $idx_name >= ?
7fca91be 290EOS
d9672fb9 291 }
292 else {
6a6394f1 293 push @{$self->{limit_bind}}, [ $self->__offset_bindtype => $offset + 1 ], [ $self->__total_bindtype => $offset + $rows ];
69d3c270 294
295 return <<EOS;
cecf64bc 296SELECT $sq_attrs->{selection_outer} FROM (
b775fa8e 297 SELECT $sq_attrs->{selection_outer}, ROWNUM AS $idx_name FROM (
cecf64bc 298 SELECT $sq_attrs->{selection_inner} $sq_attrs->{query_leftover}${order_group_having}
6a6394f1 299 ) $qalias
300) $qalias WHERE $idx_name BETWEEN ? AND ?
d9672fb9 301EOS
6a6394f1 302 }
303}
7fca91be 304
6a6394f1 305# used by _Top and _FetchFirst below
96eacdb7 306sub _prep_for_skimming_limit {
307 my ( $self, $sql, $rs_attrs ) = @_;
7fca91be 308
7fca91be 309 # get selectors
cecf64bc 310 my $sq_attrs = $self->_subqueried_limit_attrs ($sql, $rs_attrs);
7fca91be 311
312 my $requested_order = delete $rs_attrs->{order_by};
cecf64bc 313 $sq_attrs->{order_by_requested} = $self->_order_by ($requested_order);
314 $sq_attrs->{grpby_having} = $self->_parse_rs_attrs ($rs_attrs);
7fca91be 315
a66b662c 316 # without an offset things are easy
317 if (! $rs_attrs->{offset}) {
318 $sq_attrs->{order_by_inner} = $sq_attrs->{order_by_requested};
86bb5a27 319 }
320 else {
a66b662c 321 $sq_attrs->{quoted_rs_alias} = $self->_quote ($rs_attrs->{alias});
322
323 # localise as we already have all the bind values we need
324 local $self->{order_bind};
325
326 # make up an order unless supplied or sanity check what we are given
327 my $inner_order;
328 if ($sq_attrs->{order_by_requested}) {
329 $self->throw_exception (
330 'Unable to safely perform "skimming type" limit with supplied unstable order criteria'
9cc3585d 331 ) unless ($rs_attrs->{result_source}->schema->storage->_order_by_is_stable(
a66b662c 332 $rs_attrs->{from},
5f11e54f 333 $requested_order,
334 $rs_attrs->{where},
335 ));
7fca91be 336
a66b662c 337 $inner_order = $requested_order;
338 }
339 else {
340 $inner_order = [ map
341 { "$rs_attrs->{alias}.$_" }
342 ( @{
9cc3585d 343 $rs_attrs->{result_source}->_identifying_column_set
a66b662c 344 ||
345 $self->throw_exception(sprintf(
346 'Unable to auto-construct stable order criteria for "skimming type" limit '
9cc3585d 347 . "dialect based on source '%s'", $rs_attrs->{result_source}->name) );
a66b662c 348 } )
349 ];
350 }
7fca91be 351
a66b662c 352 $sq_attrs->{order_by_inner} = $self->_order_by ($inner_order);
cecf64bc 353
a66b662c 354 my @out_chunks;
355 for my $ch ($self->_order_by_chunks ($inner_order)) {
356 $ch = $ch->[0] if ref $ch eq 'ARRAY';
7fca91be 357
cb3e87f5 358 ($ch, my $is_desc) = $self->_split_order_chunk($ch);
359
360 # !NOTE! outside chunks come in reverse order ( !$is_desc )
361 push @out_chunks, { ($is_desc ? '-asc' : '-desc') => \$ch };
7fca91be 362 }
363
a66b662c 364 $sq_attrs->{order_by_middle} = $self->_order_by (\@out_chunks);
365
366 # this is the order supplement magic
367 $sq_attrs->{selection_middle} = $sq_attrs->{selection_outer};
368 if (my $extra_order_sel = $sq_attrs->{order_supplement}) {
369 for my $extra_col (sort
370 { $extra_order_sel->{$a} cmp $extra_order_sel->{$b} }
371 keys %$extra_order_sel
372 ) {
373 $sq_attrs->{selection_inner} .= sprintf (', %s AS %s',
374 $extra_col,
375 $extra_order_sel->{$extra_col},
376 );
377
378 $sq_attrs->{selection_middle} .= ', ' . $extra_order_sel->{$extra_col};
379 }
380
381 # Whatever order bindvals there are, they will be realiased and
382 # reselected, and need to show up at end of the initial inner select
383 push @{$self->{select_bind}}, @{$self->{order_bind}};
cecf64bc 384 }
86bb5a27 385
a66b662c 386 # and this is order re-alias magic
387 for my $map ($sq_attrs->{order_supplement}, $sq_attrs->{outer_renames}) {
833733fe 388 for my $col (sort { (length $b) <=> (length $a) } keys %{$map||{}}) {
a66b662c 389 my $re_col = quotemeta ($col);
390 $_ =~ s/$re_col/$map->{$col}/
391 for ($sq_attrs->{order_by_middle}, $sq_attrs->{order_by_requested});
392 }
7fca91be 393 }
394 }
395
cecf64bc 396 $sq_attrs;
96eacdb7 397}
398
399=head2 Top
400
401 SELECT * FROM
402
403 SELECT TOP $limit FROM (
404 SELECT TOP $limit FROM (
405 SELECT TOP ($limit+$offset) ...
406 ) ORDER BY $reversed_original_order
407 ) ORDER BY $original_order
408
409Unreliable Top-based implementation, supported by B<< MSSQL < 2005 >>.
410
411=head3 CAVEAT
412
413Due to its implementation, this limit dialect returns B<incorrect results>
414when $limit+$offset > total amount of rows in the resultset.
415
416=cut
417
418sub _Top {
419 my ( $self, $sql, $rs_attrs, $rows, $offset ) = @_;
420
cecf64bc 421 my $lim = $self->_prep_for_skimming_limit($sql, $rs_attrs);
7fca91be 422
423 $sql = sprintf ('SELECT TOP %u %s %s %s %s',
424 $rows + ($offset||0),
a66b662c 425 $offset ? $lim->{selection_inner} : $lim->{selection_original},
cecf64bc 426 $lim->{query_leftover},
427 $lim->{grpby_having},
428 $lim->{order_by_inner},
7fca91be 429 );
430
431 $sql = sprintf ('SELECT TOP %u %s FROM ( %s ) %s %s',
432 $rows,
cecf64bc 433 $lim->{selection_middle},
7fca91be 434 $sql,
cecf64bc 435 $lim->{quoted_rs_alias},
436 $lim->{order_by_middle},
7fca91be 437 ) if $offset;
438
1b07861d 439 $sql = sprintf ('SELECT %s FROM ( %s ) %s %s',
cecf64bc 440 $lim->{selection_outer},
96eacdb7 441 $sql,
cecf64bc 442 $lim->{quoted_rs_alias},
443 $lim->{order_by_requested},
444 ) if $offset and (
445 $lim->{order_by_requested} or $lim->{selection_middle} ne $lim->{selection_outer}
446 );
96eacdb7 447
448 return $sql;
449}
450
451=head2 FetchFirst
452
453 SELECT * FROM
454 (
455 SELECT * FROM (
456 SELECT * FROM (
457 SELECT * FROM ...
458 ) ORDER BY $reversed_original_order
459 FETCH FIRST $limit ROWS ONLY
460 ) ORDER BY $original_order
461 FETCH FIRST $limit ROWS ONLY
462 )
463
464Unreliable FetchFirst-based implementation, supported by B<< IBM DB2 <= V5R3 >>.
465
466=head3 CAVEAT
467
468Due to its implementation, this limit dialect returns B<incorrect results>
469when $limit+$offset > total amount of rows in the resultset.
470
471=cut
472
473sub _FetchFirst {
474 my ( $self, $sql, $rs_attrs, $rows, $offset ) = @_;
475
cecf64bc 476 my $lim = $self->_prep_for_skimming_limit($sql, $rs_attrs);
96eacdb7 477
478 $sql = sprintf ('SELECT %s %s %s %s FETCH FIRST %u ROWS ONLY',
a66b662c 479 $offset ? $lim->{selection_inner} : $lim->{selection_original},
cecf64bc 480 $lim->{query_leftover},
481 $lim->{grpby_having},
482 $lim->{order_by_inner},
96eacdb7 483 $rows + ($offset||0),
484 );
485
486 $sql = sprintf ('SELECT %s FROM ( %s ) %s %s FETCH FIRST %u ROWS ONLY',
cecf64bc 487 $lim->{selection_middle},
96eacdb7 488 $sql,
cecf64bc 489 $lim->{quoted_rs_alias},
490 $lim->{order_by_middle},
96eacdb7 491 $rows,
492 ) if $offset;
493
cecf64bc 494
1b07861d 495 $sql = sprintf ('SELECT %s FROM ( %s ) %s %s',
cecf64bc 496 $lim->{selection_outer},
7fca91be 497 $sql,
cecf64bc 498 $lim->{quoted_rs_alias},
499 $lim->{order_by_requested},
cecf64bc 500 ) if $offset and (
501 $lim->{order_by_requested} or $lim->{selection_middle} ne $lim->{selection_outer}
502 );
7fca91be 503
7fca91be 504 return $sql;
505}
506
d5dedbd6 507=head2 GenericSubQ
508
509 SELECT * FROM (
510 SELECT ...
511 )
512 WHERE (
513 SELECT COUNT(*) FROM $original_table cnt WHERE cnt.id < $original_table.id
514 ) BETWEEN $offset AND ($offset+$rows-1)
515
516This is the most evil limit "dialect" (more of a hack) for I<really> stupid
517databases. It works by ordering the set by some unique column, and calculating
518the amount of rows that have a less-er value (thus emulating a L</RowNum>-like
519index). Of course this implies the set can only be ordered by a single unique
038b8126 520column.
521
522Also note that this technique can be and often is B<excruciatingly slow>. You
523may have much better luck using L<DBIx::Class::ResultSet/software_limit>
524instead.
d5dedbd6 525
526Currently used by B<Sybase ASE>, due to lack of any other option.
527
528=cut
7fca91be 529sub _GenericSubQ {
530 my ($self, $sql, $rs_attrs, $rows, $offset) = @_;
531
9cc3585d 532 my $main_rsrc = $rs_attrs->{result_source};
7fca91be 533
318e3d94 534 # Explicitly require an order_by
535 # GenSubQ is slow enough as it is, just emulating things
536 # like in other cases is not wise - make the user work
537 # to shoot their DBA in the foot
302d35f8 538 $self->throw_exception (
318e3d94 539 'Generic Subquery Limit does not work on resultsets without an order. Provide a stable, '
9cc3585d 540 . 'main-table-based order criteria.'
302d35f8 541 ) unless $rs_attrs->{order_by};
318e3d94 542
9cc3585d 543 my $usable_order_colinfo = $main_rsrc->storage->_extract_colinfo_of_stable_main_source_order_by_portion(
302d35f8 544 $rs_attrs
545 );
546
547 $self->throw_exception(
548 'Generic Subquery Limit can not work with order criteria based on sources other than the main one'
549 ) if (
550 ! keys %{$usable_order_colinfo||{}}
551 or
552 grep
553 { $_->{-source_alias} ne $rs_attrs->{alias} }
554 (values %$usable_order_colinfo)
318e3d94 555 );
556
557###
558###
559### we need to know the directions after we figured out the above - reextract *again*
560### this is eyebleed - trying to get it to work at first
302d35f8 561 my $supplied_order = delete $rs_attrs->{order_by};
562
318e3d94 563 my @order_bits = do {
7fca91be 564 local $self->{quote_char};
2d841fdc 565 local $self->{order_bind};
318e3d94 566 map { ref $_ ? $_->[0] : $_ } $self->_order_by_chunks ($supplied_order)
567 };
7fca91be 568
318e3d94 569 # truncate to what we'll use
df4312bc 570 $#order_bits = ( (keys %$usable_order_colinfo) - 1 );
7fca91be 571
318e3d94 572 # @order_bits likely will come back quoted (due to how the prefetch
573 # rewriter operates
574 # Hence supplement the column_info lookup table with quoted versions
575 if ($self->quote_char) {
df4312bc 576 $usable_order_colinfo->{$self->_quote($_)} = $usable_order_colinfo->{$_}
577 for keys %$usable_order_colinfo;
318e3d94 578 }
7fca91be 579
318e3d94 580# calculate the condition
581 my $count_tbl_alias = 'rownum__emulation';
9cc3585d 582 my $main_alias = $rs_attrs->{alias};
583 my $main_tbl_name = $main_rsrc->name;
7fca91be 584
318e3d94 585 my (@unqualified_names, @qualified_names, @is_desc, @new_order_by);
7fca91be 586
318e3d94 587 for my $bit (@order_bits) {
7fca91be 588
cb3e87f5 589 ($bit, my $is_desc) = $self->_split_order_chunk($bit);
7fca91be 590
318e3d94 591 push @is_desc, $is_desc;
df4312bc 592 push @unqualified_names, $usable_order_colinfo->{$bit}{-colname};
593 push @qualified_names, $usable_order_colinfo->{$bit}{-fq_colname};
7fca91be 594
df4312bc 595 push @new_order_by, { ($is_desc ? '-desc' : '-asc') => $usable_order_colinfo->{$bit}{-fq_colname} };
2d841fdc 596 };
7fca91be 597
318e3d94 598 my (@where_cond, @skip_colpair_stack);
599 for my $i (0 .. $#order_bits) {
df4312bc 600 my $ci = $usable_order_colinfo->{$order_bits[$i]};
318e3d94 601
9cc3585d 602 my ($subq_col, $main_col) = map { "$_.$ci->{-colname}" } ($count_tbl_alias, $main_alias);
318e3d94 603 my $cur_cond = { $subq_col => { ($is_desc[$i] ? '>' : '<') => { -ident => $main_col } } };
604
605 push @skip_colpair_stack, [
606 { $main_col => { -ident => $subq_col } },
607 ];
608
609 # we can trust the nullability flag because
610 # we already used it during _id_col_set resolution
611 #
612 if ($ci->{is_nullable}) {
613 push @{$skip_colpair_stack[-1]}, { $main_col => undef, $subq_col=> undef };
614
615 $cur_cond = [
616 {
617 ($is_desc[$i] ? $subq_col : $main_col) => { '!=', undef },
618 ($is_desc[$i] ? $main_col : $subq_col) => undef,
619 },
620 {
621 $subq_col => { '!=', undef },
622 $main_col => { '!=', undef },
623 -and => $cur_cond,
624 },
625 ];
626 }
cecf64bc 627
318e3d94 628 push @where_cond, { '-and', => [ @skip_colpair_stack[0..$i-1], $cur_cond ] };
629 }
7fca91be 630
318e3d94 631# reuse the sqlmaker WHERE, this will not be returning binds
632 my $counted_where = do {
633 local $self->{where_bind};
634 $self->where(\@where_cond);
635 };
636
637# construct the rownum condition by hand
69d3c270 638 my $rownum_cond;
639 if ($offset) {
640 $rownum_cond = 'BETWEEN ? AND ?';
69d3c270 641 push @{$self->{limit_bind}},
642 [ $self->__offset_bindtype => $offset ],
643 [ $self->__total_bindtype => $offset + $rows - 1]
644 ;
645 }
646 else {
647 $rownum_cond = '< ?';
69d3c270 648 push @{$self->{limit_bind}},
649 [ $self->__rows_bindtype => $rows ]
650 ;
651 }
652
318e3d94 653# and what we will order by inside
654 my $inner_order_sql = do {
655 local $self->{order_bind};
656
657 my $s = $self->_order_by (\@new_order_by);
658
659 $self->throw_exception('Inner gensubq order may not contain binds... something went wrong')
660 if @{$self->{order_bind}};
661
662 $s;
663 };
664
665### resume originally scheduled programming
666###
667###
668
669 # we need to supply the order for the supplements to be properly calculated
670 my $sq_attrs = $self->_subqueried_limit_attrs (
671 $sql, { %$rs_attrs, order_by => \@new_order_by }
672 );
673
674 my $in_sel = $sq_attrs->{selection_inner};
675
676 # add the order supplement (if any) as this is what will be used for the outer WHERE
677 $in_sel .= ", $_" for sort keys %{$sq_attrs->{order_supplement}};
678
679 my $group_having_sql = $self->_parse_rs_attrs($rs_attrs);
680
2d841fdc 681
69d3c270 682 return sprintf ("
cecf64bc 683SELECT $sq_attrs->{selection_outer}
7fca91be 684 FROM (
cecf64bc 685 SELECT $in_sel $sq_attrs->{query_leftover}${group_having_sql}
7fca91be 686 ) %s
318e3d94 687WHERE ( SELECT COUNT(*) FROM %s %s $counted_where ) $rownum_cond
688$inner_order_sql
69d3c270 689 ", map { $self->_quote ($_) } (
690 $rs_attrs->{alias},
9cc3585d 691 $main_tbl_name,
69d3c270 692 $count_tbl_alias,
69d3c270 693 ));
7fca91be 694}
695
696
697# !!! THIS IS ALSO HORRIFIC !!! /me ashamed
698#
699# Generates inner/outer select lists for various limit dialects
700# which result in one or more subqueries (e.g. RNO, Top, RowNum)
9cc3585d 701# Any non-main-table columns need to have their table qualifier
7fca91be 702# turned into a column alias (otherwise names in subqueries clash
703# and/or lose their source table)
704#
69d3c270 705# Returns mangled proto-sql, inner/outer strings of SQL QUOTED selectors
706# with aliases (to be used in whatever select statement), and an alias
8273e845 707# index hashref of QUOTED SEL => QUOTED ALIAS pairs (to maybe be used
69d3c270 708# for string-subst higher up).
7fca91be 709# If an order_by is supplied, the inner select needs to bring out columns
710# used in implicit (non-selected) orders, and the order condition itself
711# needs to be realiased to the proper names in the outer query. Thus we
712# also return a hashref (order doesn't matter) of QUOTED EXTRA-SEL =>
713# QUOTED ALIAS pairs, which is a list of extra selectors that do *not*
714# exist in the original select list
7fca91be 715sub _subqueried_limit_attrs {
69d3c270 716 my ($self, $proto_sql, $rs_attrs) = @_;
7fca91be 717
70c28808 718 $self->throw_exception(
719 'Limit dialect implementation usable only in the context of DBIC (missing $rs_attrs)'
720 ) unless ref ($rs_attrs) eq 'HASH';
7fca91be 721
f74d22e2 722 # mangle the input sql as we will be replacing the selector entirely
723 unless (
724 $rs_attrs->{_selector_sql}
725 and
726 $proto_sql =~ s/^ \s* SELECT \s* \Q$rs_attrs->{_selector_sql}//ix
727 ) {
728 $self->throw_exception("Unrecognizable SELECT: $proto_sql");
729 }
69d3c270 730
3f5b99fe 731 my ($re_sep, $re_alias) = map { quotemeta $_ } ( $self->{name_sep}, $rs_attrs->{alias} );
7fca91be 732
733 # correlate select and as, build selection index
734 my (@sel, $in_sel_index);
735 for my $i (0 .. $#{$rs_attrs->{select}}) {
736
737 my $s = $rs_attrs->{select}[$i];
7fca91be 738 my $sql_alias = (ref $s) eq 'HASH' ? $s->{-as} : undef;
739
ad1d374e 740 # we throw away the @bind here deliberately
741 my ($sql_sel) = $self->_recurse_fields ($s);
742
7fca91be 743 push @sel, {
90ed89cb 744 arg => $s,
7fca91be 745 sql => $sql_sel,
69d3c270 746 unquoted_sql => do {
747 local $self->{quote_char};
ad1d374e 748 ($self->_recurse_fields ($s))[0]; # ignore binds again
69d3c270 749 },
7fca91be 750 as =>
751 $sql_alias
752 ||
753 $rs_attrs->{as}[$i]
754 ||
70c28808 755 $self->throw_exception("Select argument $i ($s) without corresponding 'as'")
7fca91be 756 ,
757 };
758
f1be7448 759 # anything with a placeholder in it needs re-selection
760 $in_sel_index->{$sql_sel}++ unless $sql_sel =~ / (?: ^ | \W ) \? (?: \W | $ ) /x;
761
7fca91be 762 $in_sel_index->{$self->_quote ($sql_alias)}++ if $sql_alias;
763
764 # record unqualified versions too, so we do not have
765 # to reselect the same column twice (in qualified and
766 # unqualified form)
767 if (! ref $s && $sql_sel =~ / $re_sep (.+) $/x) {
768 $in_sel_index->{$1}++;
769 }
770 }
771
772
773 # re-alias and remove any name separators from aliases,
774 # unless we are dealing with the current source alias
775 # (which will transcend the subqueries as it is necessary
776 # for possible further chaining)
4d45ab4b 777 # same for anything we do not recognize
cecf64bc 778 my ($sel, $renamed);
7fca91be 779 for my $node (@sel) {
a66b662c 780 push @{$sel->{original}}, $node->{sql};
781
3f5b99fe 782 if (
4d45ab4b 783 ! $in_sel_index->{$node->{sql}}
784 or
3f5b99fe 785 $node->{as} =~ / (?<! ^ $re_alias ) \. /x
786 or
787 $node->{unquoted_sql} =~ / (?<! ^ $re_alias ) $re_sep /x
788 ) {
7fca91be 789 $node->{as} = $self->_unqualify_colname($node->{as});
790 my $quoted_as = $self->_quote($node->{as});
cecf64bc 791 push @{$sel->{inner}}, sprintf '%s AS %s', $node->{sql}, $quoted_as;
792 push @{$sel->{outer}}, $quoted_as;
793 $renamed->{$node->{sql}} = $quoted_as;
7fca91be 794 }
795 else {
cecf64bc 796 push @{$sel->{inner}}, $node->{sql};
90ed89cb 797 push @{$sel->{outer}}, $self->_quote (ref $node->{arg} ? $node->{as} : $node->{arg});
7fca91be 798 }
799 }
cecf64bc 800
7fca91be 801 # see if the order gives us anything
cecf64bc 802 my $extra_order_sel;
7fca91be 803 for my $chunk ($self->_order_by_chunks ($rs_attrs->{order_by})) {
804 # order with bind
805 $chunk = $chunk->[0] if (ref $chunk) eq 'ARRAY';
cb3e87f5 806 ($chunk) = $self->_split_order_chunk($chunk);
7fca91be 807
808 next if $in_sel_index->{$chunk};
809
cecf64bc 810 $extra_order_sel->{$chunk} ||= $self->_quote (
08a1eaad 811 'ORDER__BY__' . sprintf '%03d', scalar keys %{$extra_order_sel||{}}
7fca91be 812 );
813 }
814
cecf64bc 815 return {
816 query_leftover => $proto_sql,
817 (map {( "selection_$_" => join (', ', @{$sel->{$_}} ) )} keys %$sel ),
818 outer_renames => $renamed,
819 order_supplement => $extra_order_sel,
820 };
7fca91be 821}
822
823sub _unqualify_colname {
824 my ($self, $fqcn) = @_;
3f5b99fe 825 $fqcn =~ s/ \. /__/xg;
7fca91be 826 return $fqcn;
827}
828
a2bd3796 829=head1 FURTHER QUESTIONS?
d5dedbd6 830
a2bd3796 831Check the list of L<additional DBIC resources|DBIx::Class/GETTING HELP/SUPPORT>.
d5dedbd6 832
a2bd3796 833=head1 COPYRIGHT AND LICENSE
d5dedbd6 834
a2bd3796 835This module is free software L<copyright|DBIx::Class/COPYRIGHT AND LICENSE>
836by the L<DBIx::Class (DBIC) authors|DBIx::Class/AUTHORS>. You can
837redistribute it and/or modify it under the same terms as the
838L<DBIx::Class library|DBIx::Class/COPYRIGHT AND LICENSE>.
d5dedbd6 839
840=cut
a2bd3796 841
8421;