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1 | package DBIx::Class::SQLMaker::LimitDialects; |
7fca91be |
2 | |
3 | use warnings; |
4 | use strict; |
5 | |
7fca91be |
6 | use List::Util 'first'; |
7 | use namespace::clean; |
8 | |
fcb7fcbb |
9 | # constants are used not only here, but also in comparison tests |
10 | sub __rows_bindtype () { |
11 | +{ sqlt_datatype => 'integer' } |
12 | } |
13 | sub __offset_bindtype () { |
14 | +{ sqlt_datatype => 'integer' } |
15 | } |
16 | sub __total_bindtype () { |
17 | +{ sqlt_datatype => 'integer' } |
18 | } |
19 | |
d5dedbd6 |
20 | =head1 NAME |
21 | |
22 | DBIx::Class::SQLMaker::LimitDialects - SQL::Abstract::Limit-like functionality for DBIx::Class::SQLMaker |
23 | |
24 | =head1 DESCRIPTION |
25 | |
26 | This module replicates a lot of the functionality originally found in |
27 | L<SQL::Abstract::Limit>. While simple limits would work as-is, the more |
28 | complex dialects that require e.g. subqueries could not be reliably |
29 | implemented without taking full advantage of the metadata locked within |
30 | L<DBIx::Class::ResultSource> classes. After reimplementation of close to |
31 | 80% of the L<SQL::Abstract::Limit> functionality it was deemed more |
32 | practical to simply make an independent DBIx::Class-specific limit-dialect |
33 | provider. |
34 | |
35 | =head1 SQL LIMIT DIALECTS |
36 | |
37 | Note that the actual implementations listed below never use C<*> literally. |
38 | Instead proper re-aliasing of selectors and order criteria is done, so that |
39 | the limit dialect are safe to use on joined resultsets with clashing column |
40 | names. |
41 | |
42 | Currently the provided dialects are: |
43 | |
d5dedbd6 |
44 | =head2 LimitOffset |
45 | |
46 | SELECT ... LIMIT $limit OFFSET $offset |
47 | |
48 | Supported by B<PostgreSQL> and B<SQLite> |
49 | |
50 | =cut |
7fca91be |
51 | sub _LimitOffset { |
fcb7fcbb |
52 | my ( $self, $sql, $rs_attrs, $rows, $offset ) = @_; |
53 | $sql .= $self->_parse_rs_attrs( $rs_attrs ) . " LIMIT ?"; |
54 | push @{$self->{limit_bind}}, [ $self->__rows_bindtype => $rows ]; |
55 | if ($offset) { |
56 | $sql .= " OFFSET ?"; |
57 | push @{$self->{limit_bind}}, [ $self->__offset_bindtype => $offset ]; |
58 | } |
7fca91be |
59 | return $sql; |
60 | } |
61 | |
d5dedbd6 |
62 | =head2 LimitXY |
63 | |
64 | SELECT ... LIMIT $offset $limit |
65 | |
66 | Supported by B<MySQL> and any L<SQL::Statement> based DBD |
67 | |
68 | =cut |
7fca91be |
69 | sub _LimitXY { |
fcb7fcbb |
70 | my ( $self, $sql, $rs_attrs, $rows, $offset ) = @_; |
71 | $sql .= $self->_parse_rs_attrs( $rs_attrs ) . " LIMIT "; |
72 | if ($offset) { |
73 | $sql .= '?, '; |
74 | push @{$self->{limit_bind}}, [ $self->__offset_bindtype => $offset ]; |
75 | } |
76 | $sql .= '?'; |
77 | push @{$self->{limit_bind}}, [ $self->__rows_bindtype => $rows ]; |
78 | |
7fca91be |
79 | return $sql; |
80 | } |
d5dedbd6 |
81 | |
82 | =head2 RowNumberOver |
83 | |
84 | SELECT * FROM ( |
85 | SELECT *, ROW_NUMBER() OVER( ORDER BY ... ) AS RNO__ROW__INDEX FROM ( |
86 | SELECT ... |
87 | ) |
88 | ) WHERE RNO__ROW__INDEX BETWEEN ($offset+1) AND ($limit+$offset) |
89 | |
90 | |
91 | ANSI standard Limit/Offset implementation. Supported by B<DB2> and |
92 | B<< MSSQL >= 2005 >>. |
93 | |
94 | =cut |
7fca91be |
95 | sub _RowNumberOver { |
96 | my ($self, $sql, $rs_attrs, $rows, $offset ) = @_; |
97 | |
98 | # mangle the input sql as we will be replacing the selector |
99 | $sql =~ s/^ \s* SELECT \s+ .+? \s+ (?= \b FROM \b )//ix |
70c28808 |
100 | or $self->throw_exception("Unrecognizable SELECT: $sql"); |
7fca91be |
101 | |
102 | # get selectors, and scan the order_by (if any) |
103 | my ($in_sel, $out_sel, $alias_map, $extra_order_sel) |
104 | = $self->_subqueried_limit_attrs ( $rs_attrs ); |
105 | |
106 | # make up an order if none exists |
107 | my $requested_order = (delete $rs_attrs->{order_by}) || $self->_rno_default_order; |
108 | my $rno_ord = $self->_order_by ($requested_order); |
109 | |
110 | # this is the order supplement magic |
111 | my $mid_sel = $out_sel; |
112 | if ($extra_order_sel) { |
113 | for my $extra_col (sort |
114 | { $extra_order_sel->{$a} cmp $extra_order_sel->{$b} } |
115 | keys %$extra_order_sel |
116 | ) { |
117 | $in_sel .= sprintf (', %s AS %s', |
118 | $extra_col, |
119 | $extra_order_sel->{$extra_col}, |
120 | ); |
121 | |
122 | $mid_sel .= ', ' . $extra_order_sel->{$extra_col}; |
123 | } |
124 | } |
125 | |
126 | # and this is order re-alias magic |
127 | for ($extra_order_sel, $alias_map) { |
128 | for my $col (keys %$_) { |
129 | my $re_col = quotemeta ($col); |
130 | $rno_ord =~ s/$re_col/$_->{$col}/; |
131 | } |
132 | } |
133 | |
134 | # whatever is left of the order_by (only where is processed at this point) |
135 | my $group_having = $self->_parse_rs_attrs($rs_attrs); |
136 | |
137 | my $qalias = $self->_quote ($rs_attrs->{alias}); |
138 | my $idx_name = $self->_quote ('rno__row__index'); |
139 | |
fcb7fcbb |
140 | $sql = <<EOS; |
7fca91be |
141 | |
142 | SELECT $out_sel FROM ( |
143 | SELECT $mid_sel, ROW_NUMBER() OVER( $rno_ord ) AS $idx_name FROM ( |
144 | SELECT $in_sel ${sql}${group_having} |
145 | ) $qalias |
fcb7fcbb |
146 | ) $qalias WHERE $idx_name >= ? AND $idx_name <= ? |
7fca91be |
147 | |
148 | EOS |
fcb7fcbb |
149 | push @{$self->{limit_bind}}, [ $self->__offset_bindtype => $offset + 1], [ $self->__total_bindtype => $offset + $rows ]; |
7fca91be |
150 | |
7fca91be |
151 | return $sql; |
152 | } |
153 | |
154 | # some databases are happy with OVER (), some need OVER (ORDER BY (SELECT (1)) ) |
155 | sub _rno_default_order { |
156 | return undef; |
157 | } |
158 | |
d5dedbd6 |
159 | =head2 SkipFirst |
160 | |
161 | SELECT SKIP $offset FIRST $limit * FROM ... |
162 | |
163 | Suported by B<Informix>, almost like LimitOffset. According to |
164 | L<SQL::Abstract::Limit> C<... SKIP $offset LIMIT $limit ...> is also supported. |
165 | |
166 | =cut |
7fca91be |
167 | sub _SkipFirst { |
168 | my ($self, $sql, $rs_attrs, $rows, $offset) = @_; |
169 | |
170 | $sql =~ s/^ \s* SELECT \s+ //ix |
70c28808 |
171 | or $self->throw_exception("Unrecognizable SELECT: $sql"); |
7fca91be |
172 | |
173 | return sprintf ('SELECT %s%s%s%s', |
174 | $offset |
fcb7fcbb |
175 | ? do { |
176 | push @{$self->{limit_bind}}, [ $self->__offset_bindtype => $offset]; |
177 | 'SKIP ? ' |
178 | } |
7fca91be |
179 | : '' |
180 | , |
fcb7fcbb |
181 | do { |
182 | push @{$self->{limit_bind}}, [ $self->__rows_bindtype => $rows ]; |
183 | 'FIRST ? ' |
184 | }, |
7fca91be |
185 | $sql, |
186 | $self->_parse_rs_attrs ($rs_attrs), |
187 | ); |
188 | } |
189 | |
d5dedbd6 |
190 | =head2 FirstSkip |
191 | |
192 | SELECT FIRST $limit SKIP $offset * FROM ... |
193 | |
194 | Supported by B<Firebird/Interbase>, reverse of SkipFirst. According to |
195 | L<SQL::Abstract::Limit> C<... ROWS $limit TO $offset ...> is also supported. |
196 | |
197 | =cut |
7fca91be |
198 | sub _FirstSkip { |
199 | my ($self, $sql, $rs_attrs, $rows, $offset) = @_; |
200 | |
201 | $sql =~ s/^ \s* SELECT \s+ //ix |
70c28808 |
202 | or $self->throw_exception("Unrecognizable SELECT: $sql"); |
7fca91be |
203 | |
204 | return sprintf ('SELECT %s%s%s%s', |
fcb7fcbb |
205 | do { |
206 | push @{$self->{limit_bind}}, [ $self->__rows_bindtype => $rows ]; |
207 | 'FIRST ? ' |
208 | }, |
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209 | $offset |
fcb7fcbb |
210 | ? do { |
211 | push @{$self->{limit_bind}}, [ $self->__offset_bindtype => $offset]; |
212 | 'SKIP ? ' |
213 | } |
7fca91be |
214 | : '' |
215 | , |
216 | $sql, |
217 | $self->_parse_rs_attrs ($rs_attrs), |
218 | ); |
219 | } |
220 | |
d5dedbd6 |
221 | =head2 RowNum |
222 | |
223 | SELECT * FROM ( |
224 | SELECT *, ROWNUM rownum__index FROM ( |
225 | SELECT ... |
d9672fb9 |
226 | ) WHERE ROWNUM <= ($limit+$offset) |
227 | ) WHERE rownum__index >= ($offset+1) |
d5dedbd6 |
228 | |
229 | Supported by B<Oracle>. |
230 | |
231 | =cut |
7fca91be |
232 | sub _RowNum { |
233 | my ( $self, $sql, $rs_attrs, $rows, $offset ) = @_; |
234 | |
235 | # mangle the input sql as we will be replacing the selector |
236 | $sql =~ s/^ \s* SELECT \s+ .+? \s+ (?= \b FROM \b )//ix |
70c28808 |
237 | or $self->throw_exception("Unrecognizable SELECT: $sql"); |
7fca91be |
238 | |
239 | my ($insel, $outsel) = $self->_subqueried_limit_attrs ($rs_attrs); |
240 | |
241 | my $qalias = $self->_quote ($rs_attrs->{alias}); |
242 | my $idx_name = $self->_quote ('rownum__index'); |
243 | my $order_group_having = $self->_parse_rs_attrs($rs_attrs); |
244 | |
d9672fb9 |
245 | if ($offset) { |
246 | |
fcb7fcbb |
247 | push @{$self->{limit_bind}}, [ $self->__total_bindtype => $offset + $rows ], [ $self->__offset_bindtype => $offset + 1 ]; |
248 | $sql =<<"EOS"; |
7fca91be |
249 | SELECT $outsel FROM ( |
250 | SELECT $outsel, ROWNUM $idx_name FROM ( |
251 | SELECT $insel ${sql}${order_group_having} |
fcb7fcbb |
252 | ) $qalias WHERE ROWNUM <= ? |
253 | ) $qalias WHERE $idx_name >= ? |
7fca91be |
254 | EOS |
d9672fb9 |
255 | } |
256 | else { |
fcb7fcbb |
257 | push @{$self->{limit_bind}}, [ $self->__rows_bindtype => $rows ]; |
258 | $sql =<<"EOS"; |
d9672fb9 |
259 | SELECT $outsel FROM ( |
260 | SELECT $insel ${sql}${order_group_having} |
fcb7fcbb |
261 | ) $qalias WHERE ROWNUM <= ? |
d9672fb9 |
262 | EOS |
263 | } |
7fca91be |
264 | |
7fca91be |
265 | return $sql; |
266 | } |
267 | |
96eacdb7 |
268 | # used by _Top and _FetchFirst |
269 | sub _prep_for_skimming_limit { |
270 | my ( $self, $sql, $rs_attrs ) = @_; |
7fca91be |
271 | |
272 | # mangle the input sql as we will be replacing the selector |
273 | $sql =~ s/^ \s* SELECT \s+ .+? \s+ (?= \b FROM \b )//ix |
70c28808 |
274 | or $self->throw_exception("Unrecognizable SELECT: $sql"); |
7fca91be |
275 | |
96eacdb7 |
276 | my %r = ( inner_sql => $sql ); |
277 | |
7fca91be |
278 | # get selectors |
96eacdb7 |
279 | my ($alias_map, $extra_order_sel); |
280 | ($r{in_sel}, $r{out_sel}, $alias_map, $extra_order_sel) |
7fca91be |
281 | = $self->_subqueried_limit_attrs ($rs_attrs); |
282 | |
283 | my $requested_order = delete $rs_attrs->{order_by}; |
96eacdb7 |
284 | $r{order_by_requested} = $self->_order_by ($requested_order); |
7fca91be |
285 | |
286 | # make up an order unless supplied |
96eacdb7 |
287 | my $inner_order = ($r{order_by_requested} |
7fca91be |
288 | ? $requested_order |
289 | : [ map |
3f5b99fe |
290 | { "$rs_attrs->{alias}.$_" } |
4376a157 |
291 | ( $rs_attrs->{_rsroot_rsrc}->_pri_cols ) |
7fca91be |
292 | ] |
293 | ); |
294 | |
7fca91be |
295 | # localise as we already have all the bind values we need |
296 | { |
297 | local $self->{order_bind}; |
96eacdb7 |
298 | $r{order_by_inner} = $self->_order_by ($inner_order); |
7fca91be |
299 | |
300 | my @out_chunks; |
301 | for my $ch ($self->_order_by_chunks ($inner_order)) { |
302 | $ch = $ch->[0] if ref $ch eq 'ARRAY'; |
303 | |
304 | $ch =~ s/\s+ ( ASC|DESC ) \s* $//ix; |
305 | my $dir = uc ($1||'ASC'); |
306 | |
307 | push @out_chunks, \join (' ', $ch, $dir eq 'ASC' ? 'DESC' : 'ASC' ); |
308 | } |
309 | |
96eacdb7 |
310 | $r{order_by_reversed} = $self->_order_by (\@out_chunks); |
7fca91be |
311 | } |
312 | |
313 | # this is the order supplement magic |
96eacdb7 |
314 | $r{mid_sel} = $r{out_sel}; |
7fca91be |
315 | if ($extra_order_sel) { |
316 | for my $extra_col (sort |
317 | { $extra_order_sel->{$a} cmp $extra_order_sel->{$b} } |
318 | keys %$extra_order_sel |
319 | ) { |
96eacdb7 |
320 | $r{in_sel} .= sprintf (', %s AS %s', |
7fca91be |
321 | $extra_col, |
322 | $extra_order_sel->{$extra_col}, |
323 | ); |
324 | |
96eacdb7 |
325 | $r{mid_sel} .= ', ' . $extra_order_sel->{$extra_col}; |
7fca91be |
326 | } |
327 | |
328 | # since whatever order bindvals there are, they will be realiased |
329 | # and need to show up in front of the entire initial inner subquery |
4c2b30d6 |
330 | # *unshift* the selector bind stack to make this happen (horrible, |
331 | # horrible, but we don't have another mechanism yet) |
332 | unshift @{$self->{select_bind}}, @{$self->{order_bind}}; |
7fca91be |
333 | } |
334 | |
335 | # and this is order re-alias magic |
336 | for my $map ($extra_order_sel, $alias_map) { |
337 | for my $col (keys %$map) { |
338 | my $re_col = quotemeta ($col); |
339 | $_ =~ s/$re_col/$map->{$col}/ |
96eacdb7 |
340 | for ($r{order_by_reversed}, $r{order_by_requested}); |
7fca91be |
341 | } |
342 | } |
343 | |
344 | # generate the rest of the sql |
96eacdb7 |
345 | $r{grpby_having} = $self->_parse_rs_attrs ($rs_attrs); |
7fca91be |
346 | |
96eacdb7 |
347 | $r{quoted_rs_alias} = $self->_quote ($rs_attrs->{alias}); |
348 | |
349 | \%r; |
350 | } |
351 | |
352 | =head2 Top |
353 | |
354 | SELECT * FROM |
355 | |
356 | SELECT TOP $limit FROM ( |
357 | SELECT TOP $limit FROM ( |
358 | SELECT TOP ($limit+$offset) ... |
359 | ) ORDER BY $reversed_original_order |
360 | ) ORDER BY $original_order |
361 | |
362 | Unreliable Top-based implementation, supported by B<< MSSQL < 2005 >>. |
363 | |
364 | =head3 CAVEAT |
365 | |
366 | Due to its implementation, this limit dialect returns B<incorrect results> |
367 | when $limit+$offset > total amount of rows in the resultset. |
368 | |
369 | =cut |
370 | |
371 | sub _Top { |
372 | my ( $self, $sql, $rs_attrs, $rows, $offset ) = @_; |
373 | |
374 | my %l = %{ $self->_prep_for_skimming_limit($sql, $rs_attrs) }; |
7fca91be |
375 | |
376 | $sql = sprintf ('SELECT TOP %u %s %s %s %s', |
377 | $rows + ($offset||0), |
96eacdb7 |
378 | $l{in_sel}, |
379 | $l{inner_sql}, |
380 | $l{grpby_having}, |
381 | $l{order_by_inner}, |
7fca91be |
382 | ); |
383 | |
384 | $sql = sprintf ('SELECT TOP %u %s FROM ( %s ) %s %s', |
385 | $rows, |
96eacdb7 |
386 | $l{mid_sel}, |
7fca91be |
387 | $sql, |
96eacdb7 |
388 | $l{quoted_rs_alias}, |
389 | $l{order_by_reversed}, |
7fca91be |
390 | ) if $offset; |
391 | |
392 | $sql = sprintf ('SELECT TOP %u %s FROM ( %s ) %s %s', |
393 | $rows, |
96eacdb7 |
394 | $l{out_sel}, |
395 | $sql, |
396 | $l{quoted_rs_alias}, |
397 | $l{order_by_requested}, |
398 | ) if ( ($offset && $l{order_by_requested}) || ($l{mid_sel} ne $l{out_sel}) ); |
399 | |
400 | return $sql; |
401 | } |
402 | |
403 | =head2 FetchFirst |
404 | |
405 | SELECT * FROM |
406 | ( |
407 | SELECT * FROM ( |
408 | SELECT * FROM ( |
409 | SELECT * FROM ... |
410 | ) ORDER BY $reversed_original_order |
411 | FETCH FIRST $limit ROWS ONLY |
412 | ) ORDER BY $original_order |
413 | FETCH FIRST $limit ROWS ONLY |
414 | ) |
415 | |
416 | Unreliable FetchFirst-based implementation, supported by B<< IBM DB2 <= V5R3 >>. |
417 | |
418 | =head3 CAVEAT |
419 | |
420 | Due to its implementation, this limit dialect returns B<incorrect results> |
421 | when $limit+$offset > total amount of rows in the resultset. |
422 | |
423 | =cut |
424 | |
425 | sub _FetchFirst { |
426 | my ( $self, $sql, $rs_attrs, $rows, $offset ) = @_; |
427 | |
428 | my %l = %{ $self->_prep_for_skimming_limit($sql, $rs_attrs) }; |
429 | |
430 | $sql = sprintf ('SELECT %s %s %s %s FETCH FIRST %u ROWS ONLY', |
431 | $l{in_sel}, |
432 | $l{inner_sql}, |
433 | $l{grpby_having}, |
434 | $l{order_by_inner}, |
435 | $rows + ($offset||0), |
436 | ); |
437 | |
438 | $sql = sprintf ('SELECT %s FROM ( %s ) %s %s FETCH FIRST %u ROWS ONLY', |
439 | $l{mid_sel}, |
440 | $sql, |
441 | $l{quoted_rs_alias}, |
442 | $l{order_by_reversed}, |
443 | $rows, |
444 | ) if $offset; |
445 | |
446 | $sql = sprintf ('SELECT %s FROM ( %s ) %s %s FETCH FIRST %u ROWS ONLY', |
447 | $l{out_sel}, |
7fca91be |
448 | $sql, |
96eacdb7 |
449 | $l{quoted_rs_alias}, |
450 | $l{order_by_requested}, |
451 | $rows, |
452 | ) if ( ($offset && $l{order_by_requested}) || ($l{mid_sel} ne $l{out_sel}) ); |
7fca91be |
453 | |
7fca91be |
454 | return $sql; |
455 | } |
456 | |
d5dedbd6 |
457 | =head2 RowCountOrGenericSubQ |
458 | |
459 | This is not exactly a limit dialect, but more of a proxy for B<Sybase ASE>. |
460 | If no $offset is supplied the limit is simply performed as: |
461 | |
462 | SET ROWCOUNT $limit |
463 | SELECT ... |
464 | SET ROWCOUNT 0 |
465 | |
466 | Otherwise we fall back to L</GenericSubQ> |
467 | |
468 | =cut |
96eacdb7 |
469 | |
7fca91be |
470 | sub _RowCountOrGenericSubQ { |
471 | my $self = shift; |
472 | my ($sql, $rs_attrs, $rows, $offset) = @_; |
473 | |
474 | return $self->_GenericSubQ(@_) if $offset; |
475 | |
476 | return sprintf <<"EOF", $rows, $sql; |
477 | SET ROWCOUNT %d |
478 | %s |
479 | SET ROWCOUNT 0 |
480 | EOF |
481 | } |
482 | |
d5dedbd6 |
483 | =head2 GenericSubQ |
484 | |
485 | SELECT * FROM ( |
486 | SELECT ... |
487 | ) |
488 | WHERE ( |
489 | SELECT COUNT(*) FROM $original_table cnt WHERE cnt.id < $original_table.id |
490 | ) BETWEEN $offset AND ($offset+$rows-1) |
491 | |
492 | This is the most evil limit "dialect" (more of a hack) for I<really> stupid |
493 | databases. It works by ordering the set by some unique column, and calculating |
494 | the amount of rows that have a less-er value (thus emulating a L</RowNum>-like |
495 | index). Of course this implies the set can only be ordered by a single unique |
496 | column. Also note that this technique can be and often is B<excruciatingly |
497 | slow>. |
498 | |
499 | Currently used by B<Sybase ASE>, due to lack of any other option. |
500 | |
501 | =cut |
7fca91be |
502 | sub _GenericSubQ { |
503 | my ($self, $sql, $rs_attrs, $rows, $offset) = @_; |
504 | |
4376a157 |
505 | my $root_rsrc = $rs_attrs->{_rsroot_rsrc}; |
7fca91be |
506 | my $root_tbl_name = $root_rsrc->name; |
507 | |
508 | # mangle the input sql as we will be replacing the selector |
509 | $sql =~ s/^ \s* SELECT \s+ .+? \s+ (?= \b FROM \b )//ix |
70c28808 |
510 | or $self->throw_exception("Unrecognizable SELECT: $sql"); |
7fca91be |
511 | |
512 | my ($order_by, @rest) = do { |
513 | local $self->{quote_char}; |
514 | $self->_order_by_chunks ($rs_attrs->{order_by}) |
515 | }; |
516 | |
517 | unless ( |
518 | $order_by |
519 | && |
520 | ! @rest |
521 | && |
522 | ( ! ref $order_by |
523 | || |
524 | ( ref $order_by eq 'ARRAY' and @$order_by == 1 ) |
525 | ) |
526 | ) { |
70c28808 |
527 | $self->throw_exception ( |
7fca91be |
528 | 'Generic Subquery Limit does not work on resultsets without an order, or resultsets ' |
529 | . 'with complex order criteria (multicolumn and/or functions). Provide a single, ' |
530 | . 'unique-column order criteria.' |
531 | ); |
532 | } |
533 | |
534 | ($order_by) = @$order_by if ref $order_by; |
535 | |
536 | $order_by =~ s/\s+ ( ASC|DESC ) \s* $//ix; |
537 | my $direction = lc ($1 || 'asc'); |
538 | |
539 | my ($unq_sort_col) = $order_by =~ /(?:^|\.)([^\.]+)$/; |
540 | |
541 | my $inf = $root_rsrc->storage->_resolve_column_info ( |
542 | $rs_attrs->{from}, [$order_by, $unq_sort_col] |
543 | ); |
544 | |
70c28808 |
545 | my $ord_colinfo = $inf->{$order_by} || $self->throw_exception("Unable to determine source of order-criteria '$order_by'"); |
7fca91be |
546 | |
547 | if ($ord_colinfo->{-result_source}->name ne $root_tbl_name) { |
70c28808 |
548 | $self->throw_exception(sprintf |
549 | "Generic Subquery Limit order criteria can be only based on the root-source '%s'" |
550 | . " (aliased as '%s')", $root_rsrc->source_name, $rs_attrs->{alias}, |
551 | ); |
7fca91be |
552 | } |
553 | |
554 | # make sure order column is qualified |
555 | $order_by = "$rs_attrs->{alias}.$order_by" |
556 | unless $order_by =~ /^$rs_attrs->{alias}\./; |
557 | |
558 | my $is_u; |
559 | my $ucs = { $root_rsrc->unique_constraints }; |
560 | for (values %$ucs ) { |
561 | if (@$_ == 1 && "$rs_attrs->{alias}.$_->[0]" eq $order_by) { |
562 | $is_u++; |
563 | last; |
564 | } |
565 | } |
70c28808 |
566 | $self->throw_exception( |
567 | "Generic Subquery Limit order criteria column '$order_by' must be unique (no unique constraint found)" |
568 | ) unless $is_u; |
7fca91be |
569 | |
570 | my ($in_sel, $out_sel, $alias_map, $extra_order_sel) |
571 | = $self->_subqueried_limit_attrs ($rs_attrs); |
572 | |
573 | my $cmp_op = $direction eq 'desc' ? '>' : '<'; |
574 | my $count_tbl_alias = 'rownum__emulation'; |
575 | |
576 | my $order_sql = $self->_order_by (delete $rs_attrs->{order_by}); |
577 | my $group_having_sql = $self->_parse_rs_attrs($rs_attrs); |
578 | |
579 | # add the order supplement (if any) as this is what will be used for the outer WHERE |
580 | $in_sel .= ", $_" for keys %{$extra_order_sel||{}}; |
581 | |
582 | $sql = sprintf (<<EOS, |
583 | SELECT $out_sel |
584 | FROM ( |
585 | SELECT $in_sel ${sql}${group_having_sql} |
586 | ) %s |
587 | WHERE ( SELECT COUNT(*) FROM %s %s WHERE %s $cmp_op %s ) %s |
588 | $order_sql |
589 | EOS |
590 | ( map { $self->_quote ($_) } ( |
591 | $rs_attrs->{alias}, |
592 | $root_tbl_name, |
593 | $count_tbl_alias, |
594 | "$count_tbl_alias.$unq_sort_col", |
595 | $order_by, |
596 | )), |
597 | $offset |
fcb7fcbb |
598 | ? do { |
599 | push @{$self->{limit_bind}}, |
600 | [ $self->__offset_bindtype => $offset ], [ $self->__total_bindtype => $offset + $rows - 1]; |
601 | 'BETWEEN ? AND ?'; |
602 | } |
603 | : do { |
604 | push @{$self->{limit_bind}}, [ $self->__rows_bindtype => $rows ]; |
605 | '< ?'; |
606 | } |
7fca91be |
607 | , |
608 | ); |
609 | |
7fca91be |
610 | return $sql; |
611 | } |
612 | |
613 | |
614 | # !!! THIS IS ALSO HORRIFIC !!! /me ashamed |
615 | # |
616 | # Generates inner/outer select lists for various limit dialects |
617 | # which result in one or more subqueries (e.g. RNO, Top, RowNum) |
618 | # Any non-root-table columns need to have their table qualifier |
619 | # turned into a column alias (otherwise names in subqueries clash |
620 | # and/or lose their source table) |
621 | # |
622 | # Returns inner/outer strings of SQL QUOTED selectors with aliases |
623 | # (to be used in whatever select statement), and an alias index hashref |
624 | # of QUOTED SEL => QUOTED ALIAS pairs (to maybe be used for string-subst |
625 | # higher up). |
626 | # If an order_by is supplied, the inner select needs to bring out columns |
627 | # used in implicit (non-selected) orders, and the order condition itself |
628 | # needs to be realiased to the proper names in the outer query. Thus we |
629 | # also return a hashref (order doesn't matter) of QUOTED EXTRA-SEL => |
630 | # QUOTED ALIAS pairs, which is a list of extra selectors that do *not* |
631 | # exist in the original select list |
7fca91be |
632 | sub _subqueried_limit_attrs { |
633 | my ($self, $rs_attrs) = @_; |
634 | |
70c28808 |
635 | $self->throw_exception( |
636 | 'Limit dialect implementation usable only in the context of DBIC (missing $rs_attrs)' |
637 | ) unless ref ($rs_attrs) eq 'HASH'; |
7fca91be |
638 | |
3f5b99fe |
639 | my ($re_sep, $re_alias) = map { quotemeta $_ } ( $self->{name_sep}, $rs_attrs->{alias} ); |
7fca91be |
640 | |
641 | # correlate select and as, build selection index |
642 | my (@sel, $in_sel_index); |
643 | for my $i (0 .. $#{$rs_attrs->{select}}) { |
644 | |
645 | my $s = $rs_attrs->{select}[$i]; |
646 | my $sql_sel = $self->_recurse_fields ($s); |
647 | my $sql_alias = (ref $s) eq 'HASH' ? $s->{-as} : undef; |
648 | |
7fca91be |
649 | push @sel, { |
650 | sql => $sql_sel, |
651 | unquoted_sql => do { local $self->{quote_char}; $self->_recurse_fields ($s) }, |
652 | as => |
653 | $sql_alias |
654 | || |
655 | $rs_attrs->{as}[$i] |
656 | || |
70c28808 |
657 | $self->throw_exception("Select argument $i ($s) without corresponding 'as'") |
7fca91be |
658 | , |
659 | }; |
660 | |
661 | $in_sel_index->{$sql_sel}++; |
662 | $in_sel_index->{$self->_quote ($sql_alias)}++ if $sql_alias; |
663 | |
664 | # record unqualified versions too, so we do not have |
665 | # to reselect the same column twice (in qualified and |
666 | # unqualified form) |
667 | if (! ref $s && $sql_sel =~ / $re_sep (.+) $/x) { |
668 | $in_sel_index->{$1}++; |
669 | } |
670 | } |
671 | |
672 | |
673 | # re-alias and remove any name separators from aliases, |
674 | # unless we are dealing with the current source alias |
675 | # (which will transcend the subqueries as it is necessary |
676 | # for possible further chaining) |
677 | my (@in_sel, @out_sel, %renamed); |
678 | for my $node (@sel) { |
3f5b99fe |
679 | if ( |
680 | $node->{as} =~ / (?<! ^ $re_alias ) \. /x |
681 | or |
682 | $node->{unquoted_sql} =~ / (?<! ^ $re_alias ) $re_sep /x |
683 | ) { |
7fca91be |
684 | $node->{as} = $self->_unqualify_colname($node->{as}); |
685 | my $quoted_as = $self->_quote($node->{as}); |
686 | push @in_sel, sprintf '%s AS %s', $node->{sql}, $quoted_as; |
687 | push @out_sel, $quoted_as; |
688 | $renamed{$node->{sql}} = $quoted_as; |
689 | } |
690 | else { |
691 | push @in_sel, $node->{sql}; |
692 | push @out_sel, $self->_quote ($node->{as}); |
693 | } |
694 | } |
695 | |
696 | # see if the order gives us anything |
697 | my %extra_order_sel; |
698 | for my $chunk ($self->_order_by_chunks ($rs_attrs->{order_by})) { |
699 | # order with bind |
700 | $chunk = $chunk->[0] if (ref $chunk) eq 'ARRAY'; |
701 | $chunk =~ s/\s+ (?: ASC|DESC ) \s* $//ix; |
702 | |
703 | next if $in_sel_index->{$chunk}; |
704 | |
705 | $extra_order_sel{$chunk} ||= $self->_quote ( |
706 | 'ORDER__BY__' . scalar keys %extra_order_sel |
707 | ); |
708 | } |
709 | |
710 | return ( |
711 | (map { join (', ', @$_ ) } ( |
712 | \@in_sel, |
713 | \@out_sel) |
714 | ), |
715 | \%renamed, |
716 | keys %extra_order_sel ? \%extra_order_sel : (), |
717 | ); |
718 | } |
719 | |
720 | sub _unqualify_colname { |
721 | my ($self, $fqcn) = @_; |
3f5b99fe |
722 | $fqcn =~ s/ \. /__/xg; |
7fca91be |
723 | return $fqcn; |
724 | } |
725 | |
726 | 1; |
d5dedbd6 |
727 | |
728 | =head1 AUTHORS |
729 | |
730 | See L<DBIx::Class/CONTRIBUTORS>. |
731 | |
732 | =head1 LICENSE |
733 | |
734 | You may distribute this code under the same terms as Perl itself. |
735 | |
736 | =cut |