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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, $offset ) = @_; |
97 | |
7fca91be |
98 | # get selectors, and scan the order_by (if any) |
69d3c270 |
99 | my ($stripped_sql, $in_sel, $out_sel, $alias_map, $extra_order_sel) |
100 | = $self->_subqueried_limit_attrs ( $sql, $rs_attrs ); |
7fca91be |
101 | |
102 | # make up an order if none exists |
103 | my $requested_order = (delete $rs_attrs->{order_by}) || $self->_rno_default_order; |
104 | my $rno_ord = $self->_order_by ($requested_order); |
105 | |
106 | # this is the order supplement magic |
107 | my $mid_sel = $out_sel; |
108 | if ($extra_order_sel) { |
109 | for my $extra_col (sort |
110 | { $extra_order_sel->{$a} cmp $extra_order_sel->{$b} } |
111 | keys %$extra_order_sel |
112 | ) { |
113 | $in_sel .= sprintf (', %s AS %s', |
114 | $extra_col, |
115 | $extra_order_sel->{$extra_col}, |
116 | ); |
117 | |
118 | $mid_sel .= ', ' . $extra_order_sel->{$extra_col}; |
119 | } |
120 | } |
121 | |
122 | # and this is order re-alias magic |
123 | for ($extra_order_sel, $alias_map) { |
124 | for my $col (keys %$_) { |
125 | my $re_col = quotemeta ($col); |
126 | $rno_ord =~ s/$re_col/$_->{$col}/; |
127 | } |
128 | } |
129 | |
130 | # whatever is left of the order_by (only where is processed at this point) |
131 | my $group_having = $self->_parse_rs_attrs($rs_attrs); |
132 | |
133 | my $qalias = $self->_quote ($rs_attrs->{alias}); |
134 | my $idx_name = $self->_quote ('rno__row__index'); |
135 | |
69d3c270 |
136 | push @{$self->{limit_bind}}, [ $self->__offset_bindtype => $offset + 1], [ $self->__total_bindtype => $offset + $rows ]; |
137 | |
138 | return <<EOS; |
7fca91be |
139 | |
140 | SELECT $out_sel FROM ( |
141 | SELECT $mid_sel, ROW_NUMBER() OVER( $rno_ord ) AS $idx_name FROM ( |
69d3c270 |
142 | SELECT $in_sel ${stripped_sql}${group_having} |
7fca91be |
143 | ) $qalias |
fcb7fcbb |
144 | ) $qalias WHERE $idx_name >= ? AND $idx_name <= ? |
7fca91be |
145 | |
146 | EOS |
147 | |
7fca91be |
148 | } |
149 | |
150 | # some databases are happy with OVER (), some need OVER (ORDER BY (SELECT (1)) ) |
151 | sub _rno_default_order { |
152 | return undef; |
153 | } |
154 | |
d5dedbd6 |
155 | =head2 SkipFirst |
156 | |
157 | SELECT SKIP $offset FIRST $limit * FROM ... |
158 | |
159 | Suported by B<Informix>, almost like LimitOffset. According to |
160 | L<SQL::Abstract::Limit> C<... SKIP $offset LIMIT $limit ...> is also supported. |
161 | |
162 | =cut |
7fca91be |
163 | sub _SkipFirst { |
164 | my ($self, $sql, $rs_attrs, $rows, $offset) = @_; |
165 | |
166 | $sql =~ s/^ \s* SELECT \s+ //ix |
70c28808 |
167 | or $self->throw_exception("Unrecognizable SELECT: $sql"); |
7fca91be |
168 | |
169 | return sprintf ('SELECT %s%s%s%s', |
170 | $offset |
fcb7fcbb |
171 | ? do { |
172 | push @{$self->{limit_bind}}, [ $self->__offset_bindtype => $offset]; |
173 | 'SKIP ? ' |
174 | } |
7fca91be |
175 | : '' |
176 | , |
fcb7fcbb |
177 | do { |
178 | push @{$self->{limit_bind}}, [ $self->__rows_bindtype => $rows ]; |
179 | 'FIRST ? ' |
180 | }, |
7fca91be |
181 | $sql, |
182 | $self->_parse_rs_attrs ($rs_attrs), |
183 | ); |
184 | } |
185 | |
d5dedbd6 |
186 | =head2 FirstSkip |
187 | |
188 | SELECT FIRST $limit SKIP $offset * FROM ... |
189 | |
190 | Supported by B<Firebird/Interbase>, reverse of SkipFirst. According to |
191 | L<SQL::Abstract::Limit> C<... ROWS $limit TO $offset ...> is also supported. |
192 | |
193 | =cut |
7fca91be |
194 | sub _FirstSkip { |
195 | my ($self, $sql, $rs_attrs, $rows, $offset) = @_; |
196 | |
197 | $sql =~ s/^ \s* SELECT \s+ //ix |
70c28808 |
198 | or $self->throw_exception("Unrecognizable SELECT: $sql"); |
7fca91be |
199 | |
200 | return sprintf ('SELECT %s%s%s%s', |
fcb7fcbb |
201 | do { |
202 | push @{$self->{limit_bind}}, [ $self->__rows_bindtype => $rows ]; |
203 | 'FIRST ? ' |
204 | }, |
7fca91be |
205 | $offset |
fcb7fcbb |
206 | ? do { |
207 | push @{$self->{limit_bind}}, [ $self->__offset_bindtype => $offset]; |
208 | 'SKIP ? ' |
209 | } |
7fca91be |
210 | : '' |
211 | , |
212 | $sql, |
213 | $self->_parse_rs_attrs ($rs_attrs), |
214 | ); |
215 | } |
216 | |
d5dedbd6 |
217 | =head2 RowNum |
218 | |
219 | SELECT * FROM ( |
220 | SELECT *, ROWNUM rownum__index FROM ( |
221 | SELECT ... |
d9672fb9 |
222 | ) WHERE ROWNUM <= ($limit+$offset) |
223 | ) WHERE rownum__index >= ($offset+1) |
d5dedbd6 |
224 | |
225 | Supported by B<Oracle>. |
226 | |
227 | =cut |
7fca91be |
228 | sub _RowNum { |
229 | my ( $self, $sql, $rs_attrs, $rows, $offset ) = @_; |
230 | |
69d3c270 |
231 | my ($stripped_sql, $insel, $outsel) = $self->_subqueried_limit_attrs ($sql, $rs_attrs); |
7fca91be |
232 | |
233 | my $qalias = $self->_quote ($rs_attrs->{alias}); |
234 | my $idx_name = $self->_quote ('rownum__index'); |
235 | my $order_group_having = $self->_parse_rs_attrs($rs_attrs); |
236 | |
69d3c270 |
237 | |
d9672fb9 |
238 | if ($offset) { |
239 | |
fcb7fcbb |
240 | push @{$self->{limit_bind}}, [ $self->__total_bindtype => $offset + $rows ], [ $self->__offset_bindtype => $offset + 1 ]; |
69d3c270 |
241 | |
242 | return <<EOS; |
7fca91be |
243 | SELECT $outsel FROM ( |
244 | SELECT $outsel, ROWNUM $idx_name FROM ( |
69d3c270 |
245 | SELECT $insel ${stripped_sql}${order_group_having} |
fcb7fcbb |
246 | ) $qalias WHERE ROWNUM <= ? |
247 | ) $qalias WHERE $idx_name >= ? |
7fca91be |
248 | EOS |
69d3c270 |
249 | |
d9672fb9 |
250 | } |
251 | else { |
fcb7fcbb |
252 | push @{$self->{limit_bind}}, [ $self->__rows_bindtype => $rows ]; |
69d3c270 |
253 | |
254 | return <<EOS; |
d9672fb9 |
255 | SELECT $outsel FROM ( |
69d3c270 |
256 | SELECT $insel ${stripped_sql}${order_group_having} |
fcb7fcbb |
257 | ) $qalias WHERE ROWNUM <= ? |
d9672fb9 |
258 | EOS |
7fca91be |
259 | |
69d3c270 |
260 | } |
7fca91be |
261 | } |
262 | |
96eacdb7 |
263 | # used by _Top and _FetchFirst |
264 | sub _prep_for_skimming_limit { |
265 | my ( $self, $sql, $rs_attrs ) = @_; |
7fca91be |
266 | |
7fca91be |
267 | # get selectors |
69d3c270 |
268 | my (%r, $alias_map, $extra_order_sel); |
269 | ($r{inner_sql}, $r{in_sel}, $r{out_sel}, $alias_map, $extra_order_sel) |
270 | = $self->_subqueried_limit_attrs ($sql, $rs_attrs); |
7fca91be |
271 | |
272 | my $requested_order = delete $rs_attrs->{order_by}; |
96eacdb7 |
273 | $r{order_by_requested} = $self->_order_by ($requested_order); |
7fca91be |
274 | |
275 | # make up an order unless supplied |
96eacdb7 |
276 | my $inner_order = ($r{order_by_requested} |
7fca91be |
277 | ? $requested_order |
278 | : [ map |
3f5b99fe |
279 | { "$rs_attrs->{alias}.$_" } |
4376a157 |
280 | ( $rs_attrs->{_rsroot_rsrc}->_pri_cols ) |
7fca91be |
281 | ] |
282 | ); |
283 | |
7fca91be |
284 | # localise as we already have all the bind values we need |
285 | { |
286 | local $self->{order_bind}; |
96eacdb7 |
287 | $r{order_by_inner} = $self->_order_by ($inner_order); |
7fca91be |
288 | |
289 | my @out_chunks; |
290 | for my $ch ($self->_order_by_chunks ($inner_order)) { |
291 | $ch = $ch->[0] if ref $ch eq 'ARRAY'; |
292 | |
293 | $ch =~ s/\s+ ( ASC|DESC ) \s* $//ix; |
294 | my $dir = uc ($1||'ASC'); |
295 | |
296 | push @out_chunks, \join (' ', $ch, $dir eq 'ASC' ? 'DESC' : 'ASC' ); |
297 | } |
298 | |
96eacdb7 |
299 | $r{order_by_reversed} = $self->_order_by (\@out_chunks); |
7fca91be |
300 | } |
301 | |
302 | # this is the order supplement magic |
96eacdb7 |
303 | $r{mid_sel} = $r{out_sel}; |
7fca91be |
304 | if ($extra_order_sel) { |
305 | for my $extra_col (sort |
306 | { $extra_order_sel->{$a} cmp $extra_order_sel->{$b} } |
307 | keys %$extra_order_sel |
308 | ) { |
96eacdb7 |
309 | $r{in_sel} .= sprintf (', %s AS %s', |
7fca91be |
310 | $extra_col, |
311 | $extra_order_sel->{$extra_col}, |
312 | ); |
313 | |
96eacdb7 |
314 | $r{mid_sel} .= ', ' . $extra_order_sel->{$extra_col}; |
7fca91be |
315 | } |
316 | |
317 | # since whatever order bindvals there are, they will be realiased |
318 | # and need to show up in front of the entire initial inner subquery |
4c2b30d6 |
319 | # *unshift* the selector bind stack to make this happen (horrible, |
320 | # horrible, but we don't have another mechanism yet) |
321 | unshift @{$self->{select_bind}}, @{$self->{order_bind}}; |
7fca91be |
322 | } |
323 | |
324 | # and this is order re-alias magic |
325 | for my $map ($extra_order_sel, $alias_map) { |
326 | for my $col (keys %$map) { |
327 | my $re_col = quotemeta ($col); |
328 | $_ =~ s/$re_col/$map->{$col}/ |
96eacdb7 |
329 | for ($r{order_by_reversed}, $r{order_by_requested}); |
7fca91be |
330 | } |
331 | } |
332 | |
333 | # generate the rest of the sql |
96eacdb7 |
334 | $r{grpby_having} = $self->_parse_rs_attrs ($rs_attrs); |
7fca91be |
335 | |
96eacdb7 |
336 | $r{quoted_rs_alias} = $self->_quote ($rs_attrs->{alias}); |
337 | |
338 | \%r; |
339 | } |
340 | |
341 | =head2 Top |
342 | |
343 | SELECT * FROM |
344 | |
345 | SELECT TOP $limit FROM ( |
346 | SELECT TOP $limit FROM ( |
347 | SELECT TOP ($limit+$offset) ... |
348 | ) ORDER BY $reversed_original_order |
349 | ) ORDER BY $original_order |
350 | |
351 | Unreliable Top-based implementation, supported by B<< MSSQL < 2005 >>. |
352 | |
353 | =head3 CAVEAT |
354 | |
355 | Due to its implementation, this limit dialect returns B<incorrect results> |
356 | when $limit+$offset > total amount of rows in the resultset. |
357 | |
358 | =cut |
359 | |
360 | sub _Top { |
361 | my ( $self, $sql, $rs_attrs, $rows, $offset ) = @_; |
362 | |
363 | my %l = %{ $self->_prep_for_skimming_limit($sql, $rs_attrs) }; |
7fca91be |
364 | |
365 | $sql = sprintf ('SELECT TOP %u %s %s %s %s', |
366 | $rows + ($offset||0), |
96eacdb7 |
367 | $l{in_sel}, |
368 | $l{inner_sql}, |
369 | $l{grpby_having}, |
370 | $l{order_by_inner}, |
7fca91be |
371 | ); |
372 | |
373 | $sql = sprintf ('SELECT TOP %u %s FROM ( %s ) %s %s', |
374 | $rows, |
96eacdb7 |
375 | $l{mid_sel}, |
7fca91be |
376 | $sql, |
96eacdb7 |
377 | $l{quoted_rs_alias}, |
378 | $l{order_by_reversed}, |
7fca91be |
379 | ) if $offset; |
380 | |
381 | $sql = sprintf ('SELECT TOP %u %s FROM ( %s ) %s %s', |
382 | $rows, |
96eacdb7 |
383 | $l{out_sel}, |
384 | $sql, |
385 | $l{quoted_rs_alias}, |
386 | $l{order_by_requested}, |
387 | ) if ( ($offset && $l{order_by_requested}) || ($l{mid_sel} ne $l{out_sel}) ); |
388 | |
389 | return $sql; |
390 | } |
391 | |
392 | =head2 FetchFirst |
393 | |
394 | SELECT * FROM |
395 | ( |
396 | SELECT * FROM ( |
397 | SELECT * FROM ( |
398 | SELECT * FROM ... |
399 | ) ORDER BY $reversed_original_order |
400 | FETCH FIRST $limit ROWS ONLY |
401 | ) ORDER BY $original_order |
402 | FETCH FIRST $limit ROWS ONLY |
403 | ) |
404 | |
405 | Unreliable FetchFirst-based implementation, supported by B<< IBM DB2 <= V5R3 >>. |
406 | |
407 | =head3 CAVEAT |
408 | |
409 | Due to its implementation, this limit dialect returns B<incorrect results> |
410 | when $limit+$offset > total amount of rows in the resultset. |
411 | |
412 | =cut |
413 | |
414 | sub _FetchFirst { |
415 | my ( $self, $sql, $rs_attrs, $rows, $offset ) = @_; |
416 | |
417 | my %l = %{ $self->_prep_for_skimming_limit($sql, $rs_attrs) }; |
418 | |
419 | $sql = sprintf ('SELECT %s %s %s %s FETCH FIRST %u ROWS ONLY', |
420 | $l{in_sel}, |
421 | $l{inner_sql}, |
422 | $l{grpby_having}, |
423 | $l{order_by_inner}, |
424 | $rows + ($offset||0), |
425 | ); |
426 | |
427 | $sql = sprintf ('SELECT %s FROM ( %s ) %s %s FETCH FIRST %u ROWS ONLY', |
428 | $l{mid_sel}, |
429 | $sql, |
430 | $l{quoted_rs_alias}, |
431 | $l{order_by_reversed}, |
432 | $rows, |
433 | ) if $offset; |
434 | |
435 | $sql = sprintf ('SELECT %s FROM ( %s ) %s %s FETCH FIRST %u ROWS ONLY', |
436 | $l{out_sel}, |
7fca91be |
437 | $sql, |
96eacdb7 |
438 | $l{quoted_rs_alias}, |
439 | $l{order_by_requested}, |
440 | $rows, |
441 | ) if ( ($offset && $l{order_by_requested}) || ($l{mid_sel} ne $l{out_sel}) ); |
7fca91be |
442 | |
7fca91be |
443 | return $sql; |
444 | } |
445 | |
d5dedbd6 |
446 | =head2 RowCountOrGenericSubQ |
447 | |
448 | This is not exactly a limit dialect, but more of a proxy for B<Sybase ASE>. |
449 | If no $offset is supplied the limit is simply performed as: |
450 | |
451 | SET ROWCOUNT $limit |
452 | SELECT ... |
453 | SET ROWCOUNT 0 |
454 | |
455 | Otherwise we fall back to L</GenericSubQ> |
456 | |
457 | =cut |
96eacdb7 |
458 | |
7fca91be |
459 | sub _RowCountOrGenericSubQ { |
460 | my $self = shift; |
461 | my ($sql, $rs_attrs, $rows, $offset) = @_; |
462 | |
463 | return $self->_GenericSubQ(@_) if $offset; |
464 | |
465 | return sprintf <<"EOF", $rows, $sql; |
466 | SET ROWCOUNT %d |
467 | %s |
468 | SET ROWCOUNT 0 |
469 | EOF |
470 | } |
471 | |
d5dedbd6 |
472 | =head2 GenericSubQ |
473 | |
474 | SELECT * FROM ( |
475 | SELECT ... |
476 | ) |
477 | WHERE ( |
478 | SELECT COUNT(*) FROM $original_table cnt WHERE cnt.id < $original_table.id |
479 | ) BETWEEN $offset AND ($offset+$rows-1) |
480 | |
481 | This is the most evil limit "dialect" (more of a hack) for I<really> stupid |
482 | databases. It works by ordering the set by some unique column, and calculating |
483 | the amount of rows that have a less-er value (thus emulating a L</RowNum>-like |
484 | index). Of course this implies the set can only be ordered by a single unique |
485 | column. Also note that this technique can be and often is B<excruciatingly |
486 | slow>. |
487 | |
488 | Currently used by B<Sybase ASE>, due to lack of any other option. |
489 | |
490 | =cut |
7fca91be |
491 | sub _GenericSubQ { |
492 | my ($self, $sql, $rs_attrs, $rows, $offset) = @_; |
493 | |
4376a157 |
494 | my $root_rsrc = $rs_attrs->{_rsroot_rsrc}; |
7fca91be |
495 | my $root_tbl_name = $root_rsrc->name; |
496 | |
7fca91be |
497 | my ($order_by, @rest) = do { |
498 | local $self->{quote_char}; |
499 | $self->_order_by_chunks ($rs_attrs->{order_by}) |
500 | }; |
501 | |
502 | unless ( |
503 | $order_by |
504 | && |
505 | ! @rest |
506 | && |
507 | ( ! ref $order_by |
508 | || |
509 | ( ref $order_by eq 'ARRAY' and @$order_by == 1 ) |
510 | ) |
511 | ) { |
70c28808 |
512 | $self->throw_exception ( |
7fca91be |
513 | 'Generic Subquery Limit does not work on resultsets without an order, or resultsets ' |
514 | . 'with complex order criteria (multicolumn and/or functions). Provide a single, ' |
515 | . 'unique-column order criteria.' |
516 | ); |
517 | } |
518 | |
519 | ($order_by) = @$order_by if ref $order_by; |
520 | |
521 | $order_by =~ s/\s+ ( ASC|DESC ) \s* $//ix; |
522 | my $direction = lc ($1 || 'asc'); |
523 | |
524 | my ($unq_sort_col) = $order_by =~ /(?:^|\.)([^\.]+)$/; |
525 | |
526 | my $inf = $root_rsrc->storage->_resolve_column_info ( |
527 | $rs_attrs->{from}, [$order_by, $unq_sort_col] |
528 | ); |
529 | |
70c28808 |
530 | my $ord_colinfo = $inf->{$order_by} || $self->throw_exception("Unable to determine source of order-criteria '$order_by'"); |
7fca91be |
531 | |
532 | if ($ord_colinfo->{-result_source}->name ne $root_tbl_name) { |
70c28808 |
533 | $self->throw_exception(sprintf |
534 | "Generic Subquery Limit order criteria can be only based on the root-source '%s'" |
535 | . " (aliased as '%s')", $root_rsrc->source_name, $rs_attrs->{alias}, |
536 | ); |
7fca91be |
537 | } |
538 | |
539 | # make sure order column is qualified |
540 | $order_by = "$rs_attrs->{alias}.$order_by" |
541 | unless $order_by =~ /^$rs_attrs->{alias}\./; |
542 | |
543 | my $is_u; |
544 | my $ucs = { $root_rsrc->unique_constraints }; |
545 | for (values %$ucs ) { |
546 | if (@$_ == 1 && "$rs_attrs->{alias}.$_->[0]" eq $order_by) { |
547 | $is_u++; |
548 | last; |
549 | } |
550 | } |
70c28808 |
551 | $self->throw_exception( |
552 | "Generic Subquery Limit order criteria column '$order_by' must be unique (no unique constraint found)" |
553 | ) unless $is_u; |
7fca91be |
554 | |
69d3c270 |
555 | my ($stripped_sql, $in_sel, $out_sel, $alias_map, $extra_order_sel) |
556 | = $self->_subqueried_limit_attrs ($sql, $rs_attrs); |
7fca91be |
557 | |
558 | my $cmp_op = $direction eq 'desc' ? '>' : '<'; |
559 | my $count_tbl_alias = 'rownum__emulation'; |
560 | |
561 | my $order_sql = $self->_order_by (delete $rs_attrs->{order_by}); |
562 | my $group_having_sql = $self->_parse_rs_attrs($rs_attrs); |
563 | |
564 | # add the order supplement (if any) as this is what will be used for the outer WHERE |
565 | $in_sel .= ", $_" for keys %{$extra_order_sel||{}}; |
566 | |
69d3c270 |
567 | my $rownum_cond; |
568 | if ($offset) { |
569 | $rownum_cond = 'BETWEEN ? AND ?'; |
570 | |
571 | push @{$self->{limit_bind}}, |
572 | [ $self->__offset_bindtype => $offset ], |
573 | [ $self->__total_bindtype => $offset + $rows - 1] |
574 | ; |
575 | } |
576 | else { |
577 | $rownum_cond = '< ?'; |
578 | |
579 | push @{$self->{limit_bind}}, |
580 | [ $self->__rows_bindtype => $rows ] |
581 | ; |
582 | } |
583 | |
584 | return sprintf (" |
7fca91be |
585 | SELECT $out_sel |
586 | FROM ( |
69d3c270 |
587 | SELECT $in_sel ${stripped_sql}${group_having_sql} |
7fca91be |
588 | ) %s |
69d3c270 |
589 | WHERE ( SELECT COUNT(*) FROM %s %s WHERE %s $cmp_op %s ) $rownum_cond |
7fca91be |
590 | $order_sql |
69d3c270 |
591 | ", map { $self->_quote ($_) } ( |
592 | $rs_attrs->{alias}, |
593 | $root_tbl_name, |
594 | $count_tbl_alias, |
595 | "$count_tbl_alias.$unq_sort_col", |
596 | $order_by, |
597 | )); |
7fca91be |
598 | } |
599 | |
600 | |
601 | # !!! THIS IS ALSO HORRIFIC !!! /me ashamed |
602 | # |
603 | # Generates inner/outer select lists for various limit dialects |
604 | # which result in one or more subqueries (e.g. RNO, Top, RowNum) |
605 | # Any non-root-table columns need to have their table qualifier |
606 | # turned into a column alias (otherwise names in subqueries clash |
607 | # and/or lose their source table) |
608 | # |
69d3c270 |
609 | # Returns mangled proto-sql, inner/outer strings of SQL QUOTED selectors |
610 | # with aliases (to be used in whatever select statement), and an alias |
611 | # index hashref of QUOTED SEL => QUOTED ALIAS pairs (to maybe be used |
612 | # for string-subst higher up). |
7fca91be |
613 | # If an order_by is supplied, the inner select needs to bring out columns |
614 | # used in implicit (non-selected) orders, and the order condition itself |
615 | # needs to be realiased to the proper names in the outer query. Thus we |
616 | # also return a hashref (order doesn't matter) of QUOTED EXTRA-SEL => |
617 | # QUOTED ALIAS pairs, which is a list of extra selectors that do *not* |
618 | # exist in the original select list |
7fca91be |
619 | sub _subqueried_limit_attrs { |
69d3c270 |
620 | my ($self, $proto_sql, $rs_attrs) = @_; |
7fca91be |
621 | |
70c28808 |
622 | $self->throw_exception( |
623 | 'Limit dialect implementation usable only in the context of DBIC (missing $rs_attrs)' |
624 | ) unless ref ($rs_attrs) eq 'HASH'; |
7fca91be |
625 | |
69d3c270 |
626 | # mangle the input sql as we will be replacing the selector |
627 | $proto_sql =~ s/^ \s* SELECT \s+ .+ \s+ (?= \b FROM \b )//ix |
628 | or $self->throw_exception("Unrecognizable SELECT: $proto_sql"); |
629 | |
3f5b99fe |
630 | my ($re_sep, $re_alias) = map { quotemeta $_ } ( $self->{name_sep}, $rs_attrs->{alias} ); |
7fca91be |
631 | |
69d3c270 |
632 | # insulate from the multiple _recurse_fields calls below |
633 | local $self->{select_bind}; |
634 | |
7fca91be |
635 | # correlate select and as, build selection index |
636 | my (@sel, $in_sel_index); |
637 | for my $i (0 .. $#{$rs_attrs->{select}}) { |
638 | |
639 | my $s = $rs_attrs->{select}[$i]; |
640 | my $sql_sel = $self->_recurse_fields ($s); |
641 | my $sql_alias = (ref $s) eq 'HASH' ? $s->{-as} : undef; |
642 | |
7fca91be |
643 | push @sel, { |
644 | sql => $sql_sel, |
69d3c270 |
645 | unquoted_sql => do { |
646 | local $self->{quote_char}; |
647 | $self->_recurse_fields ($s); |
648 | }, |
7fca91be |
649 | as => |
650 | $sql_alias |
651 | || |
652 | $rs_attrs->{as}[$i] |
653 | || |
70c28808 |
654 | $self->throw_exception("Select argument $i ($s) without corresponding 'as'") |
7fca91be |
655 | , |
656 | }; |
657 | |
658 | $in_sel_index->{$sql_sel}++; |
659 | $in_sel_index->{$self->_quote ($sql_alias)}++ if $sql_alias; |
660 | |
661 | # record unqualified versions too, so we do not have |
662 | # to reselect the same column twice (in qualified and |
663 | # unqualified form) |
664 | if (! ref $s && $sql_sel =~ / $re_sep (.+) $/x) { |
665 | $in_sel_index->{$1}++; |
666 | } |
667 | } |
668 | |
669 | |
670 | # re-alias and remove any name separators from aliases, |
671 | # unless we are dealing with the current source alias |
672 | # (which will transcend the subqueries as it is necessary |
673 | # for possible further chaining) |
674 | my (@in_sel, @out_sel, %renamed); |
675 | for my $node (@sel) { |
3f5b99fe |
676 | if ( |
677 | $node->{as} =~ / (?<! ^ $re_alias ) \. /x |
678 | or |
679 | $node->{unquoted_sql} =~ / (?<! ^ $re_alias ) $re_sep /x |
680 | ) { |
7fca91be |
681 | $node->{as} = $self->_unqualify_colname($node->{as}); |
682 | my $quoted_as = $self->_quote($node->{as}); |
683 | push @in_sel, sprintf '%s AS %s', $node->{sql}, $quoted_as; |
684 | push @out_sel, $quoted_as; |
685 | $renamed{$node->{sql}} = $quoted_as; |
686 | } |
687 | else { |
688 | push @in_sel, $node->{sql}; |
689 | push @out_sel, $self->_quote ($node->{as}); |
690 | } |
691 | } |
7fca91be |
692 | # see if the order gives us anything |
693 | my %extra_order_sel; |
694 | for my $chunk ($self->_order_by_chunks ($rs_attrs->{order_by})) { |
695 | # order with bind |
696 | $chunk = $chunk->[0] if (ref $chunk) eq 'ARRAY'; |
697 | $chunk =~ s/\s+ (?: ASC|DESC ) \s* $//ix; |
698 | |
699 | next if $in_sel_index->{$chunk}; |
700 | |
701 | $extra_order_sel{$chunk} ||= $self->_quote ( |
702 | 'ORDER__BY__' . scalar keys %extra_order_sel |
703 | ); |
704 | } |
705 | |
706 | return ( |
69d3c270 |
707 | $proto_sql, |
7fca91be |
708 | (map { join (', ', @$_ ) } ( |
709 | \@in_sel, |
710 | \@out_sel) |
711 | ), |
712 | \%renamed, |
713 | keys %extra_order_sel ? \%extra_order_sel : (), |
714 | ); |
715 | } |
716 | |
717 | sub _unqualify_colname { |
718 | my ($self, $fqcn) = @_; |
3f5b99fe |
719 | $fqcn =~ s/ \. /__/xg; |
7fca91be |
720 | return $fqcn; |
721 | } |
722 | |
723 | 1; |
d5dedbd6 |
724 | |
725 | =head1 AUTHORS |
726 | |
727 | See L<DBIx::Class/CONTRIBUTORS>. |
728 | |
729 | =head1 LICENSE |
730 | |
731 | You may distribute this code under the same terms as Perl itself. |
732 | |
733 | =cut |