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1 | # Test to ensure we get a consistent result set wether or not we use the |
2 | # prefetch option in combination rows (LIMIT). |
3 | use strict; |
4 | use warnings; |
5 | |
6 | use Test::More; |
7 | use lib qw(t/lib); |
8 | use DBICTest; |
9 | |
10 | plan $@ ? (skip_all => 'needs DBD::SQLite for testing') : (tests => 2); |
11 | |
12 | my $schema = DBICTest->init_schema(); |
13 | my $no_prefetch = $schema->resultset('Artist')->search( |
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14 | undef, |
15 | { rows => 3 } |
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16 | ); |
17 | |
18 | my $use_prefetch = $schema->resultset('Artist')->search( |
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19 | undef, |
20 | { |
21 | prefetch => 'cds', |
22 | rows => 3 |
23 | } |
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24 | ); |
25 | |
26 | my $no_prefetch_count = 0; |
27 | my $use_prefetch_count = 0; |
28 | |
29 | is($no_prefetch->count, $use_prefetch->count, '$no_prefetch->count == $use_prefetch->count'); |
30 | |
31 | TODO: { |
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32 | local $TODO = "This is a difficult bug to fix, workaround is not to use prefetch with rows"; |
33 | $no_prefetch_count++ while $no_prefetch->next; |
34 | $use_prefetch_count++ while $use_prefetch->next; |
35 | is( |
36 | $no_prefetch_count, |
37 | $use_prefetch_count, |
38 | "manual row count confirms consistency" |
39 | . " (\$no_prefetch_count == $no_prefetch_count, " |
40 | . " \$use_prefetch_count == $use_prefetch_count)" |
41 | ); |
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42 | } |
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43 | |
44 | __END__ |
45 | The fix is to, when using prefetch, take the query and put it into a subquery |
46 | joined to the tables we're prefetching from. This might result in the same |
47 | table being joined once in the main subquery and once in the main query. This |
48 | may actually resolve other, unknown edgecase bugs. It is also the right way |
49 | to do prefetching. Optimizations can come later. |
50 | |
51 | This means that: |
52 | $foo_rs->search( |
53 | { ... }, |
54 | { |
55 | prefetch => 'bar', |
56 | ... |
57 | }, |
58 | ); |
59 | |
60 | becomes: |
61 | my $temp = $foo_rs->search( |
62 | { ... }, |
63 | { |
64 | join => 'bar', |
65 | ... |
66 | }, |
67 | ); |
68 | $foo_rs->storage->schema->resultset('foo')->search( |
69 | undef, |
70 | { |
71 | from => [ |
72 | { me => $temp->as_query }, |
73 | ], |
74 | prefetch => 'bar', |
75 | }, |
76 | ); |
77 | |
78 | Problem: |
79 | * The prefetch->join change needs to happen ONLY IF there are conditions |
80 | that depend on bar being joined. |
81 | * How will this work when the $rs is further searched on? Those clauses |
82 | need to be added to the subquery, not the outer one. This is particularly |
83 | true if rows is added in the attribute later per the Pager. |