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1 | package DBIx::Class::Storage::DBI::MSSQL; |
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2 | |
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3 | use strict; |
4 | use warnings; |
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5 | |
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6 | use base qw/DBIx::Class::Storage::DBI::UniqueIdentifier/; |
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7 | use mro 'c3'; |
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8 | |
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9 | use List::Util(); |
10 | |
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11 | __PACKAGE__->mk_group_accessors(simple => qw/ |
12 | _identity _identity_method |
13 | /); |
14 | |
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15 | __PACKAGE__->sql_maker_class('DBIx::Class::SQLAHacks::MSSQL'); |
16 | |
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17 | sub _set_identity_insert { |
18 | my ($self, $table) = @_; |
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19 | |
20 | my $sql = sprintf ( |
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21 | 'SET IDENTITY_INSERT %s ON', |
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22 | $self->sql_maker->_quote ($table), |
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23 | ); |
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24 | |
25 | my $dbh = $self->_get_dbh; |
26 | eval { $dbh->do ($sql) }; |
27 | if ($@) { |
28 | $self->throw_exception (sprintf "Error executing '%s': %s", |
29 | $sql, |
30 | $dbh->errstr, |
31 | ); |
32 | } |
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33 | } |
34 | |
aac1a358 |
35 | sub _unset_identity_insert { |
36 | my ($self, $table) = @_; |
37 | |
38 | my $sql = sprintf ( |
39 | 'SET IDENTITY_INSERT %s OFF', |
40 | $self->sql_maker->_quote ($table), |
41 | ); |
42 | |
43 | my $dbh = $self->_get_dbh; |
44 | $dbh->do ($sql); |
45 | } |
46 | |
5a77aa8b |
47 | sub insert_bulk { |
48 | my $self = shift; |
49 | my ($source, $cols, $data) = @_; |
50 | |
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51 | my $is_identity_insert = (List::Util::first |
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52 | { $source->column_info ($_)->{is_auto_increment} } |
53 | (@{$cols}) |
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54 | ) |
55 | ? 1 |
56 | : 0; |
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57 | |
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58 | if ($is_identity_insert) { |
59 | $self->_set_identity_insert ($source->name); |
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60 | } |
61 | |
62 | $self->next::method(@_); |
63 | |
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64 | if ($is_identity_insert) { |
65 | $self->_unset_identity_insert ($source->name); |
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66 | } |
67 | } |
68 | |
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69 | sub insert { |
70 | my $self = shift; |
71 | my ($source, $to_insert) = @_; |
72 | |
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73 | my $supplied_col_info = $self->_resolve_column_info($source, [keys %$to_insert] ); |
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74 | |
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75 | my $is_identity_insert = (List::Util::first { $_->{is_auto_increment} } (values %$supplied_col_info) ) |
76 | ? 1 |
77 | : 0; |
78 | |
79 | if ($is_identity_insert) { |
80 | $self->_set_identity_insert ($source->name); |
afcfff01 |
81 | } |
82 | |
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83 | my $updated_cols = $self->next::method(@_); |
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84 | |
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85 | if ($is_identity_insert) { |
86 | $self->_unset_identity_insert ($source->name); |
87 | } |
88 | |
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89 | return $updated_cols; |
90 | } |
91 | |
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92 | sub _prep_for_execute { |
93 | my $self = shift; |
94 | my ($op, $extra_bind, $ident, $args) = @_; |
95 | |
96 | # cast MONEY values properly |
97 | if ($op eq 'insert' || $op eq 'update') { |
98 | my $fields = $args->[0]; |
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99 | |
100 | for my $col (keys %$fields) { |
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101 | # $ident is a result source object with INSERT/UPDATE ops |
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102 | if ($ident->column_info ($col)->{data_type} |
103 | && |
104 | $ident->column_info ($col)->{data_type} =~ /^money\z/i) { |
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105 | my $val = $fields->{$col}; |
106 | $fields->{$col} = \['CAST(? AS MONEY)', [ $col => $val ]]; |
107 | } |
108 | } |
109 | } |
110 | |
111 | my ($sql, $bind) = $self->next::method (@_); |
112 | |
113 | if ($op eq 'insert') { |
114 | $sql .= ';SELECT SCOPE_IDENTITY()'; |
115 | |
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116 | } |
117 | |
118 | return ($sql, $bind); |
119 | } |
120 | |
121 | sub _execute { |
122 | my $self = shift; |
123 | my ($op) = @_; |
124 | |
125 | my ($rv, $sth, @bind) = $self->dbh_do($self->can('_dbh_execute'), @_); |
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126 | |
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127 | if ($op eq 'insert') { |
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128 | |
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129 | # this should bring back the result of SELECT SCOPE_IDENTITY() we tacked |
130 | # on in _prep_for_execute above |
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131 | my ($identity) = eval { $sth->fetchrow_array }; |
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132 | |
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133 | # SCOPE_IDENTITY failed, but we can do something else |
134 | if ( (! $identity) && $self->_identity_method) { |
135 | ($identity) = $self->_dbh->selectrow_array( |
136 | 'select ' . $self->_identity_method |
137 | ); |
138 | } |
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139 | |
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140 | $self->_identity($identity); |
141 | $sth->finish; |
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142 | } |
143 | |
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144 | return wantarray ? ($rv, $sth, @bind) : $rv; |
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145 | } |
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146 | |
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147 | sub last_insert_id { shift->_identity } |
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148 | |
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149 | # |
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150 | # MSSQL is retarded wrt ordered subselects. One needs to add a TOP |
151 | # to *all* subqueries, but one also can't use TOP 100 PERCENT |
152 | # http://sqladvice.com/forums/permalink/18496/22931/ShowThread.aspx#22931 |
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153 | # |
154 | sub _select_args_to_query { |
155 | my $self = shift; |
156 | |
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157 | my ($sql, $prep_bind, @rest) = $self->next::method (@_); |
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158 | |
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159 | # see if this is an ordered subquery |
160 | my $attrs = $_[3]; |
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161 | if ( scalar $self->_parse_order_by ($attrs->{order_by}) ) { |
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162 | $self->throw_exception( |
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163 | 'An ordered subselect encountered - this is not safe! Please see "Ordered Subselects" in DBIx::Class::Storage::DBI::MSSQL |
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164 | ') unless $attrs->{unsafe_subselect_ok}; |
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165 | my $max = 2 ** 32; |
166 | $sql =~ s/^ \s* SELECT \s/SELECT TOP $max /xi; |
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167 | } |
168 | |
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169 | return wantarray |
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170 | ? ($sql, $prep_bind, @rest) |
171 | : \[ "($sql)", @$prep_bind ] |
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172 | ; |
173 | } |
174 | |
175 | |
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176 | # savepoint syntax is the same as in Sybase ASE |
177 | |
178 | sub _svp_begin { |
179 | my ($self, $name) = @_; |
180 | |
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181 | $self->_get_dbh->do("SAVE TRANSACTION $name"); |
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182 | } |
183 | |
184 | # A new SAVE TRANSACTION with the same name releases the previous one. |
185 | sub _svp_release { 1 } |
186 | |
187 | sub _svp_rollback { |
188 | my ($self, $name) = @_; |
189 | |
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190 | $self->_get_dbh->do("ROLLBACK TRANSACTION $name"); |
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191 | } |
192 | |
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193 | sub build_datetime_parser { |
194 | my $self = shift; |
195 | my $type = "DateTime::Format::Strptime"; |
196 | eval "use ${type}"; |
197 | $self->throw_exception("Couldn't load ${type}: $@") if $@; |
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198 | return $type->new( pattern => '%Y-%m-%d %H:%M:%S' ); # %F %T |
199 | } |
200 | |
201 | sub sqlt_type { 'SQLServer' } |
202 | |
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203 | sub sql_maker { |
204 | my $self = shift; |
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205 | |
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206 | unless ($self->_sql_maker) { |
207 | unless ($self->{_sql_maker_opts}{limit_dialect}) { |
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208 | |
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209 | my $version = $self->_server_info->{normalized_dbms_version} || 0; |
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210 | |
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211 | $self->{_sql_maker_opts} = { |
212 | limit_dialect => ($version >= 9 ? 'RowNumberOver' : 'Top'), |
213 | %{$self->{_sql_maker_opts}||{}} |
214 | }; |
215 | } |
216 | |
217 | my $maker = $self->next::method (@_); |
218 | } |
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219 | |
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220 | return $self->_sql_maker; |
ed8de058 |
221 | } |
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222 | |
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223 | sub _ping { |
224 | my $self = shift; |
225 | |
226 | my $dbh = $self->_dbh or return 0; |
227 | |
228 | local $dbh->{RaiseError} = 1; |
229 | local $dbh->{PrintError} = 0; |
230 | |
231 | eval { |
232 | $dbh->do('select 1'); |
233 | }; |
234 | |
235 | return $@ ? 0 : 1; |
236 | } |
237 | |
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238 | 1; |
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239 | |
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240 | =head1 NAME |
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241 | |
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242 | DBIx::Class::Storage::DBI::MSSQL - Base Class for Microsoft SQL Server support |
243 | in DBIx::Class |
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244 | |
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245 | =head1 SYNOPSIS |
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246 | |
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247 | This is the base class for Microsoft SQL Server support, used by |
248 | L<DBIx::Class::Storage::DBI::ODBC::Microsoft_SQL_Server> and |
249 | L<DBIx::Class::Storage::DBI::Sybase::Microsoft_SQL_Server>. |
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250 | |
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251 | =head1 IMPLEMENTATION NOTES |
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252 | |
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253 | =head2 IDENTITY information |
254 | |
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255 | Microsoft SQL Server supports three methods of retrieving the IDENTITY |
256 | value for inserted row: IDENT_CURRENT, @@IDENTITY, and SCOPE_IDENTITY(). |
257 | SCOPE_IDENTITY is used here because it is the safest. However, it must |
258 | be called is the same execute statement, not just the same connection. |
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259 | |
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260 | So, this implementation appends a SELECT SCOPE_IDENTITY() statement |
261 | onto each INSERT to accommodate that requirement. |
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262 | |
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263 | C<SELECT @@IDENTITY> can also be used by issuing: |
264 | |
265 | $self->_identity_method('@@identity'); |
266 | |
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267 | it will only be used if SCOPE_IDENTITY() fails. |
268 | |
269 | This is more dangerous, as inserting into a table with an on insert trigger that |
270 | inserts into another table with an identity will give erroneous results on |
271 | recent versions of SQL Server. |
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272 | |
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273 | =head2 identity insert |
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274 | |
275 | Be aware that we have tried to make things as simple as possible for our users. |
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276 | For MSSQL that means that when a user tries to create a row, while supplying an |
277 | explicit value for an autoincrementing column, we will try to issue the |
278 | appropriate database call to make this possible, namely C<SET IDENTITY_INSERT |
279 | $table_name ON>. Unfortunately this operation in MSSQL requires the |
280 | C<db_ddladmin> privilege, which is normally not included in the standard |
281 | write-permissions. |
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282 | |
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283 | =head2 Ordered Subselects |
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284 | |
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285 | If you attempted the following query (among many others) in Microsoft SQL |
286 | Server |
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287 | |
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288 | $rs->search ({}, { |
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289 | prefetch => 'relation', |
290 | rows => 2, |
291 | offset => 3, |
292 | }); |
293 | |
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294 | You may be surprised to receive an exception. The reason for this is a quirk |
295 | in the MSSQL engine itself, and sadly doesn't have a sensible workaround due |
296 | to the way DBIC is built. DBIC can do truly wonderful things with the aid of |
297 | subselects, and does so automatically when necessary. The list of situations |
298 | when a subselect is necessary is long and still changes often, so it can not |
299 | be exhaustively enumerated here. The general rule of thumb is a joined |
300 | L<has_many|DBIx::Class::Relationship/has_many> relationship with limit/group |
301 | applied to the left part of the join. |
302 | |
303 | In its "pursuit of standards" Microsft SQL Server goes to great lengths to |
304 | forbid the use of ordered subselects. This breaks a very useful group of |
305 | searches like "Give me things number 4 to 6 (ordered by name), and prefetch |
306 | all their relations, no matter how many". While there is a hack which fools |
307 | the syntax checker, the optimizer may B<still elect to break the subselect>. |
308 | Testing has determined that while such breakage does occur (the test suite |
309 | contains an explicit test which demonstrates the problem), it is relative |
310 | rare. The benefits of ordered subselects are on the other hand too great to be |
311 | outright disabled for MSSQL. |
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312 | |
313 | Thus compromise between usability and perfection is the MSSQL-specific |
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314 | L<resultset attribute|DBIx::Class::ResultSet/ATTRIBUTES> C<unsafe_subselect_ok>. |
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315 | It is deliberately not possible to set this on the Storage level, as the user |
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316 | should inspect (and preferably regression-test) the return of every such |
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317 | ResultSet individually. The example above would work if written like: |
318 | |
319 | $rs->search ({}, { |
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320 | unsafe_subselect_ok => 1, |
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321 | prefetch => 'relation', |
322 | rows => 2, |
323 | offset => 3, |
324 | }); |
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325 | |
326 | If it is possible to rewrite the search() in a way that will avoid the need |
327 | for this flag - you are urged to do so. If DBIC internals insist that an |
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328 | ordered subselect is necessary for an operation, and you believe there is a |
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329 | different/better way to get the same result - please file a bugreport. |
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330 | |
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331 | =head1 AUTHOR |
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332 | |
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333 | See L<DBIx::Class/AUTHOR> and L<DBIx::Class/CONTRIBUTORS>. |
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334 | |
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335 | =head1 LICENSE |
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336 | |
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337 | You may distribute this code under the same terms as Perl itself. |
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338 | |
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339 | =cut |