[Bps-public-commit] dbix-searchbuilder branch, master, updated. d77dd287821520704bf5a99b2b60b8879e81eb8d

[Ruslan Zakirov]

The branch, master has been updated
       via  d77dd287821520704bf5a99b2b60b8879e81eb8d (commit)
      from  71f530e5ae278846fcad0b0995b55d3d8a5c79db (commit)

Summary of changes:
 SearchBuilder/Handle/Pg.pm |    9 +++++++--
 1 files changed, 7 insertions(+), 2 deletions(-)

- Log -----------------------------------------------------------------
commit d77dd287821520704bf5a99b2b60b8879e81eb8d
Author: Ruslan Zakirov <ruz at bestpractical.com>
Date:   Mon Mar 22 19:43:26 2010 +0300

    update code comment to make it clear why old approach didn't work

diff --git a/SearchBuilder/Handle/Pg.pm b/SearchBuilder/Handle/Pg.pm
index bbeb69a..5dec864 100755
--- a/SearchBuilder/Handle/Pg.pm
+++ b/SearchBuilder/Handle/Pg.pm
@@ -230,8 +230,13 @@ sub DistinctQuery {
     return $self->SUPER::DistinctQuery( $statementref, $sb, @_ )
         if $sb->_OrderClause !~ /(?<!main)\./;
 
-    # If we are ordering by something not in 'main', we need to GROUP
-    # BY and adjust the ORDER_BY accordingly
+    # "SELECT main.* FROM ( SELECT id FROM ... ORDER BY ... ) as dist,
+    # X main WHERE (main.id = dist.id);" doesn't work in some cases.
+    # It's hard to show with tests. Pg's optimizer can choose execution
+    # plan not guaranting order
+
+    # So if we are ordering by something that is not in 'main', the we GROUP
+    # BY all columns and adjust the ORDER_BY accordingly
     local $sb->{group_by} = [ map {+{FIELD => $_}} $self->Fields($table) ];
     local $sb->{'order_by'} = [
         map {

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