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* Avoid adding DISTINCT if possible

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* Added comments
This commit is contained in:
Aaron Schulz 2011-03-22 13:11:28 +00:00
parent f6e0bc9324
commit 45191d2a50
1 changed files with 21 additions and 4 deletions
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25
includes/LogEventsList.php
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@ -938,12 +938,21 @@ class LogPager extends ReverseChronologicalPager {
$this->mConds[] = 'user_id = log_user';
$index = array();
$options = array();
# Add log_search table if there are conditions on it
if( array_key_exists('ls_field',$this->mConds) ) {
# Add log_search table if there are conditions on it.
# This filters the results to only include log rows that have
# log_search records with the specified ls_field and ls_value values.
if( array_key_exists( 'ls_field', $this->mConds ) ) {
$tables[] = 'log_search';
$index['log_search'] = 'ls_field_val';
$index['logging'] = 'PRIMARY';
$options[] = 'DISTINCT';
if ( !$this->hasEqualsClause( 'ls_field' )
|| !$this->hasEqualsClause( 'ls_value' ) )
{
# Since (ls_field,ls_value,ls_logid) is unique, if the condition is
# to match a specific (ls_field,ls_value) tuple, then there will be
# no duplicate log rows. Otherwise, we need to remove the duplicates.
$options[] = 'DISTINCT';
}
# Avoid usage of the wrong index by limiting
# the choices of available indexes. This mainly
# avoids site-breaking filesorts.
@ -967,7 +976,7 @@ class LogPager extends ReverseChronologicalPager {
'conds' => $this->mConds,
'options' => $options,
'join_conds' => array(
'user' => array( 'INNER JOIN', 'user_id=log_user' ),
'user' => array( 'INNER JOIN', 'user_id=log_user' ),
'log_search' => array( 'INNER JOIN', 'ls_log_id=log_id' )
)
);
@ -977,6 +986,14 @@ class LogPager extends ReverseChronologicalPager {
return $info;
}
// Checks if $this->mConds has $field matched to a *single* value
protected function hasEqualsClause( $field ) {
return (
array_key_exists( $field, $this->mConds ) &&
( !is_array( $this->mConds[$field] ) || count( $this->mConds[$field] ) == 1 )
);
}
function getIndexField() {
return 'log_timestamp';
}