/**
* Adds extra indices for reverse foreign keys
* This is required for MySQL databases,
* and is called from Database::doFinalInitialization()
*/
public function addExtraIndices()
{
/**
* A collection of indexed columns. The keys is the column name
* (concatenated with a comma in the case of multi-col index), the value is
* an array with the names of the indexes that index these columns. We use
* it to determine which additional indexes must be created for foreign
* keys. It could also be used to detect duplicate indexes, but this is not
* implemented yet.
* @var array
*/
$_indices = array();
$this->collectIndexedColumns('PRIMARY', $this->getPrimaryKey(), $_indices);
$_tableIndices = array_merge($this->getIndices(), $this->getUnices());
foreach ($_tableIndices as $_index) {
$this->collectIndexedColumns($_index->getName(), $_index->getColumns(), $_indices);
}
// we're determining which tables have foreign keys that point to this table,
// since MySQL needs an index on any column that is referenced by another table
// (yep, MySQL _is_ a PITA)
$counter = 0;
foreach ($this->getReferrers() as $foreignKey) {
$referencedColumns = $foreignKey->getForeignColumnObjects();
$referencedColumnsHash = $this->getColumnList($referencedColumns);
if (!array_key_exists($referencedColumnsHash, $_indices)) {
// no matching index defined in the schema, so we have to create one
$index = new Index();
$index->setName(sprintf('I_referenced_%s_%s', $foreignKey->getName(), ++$counter));
$index->setColumns($referencedColumns);
$index->resetColumnSize();
$this->addIndex($index);
// Add this new index to our collection, otherwise we might add it again (bug #725)
$this->collectIndexedColumns($index->getName(), $referencedColumns, $_indices);
}
}
// we're adding indices for this table foreign keys
foreach ($this->getForeignKeys() as $foreignKey) {
$localColumns = $foreignKey->getLocalColumnObjects();
$localColumnsHash = $this->getColumnList($localColumns);
if (!array_key_exists($localColumnsHash, $_indices)) {
// no matching index defined in the schema, so we have to create one. MySQL needs indices on any columns that serve as foreign keys. these are not auto-created prior to 4.1.2
$index = new Index();
$index->setName(substr_replace($foreignKey->getName(), 'FI_', strrpos($foreignKey->getName(), 'FK_'), 3));
$index->setColumns($localColumns);
$index->resetColumnSize();
$this->addIndex($index);
$this->collectIndexedColumns($index->getName(), $localColumns, $_indices);
}
}
}
/**
* <p>Adds extra indices for multi-part primary key columns.</p>
*
* <p>For databases like MySQL, values in a where clause much
* match key part order from the left to right. So, in the key
* definition <code>PRIMARY KEY (FOO_ID, BAR_ID)</code>,
* <code>FOO_ID</code> <i>must</i> be the first element used in
* the <code>where</code> clause of the SQL query used against
* this table for the primary key index to be used. This feature
* could cause problems under MySQL with heavily indexed tables,
* as MySQL currently only supports 16 indices per table (i.e. it
* might cause too many indices to be created).</p>
*
* <p>See <a href="http://www.mysql.com/doc/E/X/EXPLAIN.html">the
* manual</a> for a better description of why heavy indexing is
* useful for quickly searchable database tables.</p>
*/
private function doHeavyIndexing()
{
if (self::DEBUG) {
print "doHeavyIndex() called on table " . $this->name . "\n";
}
$pk = $this->getPrimaryKey();
$size = count($pk);
// We start at an offset of 1 because the entire column
// list is generally implicitly indexed by the fact that
// it's a primary key.
for ($i = 1; $i < $size; $i++) {
$idx = new Index();
$idx->setColumns(array_slice($pk, $i, $size));
$this->addIndex($idx);
}
}
