/**
* The new SQL store's implementation of query answering. This function
* works in two stages: First, the nested conditions of the given query
* object are preprocessed to compute an abstract representation of the
* SQL query that is to be executed. Since query conditions correspond to
* joins with property tables in most cases, this abstract representation
* is essentially graph-like description of how property tables are joined.
* Moreover, this graph is tree-shaped, since all query conditions are
* tree-shaped. Each part of this abstract query structure is represented
* by an SMWSQLStore2Query object in the array m_queries.
*
* As a second stage of processing, the thus prepared SQL query is actually
* executed. Typically, this means that the joins are collapsed into one
* SQL query to retrieve results. In some cases, such as in dbug mode, the
* execution might be restricted and not actually perform the whole query.
*
* The two-stage process helps to separate tasks, and it also allows for
* better optimisations: it is left to the execution engine how exactly the
* query result is to be obtained. For example, one could pre-compute
* partial suib-results in temporary tables (or even cache them somewhere),
* instead of passing one large join query to the DB (of course, it might
* be large only if the configuration of SMW allows it). For some DBMS, a
* step-wise execution of the query might lead to better performance, since
* it exploits the tree-structure of the joins, which is important for fast
* processing -- not all DBMS might be able in seeing this by themselves.
*
* @param SMWQuery $query
*/
public function getQueryResult(SMWQuery $query)
{
global $smwgIgnoreQueryErrors, $smwgQSortingSupport;
if (!$smwgIgnoreQueryErrors && $query->querymode != SMWQuery::MODE_DEBUG && count($query->getErrors()) > 0) {
return new SMWQueryResult($query->getDescription()->getPrintrequests(), $query, array(), $this->m_store, false);
// NOTE: we check this here to prevent unnecessary work, but we check it after query processing below again in case more errors occurred
} elseif ($query->querymode == SMWQuery::MODE_NONE) {
// don't query, but return something to printer
return new SMWQueryResult($query->getDescription()->getPrintrequests(), $query, array(), $this->m_store, true);
}
$this->m_qmode = $query->querymode;
$this->m_queries = array();
$this->m_hierarchies = array();
$this->m_querylog = array();
$this->m_errors = array();
SMWSQLStore2Query::$qnum = 0;
$this->m_sortkeys = $query->sortkeys;
// *** First compute abstract representation of the query (compilation) ***//
wfProfileIn('SMWSQLStore2Queries::compileMainQuery (SMW)');
$qid = $this->compileQueries($query->getDescription());
// compile query, build query "plan"
wfProfileOut('SMWSQLStore2Queries::compileMainQuery (SMW)');
if ($qid < 0) {
// no valid/supported condition; ensure that at least only proper pages are delivered
$qid = SMWSQLStore2Query::$qnum;
$q = new SMWSQLStore2Query();
$q->jointable = 'smw_ids';
$q->joinfield = "{$q->alias}.smw_id";
$q->where = "{$q->alias}.smw_iw!=" . $this->m_dbs->addQuotes(SMW_SQL2_SMWIW) . " AND {$q->alias}.smw_iw!=" . $this->m_dbs->addQuotes(SMW_SQL2_SMWREDIIW) . " AND {$q->alias}.smw_iw!=" . $this->m_dbs->addQuotes(SMW_SQL2_SMWBORDERIW) . " AND {$q->alias}.smw_iw!=" . $this->m_dbs->addQuotes(SMW_SQL2_SMWINTDEFIW);
$this->m_queries[$qid] = $q;
}
if ($this->m_queries[$qid]->jointable != 'smw_ids') {
// manually make final root query (to retrieve namespace,title):
$rootid = SMWSQLStore2Query::$qnum;
$qobj = new SMWSQLStore2Query();
$qobj->jointable = 'smw_ids';
$qobj->joinfield = "{$qobj->alias}.smw_id";
$qobj->components = array($qid => "{$qobj->alias}.smw_id");
$qobj->sortfields = $this->m_queries[$qid]->sortfields;
$this->m_queries[$rootid] = $qobj;
} else {
// not such a common case, but worth avoiding the additional inner join:
$rootid = $qid;
}
// commented by ning, no need to sort
// // Include order conditions (may extend query if needed for sorting):
// if ( $smwgQSortingSupport ) {
// $this->applyOrderConditions( $rootid );
// }
if (!$smwgIgnoreQueryErrors && $query->querymode != SMWQuery::MODE_DEBUG && count($this->m_errors) > 0) {
// stop here if new errors happened
$query->addErrors($this->m_errors);
return new SMWQueryResult($query->getDescription()->getPrintrequests(), $query, array(), $this->m_store, false);
}
// *** Now execute the computed query ***//
wfProfileIn('SMWSQLStore2Queries::executeMainQuery (SMW)');
$this->executeQueries($this->m_queries[$rootid]);
// execute query tree, resolve all dependencies
wfProfileOut('SMWSQLStore2Queries::executeMainQuery (SMW)');
$result = $this->getNMQueryResult($query, $rootid);
$this->cleanUp();
$query->addErrors($this->m_errors);
return $result;
}
/**
* The new SQL store's implementation of query answering.
*/
public function getQueryResult(SMWQuery $query)
{
if ($query->querymode == SMWQuery::MODE_NONE) {
// don't query, but return something to printer
$result = new SMWQueryResult($query->getDescription()->getPrintrequests(), $query, true);
return $result;
}
$this->m_qmode = $query->querymode;
$this->m_queries = array();
$this->m_hierarchies = array();
$this->m_querylog = array();
$this->m_errors = array();
SMWSQLStore2Query::$qnum = 0;
$this->m_sortkeys = $query->sortkeys;
// manually make final root query (to retrieve namespace,title):
$rootid = SMWSQLStore2Query::$qnum;
$qobj = new SMWSQLStore2Query();
$qobj->jointable = 'smw_ids';
$qobj->joinfield = "{$qobj->alias}.smw_id";
// build query dependency tree:
wfProfileIn('SMWSQLStore2Queries::compileMainQuery (SMW)');
$qid = $this->compileQueries($query->getDescription());
// compile query, build query "plan"
wfProfileOut('SMWSQLStore2Queries::compileMainQuery (SMW)');
if ($qid < 0) {
// no valid/supported condition; ensure that at least only proper pages are delivered
$qid = SMWSQLStore2Query::$qnum;
$q = new SMWSQLStore2Query();
$q->jointable = 'smw_ids';
$q->joinfield = "{$q->alias}.smw_id";
$q->where = "{$q->alias}.smw_iw!=" . $this->m_dbs->addQuotes(SMW_SQL2_SMWIW) . " AND {$q->alias}.smw_iw!=" . $this->m_dbs->addQuotes(SMW_SQL2_SMWREDIIW) . " AND {$q->alias}.smw_iw!=" . $this->m_dbs->addQuotes(SMW_SQL2_SMWBORDERIW) . " AND {$q->alias}.smw_iw!=" . $this->m_dbs->addQuotes(SMW_SQL2_SMWINTDEFIW);
$this->m_queries[$qid] = $q;
}
// append query to root:
$qobj->components = array($qid => "{$qobj->alias}.smw_id");
$qobj->sortfields = $this->m_queries[$qid]->sortfields;
$this->m_queries[$rootid] = $qobj;
$this->applyOrderConditions($query, $rootid);
// may extend query if needed for sorting
wfProfileIn('SMWSQLStore2Queries::executeMainQuery (SMW)');
$this->executeQueries($this->m_queries[$rootid]);
// execute query tree, resolve all dependencies
wfProfileOut('SMWSQLStore2Queries::executeMainQuery (SMW)');
$result = $this->getNMQueryResult($query, $rootid);
$this->cleanUp();
$query->addErrors($this->m_errors);
return $result;
}
