/**
* Helper function for reading all data for from a given property table
* (specified by an SMWSQLStore3Table object), based on certain
* restrictions. The function can filter data based on the subject (1)
* or on the property it belongs to (2) -- but one of those must be
* done. The Boolean $issubject is true for (1) and false for (2).
*
* In case (1), the first two parameters are taken to refer to a
* subject; in case (2) they are taken to refer to a property. In any
* case, the retrieval is limited to the specified $proptable. The
* parameters are an internal $id (of a subject or property), and an
* $object (being an DIWikiPage or SMWDIProperty). Moreover, when
* filtering by property, it is assumed that the given $proptable
* belongs to the property: if it is a table with fixed property, it
* will not be checked that this is the same property as the one that
* was given in $object.
*
* In case (1), the result in general is an array of pairs (arrays of
* size 2) consisting of a property key (string), and DB keys (array if
* many, string if one) from which a datvalue object for this value can
* be built. It is possible that some of the DB keys are based on
* internal objects; these will be represented by similar result arrays
* of (recursive calls of) fetchSemanticData().
*
* In case (2), the result is simply an array of DB keys (array)
* without the property keys. Container objects will be encoded with
* nested arrays like in case (1).
*
* @todo Maybe share DB handler; asking for it seems to take quite some
* time and we do not want to change it in one call.
*
* @param integer $id
* @param SMWDataItem $object
* @param TableDefinition $propTable
* @param boolean $isSubject
* @param SMWRequestOptions $requestOptions
*
* @return array
*/
private function fetchSemanticData($id, SMWDataItem $object = null, TableDefinition $propTable, $isSubject = true, SMWRequestOptions $requestOptions = null)
{
// stop if there is not enough data:
// properties always need to be given as object,
// subjects at least if !$proptable->idsubject
if ($id == 0 || is_null($object) && (!$isSubject || !$propTable->usesIdSubject())) {
return array();
}
$result = array();
$db = $this->store->getConnection();
$diHandler = $this->store->getDataItemHandlerForDIType($propTable->getDiType());
// *** First build $from, $select, and $where for the DB query ***//
$from = $db->tableName($propTable->getName());
// always use actual table
$select = '';
$where = '';
if ($isSubject) {
// restrict subject, select property
$where .= $propTable->usesIdSubject() ? 's_id=' . $db->addQuotes($id) : 's_title=' . $db->addQuotes($object->getDBkey()) . ' AND s_namespace=' . $db->addQuotes($object->getNamespace());
if (!$propTable->isFixedPropertyTable()) {
// select property name
$from .= ' INNER JOIN ' . $db->tableName(SMWSql3SmwIds::tableName) . ' AS p ON p_id=p.smw_id';
$select .= 'p.smw_title as prop';
}
// else: fixed property, no select needed
} elseif (!$propTable->isFixedPropertyTable()) {
// restrict property only
$where .= 'p_id=' . $db->addQuotes($id);
}
$valuecount = 0;
// Don't use DISTINCT for value of one subject:
$usedistinct = !$isSubject;
$valueField = $diHandler->getIndexField();
$labelField = $diHandler->getLabelField();
$fields = $diHandler->getFetchFields();
foreach ($fields as $fieldname => $typeid) {
// select object column(s)
if ($typeid == 'p') {
// get data from ID table
$from .= ' INNER JOIN ' . $db->tableName(SMWSql3SmwIds::tableName) . " AS o{$valuecount} ON {$fieldname}=o{$valuecount}.smw_id";
$select .= ($select !== '' ? ',' : '') . "{$fieldname} AS id{$valuecount}" . ",o{$valuecount}.smw_title AS v{$valuecount}" . ",o{$valuecount}.smw_namespace AS v" . ($valuecount + 1) . ",o{$valuecount}.smw_iw AS v" . ($valuecount + 2) . ",o{$valuecount}.smw_sortkey AS v" . ($valuecount + 3) . ",o{$valuecount}.smw_subobject AS v" . ($valuecount + 4);
if ($valueField == $fieldname) {
$valueField = "o{$valuecount}.smw_sortkey";
}
if ($labelField == $fieldname) {
$labelField = "o{$valuecount}.smw_sortkey";
}
$valuecount += 4;
} else {
$select .= ($select !== '' ? ',' : '') . "{$fieldname} AS v{$valuecount}";
}
$valuecount += 1;
}
if (!$isSubject) {
// Apply sorting/string matching; only with given property
$where .= $this->store->getSQLConditions($requestOptions, $valueField, $labelField, $where !== '');
} else {
$valueField = '';
}
// *** Now execute the query and read the results ***//
$res = $db->select($from, $select, $where, __METHOD__, $usedistinct ? $this->store->getSQLOptions($requestOptions, $valueField) + array('DISTINCT') : $this->store->getSQLOptions($requestOptions, $valueField));
foreach ($res as $row) {
$valueHash = '';
if ($isSubject) {
// use joined or predefined property name
$propertykey = $propTable->isFixedPropertyTable() ? $propTable->getFixedProperty() : $row->prop;
$valueHash = $propertykey;
}
// Use enclosing array only for results with many values:
if ($valuecount > 1) {
$valuekeys = array();
for ($i = 0; $i < $valuecount; $i += 1) {
// read the value fields from the current row
$fieldname = "v{$i}";
$valuekeys[] = $row->{$fieldname};
}
} else {
$valuekeys = $row->v0;
}
// #Issue 615
// If the iw field contains a redirect marker then remove it
if (isset($valuekeys[2]) && $valuekeys[2] === SMW_SQL3_SMWREDIIW) {
$valuekeys[2] = '';
}
// The valueHash prevents from inserting duplicate entries of the same content
$valueHash = $valuecount > 1 ? md5($valueHash . implode('#', $valuekeys)) : md5($valueHash . $valuekeys);
// Filter out any accidentally retrieved internal things (interwiki starts with ":"):
if ($valuecount < 3 || implode('', $fields) != 'p' || $valuekeys[2] === '' || $valuekeys[2][0] != ':') {
if (isset($result[$valueHash])) {
$this->store->getLogger()->log(__METHOD__, "found duplicate for {$propertykey} " . (is_array($valuekeys) ? implode(',', $valuekeys) : $valuekeys));
}
$result[$valueHash] = $isSubject ? array($propertykey, $valuekeys) : $valuekeys;
}
}
$db->freeResult($res);
return $result;
}
/**
* Using a preprocessed internal query description referenced by $rootid,
* compute the proper result instance output for the given query.
* @todo The SQL standard requires us to select all fields by which we sort, leading
* to wrong results regarding the given limit: the user expects limit to be applied to
* the number of distinct pages, but we can use DISTINCT only to whole rows. Thus, if
* rows contain sortfields, then pages with multiple values for that field are distinct
* and appear multiple times in the result. Filtering duplicates in post processing
* would still allow such duplicates to push aside wanted values, leading to less than
* "limit" results although there would have been "limit" really distinct results. For
* this reason, we select sortfields only for POSTGRES. MySQL is able to perform what
* we want here. It would be nice if we could eliminate the bug in POSTGRES as well.
*
* @param Query $query
* @param integer $rootid
*
* @return QueryResult
*/
private function getInstanceQueryResult(Query $query, $rootid)
{
global $wgDBtype;
$db = $this->store->getConnection();
$qobj = $this->querySegments[$rootid];
if ($qobj->joinfield === '') {
// empty result, no query needed
$result = new QueryResult($query->getDescription()->getPrintrequests(), $query, array(), $this->store, false);
return $result;
}
$sql_options = $this->getSQLOptions($query, $rootid);
// Selecting those is required in standard SQL (but MySQL does not require it).
$sortfields = implode($qobj->sortfields, ',');
$res = $db->select($db->tableName($qobj->joinTable) . " AS {$qobj->alias}" . $qobj->from, "DISTINCT {$qobj->alias}.smw_id AS id,{$qobj->alias}.smw_title AS t,{$qobj->alias}.smw_namespace AS ns,{$qobj->alias}.smw_iw AS iw,{$qobj->alias}.smw_subobject AS so,{$qobj->alias}.smw_sortkey AS sortkey" . ($wgDBtype == 'postgres' ? ($sortfields ? ',' : '') . $sortfields : ''), $qobj->where, __METHOD__, $sql_options);
$qr = array();
$count = 0;
// the number of fetched results ( != number of valid results in array $qr)
$missedCount = 0;
$dataItemCache = array();
$logToTable = array();
$hasFurtherResults = false;
$prs = $query->getDescription()->getPrintrequests();
$diHandler = $this->store->getDataItemHandlerForDIType(DataItem::TYPE_WIKIPAGE);
while ($count < $query->getLimit() && ($row = $db->fetchObject($res))) {
if ($row->iw === '' || $row->iw[0] != ':') {
// Catch exception for non-existing predefined properties that
// still registered within non-updated pages (@see bug 48711)
try {
$dataItem = $diHandler->dataItemFromDBKeys(array($row->t, intval($row->ns), $row->iw, '', $row->so));
} catch (InvalidPredefinedPropertyException $e) {
$logToTable[$row->t] = "issue creating a {$row->t} dataitem from a database row";
$this->store->getLogger()->log(__METHOD__, $e->getMessage());
$dataItem = '';
}
if ($dataItem instanceof DIWikiPage && !isset($dataItemCache[$dataItem->getHash()])) {
$count++;
$dataItemCache[$dataItem->getHash()] = true;
$qr[] = $dataItem;
// These IDs are usually needed for displaying the page (esp. if more property values are displayed):
$this->store->smwIds->setCache($row->t, $row->ns, $row->iw, $row->so, $row->id, $row->sortkey);
} else {
$missedCount++;
$logToTable[$row->t] = "skip result for {$row->t} existing cache entry / query " . $query->getHash();
}
} else {
$missedCount++;
$logToTable[$row->t] = "skip result for {$row->t} due to an internal `{$row->iw}` pointer / query " . $query->getHash();
}
}
if ($db->fetchObject($res)) {
$count++;
}
if ($logToTable !== array()) {
foreach ($logToTable as $key => $entry) {
$this->store->getLogger()->logToTable('sqlstore-query-execution', 'query performer', $key, $entry);
}
}
if ($count > $query->getLimit() || $count + $missedCount > $query->getLimit()) {
$hasFurtherResults = true;
}
$db->freeResult($res);
$result = new QueryResult($prs, $query, $qr, $this->store, $hasFurtherResults);
return $result;
}
