/v1/mod_semanticweb/arc/store/ARC2_StoreDeleteQueryHandler.php

<?php

/*

homepage: http://arc.semsol.org/

license:  http://arc.semsol.org/license



class:    ARC2 RDF Store DELETE Query Handler

author:   Benjamin Nowack

version:  2008-08-31 (Tweak: improved cleanTableReferences method (~3 times faster) + necessity check)

*/



ARC2::inc('StoreQueryHandler');



class ARC2_StoreDeleteQueryHandler extends ARC2_StoreQueryHandler {



  function __construct($a = '', &$caller) {/* caller has to be a store */

    parent::__construct($a, $caller);

  }

  

  function ARC2_StoreDeleteQueryHandler($a = '', &$caller) {

    $this->__construct($a, $caller);

  }



  function __init() {/* db_con */

    parent::__init();

    $this->store =& $this->caller;

    $this->handler_type = 'delete';

  }



  /*  */

  

  function runQuery($infos) {

    $this->infos = $infos;

    $con = $this->store->getDBCon();

    $t1 = ARC2::mtime();

    /* delete */

    $this->refs_deleted = false;

    if (!$this->v('construct_triples', array(), $this->infos['query'])) {

      $tc = $this->deleteTargetGraphs();

    }

    elseif (!$this->v('pattern', array(), $this->infos['query'])) {

      $tc = $this->deleteTriples();

    }

    else {

      $tc = $this->deleteConstructedGraph();

    }

    $t2 = ARC2::mtime();

    /* clean up */

    if ($tc && ($this->refs_deleted || (rand(1, 100) == 1))) $this->cleanTableReferences();

    if ($tc && (rand(1, 50) == 1)) $this->store->optimizeTables();

    if ($tc && (rand(1, 500) == 1)) $this->cleanValueTables();

    $t3 = ARC2::mtime();

    $index_dur = round($t3 - $t2, 4);

    $dur = round($t3 - $t1, 4);

    return array(

      't_count' => $tc,

      'delete_time' => $dur,

      'index_update_time' => $index_dur,

    );

  }

  

  /*  */



  function deleteTargetGraphs() {

    $tbl_prefix = $this->store->getTablePrefix();

    $r = 0;

    $con = $this->store->getDBCon();

    foreach ($this->infos['query']['target_graphs'] as $g) {

      if ($g_id = $this->getTermID($g, 'g')) {

        $rs = mysql_query('DELETE FROM ' . $tbl_prefix . 'g2t WHERE g = ' .$g_id, $con);

        $r += mysql_affected_rows($con);

      }

    }

    $this->refs_deleted = $r ? 1 : 0;

    return $r;

  }

  

  /*  */

  

  function deleteTriples() {

    $r = 0;

    $dbv = $this->store->getDBVersion();

    $tbl_prefix = $this->store->getTablePrefix();

    $con = $this->store->getDBCon();

    /* graph restriction */

    $tgs = $this->infos['query']['target_graphs'];

    $gq = '';

    foreach ($tgs as $g) {

      if ($g_id = $this->getTermID($g, 'g')) {

        $gq .= $gq ? ', ' . $g_id : $g_id;

      }

    }

    $gq = $gq ? ' AND G.g IN (' . $gq . ')' : '';

    /* triples */

    foreach ($this->infos['query']['construct_triples'] as $t) {

      $q = '';

      $skip = 0;

      foreach (array('s', 'p', 'o') as $term) {

        if (isset($t[$term . '_type']) && preg_match('/(var)/', $t[$term . '_type'])) {

          //$skip = 1;

        }

        else {

          $term_id = $this->getTermID($t[$term], $term);

          $q .= $q ? ' AND ' : '';

          $q .= 'T.' . $term . '=' . $term_id;

        }

      }

      if ($skip) {

        continue;

      }

      if ($gq) {

        $sql = ($dbv < '04-01') ? 'DELETE ' . $tbl_prefix . 'g2t' : 'DELETE G';

        $sql .= '

          FROM ' . $tbl_prefix . 'g2t G 

          JOIN ' . $this->getTripleTable() . ' T ON (T.t = G.t' . $gq . ')

          WHERE ' . $q . '

        ';

        $this->refs_deleted = 1;

      }

      else {/* triples only */

        $sql = ($dbv < '04-01') ? 'DELETE ' . $this->getTripleTable() : 'DELETE T';

        $sql .= ' FROM ' . $this->getTripleTable() . ' T WHERE ' . $q;

      }

      $rs = mysql_query($sql, $con);

      if ($er = mysql_error($con)) {

        $this->addError($er .' in ' . $sql);

      }

      $r += mysql_affected_rows($con);

    }

    return $r;

  }

  

  /*  */

  

  function deleteConstructedGraph() {

    ARC2::inc('StoreConstructQueryHandler');

    $h =& new ARC2_StoreConstructQueryHandler($this->a, $this->store);

    $sub_r = $h->runQuery($this->infos);

    $triples = ARC2::getTriplesFromIndex($sub_r);

    $tgs = $this->infos['query']['target_graphs'];

    $this->infos = array('query' => array('construct_triples' => $triples, 'target_graphs' => $tgs));

    return $this->deleteTriples();

  }

  

  /*  */

  

  function cleanTableReferences() {

    /* lock */

    if (!$this->store->getLock()) return $this->addError('Could not get lock in "cleanTableReferences"');

    $con = $this->store->getDBCon();

    $tbl_prefix = $this->store->getTablePrefix();

    $dbv = $this->store->getDBVersion();

    /* check for unconnected triples */

    $sql = '

      SELECT T.t FROM '. $tbl_prefix . 'triple T LEFT JOIN '. $tbl_prefix . 'g2t G ON ( G.t = T.t )

      WHERE G.t IS NULL LIMIT 1

    ';

    if (($rs = mysql_query($sql, $con)) && mysql_num_rows($rs)) {

      /* delete unconnected triples */

      $sql = ($dbv < '04-01') ? 'DELETE ' . $tbl_prefix . 'triple' : 'DELETE T';

      $sql .= '

        FROM ' . $tbl_prefix . 'triple T 

        LEFT JOIN ' . $tbl_prefix . 'g2t G ON (G.t = T.t)

        WHERE G.t IS NULL

      ';

      mysql_query($sql, $con);

    }

    /* check for unconnected graph refs */

    if ((rand(1, 100) == 1)) {

      $sql = '

        SELECT G.g FROM '. $tbl_prefix . 'g2t G LEFT JOIN '. $tbl_prefix . 'triple T ON ( T.t = G.t )

        WHERE T.t IS NULL LIMIT 1

      ';

      if (($rs = mysql_query($sql, $con)) && mysql_num_rows($rs)) {

        /* delete unconnected graph refs */

        $sql = ($dbv < '04-01') ? 'DELETE ' . $tbl_prefix . 'g2t' : 'DELETE G';

        $sql .= '

          FROM ' . $tbl_prefix . 'g2t G 

          LEFT JOIN ' . $tbl_prefix . 'triple T ON (T.t = G.t)

          WHERE T.t IS NULL

        ';

        mysql_query($sql, $con);

      }

    }

    /* release lock */

    $this->store->releaseLock();

  }

  

  /*  */



  function cleanValueTables() {



  }

  

  /*  */



}