Menu
▾
▴
Re: [Rdfapi-php-interest] FindIterator over a Database
|
From: P.L.Coetzee <P.L...@op...> - 2007-07-02 08:33:10
|
Dear all,
As Christian suggested, I've modified the MysqlFindIterator I posted =
previously to use the same ADODB mechanism as RAP prefers. Instead of =
taking connection parameters and model URI on the constructor, it now =
takes the DBModel which you wish to execute the find() over and extracts =
its data from that. Thanks for suggesting the change Christian - it =
should hopefully be more widely usable now :)
As ever, comments gratefully received!
Cheers,
Peter
______________________________________________________
ADOFindIterator.class.php:
<?php
/*
* Find Iterator operating over an ADODB Connection, to work in ~linear =
time
* Particular application in iterating over large datasets, performs =
faster
* + in a more scalable manner than the existing FindIterator class.
*
* Author: Peter Coetzee
*
*/
class ADOFindIter {
private $curr;
private $res;
private $dbConn;
private $dummy;
// Pre: $dbmodel is a connected RAP DB Model.
// Post: Prepare Iterator for operation. If $ordered =3D=3D =
true,
// select rows ordered by subject then predicate, for ease
// of processing.
public function ADOFindIter( $dbModel, $ordered=3Dfalse,
$sub=3Dnull, $pred=3Dnull, =
$obj=3Dnull ) {
$this->dbConn =3D $dbModel->getDbConn();
$modelID =3D $dbModel->getModelID();
$sql =3D "SELECT subject, predicate, object, =
subject_is, " .
"object_is, l_language, l_datatype FROM =
statements " .
"WHERE modelID =3D $modelID";
if ( $sub !=3D null )
$sql .=3D " AND subject =3D '$sub'";
if ( $pred !=3D null )
$sql .=3D " AND predicate =3D '$pred'";
if ( $obj !=3D null )
$sql .=3D " AND object =3D '$obj'";
if ( $ordered )
$sql .=3D " ORDER BY subject, predicate";
$this->res =3D &$this->dbConn->Execute( $sql ) or
die( "ADODB error: " . =
$dbConn->ErrorMsg() );
$this->dummy =3D ModelFactory::getDefaultModel();
$this->curr =3D $this->res->fields;
}
// Post: Return the next statement in the Iterator
public function next() {
if ( $this->curr =3D=3D null && !$this->hasNext() )
return null;
if ( $this->curr[4] =3D=3D 'l' ) {
$object =3D new Literal( $this->curr[2] );
if ( $this->curr[5] !=3D '' && $this->curr[5] =
!=3D null )
$object->setLanguage( $this->curr[5] );
if ( $this->curr[6] !=3D '' && $this->curr[6] =
!=3D null )
$object->setDatatype( $this->curr[6] );
} else if ( $this->curr[4] =3D=3D 'b' ) {
$object =3D new BlankNode( $this->dummy );
} else {
$object =3D new Resource( $this->curr[2] );
}
$predicate =3D new Resource( $this->curr[1] );
if ( $this->curr[3] =3D=3D 'r' )
$subject =3D new Resource( $this->curr[0] );
else
$subject =3D new BlankNode( $this->dummy );
$this->curr =3D null;
return new Statement( $subject, $predicate, $object );
}
// Post: True iff there is another Statement in the Iterator
public function hasNext() {
return $this->curr =3D=3D null ? ( !$this->res->EOF &&
$this->res->MoveNext() &&
$this->curr =3D $this->res->fields ) : =
true;
}
// Post: Answer the number of Statements in the Iterator
public function size() {
return $this->res->RecordCount();
}
// Post: Free up resources used by this Iterator. Behaviour of =
any
// subsequent calls is undefined.
public function free() {
$this->res->Close();
}
}
?>
-----Original Message-----
From: rdf...@li... on behalf of =
P.L.Coetzee
Sent: Mon 02/07/2007 08:13
To: Christian Weiske; rdf...@li...
Subject: Re: [Rdfapi-php-interest] FindIterator over a Database
=20
Christian,
I should imagine so - it started off as a simple exercise "make it work =
for me", so I've not looked all that much into the innards of RAP etc. I =
shall do so this morning, and post back once I've got something worth =
looking at (or catastrophic failure, whichever comes first ;)
Cheers,
Peter
P.S. - As an occasional-Jena-user, your benchmarks were particularly =
intriguing! Thanks for sharing :)
-----Original Message-----
From: rdf...@li... on behalf of =
Christian Weiske
Sent: Sat 30/06/2007 07:43
To: rdf...@li...
Subject: Re: [Rdfapi-php-interest] FindIterator over a Database
=20
Peter,
> This has led me to write the attached MysqlFindIterator class, which =20
> bypasses the RAP API, and instead queries the database directly. It =20
> scales in approximately linear time, so is useful for these large =20
> resultsets. At the moment I've only written it to handle MySQL =20
> databases, but it should be easily modifiable for whatever DB Driver =20
> you wish to use.
Do you think it is possible to use RAP's preferred connection to =
databases, ADODB?
--=20
Mit freundlichen Gr=FC=DFen/Regards,
Christian Weiske
-------------------------------------------------------------------------=
This SF.net email is sponsored by DB2 Express
Download DB2 Express C - the FREE version of DB2 express and take
control of your XML. No limits. Just data. Click to get it now.
http://sourceforge.net/powerbar/db2/
_______________________________________________
Rdfapi-php-interest mailing list
Rdf...@li...
https://lists.sourceforge.net/lists/listinfo/rdfapi-php-interest
-------------------------------------------------------------------------=
This SF.net email is sponsored by DB2 Express
Download DB2 Express C - the FREE version of DB2 express and take
control of your XML. No limits. Just data. Click to get it now.
http://sourceforge.net/powerbar/db2/
_______________________________________________
Rdfapi-php-interest mailing list
Rdf...@li...
https://lists.sourceforge.net/lists/listinfo/rdfapi-php-interest
|
