如何在Zend框架中优化模型？

Question

I need to figure out a best practice for utilizing models efficiently in Zend Framework.

Currently, I have classes extending Zend_Db_Table_Abstract which handle my queries to each class' respective table.

When I need to access say 5 of those tables from a controller, I find myself creating 5 new instances of each specific Zend_Db_Table object. This is really ineffective.

I've thought about implementing a Factory pattern to create new instances (or provide existing static copy) but am not sure. Is this the best way to go about it?

What is the correct way to handle models ensuring speed without consuming excessive resources? Should lazy loading come into play here?

[EDIT] As an example, I have a class I use to handle getting details about a location from a raw search query and need these objects in order to parse the query:

// Initialize database object
$this->dbLocations = new Model_Locations;
$this->dbStates = new Model_States;
$this->dbZipcodes = new Model_Zipcodes;
$this->dbLookup = new Model_Lookup;

In another class, I may need to access those models again so I repeat the above code. Essentially reinitializing objects that could be static/singleton.

Answer 1

I tend to work at the DbTable like you do. I've found it effective when I need to query multiple tables in a single action to create another layer of model above the dbTable. Similar to a service or domain layer. This way I only have to call a single model but I still have the functionality I need.

Here is a simple example that may eventually interact with 5 DbTable classes and most likely a couple of Row classes as well:

<?php

class Application_Model_TrackInfo
{


    protected $_track;
    protected $_bidLocation;
    protected $_weekend;
    protected $_shift;
    protected $_station;

    public function __construct() {
        //assign DbTable models to properties for convience
        $this->_track = new Application_Model_DbTable_Track();

    }

    /**
     *
     * @param type $trackId
     * @return type object
     */
    public function getByTrackId($trackId) {

        $trackData = $this->_track->fetchRow($trackId);
        //getAllInfo() Application_Model_Row_TRack
        $result = $trackData->getAllInfo();
        //returns std object reflecting data from 3 DbTable classes
        return $result;
    }

    /**
     *Get Station from trackid through bidlocationid
     *
     * @param type $trackId
     * @return type object
     */
    public function getStation($trackId){

        $data = $this->_track->fetchRow($trackId);
        //This a Application_Model_Row_Track method
        $result= $data->getStationFromBidLocation();

        return $result;
    }

} 

I hope this helps.

[EDIT] Since I wrote this answer I have learned the benefits of Domain Models and Data Mappers. Wow what a difference in my app. Not a magic bullet, but a huge improvement.
Thanks to
Alejandro Gervasio over at PHPMaster.com
Rob Allen at Akrabat.com
and
Pádraic Brady at Surviving The Deepend

for all their help in understanding this pattern.