There are TWO editions of Sphider… the classic edition using MySQLi and the PDO edition.
Why are there two versions? The classic edition uses MySQLi and prepared statements. While MySQLi, by itself, does support prepared statements, there are a couple functions used in Sphider that require MySQLnd (the “nd” stands for “native driver”). These functions are used because they are the most efficient way of doing things.
MySQLnd has been the default driver since PHP 5.4. If you install a modern version of PHP and want MySQLi, you are going to get MySQLnd. Yet SOME hosting companies DISABLE MySQLnd for those using shared hosting. (I suppose they want people to shell out a few more bucks to get VPS or Dedicated hosting.) In those situations, the classic edition just ain’t gonna work! So, there is the PDO edition.
There are those who will tell you that PDO is what you should be using anyway. They will tout how versatile PDO is, how it can do anything MySQLi can do, only better. It is true the PDO IS versatile. It can work with many different databases, not just MySQL. But there ARE some things PDO just can’t do, at least not efficiently. And there is overhead. And memory requirements.
With PDO: PHP <==> PDO <==> Your data
With MySQLi: PHP <==> Your data
The classic version of Sphider is the better, more capable edition! The PDO edition is capable enough PROVIDED you aren’t trying to build your personal version of an internet search engine. It IS possible to tax the PDO edition to the point it chokes. (It is probably possible to choke the classic edition as well, but it takes more effort.)
Remember, the intent of Sphider was/is to index a web site for the benefit of that site’s visitors. In can be used to index a number of related sites for the same purpose. An individual may stretch Sphider for personal use to index MANY sites… but it is STILL just a small indexing tool and not a Google replacement!
NOW… the final point. If you REALLY need Sphider to stretch its capabilities to the absolute limit, maybe you should be using the classic edition and not PDO. If that is the case, shell out a couple extra bucks to your host so you can get access to MySQLnd. Don’t try to pull a 20′ travel trailer with a Honda Civic.