Filtering by string in Sphinx

Sphinx doesn’t support filtering by strings as attributes (yet), so here are two options you can use to get around this limitation…

Querying by Attribute

This option requires you to define a text field in your Sphinx config and reference said field when querying your index. In your config for the source you are working with:

SELECT id, user_type \
        FROM users
sql_field_string = user_type

And in PHP:

$matches = $this->sphinxClient->Query('@user_type "^admin$"');

Full-Text Searching a Column

This is my preferred option, as you can still manage string filters with your other integer attributes, and, personally, I think it’s easier to set these up together before querying the index(es). In your Sphinx config:

SELECT id, CRC32(user_type) AS user_type \
        FROM users
sql_attr_int    = user_type

PHP would look something like this:

$this->sphinxClient->SetFilter('user_type', array(crc32('admin'));

When using this option, note that there’s a caveat in PHP’s CRC for integers on 32 bit platforms.