For more information, see Consolidating snapshots in ESX/ESXi 3.x and 4.x (1007849).
Applications can access Sphinx search daemon (searchd) using any of the three different access methods: a) via Sphinx own implementation of My SQL network protocol (using a small SQL subset called Sphinx QL, this is recommended way), b) via native search API (Sphinx API) or c) via My SQL server with a pluggable storage engine (Sphinx SE).
Official native Sphinx API implementations for PHP, Perl, Python, Ruby and Java are included within the distribution package.
API is very lightweight so porting it to a new language is known to take a few hours or days.
Disk indexes support online full-text index rebuilds, but online updates can only be done on non-text (attribute) data.
RT indexes additionally allow for online full-text index updates. Data can be loaded into disk indexes using a so-called data source.