Extension:Cognate/cognate sites table

cgsi_key
Primary key.

Schema summary
CREATE TABLE IF NOT EXISTS /*_*/cognate_sites (	 cgsi_key BIGINT SIGNED PRIMARY KEY NOT NULL,	  cgsi_dbname VARBINARY(32) NOT NULL,	  cgsi_interwiki VARBINARY(32) NOT NULL	  )/*$wgDBTableOptions*/;

(see source here)