An LDAP to SQL proxy to adapt a relational database as a directory service for an LDAP client is provided. The database may be defined in accordance with a database schema which is external to an LDAP server serving the LDAP client. The proxy comprises LDAP to SQL query and response mappings preferably for a reduced set of LDAP operations. The proxy may comprise a mechanism to maintain a plurality of persistent database connections to reduce query processing overhead. The proxy may further be adapted to maintain persistent connections to each of at least two alternative databases for executing queries to provide enhanced failsafe operations. A plurality of LDAP to SQL proxied databases may be configured for sharing query loads to enhance scalability and performance.