Identifiers that APIs in TajoClient and Tajo JDBC driver take are normalized in client API side. So, identifiers composed of upper and lower mixed characters should be used with double quote ("). This convention is different from existing JDBC driver's convention. It makes ugly code when users use TajoClient.
This patch changes their APIs to be case sensitive. In addition, this patch adds some missing JDBC APIs and fixes wrong behaviors of getTables() and getColumns() in JDBC APIs.