for bigram class, we can use sqlite instead BDB, this will be very convenient for Android or other mobile devices.
Actually we used Berkeley DB for performance issues. Every component in libpinyin has time benchmark and disk space usage analysis, to meet the requirement of response time and disk usage.
Please provide more details why sqlite is better, and how to use sqlite for bi-gram.
For android, see https://blogs.oracle.com/berkeleydb/entry/berkeley_db_and_mobile_now.
Wait for a month, Close issue.