SQLiteLog: (284) automatic index on chats

contentProvider 查询联系人的最新消息（合并查询）

mSelection = ChatConstants.DATE
        + " in (select max(" + ChatConstants.DATE + ") from "
        + ChatProvider.TABLE_CHATS + " where " + ChatConstants.ACCOUNT + " = " + account + " group by " + ChatConstants.OTHER_JID
        + " having count(*) > 0)";// 查询合并重复jid字段的所有聊天对象