摘要：Refer to for detail: https://dzone.com/articles/default-hotspot-maximum-direct-memory-size 1. Java default java -XX:+PrintFlagsFinal -version size_t M 阅读全文

摘要：Based on debian 9, postgresql 9.6 and Java 8, at Dec-24-2018 1. Debain Install * Install DB and JDBC sudo aptitude install postgresql libpostgresql-jd 阅读全文

摘要：经常不清楚需要传入多少个参数到 IN () 里面，下面是简单方法： 方法 1 - in ( SELECT * FROM unnest(?)) ) Integer[] ids={1,2,3}; try { PreparedStatement pst=conn.prepareStatement("sel 阅读全文