OverviewIn the previous article titled Why TCP needs 3 handshakes simple answers were provided to the following three questions:Can application data be carried during the first handshake?Can application data be carried during the second handshake?Can application data be carried during the third handshake?Briefly, traditional TCP requires a three-way handshake to establish a connection, and during these three handshakes, only simple SYN and ACK packets are sent.From the perspective of utilizing network bandwidth resources, the TCP header at the transport layer plus the IP header at the net...

Prerequisite KnowledgeFirst, let's look at the control bits and state machine of TCP, which form the basis for understanding the three-way handshake of TCP.TCP Packet Control BitsThe control bits in the TCP packet header are used to control the status of the TCP connection and can indicate various control information such as connection establishment, termination, reset, etc.There are six common control bits:SYN (Synchronize Sequence Numbers): Requests to establish a connection (part of the three-way handshake). It is set in the initial packet during connection establishment, indicating that th...

Keep table column as NOT NULL instead of NULL except in some special cases. This statement is cited by many articles of MySQL optimization, but they don't say why we should do this. Here we discuss about this.First why are there many people using NULL when defining table? The reasons may be:NULL the the default when defining table, the rookies or people who don't want to have much troubles will keep this default settingMany people think NOT NULL will require more spaceMany people don't want to verify the data before inserting or updating, it's more convenient when writing SQL queries.There are...