Re: PHP web farms (i.e. why msession or something like it)

Steve Meyers wrote:

PostgreSQL support transaction and row level lock, while MySQL supports lock or page level rocks. (3.x) Besides, MySQL manual states that it does not perform well when insert and update is concurrently performed. A-I 1.4 (which is the case for session management)

As I mentioned, MySQL does support row-level locking, transactions, etc. Please people, let's stop spreading the FUD of yesteryear about MySQL. In any case, the major performance hits for MyISAM tables in MySQL (which both of you seem to be referring to) come when you do selects that take a long time on tables that are updated a lot. That isn't the case with a session table -- all selects are one well-indexed row.

Oops. My reference and memory is too old. I've read about it, but I forgot ;) MySQL(InnoDB table) supports row level lock. (I guess most users are not using InnoDB, isn't?) It seems you are assuming users are not updating session data, but they refer it mainly. I think many users, who implements login with session for example, update session data every time they access. MySQL performance may vary db backend to backend. InnoDB may perform well with concurrent insert/update. Deciding which one is faster is very specific to databse usage. Therefore, most commercial RDBMS licenses do not permit publishing benchmarks. My point is, disussing which database is faster is pointless without specific usage, including specific platforms and settings. -- Yasuo Ohgaki