Today's acronym: SS2PL

SS2PL stands for strong strict two-phase locking; it’s a locking mechanism widely used in database systems today. It is based on the notion of two-phase locking:

  • Expanding phase: locks are acquired and none are released
  • Shrinking phase: locks are released and no new locks are acquired

In addition to the above requirements, SS2PL requires that both read and write locks are held until the transaction that acquired them has commited. Essentially, this means that there isn’t a shrinking phase — only an expanding phase. May I ask why, then, is it called strong strict two-phase locking and not something completely different?

I love computer science acronyms.