Strictness and serializability

Abstract

In the theory of concurrency control several notions of the correctness of logs have been developed, particularly final-state-, view-, and conflict-preserving-serializability. SR, VSR, and CPSR are the respective sets of logs. In each case a strict variant can be defined. The respective sets are SSR, SVSR, and SCPSR. While SSR has already been investigated, this is not the case for SVSR and SCPSR. In this paper we will show the following:

• —SCPSR = W2PL, W2PL being the class of weakly two-phase locked logs.

• —Implications between the notions of correctness (or inclusions of sets) are as follows (A → B reads as A $\subseteq$B):

  

The labels indicate conditions when the inclusions hold; the abbreviations used are (& = and, ¦ = or):

D : dead values do not occur

W : every transaction reads an object before writing it

R : read-only transactions do not occur

None of these conditions can be dropped; this contradicts two claims made in the relevant literature ([P79], [BSW79]).