What is a strict schedule?

Say n transactions follow a strict serializable schedule, i.e. serialize yourself using strict2PL or the like. Now let's say that the (n + 1) th transaction enters at the same time as the others and is not subject to strict 2PL. Can we say with confidence that it will only read data with data from others.



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A schedule in which a transaction can neither read nor write element X until the last transaction written by X is completed.



Here stringency means that if you have two transactions Trans1 and Trans2, if a write operation Trans1 appears before a conflicting Trans2 operation (read or write), then a commit Trans1 event will also be sent before that conflicting Trans2 operation. Severity is just to ensure efficient recovery of databases due to failure.

See this page for details http://en.wikipedia.org/wiki/Two-phase_locking



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