Concurrency Control for Resilient Nested Transactions.IdnUdry, 1983

In the pdst few years there has been consrc’er&le research on concurrency control, tncludmg both systems design and theoretIcal study The problem IS roughly as follows D&i in a large (centrahzed or dlstrlbuted) database IS assumed to be accessible to users VIM transactlons, each of wh1c.h IS a sequential program which can carry out many steps accessmg lndlvldual data objects It 155 Import & that the transactions appear to execute “atomically”, I e without intervening steps of other transactions However, It IS also desirable to permit as much concurrent operation of different transactIons as possible, for efficiency Thus, it IS not generally feasible to mslst that transactions run completely serially P notion of equivalence for executions IS defined, where two executions are equivalent provided they “look the same ” to all transactions and to all data objects The senallzable executions are lust those which are equivalent to serial executions One goal of concurrency control design IS to insure that all executions of bansactions be serlallzabl