Evaluating database system performance often requires generating synthetic databases—ones having certain statistical properties but filled with dummy information. When evaluating different database designs, it is often necessary to generate several databases and evaluate each design. As database sizes grow to terabytes, generation often takes longer than evaluation. This paper presents several database generation techniques. In particular it discusses: (1) Parallelism to get generation speedup and scaleup. (2) Congruential generators to get dense unique uniform distributions. (3) Special-case discrete logarithms to generate indices concurrent to the base table generation. (4) Modification of (2) to get exponential, normal, and self-similar distributions.

Locking, although essential in concurrent database processing, also impairs concurrency, and the latter efl~ct is quantified here.The difficult feature in locking is the interference phenomenon, by which we mean that if a particular item in the database is locked, which is true in our model for all constituent items of all transactions undergoing processing, then all arriving transactions requiring this particular item are blocked.The interference phenomenon is exactly modeled and exact formulas for equilibrium database performance, such as mean concurrency and throughput, and efficient algorithms for their computation are obtained.Formulas for large databases are derived and proved to be asymptouc; this formula is insightful, and found to fit well to exact solutions.The probabilistic model is a Markov process with combinatorial quantities as transition rates.This model is tractable because of the time reversibility of the equilibrium Markov process.In a database with Nitems and p transaction classes, the probabilistic model has O(N p) states, time reversibility reduces the calculations to evaluating the sum of O(N p) terms, the recurrence formulas that are derived here require O(Np) multiplications, and, finally, the asymptotic formula requires negligible computation.

Abstract This paper describes the design and implementation of awk, a programming language which searches a set of files for patterns, and performs specified actions upon records or fields of records which match the patterns. Awk makes common data selection and transformation operations easy to express; for example, is a complete awk program that prints all input lines whose length exceeds 72 characters. The program prints each input line with the first field replaced by its logarithm. The program prints all lines in which the first field is different from the first field of the previous line. Patterns may include boolean combinations of regular expressions and of relational operators on strings, numbers, fields, variables, and array elements. Actions may include: the same matching constructions as in patterns; arithmetic and string expressions and assignments; if‐else, while, and for statements; formatted output; and multiple output streams.

This paper presents a method for increasing concurrency in shared data bases. A data base is taken to be a collection of entities with structure, such as relations. Concurrency is increased in the sense that several readers and a single writer may access a set of entities. At the same time, either serializability or a slightly weaker form of consistency can be seen by all transactions. Each transaction is assumed to obtain all its resources when it starts. The method also allows for convenient recovery from crashes which do not affect the information on secondary storage.

An algorithm for factoring polynomials in one variable with algebraic coefficients is presented.The algorithm is based on Hensel's lemma; it is intended to be usable.