Making snapshot isolation serializable

Abstract

Snapshot Isolation (SI) is a multiversion concurrency control algorithm, first described in Berenson et al. [1995]. SI is attractive because it provides an isolation level that avoids many of the common concurrency anomalies, and has been implemented by Oracle and Microsoft SQL Server (with certain minor variations). SI does not guarantee serializability in all cases, but the TPC-C benchmark application [TPC-C], for example, executes under SI without serialization anomalies. All major database system products are delivered with default nonserializable isolation levels, often ones that encounter serialization anomalies more commonly than SI, and we suspect that numerous isolation errors occur each day at many large sites because of this, leading to corrupt data sometimes noted in data warehouse applications. The classical justification for lower isolation levels is that applications can be run under such levels to improve efficiency when they can be shown not to result in serious errors, but little or no guidance has been offered to application programmers and DBAs by vendors as to how to avoid such errors. This article develops a theory that characterizes when nonserializable executions of applications can occur under SI. Near the end of the article, we apply this theory to demonstrate that the TPC-C benchmark application has no serialization anomalies under SI, and then discuss how this demonstration can be generalized to other applications. We also present a discussion on how to modify the program logic of applications that are nonserializable under SI so that serializability will be guaranteed.

Preserving atomicity and isolation for multi-row transactions in column-oriented heterogeneous distributed databases

“…The idea of supporting atomicity and consistency for multi row distributed transaction is not new. Our work is mainly inspired by Zhang and De Sterck (2010), Padhye and Tripathi (2012), Berenson et al (1995), Lars (2011), Cahill et al (2008, Fekete et al (2004Fekete et al ( , 2005 and Revilak et al (2011). Zhang and De Sterck (2010) proposed a technique to achieve SI by creating number of global tables for storing transactional metadata in HBase itself and using them for each transaction.…”

Preserving atomicity and isolation for multi-row transactions in column-oriented heterogeneous distributed databases

“…The idea of supporting atomicity and consistency for multi row distributed transaction is not new. Our work is mainly inspired by Zhang and De Sterck (2010), Padhye and Tripathi (2012), Berenson et al (1995), Lars (2011), Cahill et al (2008, Fekete et al (2004Fekete et al ( , 2005 and Revilak et al (2011). Zhang and De Sterck (2010) proposed a technique to achieve SI by creating number of global tables for storing transactional metadata in HBase itself and using them for each transaction.…”

Semantics of Concurrent Revisions

“…Just as we do with revisions, proponents of transactions have long recognized that providing strong guarantees such as serializability [27] or linearizability [17] can be overly conservative for some applications, and have proposed alternate guarantees such as multi-version concurrency control [26] or snapshot isolation (SI) [4,11,30]. In fact, revisions can be understood as a natural generalization of snapshot isolation, extended to handle resolution of write-write conflicts following some policy (as discussed in Section 2.3), and to support nesting (as discussed in Section 2.4).…”

“…We use the definition given by Fekete et al [11]. We claim that our revision calculus is a generalization of snapshot isolation, augmented by (1) the ability to gracefully resolve write-write conflict when a suitable merge function exists for a particular location, and (2) support nontrivial nesting (Fig.…”