In this paper, a terminological framework is provided for describing different transaction-oriented recovery schemes for database systems in a conceptual rather than an implementation-dependent way. By introducing the terms materialized database, propagation strategy, and checkpoint, we obtain a means for classifying arbitrary

"From a certain point onward there is no longer any turning back. That is the point that must be reached." Kafka Protocols that allow operational sites to continue transac-tion processing even though site failures have occurred are called nonblocking. Many applications require nonblocking Qrotocols. This paper investigates the properties of non-blocking protocols. Necessary and sufficient conditions for a protocol to be nonblocking are presented and from these conditions a method for designing them is derived. Both a central site nonblocking protocol and a decentralized non-blocking protocol are presented.

Memory Management Units (MMUs) are traditionally used by operating systems to implement disk-paged virtual memory. Some operating systems allow user programs to specify the protection level (inaccessible, readonly. read-write) of pages, and allow user programs t.o handle protection violations. bur. these mechanisms are not. always robust, efficient, or well-mat. ched to the needs of applications.

The recovery subsystem of an experimental data management system is described and evaluated. The transactmn concept allows application programs to commit, abort, or partially undo their effects. The DO-UNDO-REDO protocol allows new recoverable types and operations to be added to the recovery system Apphcation programs can record data

Abstract-A formal model for atomic commit protocols for a distributed database system is introduced. The model is used to prove existence results about resilient protocols for site failures that do not partition the network and then for partitioned networks. For site failures, a pessimistic recovery technique, called independent recovery, is introduced and the class of failures for which resilient protocols exist is identified. For partitioned networks, two cases are studied: the pessimistic case in which messages are lost, and the optimistic case in which no messages are lost. In all cases, fundamental limitations on the resiliency of protocols are derived. Index Tenns-Commit protocols, crash recovery, distributed database systems, distributed systems, fault tolerance, transaction management. I.

Abstract—The two areas of online transaction processing (OLTP) and online analytical processing (OLAP) present different challenges for database architectures. Currently, customers with high rates of mission-critical transactions have split their data into two separate systems, one database for OLTP and one so-called data warehouse for OLAP. While allowing for decent transaction rates, this separation has many disadvantages including data freshness issues due to the delay caused by only periodically initiating the Extract Transform Load-data staging and excessive resource consumption due to maintaining two separate information systems. We present an efficient hybrid system, called HyPer, that can handle both OLTP and OLAP simultaneously by using hardware-assisted replication mechanisms to maintain consistent snapshots of the transactional data. HyPer is a mainmemory database system that guarantees the ACID properties of OLTP transactions and executes OLAP query sessions (multiple queries) on the same, arbitrarily current and consistent snapshot. The utilization of the processor-inherent support for virtual memory management (address translation, caching, copy on update) yields both at the same time: unprecedentedly high transaction rates as high as 100000 per second and very fast OLAP query response times on a single system executing both workloads in parallel. The performance analysis is based on a combined TPC-C and TPC-H benchmark. I.

For ten years researchers have been attempting to construct programming language systems that support orthogonal persistence above conventional operating systems.

Performance in database systems is strongly influenced by buffer management and transaction recovery methods. This paper presents the principles of the database cache, which replaces the traditional buffer. In comparison to buffer management, cache management is more carefully coordinated with transaction management, and integrates transaction recovery. High throughput of small- and medium-sized transactions is achieved by fast commit processing and low database traffic. Very fast handling of transaction failures and short restart time after system failure are guaranteed in such an environment. Very long retrieval and update transactions are also supported.

The hot-set model, characterizing the buffer requirements of relational queries, is presented. This model allows the system to determine the optimal buffer space to be allocated to a query; it can also be used by the query optimizer to derive efficient execution plans accounting for the available buffer space, and by a query scheduler to prevent thrashing. The hot-set model is compared with the working-set model. A simulation study is presented. Categories and Subject Descriptors: H.2.4 [Database Management]: Systems-query processing

* * 9111238 5 44.:itat~rlelof itairdince 5isi Il t ii. a,ia 'ritmiFl lWr~ruirtod to CUriv'tv wil it, itg rieia lawv is is a binwo Vtalere by lhe uraufily to Ofuellifili6 vO am~ii vl i rjsded In lhe diversity wich irakea Carrlege Mellon an exct iro place Cdfrrlrgo Mullen wahea tin cludle peqoe without regard to fac. ceb, flotnt r Iril r. I v 1-ndiczp. religion, creed, ancetry, hef. urge, voeean status or %ex'ahil ornentatior j IA', on livelsity does not discriorit!r arid Carnegr, Mellon University bs ropired rWotno rjs vinnatein adrnims:ons and rirkwvienroltt on Itne bars of race. i'' ( ifn I), 'qx or handicap 'i I4nlatnijii i ' 'I-IW VI of the Civil Right,; kct I(t 1964 Nidl IX of the Frliicatrional Amrendmntrls 0 ' 1972 ArM Section 504 01 the