|
|
|
@inproceedings{DBLP:conf/sigmod/Golding95,
author = {Rob Golding},
editor = {Michael J. Carey and
Donovan A. Schneider},
title = {Things Every Update Replication Customer Should Know},
booktitle = {Proceedings of the 1995 ACM SIGMOD International Conference on
Management of Data, San Jose, California, May 22-25, 1995},
publisher = {ACM Press},
year = {1995},
pages = {439-440},
ee = {http://doi.acm.org/10.1145/223784.223865},
crossref = {DBLP:conf/sigmod/95},
bibsource = {DBLP, http://dblp.uni-trier.de}
}
In the mid-1980s. Chris Date's "12 rules" for distributed database systems included replication. Replication makes transparent the problems of remote access delays and the management of data redundancy. The commercial market for distributed database features has been slowly building over the years, beginning with simple remote access gateways. Today, replication appears to deliver on the 1980s ideal, with a robust asynchronous infrastructure. Current commercial technology though, continues to fall short of that ideal.
"Asynchronous replication" is a pleasant term to describe the operation of a distributed database running without concurrency control. In practice, DBMSS which use locking mechanisms in local operation are connected into replication networks without benefit of a global serialization mechanism, such as a synchronous 2-phase commit protocol. The notion of a transaction is thus compromised.
Four properties, atomicity, consistency, isolation and durability - "ACID" for short - have come to define a transaction system. With asynchronous replication, there is no isolation of transactions. Transactions run in parallel without any guarantee that a transaction sees the most current state of the database before making an update. Updates then, are not serialized.
One of the many benefits derived from the ACID properties is a serial histoy of transaction execution, an absolute necessity to satisfy audit requirements in regulated industries. Without a serial history, it is impossible to reliably state who updated a database from state N to state N+l. Not all replication systems guarantee a serial history.
Copyright © 1995 by the ACM, Inc., used by permission. Permission to make digital or hard copies is granted provided that copies are not made or distributed for profit or direct commercial advantage, and that copies show this notice on the first page or initial screen of a display along with the full citation.
CDROM Version: Load the CDROM "Volume 1 Issue 1, SIGMOD '93-'97" and ...
, SIGMOD Record 24(2), June 1995 
Data released under the ODC-BY 1.0 license — See also our legal information page