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Transaction Logging Concepts Logical consistency, on the other hand, is managed both by the database manager, through mechanisms such as validation rules, triggers, integrity constraints, etc., and by the actions of the application. Because database changes are buffered in memory and are written back to disk only when it becomes necessary to do so, as more and more database changes are made, the disk-resident copy of the database becomes more and more out of date. To recover the database, the roll-forward process combines a backup copy of the database with the records in the after-image log to redo all the changes that were made since the backup was created. www.peg.com /techpapers/monographs/logging/logging.html   (5515 words)

DNR Coastal Management PermitTrak System The information contained in the database is also used extensively by other state and federal natural resource agencies, local governments, university researchers, environmental and community associations, and various industry groups including oil and gas production and transmission; developers, realtors and builders; and dredging and navigation. Consistency applications are submitted for projects by Federal Agencies, funded by federal monies, or occurring on Federal lands. The consistency database contains similar information to permits but many of the data fields are different, due to the different procedure to process consistencies. dnr.louisiana.gov /crm/coastmgt/databases.asp   (340 words)

[No title]   (Site not responding. Last check: 2007-10-13) A log switch is another database operation that triggers a checkpoint and therefore causes the state of the data files, redo log files, and control file to be synched with a checkpoint counter to indicate that the database is consistent. A hot standby database is created from a consistent, whole database backup of the primary database that has been loaded to the hot standby database and then a periodic or continual "archive stream" of redo transactions archived in files on the primary database are applied in the hot standby database. The tablespace structures between the source database and the destination database would have to be the same if you were transporting control files between databases because this information is recorded in the control files, i.e., number of data files per tablespace. www.indiana.edu /~dbateam/databases/oracle/oracle_bkp_rec.html   (4260 words)

kbAlertz: This article provides a general overview of the database architecture and database engine for Microsoft ... Databases are truly in a consistent state only when all the dirty pages are successfully transferred to disk during a shutdown in which no errors occur. Consistent: The database is transformed from one correct state to another. The only way to recover from physical database corruption is to restore from the last good backup (if a backup ran without errors, it is good) and roll the log files forward to bring the system to a consistent and undamaged state. www.kbalertz.com /kb_Q271987.aspx   (4059 words)

Future research   (Site not responding. Last check: 2007-10-13) I am interested in defining the database features, the interfaces, and the protocols necessary for a closer integration between the scheduler, and database consistency maintenance policies, in replicated database clusters. This would require that the database is able to respect the batch order, but at the same time can overlap execution of the queries in the batch (like a superpipelined processor). While consistent replication and caching can be done transparently in a local cluster, more sophisticated methods may be needed in a geographically distributed system, because of problems of latency, bandwidth, and possible disconnected operation. www.cs.rice.edu /~amza/Word/future.html   (1186 words)

Maintaining data consistency in mobile database broadcasts Consistent data items are provided to mobile transactions by requiring the mobile transactions to read data items committed at the same point of time. In this paper, we adopt serializability as the correctness criterion of database consistency as it is widely accepted in the database community. Consistency: It ensures that the execution schedules of the transactions are serializable. www.gisdevelopment.net /technology/mobilemapping/techmp001pf.htm   (4499 words)

NRaD TD 2747 Conventional database recovery is based on the check pointing of the database with the application of log actions to redo or undo the effects of transactions on the database at the time of a failure. While conventional database management implementations support a wide range of application areas, it has been shown by numerous researchers, product developers and vendors that this model limits the ability of databases to be applied to a wider array of computer based information processing and management applications such as those for real-time computing systems. Consistency of a transactions operations ensures correctness of transformation of the database from an initial consistent state to a new consistent state. www.nosc.mil /sti/publications/pubs/td/2747/nradtd2747txt.html   (11377 words)

ASP.NET.4GuysFromRolla.com: Maintaining Database Consistency with Transactions (via CobWeb/3.1 planetlab1.isi.jhu.edu)   (Site not responding. Last check: 2007-10-13) While databases can efficiently hold large amounts of information that can be queried, all that data and all that querying power is useless if the data is incorrect or nonsensical. Databases provide a plethora of techniques for ensuring the integrity and consistency: primary key and unique constraints can be employed to ensure entity integrity; foreign key constraints aid in ensuring relational integrity, and transactions help ensure that the database's data remains consistent. Database transactions are what ensure atomicity, one of the key features of any database system. aspnet.4guysfromrolla.com.cob-web.org:8888 /articles/072705-1.aspx   (1338 words)

Geeking with Greg: Blogger and database inconsistency Apparently, some of the boxes in their database cluster had the right data and some did not. The normal solution is to backfill the databases that missed updates, resolve any conflicts, and go on your merry way, all without impacting users. They seem to see rigid file system and database consistency as the paranoid ramblings of the anal retentive, preferring the very loose consistency guarantees offered by their core systems such as Google File System and BigTable. glinden.blogspot.com /2006/02/blogger-and-database-inconsistency.html   (709 words)

Data Concurrency and Consistency   (Site not responding. Last check: 2007-10-13) Oracle maintains data consistency in a multiuser environment by using a multiversion consistency model and various types of locks and transactions. The state of the block is consistent as of the time at which the request was submitted at the requester node. Transactions that perform database consistency checks at the application level should not assume that the data they read will remain unchanged during the execution of the transaction even though such changes are not visible to the transaction. www.usd.edu /oracle/doc/server.817/a76965/c23cnsis.htm   (7849 words)

Statement   (Site not responding. Last check: 2007-10-13) The conventional wisdom has been that either strong consistency or scalability is achievable in replicated database clusters, but not both. In particular, traditional eager protocols, which provide strong consistency for database replication, have poor scaling due to frequent conflict delays. More recently, multiple levels of loose consistency have been defined in an effort to provide both good scaling and a predefined set of consistency features. www.cs.rice.edu /~amza/Word/scaling_avail.html   (914 words)

[No title] Two environment variables, PGDATABASE and PGHOST, are necessary to locate the database and database host unless they are given on the command line. Level 1 - Verify Consistency plus SEED-related Info In addition to performing Level 0 checks, pdbverify confirms that fields in the site and experiment tables needed to write SEED volumes are filled in appropri- ately. A copy of the queries, the database environment, and passwords for the passcal team to get onto your system will speed up debugging of what went wrong with your setup. www.passcal.nmt.edu /software/man_html/pdbverify.html   (732 words)

myITforum.com : SQL 2005 Database Consistency Checks   (Site not responding. Last check: 2007-10-13) After you install SQL server 2005 for SMS or MOM or even for an in house SQL database there are certain maintenance tasks that you should perform on a regular basis. By regular basis I mean once a week or more as opposed to once a year or when you encounter database problems such as data loss or are experiencing performance issues. In all versions of SQL server in particular SQL 2005 because it is capable of performing so much more than previous versions your data and data indexes can become fragmented much like the operating system that SQL resides on and as a result you may see data corruption or even data loss. myitforum.com /articles/18/view.asp?id=9307   (205 words)

Extensible Storage Engine Database Becomes Corrupted During Consistency Check The termination routine is not called with the proper error flag, and the database is marked as consistent even though recovery did not complete. The database can be attachable/mountable and then can become corrupted when it is used or if it is located on a drive that has low disk space. Because the corruption is logical, a database that is incorrectly marked as consistent can be successfully backed up and the backup does not detect any errors. support.microsoft.com /kb/296981/EN-US   (278 words)

PASSCAL Database Manual: Chapter 10 - Database maintenance We provide numerous utilities with the PASSCAL database tools to do everything from backup (pdbackup, pdbtar) and restore (pdbrestoredb) the database, check for consistency (pdbverify) and delete unused tables (pdbvacuum), as well as cleanup (pdbtracemgr) and consolidate (pdblogmover) files. The first level checks for internal consistency of your database; the second adds a check to make sure fields needed for SEED writing have been completed. Vacuuming a database is another routine maintenance operation that may seem less than worth the effort. www.passcal.nmt.edu /software/pdb_manual/ch10.html   (682 words)

ISS X-Force Database: mssql-dbcc-bo(9659): Microsoft SQL Server Database Consistency Checker (DBCC) utilities have ... Microsoft SQL Server 2000 and Microsoft Desktop Engine (MSDE) 2000 are vulnerable to several buffer overflows in multiple Database Consistency Checker (DBCC) utilities. Database Consistency Checkers are tools that allow administrators to easily perform common maintenance tasks on databases. CVE-2002-0644: Buffer overflow in several Database Consistency Checkers (DBCCs) for Microsoft SQL Server 2000 and Microsoft Desktop Engine (MSDE) 2000 allows members of the db_owner and db_ddladmin roles to execute arbitrary code. xforce.iss.net /xforce/xfdb/9659   (443 words)

Application Specific Data Replication for Edge Services Our experiment suggests that although strong consistency and high availability are difficult to achieve for a completely general large-scale system using a generic database interface, the semantics of the specific shared objects needed by the distributed bookstore are relatively straightforward to provide. Also note that although FIFO consistency provides strong guarantees on the order that updates are observed, it does allow time delays between when an update occurs and when it is seen by an edge server. However, reasoning about consistency of distributed systems is difficult, and subtle interactions between distributed objects, each of which maintains its own consistency using specific strategies, could conceivably result in unexpected behaviors. www.cs.utexas.edu /users/dahlin/papers/www2003-edge-tpcw_xhtml   (10814 words)

Maintaining Database Consistency with Transactions Follow this step-by-step guide to learn common DBA tasksfrom database installation to database management, including using the automated management tools for storage management, memory management, and routine back ups. This study compares the effort of managing Oracle Database 10g to the effort of accomplishing equivalent tasks in Microsoft SQL Server 2005. While INSERT, UPDATE, and DELETE statements are the most granular operations for modifying a database's underlying data, at times we want to treat multiple INSERT, UPDATE, and/or DELETE statements as one atomic operation. www.databasejournal.com /news/article.php/3523336   (432 words)

SQL Server Forums at SQLTeam.com - Database consistency errors CHECKDB found 0 allocation errors and 2 consistency errors in database 'XDB'. CHECKDB found 0 allocation errors and 4 consistency errors in database 'XDB'. CHECKDB fixed 0 allocation errors and 4 consistency errors in database 'XDB'. www.sqlteam.com /forums/topic.asp?TOPIC_ID=61825   (825 words)

PHPBuilder.com - Technicks on keeping database consistency Or don't let anyone but you access to coding against your database, and definately don't allow people to have direct access to an SQL interpreter for your database. What the database does is let you run multiple queries against there own copy of the database and doesn't commit them to the database until you tell it to. When building a multi user database application you can and will have situations where multiple people are accessing the same part of the app at the same time. www.phpbuilder.com /board/showthread.php?threadid=10286322   (626 words)

Microsoft SQL Server 2000 Database Administration Part 4: Managing Data Troubleshoot a database by using the Database Consistency Checker (DBCC). Identify the guidelines for performing a Database Consistency Checker (DBCC) SHOWCONTIG. Students are expected to have an understanding of basic relational database concepts. www.netg.com /catalog_cms/detail.asp?c=US73478   (415 words)

Database consistency - Wikipedia, the free encyclopedia (via CobWeb/3.1 planetlab2.cs.virginia.edu)   (Site not responding. Last check: 2007-10-13) This article or section does not cite its references or sources. In database systems, a consistent transaction is one that does not violate any integrity constraints during its execution. If a transaction leaves the database in an illegal state, it is aborted and an error is reported. en.wikipedia.org.cob-web.org:8888 /wiki/Database_consistency   (97 words)

Testing Database Transaction Consistency   (Site not responding. Last check: 2007-10-13) AGENDA is a tool set for testing relational database applications. Two levels of checks are used to check both database state and state transition. The state check validates that the overall global consistency properties hold for the new database state. cis.poly.edu /tr/tr-cis-2003-04.shtml   (121 words)

SecurityTracker.com Archives - Microsoft Data Engine (MSDE) Buffer Overflow in Database Consistency Checker May Let ... A buffer overflow was reported in the processing of user-supplied input in some Database Consistency Checkers (DBCCs) used for database maintenance. One of these can only be run by users who have been assigned the db_owner role; the other, due to a permissions error, could be run by any user who could log onto the server interactively. Mitigating Factors: ==================== Buffer Overrun Vulnerability in Database Consistency Checkers: - Both the db_owner and db_ddladmin roles carry with them significant privileges, and only should be granted to trusted users. www.securitytracker.com /alerts/2002/Jul/1004831.html   (1243 words)

BMC Debuts Configuration-Management Database - News by InformationWeek   (Site not responding. Last check: 2007-10-13) The software is designed to help businesses unify service- and infrastructure-management tools to promote database management consistency and simplified integration among processes. Based on industry-standard IT Infrastructure Library requirements for enterprisewide database management with consistency and simplified integration among different management processes, the CMDB is also the first offering by BMC to be branded under the Atrium name, says Andrej Vlahcevic, senior product marketing manager for change and configuration management at BMC. "We believe it has to be more." The Atrium database was designed to integrate both service and infrastructure-management applications, he says, as well as complement the company's existing line of discovery tools. www.informationweek.com /story/showArticle.jhtml?articleID=57702869   (446 words)

Database Administration Consistency Definition: Database Consistency involves the checking of logical and physical compatibility in a database. Maintaining Backup Systems and Database Consistency Checks (Auerbach Publications)- The enterprise operations manager must consider the nature of the new technology used to create backups. It is not a parser of DNS datafiles, it works strictly via existing DNS query methods on a "live" system (however dnswalk can be run on a separate nameserver which has data ready to move into production). database.ittoolbox.com /topics/t.asp?t=334&p=334&h1=334   (326 words)

SQL Effects Software SQL Effects Clarity allows DBA's, Database Developers, Software Engineers, Build Engineers, QA Analysts, and other IT staff to quickly and visually verify database consistency and identify SQL object inconsistencies. SQL Effects Clarity provides a completely new way to view database differences, and allows you to focus on only the items and attributes that are important to you. Compare specific database objects on-demand or entire databases at the click of a button. www.sqleffects.com   (674 words)

ISS X-Force Database: mssql-dbcc-bo-variant(10255): Microsoft SQL Server Database Consistency Checker (DBCC) buffer ... ISS X-Force Database: mssql-dbcc-bo-variant(10255): Microsoft SQL Server Database Consistency Checker (DBCC) buffer overflow Microsoft SQL Server Database Consistency Checker (DBCC) buffer overflow Microsoft SQL Server 2000, Microsoft Desktop Engine (MSDE) 2000, Microsoft SQL Server 7.0, and Microsoft Data Engine (MSDE) 1.0 are vulnerable to several buffer overflows in multiple Database Consistency Checker (DBCC) utilities. xforce.iss.net /xforce/xfdb/10255   (496 words)

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