952:
962:
243:
972:
50:
358:
notes that a checkpoint has been made. These are used to speed up recovery. They record information that eliminates the need to read a long way into the log's past. This varies according to checkpoint algorithm. If all dirty pages are flushed while creating the checkpoint (as in
332:(CLR) notes the rollback of a particular change to the database. Each corresponds with exactly one other Update Log Record (although the corresponding update log record is not typically stored in the Compensation Log Record). It includes this extra information:
200:
369:: This is a reference to the first log record that corresponds to a dirty page. i.e. the first update that wasn't flushed at checkpoint time. This is where redo must begin on recovery.
562:
195:(LSN): A unique ID for a log record. With LSNs, logs can be recovered in constant time. Most LSNs are assigned in monotonically increasing order, which is useful in recovery
545:
557:
375:: This is a reference to the oldest log record of the oldest in-progress transaction. This is the oldest log record needed to undo all in-progress transactions.
158:. Additionally, all transactions that are already committed but whose changes were not yet materialized in the database are re-applied. Both are done to ensure
477:
techrepublic.com, Understanding the importance of transaction logs in SQL Server, SQL Server transaction log maintenance, By Crowe, Chizek, November 11, 2004
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955:
324:: Includes the value of the bytes of page before and after the page change. Some databases may have logs which include one or both images.
628:
517:
476:
295:
All log records include the general log attributes above, and also other attributes depending on their type (which is recorded in the
975:
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260:
1001:
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932:
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398:
264:
143:
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338:: This field contains the LSN of the next log record that is to be undone for transaction that wrote the last Update Log.
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124:
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1006:
907:
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38:
866:
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notes that all work has been done for this particular transaction. (It has been fully committed or aborted)
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sqlshack.com, A beginner’s guide to SQL Server transaction logs, February 11, 2014 by Ivan
Stankovic
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146:
state or not been shut down properly, the database management system reviews the database logs for
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403:
136:
393:
75:
17:
228:
Information about the actual changes that triggered the log record to be written.
209:: A link to their last log record. This implies database logs are constructed in
696:
676:
242:
210:
840:
749:
711:
686:
495:
360:
306:
notes an update (change) to the database. It includes this extra information:
196:
64:
701:
656:
526:
423:
170:
96:
60:
267: in this section. Unsourced material may be challenged and removed.
606:
219:: A reference to the database transaction generating the log record.
139:
listing changes to the database, stored in a stable storage format.
601:
661:
128:
499:
318:: Length in bytes and offset of the page are usually included.
236:
180:, a journal is the record of data altered by a given process.
43:
30:"Binary log" redirects here. For the logarithm to base 2, see
352:
notes a decision to abort and hence roll back a transaction.
169:
This term is not to be confused with other, human-readable
27:
History of actions executed by a database management system
37:"Journal (computing)" redirects here. For other uses, see
71:
173:
that a database management system usually provides.
880:
849:
793:
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649:
533:
312:: A reference to the Page ID of the modified page.
142:If, after a start, the database is found in an
511:
135:or hardware failures. Physically, a log is a
8:
225:: Describes the type of database log record.
455:Microsoft, The Transaction Log (SQL Server)
518:
504:
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346:notes a decision to commit a transaction.
283:Learn how and when to remove this message
123:) is a history of actions executed by a
447:
188:A database log record is made up of:
7:
265:adding citations to reliable sources
971:
25:
184:Anatomy of a general database log
970:
960:
951:
950:
241:
48:
961:
252:needs additional citations for
399:Error correction and detection
63:format but may read better as
1:
233:Types of database log records
997:Database management systems
527:Database management systems
178:database management systems
1023:
933:Object–relational database
414:Log-structured file system
154:the changes made by these
125:database management system
36:
29:
946:
908:Federated database system
641:Blockchain-based database
39:Journal (disambiguation)
330:Compensation Log Record
322:Before and After Images
72:converting this article
1002:Transaction processing
938:Transaction processing
893:Database normalization
836:Query rewriting system
436:Federal Standard 1037C
409:Journaling file system
299:attribute, as above).
913:Referential integrity
488:neurobs.com, Logfiles
363:), it might contain:
217:Transaction ID number
903:Distributed database
261:improve this article
923:Relational calculus
801:Concurrency control
419:Write-ahead logging
193:Log Sequence Number
109:transaction journal
18:Journal (computing)
918:Relational algebra
862:Query optimization
667:Armstrong's axioms
127:used to guarantee
74:, if appropriate.
984:
983:
592:Wide-column store
587:Document-oriented
381:Completion Record
356:Checkpoint Record
316:Length and Offset
304:Update Log Record
293:
292:
285:
166:of transactions.
150:transactions and
93:
92:
16:(Redirected from
1014:
1007:Computer logging
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953:
928:Relational model
898:Database storage
775:Stored procedure
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131:properties over
101:computer science
95:In the field of
88:
85:
79:
70:You can help by
52:
51:
44:
32:Binary logarithm
21:
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1021:
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987:
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888:Database models
876:
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831:Query optimizer
806:Data dictionary
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760:Transaction log
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672:Codd's 12 rules
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575:Column-oriented
541:Object-oriented
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105:transaction log
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707:Surrogate key
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692:Candidate key
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404:Hash function
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344:Commit Record
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250:This section
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78:is available.
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57:This article
55:
46:
45:
40:
33:
19:
759:
483:
472:
461:
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394:Data logging
380:
372:
366:
355:
350:Abort Record
349:
343:
335:
329:
321:
315:
309:
303:
296:
294:
279:
270:
259:Please help
254:verification
251:
222:
216:
206:
192:
187:
175:
168:
156:transactions
144:inconsistent
141:
120:
116:
113:database log
112:
108:
104:
94:
81:
76:Editing help
58:
976:WikiProject
867:Replication
755:Transaction
697:Foreign key
677:CAP theorem
624:Multi-model
336:undoNextLSN
211:linked list
148:uncommitted
121:audit trail
991:Categories
841:Query plan
794:Components
712:Unique key
629:comparison
563:comparison
553:Relational
546:comparison
442:References
361:PostgreSQL
197:algorithms
164:durability
152:rolls back
117:binary log
850:Functions
785:Partition
612:In-memory
570:Key–value
273:July 2016
160:atomicity
97:databases
84:June 2015
956:Category
872:Sharding
728:Relation
702:Superkey
657:Database
650:Concepts
424:Redo log
388:See also
207:Prev LSN
966:Outline
765:Trigger
721:Objects
430:Sources
373:undoLSN
367:redoLSN
199:, like
133:crashes
780:Cursor
738:column
607:NewSQL
310:PageID
107:(also
59:is in
770:Index
733:table
636:Cloud
602:NoSQL
597:Graph
534:Types
213:form.
201:ARIES
65:prose
821:ODBC
811:JDBC
750:View
687:Null
682:CRUD
662:ACID
617:list
580:list
558:list
297:Type
223:Type
171:logs
162:and
137:file
129:ACID
103:, a
61:list
816:XQJ
743:row
263:by
176:In
119:or
99:in
993::
115:,
111:,
519:e
512:t
505:v
286:)
280:(
275:)
271:(
257:.
203:.
86:)
82:(
68:.
41:.
34:.
20:)
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
