226:
data kept for archiving or auditing purposes. Hot data should be stored in ways offering fast retrieval and modification, often accomplished by in-memory storage but not always. Cold data on the other hand can be stored in a more cost-effective way and is accepted that data access will likely be slower compared to hot data. While these descriptions are useful, "hot" and "cold" lack concrete definitions.
225:
industry the terms "data temperature", or "hot data" and "cold data" have emerged to describe how data is stored in this respect. Hot data is used to describe mission-critical data that needs to be accessed frequently while cold data describes data that is needed less often and less urgently, such as
182:
While storing data in-memory confers performance advantages, it is an expensive method of data storage. An approach to realising the benefits of in-memory storage while limiting its costs is to store the most frequently accessed data in-memory and the rest on disk. Since there is no hard distinction
173:
Some IMDBs allow the database schema to specify different durability requirements for selected areas of the database – thus, faster-changing data that can easily be regenerated or that has no meaning after a system shut-down would not need to be journaled for durability (though it
126:
images, which record the state of the database at a given moment in time. The system typically generates these periodically, or at least when the IMDb does a controlled shut-down. While they give a measure of persistence to the data (in that the database does not lose everything in the case of a
260:
Another variation involves large amounts of nonvolatile memory in the server, for example, flash memory chips as addressable memory rather than structured as disk arrays. A database in this form of memory combines very fast access speed with persistence over reboots and power losses.
55:
mechanism. In-memory databases are faster than disk-optimized databases because disk access is slower than memory access and the internal optimization algorithms are simpler and execute fewer CPU instructions. Accessing data in memory eliminates
168:
to an identical standby database in the event of primary database failure. To protect against loss of data in the case of a complete system crash, replication of an IMDb is normally used in addition to one or more of the mechanisms listed
183:
between which data should be stored in-memory and which should be stored on disk, some systems dynamically update where data is stored based on the data's usage. This approach is subtly different from
503:
273:: This is a column-orientated in-memory database that stores data in its memory instead of keeping it on a disk. It claims to store data in columnar fashion in main memory and supports both
112:(atomicity, consistency, isolation, durability) properties. Volatile memory-based IMDBs can, and often do, support the other three ACID properties of atomicity, consistency and isolation.
278:
108:
devices. These devices lose all stored information when the device loses power or is reset. In this case, IMDBs can be said to lack support for the "durability" portion of the
478:
Historically, RAM was not used as a persistent data store and therefore data loss in these instances was not an issue.Whole-system
Persistence with Non-volatile Memories
82:
A potential technical hurdle with in-memory data storage is the volatility of RAM. Specifically in the event of a power loss, intentional or otherwise, data stored in
287:
This is an In-Memory
Database which is memory-optimized, relational database that claims to deliver microsecond response and extremely high throughput performance.
241:
cost, and with less customization of code, rather than using separate in-memory and on-disk databases, respectively, for its disk-less and disk-based products.
140:), a memory module that has a DRAM interface, often combined with NAND flash for the Non-Volatile data security. The first NVDIMM solutions were designed with
413:
504:
https://www.embedded.com/electronics-products/electronic-product-reviews/real-time-and-performance/4422291/AGIGARAM-NVDIMM-saves-data-through-system-failure
457:
127:
system crash) they only offer partial durability (as 'recent" changes will be lost). For full durability, they need supplementing with one of the following:
297:
229:
Manufacturing efficiency provides another reason for selecting a combined in-memory/on-disk database system. Some device product lines, especially in
369:
396:"TeleCommunication Systems Signs up as a Reseller of TimesTen; Mobile Operators and Carriers Gain Real-Time Platform for Location-Based Services"
99:
150:(NVRAM), usually in the form of static RAM backed up with battery power (battery RAM), or an electrically erasable programmable ROM (
174:
would have to be replicated for high availability), whereas configuration information would be flagged as needing preservation.
202:
performance (which is enhanced by sorting, storing and retrieving specified data entirely in memory, rather than going to disk)
644:
668:
237:, for example). If such devices require a database system, a manufacturer can adopt a hybrid database system at lower and
144:
instead of batteries for the backup power source. With this storage, IMDb can resume securely from its state upon reboot.
133:, which records changes to the database in a journal file and facilitates automatic recovery of an in-memory database.
147:
87:
417:
90:
technology, in-memory databases will be able to run at full speed and maintain data in the event of power failure.
515:
577:
72:
123:
615:
208:
161:
63:
Applications where response time is critical, such as those running telecommunications network equipment and
545:
274:
154:). With this storage, the re-booting IMDb system can recover the data store from its last consistent state.
395:
317:
119:
373:
439:
40:
601:
663:
491:
479:
565:
302:
214:
75:– mainly due to multi-core processors that can address large memory and due to less expensive
67:
networks, often use main-memory databases. IMDBs have gained much traction, especially in the
346:
48:
312:
230:
76:
60:
when querying the data, which provides faster and more predictable performance than disk.
8:
233:, include some units with permanent storage, and others that rely on memory for storage (
16:
Database management system that primarily relies on main memory for computer data storage
64:
637:- Volume 14: Very Large Data Base Systems to Zero-Memory and Markov Information Source
640:
609:
432:
307:
184:
157:
245:
222:
141:
130:
105:
83:
406:
68:
657:
198:
The flexibility of hybrid approaches allow a balance to be struck between:
52:
234:
44:
205:
cost, because a less costly hard disk can be substituted for more memory
57:
248:
to support both in-memory and on-disk tables in a single database,
165:
51:. It is contrasted with database management systems that employ a
327:
249:
151:
137:
115:
Many IMDBs have added durability via the following mechanisms:
492:
http://research.microsoft.com/apps/pubs/default.aspx?id=162804
480:
http://research.microsoft.com/apps/pubs/default.aspx?id=160853
361:
520:
339:
322:
458:"In-memory computing: what happens when the power goes out?"
109:
104:
In its simplest form, main memory databases store data on
516:"Teradata enters the in-memory fray, intelligently ZDNet"
440:"Rise of In-Memory Databases Impacts Wide Range of Jobs"
508:
298:
Comparison of relational database management systems
414:"Falling RAM Prices Drive In-Memory Database Surge"
213:form factor, because RAM chips cannot approach the
502:AGIGARAM NVDIMM saves data through system failure
177:
655:
635:Encyclopedia of Computer Science and Technology
566:"Truly these are the GOLDEN YEARS of Storage."
264:
100:Atomicity, consistency, isolation, durability
546:"What's the Diff: Hot and Cold Data Storage"
631:
540:
538:
367:
535:
450:
191:data is cached, as opposed to the most
656:
490:The Bleak Future of NAND Flash Memory
160:implementations that rely on database
602:"Oracle TimesTen In-Memory Database"
13:
86:is lost. With the introduction of
14:
680:
370:"The Rise of In-Memory Databases"
255:
148:Non-volatile random-access memory
88:non-volatile random-access memory
347:"Definition: in-memory database"
594:
570:
559:
279:online transactional processing
93:
496:
484:
472:
388:
178:Hybrids with on-disk databases
1:
625:
195:data being stored in-memory.
275:online analytical processing
7:
669:Database management systems
318:List of in-memory databases
291:
265:Notable In-memory Databases
29:main memory database system
10:
685:
632:Jack Belzer (April 1980).
614:: CS1 maint: url-status (
372:. Slashdot. Archived from
281:(OLTP) in the same system.
97:
41:database management system
43:that primarily relies on
333:
252:, was released in 1995.
71:space, starting in the
37:memory resident database
303:Distributed data store
639:. Marcel Dekker Inc.
416:. SAP. Archived from
217:of a small hard drive
49:computer data storage
313:In-memory processing
231:consumer electronics
187:, in which the most
578:"What is SAP HANA?"
193:frequently accessed
136:Non-Volatile DIMM (
131:Transaction logging
460:. 18 February 2015
420:on 4 November 2013
376:on 1 February 2013
308:Embedded databases
65:mobile advertising
21:in-memory database
646:978-0-8247-2214-2
189:recently accessed
164:, with automatic
158:High availability
676:
650:
620:
619:
613:
605:
598:
592:
591:
589:
588:
574:
568:
563:
557:
556:
554:
552:
542:
533:
532:
530:
528:
512:
506:
500:
494:
488:
482:
476:
470:
469:
467:
465:
454:
448:
447:
446:. July 13, 2012.
436:
430:
429:
427:
425:
410:
404:
403:
392:
386:
385:
383:
381:
368:Michael Vizard.
365:
359:
358:
356:
354:
343:
285:Oracle TimesTen:
684:
683:
679:
678:
677:
675:
674:
673:
664:Computer memory
654:
653:
647:
628:
623:
607:
606:
600:
599:
595:
586:
584:
576:
575:
571:
564:
560:
550:
548:
544:
543:
536:
526:
524:
514:
513:
509:
501:
497:
489:
485:
477:
473:
463:
461:
456:
455:
451:
438:
437:
433:
423:
421:
412:
411:
407:
394:
393:
389:
379:
377:
366:
362:
352:
350:
345:
344:
340:
336:
294:
267:
258:
246:database engine
223:cloud computing
180:
142:supercapacitors
106:volatile memory
102:
96:
17:
12:
11:
5:
682:
672:
671:
666:
652:
651:
645:
627:
624:
622:
621:
593:
569:
558:
534:
507:
495:
483:
471:
449:
431:
405:
387:
360:
337:
335:
332:
331:
330:
325:
320:
315:
310:
305:
300:
293:
290:
289:
288:
282:
266:
263:
257:
256:Storage memory
254:
219:
218:
211:
206:
203:
179:
176:
171:
170:
155:
145:
134:
128:
95:
92:
69:data analytics
15:
9:
6:
4:
3:
2:
681:
670:
667:
665:
662:
661:
659:
648:
642:
638:
634:
630:
629:
617:
611:
603:
597:
583:
579:
573:
567:
562:
547:
541:
539:
523:
522:
517:
511:
505:
499:
493:
487:
481:
475:
459:
453:
445:
441:
435:
419:
415:
409:
402:. 2002-06-24.
401:
400:Business Wire
397:
391:
375:
371:
364:
348:
342:
338:
329:
326:
324:
321:
319:
316:
314:
311:
309:
306:
304:
301:
299:
296:
295:
286:
283:
280:
276:
272:
269:
268:
262:
253:
251:
247:
242:
240:
236:
235:set-top boxes
232:
227:
224:
216:
212:
210:
207:
204:
201:
200:
199:
196:
194:
190:
186:
175:
167:
163:
159:
156:
153:
149:
146:
143:
139:
135:
132:
129:
125:
121:
118:
117:
116:
113:
111:
107:
101:
91:
89:
85:
80:
78:
74:
70:
66:
61:
59:
54:
50:
46:
42:
38:
34:
30:
26:
22:
636:
633:
596:
585:. Retrieved
581:
572:
561:
549:. Retrieved
525:. Retrieved
519:
510:
498:
486:
474:
462:. Retrieved
452:
443:
434:
422:. Retrieved
418:the original
408:
399:
390:
378:. Retrieved
374:the original
363:
351:. Retrieved
349:. WhatIs.com
341:
284:
270:
259:
243:
238:
228:
220:
197:
192:
188:
181:
172:
114:
103:
94:ACID support
84:volatile RAM
81:
62:
53:disk storage
36:
32:
28:
24:
20:
18:
277:(OLAP) and
209:persistence
162:replication
122:files, or,
45:main memory
658:Categories
626:References
587:2024-08-01
424:19 January
380:19 January
353:19 January
244:The first
124:checkpoint
98:See also:
464:March 10,
73:mid-2000s
58:seek time
610:cite web
551:July 28,
527:July 28,
444:Dice.com
292:See also
271:SAP HANA
166:failover
120:Snapshot
221:In the
215:density
185:caching
39:) is a
643:
328:NewSQL
250:WebDNA
169:above.
152:EEPROM
138:NVDIMM
521:ZDNet
334:Notes
323:NoSQL
239:upper
35:) or
27:, or
641:ISBN
616:link
553:2017
529:2017
466:2017
426:2013
382:2013
355:2013
110:ACID
47:for
33:MMDB
25:IMDb
582:SAP
77:RAM
19:An
660::
612:}}
608:{{
580:.
537:^
518:.
442:.
398:.
79:.
649:.
618:)
604:.
590:.
555:.
531:.
468:.
428:.
384:.
357:.
31:(
23:(
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.