In-memory database

An in-memory database (IMDb, or main memory database system (MMDB) or memory resident database) is a database management system that primarily relies on main memory for computer data storage. It is contrasted with database management systems that employ a disk storage 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 seek time when querying the data, which provides faster and more predictable performance than disk.[1][2]

Applications where response time is critical, such as those running telecommunications network equipment and mobile advertising networks, often use main-memory databases.[3] IMDBs have gained much traction, especially in the data analytics space, starting in the mid-2000s – mainly due to multi-core processors that can address large memory and due to less expensive RAM.[4][5]

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 volatile RAM is lost.[6] With the introduction of non-volatile random-access memory technology, in-memory databases will be able to run at full speed and maintain data in the event of power failure.[7][8][9]

ACID support

In its simplest form, main memory databases store data on volatile memory 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 ACID (atomicity, consistency, isolation, durability) properties. Volatile memory-based IMDBs can, and often do, support the other three ACID properties of atomicity, consistency and isolation.

Many IMDBs have added durability via the following mechanisms:

  • Snapshot files, or, checkpoint 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 system crash) they only offer partial durability (as 'recent" changes will be lost). For full durability, they need supplementing with one of the following:
  • Transaction logging, which records changes to the database in a journal file and facilitates automatic recovery of an in-memory database.
  • Non-Volatile DIMM (NVDIMM), 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 supercapacitors instead of batteries for the backup power source. With this storage, IMDb can resume securely from its state upon reboot.
  • Non-volatile random-access memory (NVRAM), usually in the form of static RAM backed up with battery power (battery RAM), or an electrically erasable programmable ROM (EEPROM). With this storage, the re-booting IMDb system can recover the data store from its last consistent state.
  • High availability implementations that rely on database replication, with automatic failover 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 above.

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 would have to be replicated for high availability), whereas configuration information would be flagged as needing preservation.

Hybrids with on-disk databases

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 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.[10] This approach is subtly different from caching, in which the most recently accessed data is cached, as opposed to the most frequently accessed data being stored in-memory.

The flexibility of hybrid approaches allow a balance to be struck between:

  • performance (which is enhanced by sorting, storing and retrieving specified data entirely in memory, rather than going to disk)
  • cost, because a less costly hard disk can be substituted for more memory
  • persistence
  • form factor, because RAM chips cannot approach the density of a small hard drive

In the cloud computing industry the terms "data temperature", or "hot data" and "cold data" have emerged to describe how data is stored in this respect.[11] 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 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.[11]

Manufacturing efficiency provides another reason for selecting a combined in-memory/on-disk database system. Some device product lines, especially in consumer electronics, include some units with permanent storage, and others that rely on memory for storage (set-top boxes, for example). If such devices require a database system, a manufacturer can adopt a hybrid database system at lower and upper 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.

The first database engine to support both in-memory and on-disk tables in a single database, WebDNA, was released in 1995.

Storage memory

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.[12]

Notable In-memory Databases

  • SAP HANA: 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 online analytical processing (OLAP) and online transactional processing (OLTP) in the same system.[13]
  • Oracle TimesTen: This is an In-Memory Database which is memory-optimized, relational database that claims to deliver microsecond response and extremely high throughput performance.[14]

See also

Notes

  1. ^ "Definition: in-memory database". WhatIs.com. Retrieved 19 January 2013.
  2. ^ Michael Vizard. "The Rise of In-Memory Databases". Slashdot. Archived from the original on 1 February 2013. Retrieved 19 January 2013.
  3. ^ "TeleCommunication Systems Signs up as a Reseller of TimesTen; Mobile Operators and Carriers Gain Real-Time Platform for Location-Based Services". Business Wire. 2002-06-24.
  4. ^ "Falling RAM Prices Drive In-Memory Database Surge". SAP. Archived from the original on 4 November 2013. Retrieved 19 January 2013.
  5. ^ "Rise of In-Memory Databases Impacts Wide Range of Jobs". Dice.com. July 13, 2012.
  6. ^ "In-memory computing: what happens when the power goes out?". 18 February 2015. Retrieved March 10, 2017.
  7. ^ 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 http://research.microsoft.com/apps/pubs/default.aspx?id=160853
  8. ^ The Bleak Future of NAND Flash Memory http://research.microsoft.com/apps/pubs/default.aspx?id=162804
  9. ^ AGIGARAM NVDIMM saves data through system failure https://www.embedded.com/electronics-products/electronic-product-reviews/real-time-and-performance/4422291/AGIGARAM-NVDIMM-saves-data-through-system-failure
  10. ^ "Teradata enters the in-memory fray, intelligently ZDNet". ZDNet. Retrieved July 28, 2017.
  11. ^ a b "What's the Diff: Hot and Cold Data Storage". Retrieved July 28, 2017.
  12. ^ "Truly these are the GOLDEN YEARS of Storage."
  13. ^ "What is SAP HANA?". SAP. Retrieved 2024-08-01.
  14. ^ "Oracle TimesTen In-Memory Database".

References

  • Jack Belzer (April 1980). Encyclopedia of Computer Science and Technology - Volume 14: Very Large Data Base Systems to Zero-Memory and Markov Information Source. Marcel Dekker Inc. ISBN 978-0-8247-2214-2.

Read other articles:

American television broadcast journalist Kiran Chetryकिरण क्षेत्रीChetry in 2010BornKiran Carrie Chetry (1974-08-26) August 26, 1974 (age 49)Patan, Bagmati, NepalNationalityAmericanOther namesKiran KshetriEducationUniversity of Maryland, College ParkSpouseChris Knowles (div. 2013)Children2 Kiran Carrie Chetry (Nepali: किरण क्षेत्री, pronounced [kiɾʌɳ t͡sʰet̪ri], born August 26, 1974) is a former American television broadc...

 

Yuuhi wo Miteiruka?(Apakah Kau Melihat Mentari Senja?)(夕陽を見ているか?)Sampul edisi reguler berlatar oranye yang ditampilkan oleh Naomi, Rona, Vienny, Yupi, Natalia, Haruka, Nabilah, Veranda, Melody, dan ShaniaSingel oleh JKT48Sisi-AYuuhi wo Miteiruka? (Apakah Kau Melihat Mentari Senja?) / SenbatsuSisi-BNagai Hikari (Cahaya Panjang) / Tim J1! 2! 3! 4! Yoroshiku! / Tim KIIIViva! Hurricane / Tim KIII (edisi reguler)Dirilis3 Juli 2013 (2013-07-03)FormatCD+DVDGenrePopLabelIndonesia...

 

ROH

Ring of HonorRing of Honor Wrestling Entertainment, LLC 種類 LLC略称 ROH本社所在地 アメリカ合衆国フロリダ州ジャクソンビル設立 2002年業種 サービス業事業内容 プロレス興行関連企画の運営代表者 トニー・カーン主要株主 トニー・カーン関係する人物 トニー・カーン外部リンク ROH公式サイト(英語)テンプレートを表示 ROHは、アメリカ合衆国のプロレス団体。正式名称はリング・...

Japanese television drama This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed.Find sources: Kamen Rider Revice – news · newspapers · books · scholar · JSTOR (July 2021) (Learn how and when to remove this template message) Kamen Rider ReviceGenre Tokusatsu Superhero fiction Supernatural fiction Crossover fiction Adventure Come...

 

سامانثا باركس   معلومات شخصية الميلاد 2 أكتوبر 1990 (العمر 33 سنة)[1]لاكسي, جزيرة مان مواطنة جزيرة مان المملكة المتحدة  أسماء أخرى سام باركس لون الشعر شعر بني  الحياة العملية المهنة ممثلة , مغنية اللغات الإنجليزية  المواقع IMDB صفحتها على IMDB[2]  تعديل مصدري - تعدي

 

Хребет Академії Наук пік Ісмаїла Самані пік Ісмаїла Самані Країна  Таджикистан Регіон Горно-Бадахшанська автономна область Довжина 60 км Ширина 20 км Найвища точка пік Ісмаїла Самані  - висота 7495 м  Хребет Академії Наук у Вікісховищі У Вікіпедії є статт

Pasquerilla WestResidence HallUniversity of Notre DameCoat of arms of Pasquerilla WestCampus quadModCoordinates41°42′14″N 86°14′06″W / 41.703887°N 86.235007°W / 41.703887; -86.235007NicknamePW, P-DubMottoPeace, Love, P-DubEstablished1981ArchitectEllerbe AssociatesArchitectural styleModernismColorsPurple and white    GenderFemaleRectorAnnie BoyleBenefactorFrank and Sylvia PasquerillaUndergraduates256ChapelSaint Clare of AssisiMascotPurple Weas...

 

Escola Superior de Cruzeiro ESC-ESEFIC Fundação 29 de dezembro de 1969 (53 anos) Tipo de instituição Pública Localização Cruzeiro, São Paulo, BrasilCoordenadas: 22° 34' 01.3 S 44° 57' 38.4 O22° 34' 01.3 S 44° 57' 38.4 O Diretor(a) João Bosco Ferreira Vice-diretor(a) Vinícius Carneiro Página oficial esccultural.com.br ESC-ESEFIC — Escola Superior de Cruzeiro e Escola de Educação Física de Cruzeiro 'Prefeito Hamilton Vieira Mendes' é...

 

Katedral BendigoSacred Heart CathedralKatedral BendigoAgamaAfiliasi agamaGereja Katolik RomaDistrikKeuskupan SandhurstEcclesiastical or organizational statusKatedral[1]Diberkati1901LokasiLokasiBendigo, Victoria  AustraliaKoordinat36°45′36″S 144°16′26″E / 36.76000°S 144.27389°E / -36.76000; 144.27389Koordinat: 36°45′36″S 144°16′26″E / 36.76000°S 144.27389°E / -36.76000; 144.27389{{#coordinates:}}: tidak bisa m...

Mandira BediBedi pada tahun 2013Lahir15 April 1972 (umur 51)[1]Kolkata, Bengal Timur, India[2]PekerjaanAktris, presenter, perancang busanaSuami/istriRaj Kaushal ​(m. 1999)​AnakVir Kaushal Mandira Bedi (lahir 15 April 1972)[1] adalah seorang aktris, perancang busana, dan presenter televisi asal India[3] yang mendapatkan status selebritis setelah memainkan peran utama dalam serial televisi tahun 1994 Shanti yang ditampilkan di sa...

 

River in Maryland, United StatesCarroll CreekCarroll Creek in Frederick, MarylandWatershed map showing Carroll CreekNative nameWalkwaki Methtegui (Shawnee)LocationCountryUnited StatesStateMarylandCitiesFrederick, TuscaroraPhysical characteristicsSource  • locationTuscarora, MD • coordinates39°27′40″N 77°29′05″W / 39.461057°N 77.484649°W / 39.461057; -77.484649 MouthMonocacy River • locationFrede...

 

Bilateral relationsBarbados–United States relations Barbados United States Diplomatic missionEmbassy of Barbados, Washington, DCEmbassy of the United States, BridgetownEnvoyAmbassador John BealeAmbassador Linda S. Taglialatela The United States and Barbados have had cordial bilateral relations since Barbados' independence in 1966. The United States has supported the government's efforts to expand the country's economic base and to provide a higher standard of living for its citizens. Barbad...

إيمانويال جوزيف سياس معلومات شخصية الميلاد 3 مايو 1748(1748-05-03)فريجوس  الوفاة 20 يونيو 1836 (88 سنة)باريس مكان الدفن مقبرة بير لاشيز  مواطنة فرنسا  الديانة الكنيسة الرومانية الكاثوليكية عضو في أكاديمية اللغة الفرنسية،  وأكاديمية العلوم الأخلاقية والسياسية الفرنسية  م...

 

Former railway station in England This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed.Find sources: Rolvenden railway station – news · newspapers · books · scholar · JSTOR (November 2022) (Learn how and when to remove this template message) RolvendenStation on heritage railwayGeneral informationLocationRolvenden, Ashford, Ken...

 

2001 Hindi crime movie by Dharmendra Not to be confused with Indian (1996 film). IndianFilm posterDirected byN. MaharajanScreenplay byN. MaharajanStory byN. MaharajanBased onVallarasu (2000)Produced byDharmendraStarringSunny DeolShilpa ShettyDanny DenzongpaRaj BabbarMukesh RishiRahul DevCinematographyA. Ramesh KumarEdited byB. S. VasuSaleemMusic byAnand Raj AnandProductioncompanyVijayta FilmsDistributed byEros InternationalRelease date 26 October 2001 (2001-10-26) Running time1...

Drama Art SceneПозорница драмске уметностиPozornica dramske umetnostiCoat of arms of the Drama Art SceneFormer namesПозорница драмских уметностиPozornica dramskih umetnosti(Drama Arts Scene)AddressOblačića Rada 17, Novi Sad SerbiaOperatorVladimir Stojanov(manager)DesignationDrama Art SceneOpened3 March 1974Years active1974 - today Websitehttps://sites.google.com/site/dopisnopozoriste/ Gajeva 30 Street in Novi Sad - one of the former seats o...

 

1982 studio album by Tim BerneSongs and Rituals in Real TimeStudio album by Tim BerneReleased1982RecordedJuly 1, 1981GenreAvant-garde jazzDowntown musicLabelEmpire Productions (USA, 1982) / Screwgun (USA, 1998)ProducerTim BerneTim Berne chronology Spectres(1981) Songs and Rituals in Real Time(1982) The Ancestors(1983) Professional ratingsReview scoresSourceRatingAllmusic[1]The Rolling Stone Jazz Record Guide[2] Songs and Rituals in Real Time is a double LP album by Tim...

 

Protected area in Queensland, AustraliaGirramay National ParkQueenslandIUCN category II (national park) Girramay National ParkNearest town or cityTullyCoordinates18°02′41″S 146°01′41″E / 18.04472°S 146.02806°E / -18.04472; 146.02806Established2007Area295 km2 (113.9 sq mi)Managing authoritiesQueensland Parks and Wildlife ServiceWebsiteGirramay National ParkSee alsoProtected areas of Queensland Girramay is a national park in Queensland, Austral...

Den här artikeln har skapats av Lsjbot, ett program (en robot) för automatisk redigering. (2015-11)Artikeln kan innehålla fakta- eller språkfel, eller ett märkligt urval av fakta, källor eller bilder. Mallen kan avlägsnas efter en kontroll av innehållet (vidare information) För andra betydelser, se Long Glacier. Long Glacier Glaciär Kontinent  Antarktis Höjdläge 31 m ö.h. Koordinater 72°30′00″S 96°43′00″V / 72.5°S 96.71667°V / -7...

 

У этого термина существуют и другие значения, см. Ёж (значения). Обыкновенный ёж Научная классификация Домен:ЭукариотыЦарство:ЖивотныеПодцарство:ЭуметазоиБез ранга:Двусторонне-симметричныеБез ранга:ВторичноротыеТип:ХордовыеПодтип:ПозвоночныеИнфратип:Челюстноротые�...

 

Strategi Solo vs Squad di Free Fire: Cara Menang Mudah!