Talk:In-memory database: Difference between revisions

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=="Main memory" or "in memory"==

I think the title of this article is mistaken. The expression "in-memory database" is much more popular than "main memory database". As evidence, I cite Google News and Yahoo News. Both of them return 5 or 6 hits for "in-memory", but none for "main memory". Moreover, the popular Computer Desktop Encyclopedia (www.computerlanguage.com) titles its article "in-memory database". Any objections to changing the title of this article? [[User:Westwind273|Westwind273]] 23:34, 24 August 2007 (UTC)

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==Key questions==

The article does not describe how the database system collect its user data from startup. And I think that is one of the main questions regarding this technology. Could some one write a few words on sentences about that? <small><span class="autosigned">— Preceding [[Wikipedia:Signatures|unsigned]] comment added by [[User:Linbenming|Linbenming]] ([[User talk:Linbenming|talk]] • [[Special:Contributions/Linbenming|contribs]]) 06:51, 28 April 2011 (UTC)</span></small><!-- Template:Unsigned --> <!--Autosigned by SineBot-->

==Nokia-Siemens Networks “One-NDS”==

Deleted from the list of in-memory database systems because this is a vertical solution (Home Location Register/Home Subscriber Server) rather than a database system. We should stick to database systems in order to preserve the integrity of the page. <small><span class="autosigned">—Preceding [[Wikipedia:Signatures|unsigned]] comment added by [[User:Jatujak|Jatujak]] ([[User talk:Jatujak|talk]] • [[Special:Contributions/Jatujak|contribs]]) 04:19, 15 February 2010 (UTC)</span></small><!-- Template:Unsigned --> <!--Autosigned by SineBot-->

"One-NDS" is the whole system, but the database server product underneath that serves the applications (and is confusingly also called the NDS) is an in-memory database system. Unfortunately I can't provide any citations but there might be some manuals floating around the internet that can verify that [[User:Dichohecho|Dichohecho]] ([[User talk:Dichohecho|talk]]) 17:53, 3 March 2020 (UTC)

== Products List ==

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In-memory database systems (unless it's just a misleading marketing term), are marked by the abscence of disk-oriented optimisations, disk-oriented OS calls, and disk-oriented durability. On some reports, this can give significant speed up of write actions in particular, when compared to a normal disk-oriented database operating completely in ram, backed by a database on RAM disk.

Data in memory is not a particular feature of IMMDB: it is misleading to suggest that it is. <span style="font-size: smaller;" class="autosigned">— Preceding [[Wikipedia:Signatures|unsigned]] comment added by [[Special:Contributions/120.148.48.44|120.148.48.44]] ([[User talk:120.148.48.44|talk]]) 02:34, 15 January 2012 (UTC)</span><!-- Template:Unsigned IP --> <!--Autosigned by SineBot-->

== Couchbase and hybrid on-disk/in-memory databases ==

I have [https://en.wikipedia.org/w/index.php?title=In-memory_database&diff=538854332&oldid=538686621 removed] the paragraph about Couchbase from this article. The editor describes it as a "hybrid In-Memory and File-based database system". All I found from the [http://www.couchbase.com/docs/couchbase-manual-2.0/couchbase-bestpractice-clusterdesign.html Couchbase documentation is this]:

:''Couchbase is well suited for applications that want most of its active dataset in memory. This data that is actively used at any given point in time is called the Working Set. It is very important that you allocate enough memory for the entire Working Set to live in memory. When there is not enough memory left for the new data that is written, some values are ejected from memory and will only exist on disk. Accessing values from disk is much slower than accessing data in memory''

Which describes the sort of write buffering/read caching behavior that also happens in every other modern database. It all boils down to how "In-memory database" is defined. Some examples:

* PostgreSQL has the "synchronous_commit" option; when turned off, then database writes/commits are acknowledged to the client while they still exist only in memory, before writing to disk -- just like Couchbase. Does this make PostgreSQL an in-memory database?

* If I run PostgreSQL on a Linux [[tmpfs]] in-memory file system, is it correct to call it an in-memory database?

* If my application only uses the MySQL "memory" storage engine, should I call MySQL an in-memory database?

I would say the only reasonable answer to these questions is "no" -- otherwise we will need to include every modern database engine under the sun, which defeats the purpose of the "in-memory database" distinction. -- [[user:intgr|intgr]]&nbsp;<small>[[user talk:intgr|[talk]]]</small> 10:26, 18 February 2013 (UTC)

== Suggested sources for expansion ==

I found the below commented-out in the "External links" section. -- [[User:Beland|Beland]] ([[User talk:Beland|talk]]) 04:14, 18 March 2013 (UTC)

----

We need to put the info from these into the main article and format as cites

* [http://db.cs.yale.edu/hstore/ H-store Project]

* [http://martinfowler.com/bliki/InMemoryTestDatabase.html Martin Fowler wiki: InMemoryTestDatabase]

* [http://www.inf.unisi.ch/projects/sprint Sprint Project]

* Article "[http://portal.acm.org/citation.cfm?id=627538 Main Memory Database Systems: An Overview]" by [[Hector Garcia-Molina]] and [[Kenneth Salem]]

== Advertisement ==

Hi, I am rather new to Wikipedia. I hope I am not doing that wrong.

I think the following sentence is pure advertisement:

"With the introduction of NVDIMM technology,[6] in-memory databases will now be able to run at full speed and maintain data in the event of power failure."

First, there are several competitors for NVM, but one calls it NVDIMM, which is by accident also referenced (i.e.g, Viking). Second, the sentence is not correct. Large vendors as Oracle, MS, and SAP are currently looking into NVM, but no one expects results the next two years since "real NVM" (not RAM with a battery) is not expected in mass production before 2014/15.

If you need more information just ask Prof. Pavlo of Carnegie-Mellon, he's working on NVM techniques for in-memory databases. <span style="font-size: smaller;" class="autosigned">— Preceding [[Wikipedia:Signatures|unsigned]] comment added by [[Special:Contributions/141.89.226.146|141.89.226.146]] ([[User talk:141.89.226.146|talk]]) 09:33, 14 October 2013 (UTC)</span><!-- Template:Unsigned IP --> <!--Autosigned by SineBot-->

:Agreed. I have removed the link to Viking. In the future, please [[WP:BOLD|be bold]] and just edit.

:The whole article is plastered with stuff about non-volatile memory and gives the wrong idea as if NVRAM solutions were commonplace. It appears that most of this bias [https://en.wikipedia.org/w/index.php?title=In-memory_database&diff=553412377&oldid=552374260 was added by user Computermemorynerd], who also wrote the biased article on [[NVDIMM]] (which I already partially cleaned up).

:I lack sufficient knowledge on this subject, but it does sound like vaporware. Should we just delete everything added?

:Is NVDIMM a vendor-specific term? In that case, should NVDIMM simply redirect to [[NVRAM]] (which is presumably vendor-neutral)? -- [[user:intgr|intgr]]&nbsp;<small>[[user talk:intgr|[talk]]]</small> 20:28, 14 October 2013 (UTC)

== External links modified ==

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