View source for Talk:Comparison of relational database management systems

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== How can MySQL possibly be ACID compliant? Surely it should be marked as "No" under ACID ==
The footnote for the MySQL DBMS support of ACID transactions says that the software will in some cases accept values outside a range specified in the data definition. I.e. .."violates the integrity [Consistency] clause"... 

By my understanding of ACID compliance this is a blatant breach of the Consistency / Integrity clause of ACID compliance - i.e. that the transaction enforces the database is taken from one consistent state to another. If the data constraints are not enforced in the transaction and it is possible to commit values outside those constraints, surely the system is not ACID compliant.  <span style="font-size: smaller;" class="autosigned">—Preceding [[Wikipedia:Signatures|unsigned]] comment added by [[Special:Contributions/93.97.38.208|93.97.38.208]] ([[User talk:93.97.38.208|talk]]) 15:14, 7 February 2010 (UTC)</span><!-- Template:UnsignedIP --> <!--Autosigned by SineBot-->


I'm changing this to 'yes' with a footnote saying the same thing that is stated in the MySQL article, that ACID is supported only when using what is sometimes not the default storage engine. The listing should say which databases SUPPORT ACID. not which ones enforce it using any possible combinations of settings and in even the rarest exception cases. I think you would find a lot of other databases would not pass your strict interpretation either, and my interpretation is arguably of more use and interest to the reader (if someone is selecting which database to use for example). 

[[User:LarsHolmberg|LarsHolmberg]] ([[User talk:LarsHolmberg|talk]]) 17:38, 19 August 2010 (UTC)

Lars: that doesn't make sense. What you're saying is akin to "this car can can go at 300mph, but you'll have to design and build a new engine to make it do that". I would say 'support' means that the product can do this, without one having to write their own storage engine to get it. Loads of RDMS's support ACID properly and out of the box by my interpretation - PostgreSQL, DB2 and Oracle being but a few popular ones. The simple fact is that because of the above problem with InnoDB not supporting ACID Consistency (and there being no other available and out of the box storage engines able to provide ACID compliance), MySQL cannot be said to support it. [[Special:Contributions/93.97.38.208|93.97.38.208]] ([[User talk:93.97.38.208|talk]]) 16:41, 21 February 2011 (UTC)

:Anyway, InnoDB is not ACID compliant, the problem is *some* engines listed for MySQL are said to be ACID compliant (like they said InnoDB is ...) and I have no information to confirm that. Sure thing is, the word should be spread that InnoDB is not 'C' compliant, including on this page .  // This brings the question of how this list was compiled and how many others aren't actually ACID compliant.[[User:Yourbane|Yourbane]] ([[User talk:Yourbane|talk]]) 10:23, 23 August 2011 (UTC)

:: How many are or are not strictly ACID compliant is an excellent question, but also a lot of work to figure out. The bold course would seem to change them all to "unknown" then change them to something that can be backed up with a reference, and keep out the changes that aren't checkable. ACID is a hot buzzword (and subject to ill-informed fanboiism in certain quarters) but all the same important enough to get it correct. Also, I support the notion that this is not a place for loose interpretations. ACID is much less useful if you only get it if you contort yourself. The only approach that makes having it useful is to make it strictly the default then optionally allow for carefully loosening the requirements for speed; the SQL standard supports this. Doing it the other way just doesn't make sense, unless you believe in the awesome power of "your mileage may vary".  <span style="font-size: smaller;" class="autosigned">— Preceding [[Wikipedia:Signatures|unsigned]] comment added by [[Special:Contributions/84.86.176.163|84.86.176.163]] ([[User talk:84.86.176.163|talk]]) 12:50, 9 February 2012 (UTC)</span><!-- Template:Unsigned IP --> <!--Autosigned by SineBot-->

== Someone needs to add information about FileMaker Pro. ==

Filemaker Pro has been around for a long time and is still used. Why is it not included?
[[User:Lehasa|Lehasa]] ([[User talk:Lehasa|talk]]) 19:06, 17 January 2009 (UTC)

== We need comparison about clustering capabilities ==

A table is definitely needed about the clustering capabilities of relational databases. For instance middleware, Master-Slave. Sync Multimaster, etc. Specially I don't have too much info about Sync Multimaster. So far I only know about Oracle and Microsoft SQL capable of that. I beleive MySQL doesn't have plan to include that and that Postgres is working on it but then I'm not sure. PLease clarify.  <span style="font-size: smaller;" class="autosigned">—Preceding [[Wikipedia:Signatures|unsigned]] comment added by [[Special:Contributions/201.220.215.11|201.220.215.11]] ([[User talk:201.220.215.11|talk]]) 07:55, 21 September 2008 (UTC)</span><!-- Template:UnsignedIP --> <!--Autosigned by SineBot-->

== Transaction types support ==

This page definitely needs an overview of which transaction types the databases support. For many applications, it is important that you can start a transaction, make 100 select queries over a period of 10 minutes, and know that the first and last query will deliver the same result if they're identical, even if the database is being used and written to by other users in the same time period. It's needed because that's the only way you can make correct multi-query reports from production databases. For instance, Microsoft SQL Server 2000 doesn't support this. Also, it would be interesting to know what the default transaction type is - because that's typically the one that people use.[[Special:Contributions/87.63.152.70|87.63.152.70]] ([[User talk:87.63.152.70|talk]]) 06:48, 1 May 2008 (UTC)
: I don't see the point you're trying to make, but this sounds like ACID 'C' and there is a whole column for that, even if it's filled with random values apparently (...)[[User:Yourbane|Yourbane]] ([[User talk:Yourbane|talk]]) 10:24, 23 August 2011 (UTC)

== Tables and views ==

So Postgres doesn't have materialized views but gets away with a "it can be done with triggers"? In that case, the same should go for MySQL. Just do a search on "materialized views mysql" and you will get similiar solutions that use stored procedures and triggers. The implementation referred to in the footnote doesn't utilize any functionality specific to Postgres. --[[User:Juha001|Juha001]] 11:26, 7 April 2006 (UTC)

:Be bold and make the change! Find one of the solutions and make a footnote to it. [[User:Turnstep|Turnstep]] 15:39, 7 April 2006 (UTC)

:I think we can't fairly say that either Postgres or MySQL "implements materialized views"; they can be crudely emulated with triggers and a procedural language, but that is hardly the same as a proper materialized view implementation. Therefore I've changed both table entries to "No", but kept the footnotes. [[User:Neilc|Neilc]] 16:55, 5 September 2006 (UTC)

:: Are even the footnotes worth keeping? If so, that note should go on every DB server which has procedures and triggers. --[[User:Craig Stuntz|Craig Stuntz]] 19:00, 5 September 2006 (UTC)

::I agree, remove the footnotes, triggers do not qualify as a materialized view. However, if the DB implements materialized views by using triggers, and does so such that there are a few defects to the implementation, then I would side with a footnote, that revealed the difference. It just seems rather pointless to say, complex things can be borne from simplicity, or that triggers make a DB [[turing-complete]]. [[User:EvanCarroll|EvanCarroll]] 18:07, 31 May 2007 (UTC)

Why are Microsoft SQL Server's indexed views only "similar" to a materialized view?
-- A.M. 14 April 2006

ease in reordering columns? [[User:Jaydlewis|Jaydlewis]] ([[User talk:Jaydlewis|talk]]) 04:50, 26 December 2008 (UTC)

==SQL compatibility==
Would this be the right place to compare SQL compatibility with each database? Or is there another article that does this?  For example, [[Interbase]] does not seem to support the MINUS operator (part of [[SQL]]).  I was hoping to find a table listing tidbits like these.  The management guys might also like a comparison of how "SQL-compliant" a database is, when it comes time to consider one. // [[User:Brick Thrower|Brick Thrower]] 15:00, 25 January 2007 (UTC)
:Personally, I think this information would be too complex to reasonably add to this article. [[User:Neilc|Neilc]] 04:35, 10 February 2007 (UTC)
:I think otherwise, and so I've made an attempt, if people wish to detail the differences let's allow it.[[User:EvanCarroll|EvanCarroll]] 17:59, 31 May 2007 (UTC)
::I think you're right but this article looks like a lot of stuff put together and nothing really clean in the end. anyone got time ? ^^[[User:Yourbane|Yourbane]] ([[User talk:Yourbane|talk]]) 10:25, 23 August 2011 (UTC)

==Abusing comparison==
I can see the argument that an empty entry in a comparison table encourages people to fill them in, but it leaves the current state of the article appearing amateurish and silly. If so little is known about an entry as to make it useless for the purpose of comparison lets exclude it entirely, rather than insert a bunch of kludgy "?" reminding us of what we do not know. We can use the discussion area for notes until enough is known to make the addition useful. *Note* I have '''not''' taken the action of reverting anything. [[User:EvanCarroll|EvanCarroll]] 15:52, 26 July 2007 (UTC)
: If you are suggesting (a) to remove a column full of "?" I agree - as long as the column does not contain anything else. If you are suggesting (b) to remove a row full of "?" I don't since the table contain a consistent list of DBMSes. Note that I am talking from my own readers perspective, not as an author. [[User:Semiliki|Semiliki]] 19:52, 30 August 2007 (UTC)

== Additional information ==

A couple of other pieces of basic information about these databases would be useful. 

A number of them, like Derby, are in-memory RDBMSes. This ought to be at least noted if not added as column of information. I'm not sure if there is some more general categorization of the RDBMS that this could be part of.
: Are you talking about how Derby and Sqlite are embeddable inside of an application and are not meant to run as a separate server process?  I think this would be a good column to put somewhere.  --[[User:Krappie|Krappie]] ([[User talk:Krappie|talk]]) 00:49, 20 April 2008 (UTC)
: Client-server vs in-process is an orthogonal issue to in-memory vs disk based. perhaps we should have an extra table to cover such issues as:
* In-memory tables (where the master copy of the table is in-memory for speed of access); subsidiary questions relate to whether such tables are persistent (there is some way to preserve their contents in case of system failure) and/or replicated (eg, copied to a standby server, or to other nodes in a cluster, depending on the distribution model), and whether a mixture of disk-based and in-memory tables can be supported in a single database.
* Client-server? in-process? (by in-process I mean that the database software is just a library that can be linked into an application, and runs in the same process as the user code; this is much faster, obviously, but a fault in the user code can corrupt the data structures used by the DBMS software, and such corruption might not be detected until very much later. Some in-process DBMSs are in-memory, others are disk-based. There is also a shared library + shared memory approach: multiple applications can have fast access to the data, especially if it is in-memory - but of course, the data vulnerability is increased.) A subsidiary question for client-server architectures is about remoteness and heterogeneity: can client and server be on different machines? Can they be on different operating systems? different underlying architectures (viz, x86 and PowerPC, with their different endianisms - for real fun, throw something like a VAX machine in the mix, with its curious floating point format!)? 
* Hot-standby capability? here a 2nd server keeps an up to date copy of the database, ready to take over at a moment's notice. Subsidiary question: is the standby updated synchronously or asynchronously? (The latter gives greater system performance, but decreases durability.) If asynchronous, can a client detect when its transaction is durable?
* Cluster replication? here, the database is distributed on a cluster of 3 or more servers, in such a way that the failure of one node does  not lose data nor does it break the overall service. This is different from partitioning, as each item of data has at least 2 homes. The distribution scheme may allow for partial replication, where a given server might only hold a selected subset of the overall database, or all nodes may hold identical data. Replication of this type requires n-way commits , and also complex logic to decide how to reconcile the data on the various nodes if connectivity has been broken. [[User:Ngpd|Ngpd]] ([[User talk:Ngpd|talk]]) 11:43, 21 April 2008 (UTC)

Nevermind the messy issue of SQL compatibility, but whether the interface to the RDBMS is SQL at all as opposed to something else should be noted. I believe Adabas is a non-SQL RDBMS, though there are SQL "gateways" that will translate SQL into a native Adabas query. There are also RDBMSes being developed (such as [http://dbappbuilder.sourceforge.net/Rel.html Rel] and [http://search.cpan.org/dist/Muldis-Rosetta/ Muldis Rosetta]) based on Date and Darwins [[The_Third_Manifesto|3rd Manifesto]], which use implementations of Tutorial D instead of SQL. I think a column should be added title "Interface" or something similar, under which should be SQL for most RDBMSes, but may be other things. --[[User:Ericjs|Ericjs]] 17:06, 31 October 2007 (UTC)
:ADABAS is not a RDBMS, so it is tempting to remove it from here. However, along with its add-on SQL gateway, as the ADABAS 2006 presentation paper at Software AG's says, perhaps the whole has many of the functionalities considered here. But so far, nothing has been filled in the tables for ADABAS, except for OS support and stored procedures (and i suppose that they're ADABAS-specific procedures anyway). So perhaps we could give it some more time, after which, if the desired info hasn't been added here, out it goes? Or, the other way around, whoever has the information will have to recreate the ADABAS rows in the tables? --[[User:Jerome Charles Potts|Jerome Potts]] ([[User talk:Jerome Charles Potts|talk]]) 06:32, 8 January 2008 (UTC)

== Database Specific Proprietary Index schemes ==

The last two columns of the available indexes table, GiST and GIN are specific to just the one database. I'm sure that all databases have some such unique index schemes. I don't think that they really belong in this article. I propose removing these two columns. [[User:TallMagic|TallMagic]] ([[User talk:TallMagic|talk]]) 19:56, 1 May 2008 (UTC)
: GIST and GIN are now supported by Informix as well. I suggest we keep the column for now. [[User:Gcalis|Gcalis]] ([[User talk:Gcalis|talk]]) 14:49, 16 March 2009 (UTC)

== Deleted contributions ==
I'd like an admin to look into how this content was deleted. [http://en.wikipedia.org/enwiki/w/index.php?title=Comparison_of_relational_database_management_systems&oldid=170703214 old revision] I wrote that in 07' and it is still true today. How will anyone know what you mean when you say schema or database if the difference can be totally confused by a bad implementation. That is fairly unbiased and agreeably worded. I've added the content again, anew. If you have a problem with it bring it up onto the discussion page. [[User:EvanCarroll|EvanCarroll]] ([[User talk:EvanCarroll|talk]]) 04:11, 26 November 2008 (UTC)

== Comparsion of Client Tools  ==

eg pgAdmin vs SQL Server Enterprise Manager...
[[User:Jaydlewis|Jaydlewis]] ([[User talk:Jaydlewis|talk]]) 04:55, 26 December 2008 (UTC)
: Now this I would say does not make as much sense as you think it does. I honestly don't care about GUI's, my server doesn't and my application doesn't. Picking a DBMS based on a client tool would be a really bad idea anyway. AND there are many tools that work on many DBMS's (from what you say, you'd need to compare pgAdmin,Toad,others vs SQL Server... not only would it take ages but it would be biased and unimportant in the end).[[User:Yourbane|Yourbane]] ([[User talk:Yourbane|talk]]) 10:29, 23 August 2011 (UTC)

== Access Control ==

I think 'Access control' section need to be renamed as 'Security'. It is more adapted as we don't speak only of access control but also confidentialy/encryption, security certification, ...

== Performance ==

It would be nice to add some performance information here. Does anyone know about benchmarking tools for DMSs? Is there a reasonable way of comparesion at all?  <span style="font-size: smaller;" class="autosigned">—Preceding [[Wikipedia:Signatures|unsigned]] comment added by [[Special:Contributions/92.229.125.242|92.229.125.242]] ([[User talk:92.229.125.242|talk]]) 16:51, 9 March 2009 (UTC)</span><!-- Template:UnsignedIP --> <!--Autosigned by SineBot-->
: There are a few benchmarks that are industry standard ... but *real* benchmarks are rare, i.e. with comparable TCO, relevant workloads etc. I've got benchmarks that show MySQL >>> PostgreSQL and others that show PostgreSQL >>>>>> MySQL, both are wrong and you'd need some smart weighting in order to do anything with such benchmarking data anyway.[[User:Yourbane|Yourbane]] ([[User talk:Yourbane|talk]]) 10:31, 23 August 2011 (UTC)

== Limits: maximum column name length ==

I'm going to add a column "MAX column name length". I do believe this information will be useful for people who is porting one database to another. For example from MS Sql Server to Firebird or Oracle.

I googled and found the following sources:

http://www.mssqlcity.com/Articles/Compare/oracle_vs_db2.htm
http://tracker.firebirdsql.org/browse/CORE-749
http://www.mssqlcity.com/Articles/Compare/sql_server_vs_oracle.htm
http://dev.mysql.com/doc/refman/5.0/en/identifiers.html
http://www.mssqlcity.com/Articles/Compare/sql_server_vs_oracle.htm
http://forums.devshed.com/postgresql-help-21/max-table-name-column-name-size-600049.html

I know some might not confirm to the wikipedia standard for sources, but at least its a start.

Regards,

==Concurrent Data Readers==

It could be interesting to add information regarding support for Concurrent Data Readers, that is the ability to "for a concurrent data reader to access more than one result set in the same database connection and query both of those result sets concurrently"
AFAIK only DB2 (http://www.databasejournal.com/features/db2/article.php/3565831) and MS SQLServer (using M.A.R.S) support it (but I guess Oracle also supports it). I have searched of any indication that opensource databases support such feature (PostgreSQL, MySQL, H2, etc) but have been unable to find any page that confirms support.

I do not to which of the already existing table should the "Concurrent Data Readers" column should be added (or perphas a new comparision table with "Connection Capabilities" should be created?  <span style="font-size: smaller;" class="autosigned">—Preceding [[Wikipedia:Signatures|unsigned]] comment added by [[Special:Contributions/201.155.6.245|201.155.6.245]] ([[User talk:201.155.6.245|talk]]) 14:36, 6 July 2009 (UTC)</span><!-- Template:UnsignedIP --> <!--Autosigned by SineBot-->


[[Special:Contributions/41.247.1.82|41.247.1.82]] ([[User talk:41.247.1.82|talk]]) 18:32, 28 May 2009 (UTC)
: I have no idea what you call a concurrent data reader, but multiple queries and multiple results in one package (i.e. one connect/query/return) is possible with both pg and MySQL. 
: I also believe the 'concurrently' is a blatant marketing lie, you cannot seek in two places at the same time, you can however multithread multiple requests.. and that's a feature any decent DBMS has.[[User:Yourbane|Yourbane]] ([[User talk:Yourbane|talk]]) 10:34, 23 August 2011 (UTC)

== Limits ==

=== Oracle ===
The column "Max table size" says "4 GB * block size (with BIGFILE tablespace)" without any explanation or footnote. This isn't easy to understand and perhaps "4 GB" is misleading or even wrong?<br /> The article [http://www.databasejournal.com/features/oracle/article.php/3559291/Super-Sizing-A-Database-Oracle-10g-Tablespace-Enhancements.htm Super-Sizing A Database: Oracle 10g Tablespace Enhancements] by Jim Czuprynski 28th October 2005 explains this much better in the section "Size Does Matter: BIGFILE Tablespaces": "A BIGFILE tablespace's datafile can now hold up to 4,294,967,296 (yes, you read that correctly - the multiplier is over 4 ''billion'') blocks of data storage space. This means that a tablespace could conceivably hold up to 128 TB of data if the maximum Oracle tablespace block size of 32K is used."<br />In other words an Oracle table can be: 4,294,967,296 * 32 kB = 128 TB.<br />--[[User:Ohedland|Ohedland]] ([[User talk:Ohedland|talk]]) 11:43, 19 August 2009 (UTC)

----
The assertion that the maximum row size in Oracle is 8KB is also incorrect.  While it does not appear in a document, at least as of version 10.2 of Oracle, the row size can easily exceed 8KB.  For example, this is perfectly valid:
<code>
  CREATE TABLE BLEAH (
    A1 CHAR(2000 BYTE),
    A2 CHAR(2000 BYTE),
    A3 CHAR(2000 BYTE),
    A4 CHAR(2000 BYTE),
    A5 CHAR(2000 BYTE),
    A6 CHAR(2000 BYTE),
    A7 CHAR(2000 BYTE));
</code>
This example can be extended to the full 1000 column limit to create a table with a physical row length of 2000000 bytes.  So, while the row length limit is not apparently documented, it is definitely not 8K.

--[[Special:Contributions/12.106.238.251|12.106.238.251]] ([[User talk:12.106.238.251|talk]]) 15:30, 16 June 2010 (UTC)

===MySQL===
MyISAM does not have a table storage limit of 256TB! The default pointer sized used by version 5+ is 6 bytes, so this is true *by default*. However all versions support up to 8 byte (64bit) pointers, and hence 2^64 bytes = 16 Exabytes is permitted. You can control this when creating your table or when altering it, by setting: MAX_ROWS and AVG_ROW_LENGTH.  <span style="font-size: smaller;" class="autosigned">—Preceding [[Wikipedia:Signatures|unsigned]] comment added by [[Special:Contributions/118.209.3.231|118.209.3.231]] ([[User talk:118.209.3.231|talk]]) 06:10, 18 December 2009 (UTC)</span><!-- Template:UnsignedIP --> <!--Autosigned by SineBot-->
:Err.. while that could possibly be true, I believe some testing is in order before talking about random unrealistic values (or I'll just whip out my 16 Exahertz CPU for the benchmarking part...) / Same goes for all the other DBMS's listing unrealistic limits that their engines may not be able to handle [[User:Yourbane|Yourbane]] ([[User talk:Yourbane|talk]]) 10:36, 23 August 2011 (UTC)

== DBMaker not listed - why? ==

Been using the beastie for 8 years in decision support role. works OK - http://www.dbmaker.com.tw/ was their link IIRC. [[Special:Contributions/212.188.108.126|212.188.108.126]] ([[User talk:212.188.108.126|talk]]) 19:02, 4 September 2009 (UTC)

== Price of them? ==

Please add price of each RDMS. Thank you!  <small><span class="autosigned">—Preceding [[Wikipedia:Signatures|unsigned]] comment added by [[User:Meocon quyet doan|Meocon quyet doan]] ([[User talk:Meocon quyet doan|talk]] • [[Special:Contributions/Meocon quyet doan|contribs]]) 03:25, 19 January 2010 (UTC)</span></small><!-- Template:Unsigned --> <!--Autosigned by SineBot-->

: Most DBMS's do not have a single 'price' (apart from those that are totally free), and some allow a choice of licensing models. Pricing might depend on a number of factors, including
:* number of developers
:* number of client applications connected to a database
:* the number of people using the overall system
:* number of databases supported by a server
:* number of processor cores on the system running the server
:* the software features that are being used
:* the size of the database(s)
: The price might or might not include the first year of support, and support fees may vary according to the level of response required. For some products, support fees might be tied to the price of development licenses while for others it is tied to the deployment licenses. 
: In summary, I believe it is seriously misleading to give the price for a product without a huge amount of explanation, and this may not be appropriate in a comparison chart. However, it may be sensible to give a link to a page on the manufacturer's web site giving pricing information (and perhaps a link to a page describing their pricing model(s)?). [[User:Ngpd|Ngpd]] ([[User talk:Ngpd|talk]]) 10:05, 21 January 2010 (UTC)
:: It's like benchmarking .. if we had some serious benchmarking, we could say for 10.000 points on benchmark A with DBMS B, you need xyz $$ - but honestly who has the time --[[User:Yourbane|Yourbane]] ([[User talk:Yourbane|talk]]) 10:37, 23 August 2011 (UTC)

==Tidying up the Comparison==
To adhere to Wikipedia policy, this comparison needs to include entries that have an article, and not include lists of external links. See for example [[Wikipedia:WTAF]] and [[Wikipedia:External links]]. [[User:Greenman|Greenman]] ([[User talk:Greenman|talk]]) 12:34, 4 February 2010 (UTC)

Can someone show what 'Shadow' partitioning is? It is a heading in the '''Partitioning''' table, but only [[Firebird]] and [[InterBase]] support it. Since these have a common origin, this would seem to be a platform-specific term. 'Shadow partitioning' is not mentioned in the [[Partition_(database)|Partitioning]] article, and I have not come across it in any RDBMS platform I have used. I suggest deleting this column. [[Special:Contributions/80.194.100.111|80.194.100.111]] ([[User talk:80.194.100.111|talk]]) 16:17, 21 September 2010 (UTC)
:If it refers to [http://www.businessdictionary.com/definition/database-shadowing.html database shadowing], as it appears to at first glance, it's hardly unique to those two, and should be merged. [[User:Greenman|Greenman]] ([[User talk:Greenman|talk]]) 20:56, 21 September 2010 (UTC)
Why is AmigaOS (and possibly also Symbian) included on the operating system compatibility table? This should only really contain mainstream (server) operating systems. Perhaps changing Unix to AIX and Solaris would also be useful. '''<span style="color:#aaa">—</span> [[User:M3tainfo|<span style="color:#0055dd">M3TA</span>]]<span style="color:#aaa">(</span>[[User_talk:M3tainfo|<span style="color:#0022aa">info</span>]]<span style="color:#aaa">) @</span>''' 19:49, 20 March 2011 (UTC)
: In that sense I would also remove all toy or deceased software ... like Access or other random stuff .. but hey this is here for the sake of completeneess, so as long as you have access and dbase, why not add amiga ;)  <small><span class="autosigned">— Preceding [[Wikipedia:Signatures|unsigned]] comment added by [[User:Yourbane|Yourbane]] ([[User talk:Yourbane|talk]] • [[Special:Contributions/Yourbane|contribs]]) 10:39, 23 August 2011 (UTC)</span></small><!-- Template:Unsigned --> <!--Autosigned by SineBot-->

== Drizzle is on the list? ==

How can a non-relational DBMS be on a list of Relation DBMS's? Sounds quite weak to me, should be removed from this list just as all other DBMS's that do not support referential integrity which is the key to being relational.  <span style="font-size: smaller;" class="autosigned">—Preceding [[Wikipedia:Signatures|unsigned]] comment added by [[Special:Contributions/82.169.68.36|82.169.68.36]] ([[User talk:82.169.68.36|talk]]) 00:24, 11 March 2010 (UTC)</span><!-- Template:UnsignedIP --> <!--Autosigned by SineBot-->

:Could you add a reference? It seems like [[Drizzle (database server)|Drizzle]] supports [[Referential integrity]] and there is a table comparison for it.

== "Free" licensed versions of proprietary products not handled well ==

The various tables don't document "free to use" versions of various proprietary products clearly.

For example:

Microsoft SQL Server Express (free to use, technical limitations)
Oracle Personal Edition (ditto)

There are a number of others, I'm sure (DB2?  Sybase? Informix?)

Also, lower cost cut down versions and embedded versions not well addressed

For example
Oracle Standard One (cut down from Enterprise--may be best handled by a footnote)
Oracle Lite (embedded, not code related)
Oracle Times10 (in memory)
Sleepycat (also now owned by Oracle, I think it qualifies as relational)


[[Special:Contributions/188.222.243.54|188.222.243.54]] ([[User talk:188.222.243.54|talk]]) 17:39, 19 May 2010 (UTC)MilesT

== db vs schemas ==

section is 100% original research - marked as such
[[User:Kaelfischer|Kaelfischer]] ([[User talk:Kaelfischer|talk]]) 22:38, 10 June 2010 (UTC)

==Modern RD Only Option==
Many people coming to the page are only interested in comparing current RDs to decide which to use. However, because all of the comparison tables are multiple screens long and compare every RD that has ever existed, they find the page to be mostly useless. We need a way to show only current information for those who want it, in order to increase utility. A method for allowing the viewer to sort information and suppress what they don't need would also be good.

This is a general comment applicable to all comparison articles.  <span style="font-size: smaller;" class="autosigned">—Preceding [[Wikipedia:Signatures|unsigned]] comment added by [[Special:Contributions/136.142.206.28|136.142.206.28]] ([[User talk:136.142.206.28|talk]]) 22:45, 15 October 2010 (UTC)</span><!-- Template:UnsignedIP --> <!--Autosigned by SineBot-->

:I do not mind removing obsolete databases. What databases would you remove?  <span style="font-size: smaller;" class="autosigned">—Preceding [[Wikipedia:Signatures|unsigned]] comment added by [[Special:Contributions/195.235.227.10|195.235.227.10]] ([[User talk:195.235.227.10|talk]]) 12:07, 1 April 2011 (UTC)</span><!-- Template:UnsignedIP --> <!--Autosigned by SineBot-->

:: I would remove most of them but I don't think that's a good idea. IMHO we should take the big ones, put them on top (Oracle,DB2,MSSQL,MySQL,PostgreSQL,Sybase,H or SQLlite and maybe one or two more) and then let the rest of the information rot on the bottom of the page xD[[User:Yourbane|Yourbane]] ([[User talk:Yourbane|talk]]) 10:41, 23 August 2011 (UTC)

::: I would only remove truly obsolete databases. But I would not change the alphabetical ordering.  <span style="font-size: smaller;" class="autosigned">— Preceding [[Wikipedia:Signatures|unsigned]] comment added by [[Special:Contributions/193.127.207.152|193.127.207.152]] ([[User talk:193.127.207.152|talk]]) 10:28, 5 October 2011 (UTC)</span><!-- Template:Unsigned IP --> <!--Autosigned by SineBot-->

== Limits Max Index Length ==

It may be interesting to also have a Max Index Length column in the Limits comparison but I do not have access to every database and this data is not quite documented in every database.

Would anyone also like to see it? Would you help me gather that information?

Here are the limits for MySQL InnoDB http://dev.mysql.com/doc/refman/5.5/en/innodb-restrictions.html#id922640  <span style="font-size: smaller;" class="autosigned">—Preceding [[Wikipedia:Signatures|unsigned]] comment added by [[Special:Contributions/195.235.227.10|195.235.227.10]] ([[User talk:195.235.227.10|talk]]) 12:34, 1 April 2011 (UTC)</span><!-- Template:UnsignedIP --> <!--Autosigned by SineBot-->

== ALTER TABLE support ==

Some databases have very basic ALTER TABLE support

http://www.sqlite.org/faq.html#q11

http://stackoverflow.com/questions/2385020/how-to-alter-a-column-datatype-for-derby-database

What section should include ALTER TABLE support?  <span style="font-size: smaller;" class="autosigned">— Preceding [[Wikipedia:Signatures|unsigned]] comment added by [[Special:Contributions/2.137.153.245|2.137.153.245]] ([[User talk:2.137.153.245|talk]]) 17:49, 26 August 2011 (UTC)</span><!-- Template:Unsigned IP --> <!--Autosigned by SineBot-->

== Native Replication API ==

I do not know what you mean by that.

Please add at least a reference or I will remove it.  <span style="font-size: smaller;" class="autosigned">— Preceding [[Wikipedia:Signatures|unsigned]] comment added by [[Special:Contributions/195.235.227.10|195.235.227.10]] ([[User talk:195.235.227.10|talk]]) 12:59, 21 September 2011 (UTC)</span><!-- Template:Unsigned IP --> <!--Autosigned by SineBot-->
: I had to remove Native Replication API as no one stepped up to provide a single reference.  <span style="font-size: smaller;" class="autosigned">— Preceding [[Wikipedia:Signatures|unsigned]] comment added by [[Special:Contributions/193.127.207.152|193.127.207.152]] ([[User talk:193.127.207.152|talk]]) 09:28, 17 October 2011 (UTC)</span><!-- Template:Unsigned IP --> <!--Autosigned by SineBot-->

== Proper fine grained locking ==

It seems like [[Oracle Database]] has proper fine grained locking while [[Microsoft SQL Server]] does not. http://stackoverflow.com/questions/1437200/sqlserver-2005-deadlock-problem-with-no-shared-records

Would someone help me filling what databases have proper fine grained locking?  <span style="font-size: smaller;" class="autosigned">— Preceding [[Wikipedia:Signatures|unsigned]] comment added by [[Special:Contributions/193.127.207.152|193.127.207.152]] ([[User talk:193.127.207.152|talk]]) 10:12, 5 October 2011 (UTC)</span><!-- Template:Unsigned IP --> <!--Autosigned by SineBot-->

== Forks ==

Someone added [[MariaDB]] again to the comparison but being just a fork has (right now) exactly the same features. http://kb.askmonty.org/en/mariadb-versus-mysql

Should we keep forks in the comparison that have the same features?  <span style="font-size: smaller;" class="autosigned">— Preceding [[Wikipedia:Signatures|unsigned]] comment added by [[Special:Contributions/193.127.207.152|193.127.207.152]] ([[User talk:193.127.207.152|talk]]) 10:35, 5 October 2011 (UTC)</span><!-- Template:Unsigned IP --> <!--Autosigned by SineBot-->

== Please categorize by serverless/client-server/etc. ==

I think that it this article would be a lot more useful if it would also categorize database management systems by whether they use a client/server model or are serverless, or any other kinds of IPC (Inter-Process Communication) that they use.  For example this makes a big difference between MySQL and SQLite.  I added the stub category "Category:Database management systems by process model".  I also [[Wikipedia:Requested_articles/Applied_arts_and_sciences/Computer_science,_computing,_and_Internet#Databases|requested an article]] for "List of serverless database management systems".  It would be helpful to programmers and readers to have a list of serverless database management systems here in the comparison groupings and/or in a separate article, and the DBMS's should be categorized as such.