23

OK, let's imagine that you have a distributed database. Let's say you have a node in Oregon and one in California. The CAP theory says that you will run into problems when setting up this type of database. For example, if you query data from one database, it needs to be the same as the data in the other database. This insures that whatever value you have ...


16

They are not really the same, because of the scope of the data ACID Atomicity Consistency : All Applied Data Changes Provide Consistent View of Data For All DB Connections Isolation Durability CAP Consistency (All Nodes Have Same Data via Eventual Consistency) Availability Partition-Tolerance : system continues to operate despite arbitrary message loss ...


13

Bigtable doesn't use SQL (a query language) so SQL can't be used directly to query the database. And Bigtable doesn't have "relations" in the same way as relational databases, it's more like bare tables. If you want to get data from two tables, you have to do two lookups, and combine the result set in the application code. In other words the "join" ...


6

A decentralised data warehouse is essentially a collection of data warehouses maintained by individual regions or business units but made available centrally. These may be on the same physical server, share reporting tools, or be made available across the organisation in some other way. There may also be centralised components such as master data ...


5

You need to talk to your network admin to see if Kerberos delegation is enabled, and whether it's constrained or not (if it's enabled and unconstrained that is a massive potential security risk, just by the by). If it is constrained then you need to register a SPN (Service Principal Name) for your SQL Server and bind your SQL Server account service to that ...


4

Bill Karwin has already given the best answer that I can think of... but I think some additional explanation might be in order as to why the link you posted in the original question probably does not provide a sufficient solution. Your DBA is, at least in one sense, correct. The problem is that the illustration is deceptive. The three distributed nodes in ...


4

Take a look at the views of Micheal Stonebraker here - pages 21 and 22. Stonebraker is both an academic and a serious commercial player in the database world (Postgres, Vertica, Informix, VoltDB inter alia). For your particular question, note his views on banking. Stonebraker is an advocate of "NewSQL". NewSQL is a two-pronged approach which addresses ...


4

I have been in a similar situation and highly recommend looking into MongoDB or HBase for your needs. The others (Cassandra/Redis) are good too, but HBase and MongoDB have been battle-tested in large environments, have a large community, good documentation (MongoDB's is better) and generally fulfill the three requirements you are looking for.


4

If I understand you right, you are going from DB2 10.1 Express-C edition to DB2 10.1 Work Group Server Edition or Enterprise Edition. If that is case then you shouldn't have any issues. The binaries for DB2 are basically the same across editions. It is just a matter of a license file that enables or disables certain features and enables/disables use of more/...


3

Using @a1ex07 answer, I used this query: SELECT TABLE_NAME, COLUMN_NAME, DATA_TYPE, IS_NULLABLE, COLUMN_DEFAULT FROM INFORMATION_SCHEMA.COLUMNS WHERE (table_schema, DATA_TYPE) = ('my_schema', 'timestamp') AND COLUMN_DEFAULT IS NOT NULL; That showed that many were using CURRENT_TIMESTAMP instead of UTC_TIMESTAMP.


3

HP Vertica has their community edition for download at https://my.vertica.com/download-community-edition/. If you don't have one already, you will be prompted to create a MyVertica login. If you have problems creating a login, please email me at dsandahl@vertica.com. If you have further issues loading your data, you can tweet at @VerticaHelp and support will ...


3

CAP theorem: specifies that a distributed system can provide two services (ex. Availability and Partition tolerance) but never three. If for example, a service provides Availability and Partitioning it can never ensure Consistency, not immediately, thus Eventual Consistency is used, which allows the infrastructure to flux between inconsistency and ...


3

Short answer In a distributed system, you can't be prevented from simultaneous withdrawals. If you want to prevent simultaneous transactions then don't use a distributed system. Clarification By "distributed system", I mean a system where two or more different components can act without waiting for confirmation from the rest of the system. Two-phase ...


3

If you are looking for data models to start with, I'd recommend you take a look at: http://www.databaseanswers.org/data_models/index.htm This is the most comprehensive list of data model examples that I found so far. In fact I have used some samples as starting point for some of my projects. These models won't show you how to take horizontal fragmentation ...


3

How big are the keys? How big are the values? Will the data arrive "continually", or is this a one-time load? Let's see all the representative queries. You have mentioned only SELECT val FROM tbl WHERE key = 'constant'; Are there others ? In general key-value stores suck big time. But maybe we can make your special case work not-too-badly.


3

The reality is that SQL Server does not have a read-write scalability story in the same way that Oracle does in RAC so whatever you choose, you will always needing to consider that data-sets in one place or the other could be slightly behind. Availability Groups are probably the easiest solution to manage but then the only thing you are scaling out is ...


3

...be expected to decrease the write time by increasing the number of nodes to which I can write. Yes. While the article is dated, Netflix performed a scalability experiment back in 2011, as detailed here: Benchmarking Cassandra Scalability on AWS - Over a million writes per second Essentially, they found that Cassandra was indeed linearly scalable. ...


2

Check out this blog: http://www.mysqlperformanceblog.com/2012/01/11/making-the-impossible-3-nodes-intercontinental-replication/ We will create 3 nodes Cluster with nodes on different continents (Europe, USA, Japan) and each node will accept write queries. The solution used is Percona XtraDB Cluster.


2

Postgres-XC does not run on Windows: Postgres-XC currently runs on the Linux Operating Systems running on 64-bit Intel(R) processors. The development team tested this with Cent-OS 5.3 and 5.4. You might be able to build the data nodes and possibly the coordinators on Windows, but the GTM will take major work to port to Windows.


2

Compare a fragmented distributed database with a replicated distributed database. A replicated database would contain all columns and all records on more than one database instance; whereas, the separate instances of a fragmented distributed database do not all contain the same columns and/or records. Vertical Fragmentation: A vertically-fragmented ...


2

Is there material on how? Yes. You can read about it at https://msdn.microsoft.com/en-us/library/dn589797.aspx Is the process as tough as it seems? Sort of. It is time consuming in that it requires careful planning in advance on how you want to structure the data, but if you're doing something with a massive database, I've personally been very pleased ...


2

It's not supported, but you can get around it.. select * from openquery( LinkedServerName, 'exec [database].dbo.sproc @Id=@Id, @PItems=@PItems output'','' @PId bigint, @PItems xml output'', valueOf@PId, valueOf@PItems output' ) There are ...


2

This is exactly what replication is designed for. Sounds like Transactional replication with updateable subscriptions will work although MS is saying this will be removed down the road (no specifics) Merge replication is also a choice, but is more complex to maintain.


2

Try enabling the DTC on the sq202 box, since that is the server initiating the distributed transaction. You will also need to have Enable Promotion of Distributed Transactions for RPC option set to True as well for the sq009 linked server located on the sq202 box; when this option is TRUE, calling a remote stored procedure starts a distributed transaction ...


2

Every write is performed on every machine, whether it is a Master or a Slave. The corollary to that is that there is a limit to write scaling with traditional Replication. Even Galera and Group Replication are just variants on Master(s) and Slave(s). Each server has all the data, and it is kept as up-to-date as is practical. Hence, Sharding is the only ...


1

I have dealt with something very similar to this. This is quite a broad problem but I'll try to offer the pointers I can after a year (and then the rest) of dealing with massive geographic data sets. I'm not saying "do these", I'm saying these ideas will be resourceful depending on your hardware situation and software needs. You clearly already have good ...


1

The first problem: Error 21488 No active subscriptions were found. The publication must have active subscriptions in order to post a tracer token. This happens when attempting to put in a tracer token without an active subscription. This error seems pretty obvious. Error 18752 Only one Log Reader Agent or log-related procedure (sp_repldone, ...


1

"Is MySQL suitable for distributing or cluster databases ?" While you certainly can do manually sharding, the truth is that the most common MySQL cluster technologies are focused in high availability. NDB Cluster is based mainly on a memory database with lots of throughput, but not necessarily low-latency and large datasets. Galera does not support ...


1

This is pretty much a textbook example for Merge Replication. Here is the Product documentation describing the scenario, and how to implement it.


1

Try the dblink. You find the description in http://www.postgresql.org/docs/current/static/contrib-dblink-function.html and http://www.postgresonline.com/journal/archives/44-Using-DbLink-to-access-other-PostgreSQL-Databases-and-Servers.html. Also a question about dblink was asked on https://stackoverflow.com/questions/3862648/how-to-use-install-dblink-in-...


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