Relational Database Management System, a widely used type of database management system characterised by its extensive use of joining as a core operational principle.

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50
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6answers
17k views

What are the differences between NoSQL and a traditional RDBMS?

What are the differences between NoSQL and a traditional RDBMS? Over the last few months, NoSQL has been frequently mentioned in the technical news. What are its most significant features relative to ...
36
votes
5answers
8k views

Which database could handle storage of billions/trillions of records?

We are looking at developing a tool to capture and analyze netflow data, of which we gather tremendous amounts of. Each day we capture about ~1.4 billion flow records which would look like this in ...
27
votes
5answers
2k views

Is it OK to keep a value which updates in a table?

We are developing a platform for prepaid cards, which basically holds data about cards and their balance, payments, etc. Up until now we had a Card entity which has a collection of Account entity, ...
21
votes
4answers
3k views

What does “index” mean on RDBMSs? [closed]

I use indexes like most developpers do (mostly on... well ! index), but i'm sure there is a lot of subtle way to optimize a database using index. I'm not sure if it is specific to any implementation ...
18
votes
6answers
2k views

Why don't databases create their own indexes automatically?

I would have thought that databases would know enough about what they encounter often and be able to respond to the demands they're placed under that they could decide to add indexes to highly ...
12
votes
5answers
3k views

Is ROLLBACK a fast operation?

Is it true that RDBMS systems are optimized for COMMIT operations? How much slower/faster are ROLLBACK operations and why?
12
votes
2answers
802 views

NoSQL and RDBMS together?

I was wondering if there are any good solutions for recording data in a NoSQL database and then converting them over to an RDBMS? For example, if you wanted to capture some data quickly, like ...
11
votes
3answers
1k views

Use MySQL to regularly do multi-way joins on 100+ GB tables?

Background: I’ve created a web application that I would like to be able to scale reasonably well. I know I'm not Google or Twitter, but my app uses a fairly large amount of data for each user and thus ...
10
votes
1answer
2k views

Commit vs Fast Commit vs Commit Cleanout in Oracle Database

I was wondering whether someone could verify my understanding regarding the differences between those 3 terms as pertaining to Oracle Databases. Many sources confuse these terms and do not explain ...
10
votes
1answer
4k views

Using MongoDB and PostgreSQL together

My current project is essentially a run of the mill document management system. That said, there are some wrinkles (surprise, surprise). While some of the wrinkles are fairly specific to the ...
9
votes
2answers
5k views

PostgreSQL vs. MySQL - Advantages / Disadvantages with a spatial component

We are the in the process of building out a web application that has a spatial data component. In the beginning our spatial data comparisons will take a given point and return matched overlapping ...
8
votes
2answers
352 views

How to modify an update in Oracle so it performs faster?

I have this query: UPDATE ( SELECT h.valid_through_dt, h.LAST_UPDATE_TMSTMP FROM ETL_FEE_SCH_TMP d, FEE_SCHEDULE_HISTORICAL h WHERE h.FUND_ID = d.FUND_ID AND ...
7
votes
1answer
205 views

Are relations slower than a big, inefficient table?

I've been asked in my job to violate the first normal form (repeating groups across columns, using empty / null values) several times, "for the sake of computer processing power". In a nutshell, a ...
6
votes
2answers
960 views

Single Drive vs Multiple Drives

Generally bottleneck of RDBMS (I am a MySQL user) performance is disk access. SSD provides great performance compared with conventional spindle drives. Question : Is it possible to improve ...
5
votes
4answers
2k views

Why are so many MPP solutions based on PostgreSQL instead of MySQL?

Astor Data, Greenplum and GridSQL all allow Massive Parallel Processing of SQL queries. They are also all built around PostgreSQL technology. Is this just because of licensing issues or are there ...
5
votes
3answers
462 views

Which databases support parallel processing across multiple servers? [closed]

I need a database engine that can utilize multiple servers for processing a single SQL query in parallel. So far I know that this is possible with the some engines, though none of them are feasible ...
5
votes
1answer
688 views

Full text search through many tables in MySQL

We have high traffic NEWS websites, I want to add a feature that every user can search through over all content of site, such as news, polls, comments, galleries,etc . Each of contents type has its ...
5
votes
1answer
226 views

Determining which isolation level is appropriate

This is a homework question. For the following transactions state the isolation level that will maximize throughput without lowering the integrity of the database. Explain the answer. ...
4
votes
4answers
522 views

In Memory Database for high transaction and volume spikes on a website [closed]

I am looking at the IA for a hypothetical application scenario, for example: A high demand application such as an online ticketing website where there can be demand for 100,000 tickets to be ...
4
votes
3answers
680 views

MySQL very slow query when changing one WHERE field despite no index/key

This is quite a confusing issue for me. I have a database full of baseball statistics. Running this query: SELECT * FROM hits JOIN stadiums ON stadiums.gameName = hits.gameName JOIN players ON ...
4
votes
1answer
491 views

Big Data vs Relational Database on making structure of Data-ware house for telecom data analysis [closed]

I'm currently doing my final year project on telecommunication mining. On starting project I got confuse on choosing database. As data on mobile communication is going on increasing so I think Big ...
4
votes
1answer
161 views

how much overhead an error in RDBMS has?

I have a class in my project. On the class I need to do two inner select, to know is there any duplication or not, but I think if I get duplication error and then manage that is better than to select. ...
4
votes
3answers
818 views

STARTUP command fails : Why is that?

I just installed Oracle Database Express Edition 11g Release 2.This is the first time I am using Oracle. Earlier I have used MySql and MSSql and I bet this one is a lot different ! These are the ...
4
votes
0answers
164 views

Which SQL datatypes exist since when and in which RDBMS? [closed]

I found a general comparision of different SQL implementations that only covers some data types (BOOLEAN and TIMESTAMP) and a comparision of datat type support in different RDBMS from 2009 that does ...
3
votes
2answers
2k views

A database in MySQL is a schema in Oracle : I do not understand this statement

Please help me understand this statement: A database in MySQL is a schema in Oracle. I have just started to use Oracle and I find it different from other RDBMS softwares I have used like MSSQL, ...
3
votes
3answers
489 views

How to achieve many to many relationship in this database design?

I am currently working on small travel application in which users can add other users' trips in their wishlist. I am facing difficulty in designing database for wishlist. What I have tried so far is: ...
3
votes
1answer
401 views

Surrogate key / Primary key: Better to use an existing unique data field or create a key field?

I am not sure if this question has been asked or not. At least I couldn't find it. I am curious about a primary key in terms of efficiency with data searching and retrieval. This is a hypothetical ...
3
votes
4answers
4k views

Why is optimistic locking faster than pessimistic locking?

Both forms of locking cause a process to wait for a correct copy of the record if its currently in use by another process. With pessimistic locking, the lock mechanism comes from the DB itself (a ...
3
votes
1answer
141 views

Optimised Schema for City-to-City Distance Table

This is my first question, forgive me if this question is simple. I'm stuck here, trying to implement the relations for the data represented below. I want to scale it vertically (new rows), instead of ...
3
votes
1answer
1k views

How mature is the Firebird database when compared with PostgreSQL and MySQL?

I have used PostgreSQL with small projects and MySQL is running in production environment. No issues with them. I have been hearing of Firebird which is again a solid RDBMS in the open-source area. ...
3
votes
1answer
2k views

Amazon SimpleDB or Amazon RDS?

I'm at a deciding point in my project of whether to implement the database using SimpleDB or Amazon RDS. The database needs to be accessed through an iPhone app and as well through a website. Here are ...
3
votes
1answer
433 views

How to Update same table on deletion in MYSQL?

In my Database I have a table: Employee with recursive association, an employee can be boss of other employee. Following is query I used to create table: CREATE TABLE IF NOT EXISTS `Employee` ...
3
votes
1answer
61 views

Why isn't there a way to label a column as “keyword”

In a typical star schema, you end up with a bunch of columns that are an ID into some lookup table, where the lookup table is pretty much just this: create table hostnames ( id primary key, ...
2
votes
6answers
855 views

Is normalization process needed?

Well after learning DBMS as a subject i got so many questions in mind. Normalization is one of them. As i learnt it there was a lot more confusion and i found that whatever we do in normalization ...
2
votes
3answers
4k views

Detecting SQL Server Utilization with a query

My current project will send queries to an sql server constantly and It may use 100% of the memory or CPU. How can I check if the server is nearing full utilization in a stored procedure so that I ...
2
votes
3answers
1k views

How does an OLAP cube database differ from an RDBMS?

Is a cube database, simply an RDBMS—such as PostgreSQL or MySQL—configured for OLAP via a star or snowflake schema? Or is a cube database different from an RDBMS, and if so how?
2
votes
2answers
265 views

how to create an incremental database copy in postgresql?

Virtual machine software like VirtualBox allow one to make incremental VM clones. That is data, once "touched" (opened writable), will be copied and stored in the incremental cache of the new clone. ...
2
votes
2answers
209 views

What is the advantage of using numeric primary keys in a relational database?

Many tables in a relational database system (in my admittedly limited experience) have this sort of structure (Oracle syntax as that's what I'm used to): create table widgets ( widget_id number ...
2
votes
3answers
659 views

Which database is best for deeply embedded database or through C DLL?

I want a deeply embedded database. Deeply embedded means that the server is started by an application and closed by the application with no tcp/ip or 0 port. The main features of consideration are: ...
2
votes
1answer
346 views

Restriction on self referencing on insert in MYSQL?

How to restrict insert on adding self referencing rows in a recursive relation table (a table contains foreign key points itself). mysql> SELECT * FROM Employee; ...
2
votes
1answer
85 views

Optimizing indexes

I just began optimizing my schemas with indexes (pretty late I guess). I never dealt with huge dataset but I'll be soon coping with about 1 to 5 millions rows. Here is the schema I'm using right now ...
2
votes
1answer
436 views

SQL Server 2008 R2 Database Diagram Error Code

I have sysadmin privileges on a SQL Server 2008 R2 server. I'm working with the development database and want to save a database diagram I created. When I try to save I get the following error ...
1
vote
1answer
367 views

Which RDBMS best fits my need? [closed]

I realise this may be come a subjective mess, but I'm hoping for some objective information on the subject. I also don't want to go shopping, I just want to know 'what to shop for'. I'm very new to ...
1
vote
2answers
143 views

How does optimistic locking actually enforce re-read/update?

My understanding of optimistic locking is that it uses a timestamp on each record in a table to determine the "version" of the record, so that when the record is access by multiple processes at the ...
1
vote
1answer
158 views

Is there a major RDBMS that DOESN'T allow column name quoting/escaping?

The title basically says it: Are there any major DBs that don't handle column name quoting/escaping? For instance, suppose I want to have a column called FROM (and let's assume I have a really good ...
1
vote
3answers
424 views

Which RDBMS has the most advanced “table-valued” functions?

Every Database Management System focuses on specific features and applications. I am using mysql, probably as it is popular and satisfies common needs. However, I came across a problem, which needs ...
1
vote
1answer
86 views

Storing many small - and a few large - strings in an RDBMS

Let's say I have a table, and (among other things) it needs to store a large number of strings. Most will be small (20-100 characters), but a few will be quite large. Reads will be frequent, writes ...
1
vote
1answer
215 views

Is there an Oracle rdbms monitoring API?

We have about a thousand customers with our application installed out of which 500 have an oracle database. Monitoring the database is only one of the requirements. Installing Oracle Enterprise ...
1
vote
1answer
352 views

How does Postgres know which logs have been archived?

I'm asking this because Postgres was hard-stopped yesterday, and I fear that there could be partial / corrupt data in one of my archived log segments. I'd like to simply delete the logs from my slave ...
1
vote
1answer
327 views

file not found - how to remove its configuration?

I run oracle 10.2.0.5. I have the following: SQL> select file#, status, error, recover, tablespace_name, name 2 from v$datafile_header 3 where recover='YES' 4 or (RECOVER IS NULL AND ...