Database Administrators Stack Exchange
Database Administrators Stack Exchange

Questions tagged [rdbms]

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

Short for Relational Database Management System, a widely used type of database manager.

Relational database management systems are the best known type of database managers today, and certainly the most successful if viewed in terms of revenue and brand profile of the vendors. Commonly used relational database management systems include Microsoft SQL Server, Oracle, MySQL, Sybase, DB/2 and PostgreSQL.

The core defining characteristic of a relational database management system is the ability to join two data sets together by matching on common column values (known as an equi-join or other predicates (known as a t-join). Relational databases are solely queried through a query language interface - typically SQL, although other query languages have been used.

The logical model behind relational databases is known as relational algebra, originally described in Edgar Codd's 1970 paper A relational model for large shared data banks. However, modern SQL dialects extend substantially on the expressiveness of this model.

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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 json format: { "tcp_flags": "0", "src_as":…
somecallmemike
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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 a traditional RDBMS? At what level (physical,…
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Is it acceptable to have circular foreign key references\How to avoid them?

Is it acceptable to have a circular reference between two tables on the foreign key field? If not, how can these situations be avoided? If so, how can data be inserted? Below is an example of where (in my opinion) a circular reference would be…
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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 requested data.
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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 project, I believe there are some general observations…
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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, and each Account has an Amount, which updates in…
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If NoSQL stands for "Not only SQL", is SQL a subset of NoSQL?

The definition is a bit confusing - basically I'm asking if SQL is a subset of the NoSQl family: I'm asking this because "Not-only" means NoSQL is much larger, but still includes SQL as a part of it. On the other hand, since we can't do typical sql…
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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?
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What does "index" mean on RDBMSs?

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 of a DBMS. My question is : what are good examples…
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Execute system commands in PostgreSQL

My requirement is to execute a system command like (ls) or a C program when a trigger executes. Is there any way to create a trigger function to solve this problem?
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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 session logs, but then you want to be able to create…
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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 them in detail so it was a bit of a challenge to…
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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 has fairly high data requirements. I want to be…
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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 native lock object), whereas with optimistic locking,…
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How to insert values in junction table for many to many relationships?

I have three tables in database: trips(trip_id(pk), trip_name(unique), user_id(fk)) places(place_id(pk), place_name(unique)) trips_places_asc(trip_id(fk), place_id(fk)) Since many trips can have many places, I have one junction table as…
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