Tagged Questions
0
votes
2answers
74 views
Why do people use MySQL while it has no INTERSECT? [closed]
I see that PostgreSQL is being developed, for example it has INTERSECT and JSON types. Why MySQL is not being developed? Why people use MySQL over PostgreSQL. What I'm missing?
3
votes
1answer
100 views
Do isolation levels only apply to SELECTS and not UPDATES? [closed]
Scenario that might demonstrate different behavior for SELECTS depending on the isolation level:
1) 0:00 Thread A runs a query that returns 1000 rows that takes 5 minutes to complete
2) 0:02 Thread B ...
3
votes
2answers
135 views
SQL ANSI JOIN precedence
I have a query that looks like this:
SELECT *
FROM TBLA A
LEFT JOIN TBLB B ON A.Col1 = B.Col2
RIGHT JOIN TBLC C ON B.Col3 = C.Col4
JOIN TBLD D ON C.Col5 = D.Col6
In which order ...
0
votes
2answers
53 views
How to remove tables and indexes?
I've a file with the SQL statements to create tables, indexes, etc, and another file with data test to use in the test database. Then, I want that they can be removed.
How to remove table and indexes ...
4
votes
2answers
231 views
For absolute performance, is SUM faster or COUNT?
This relates to counting the number of records that match a certain condition, e.g. invoice amount > $100.
I tend to prefer
COUNT(CASE WHEN invoice_amount > 100 THEN 1 END)
However, this is ...
3
votes
5answers
247 views
Alter table on live production databases
How do most "popular" (MySQL, Postgres...) database system handle altering tables on live production databases (like adding, deleting or changing the type of colums)?
I know the correct way is to ...
2
votes
1answer
81 views
Model with variable number of “properties” of different types.
I would like to have a table of microscope slides, where on top of the basic id, name,date_created would each slide also have a number of editable "properties".
Imagine one slide having
...
1
vote
1answer
215 views
Scalability limitations of PostgreSQL and MySQL
I've heard that performance of non-sharded relational database such as MySQL or PostgreSQL "breaks" beyond 10 TB.
I suspect that limits as such do exist as one would not come up with Netezza, ...
-1
votes
1answer
155 views
Database for an application similar to Chatroulette
I am making an app that is similar to Chatroulette.
When a user starts the app it finds someone that is not currently talking to anyone and have them talk to each other. At any point a user could ...
1
vote
1answer
429 views
PostgreSQL 9.1 vs MySQL 5.6 with InnoDB ? Which is better for scaling?
PostgreSQL 9.1 vs MySQL 5.6 with InnoDB. I do know that PostgreSQL offers better SQL features.
I am currently using MySQL 5.6 lab release (the one with InnoDb full text search feature)(not in ...
2
votes
2answers
166 views
MySql Vs. Postgresql for a blog application
I am designing a blog application. Which of these fits better?
In which use cases will mysql be good and for what use cases will postgresql be good?
1
vote
2answers
333 views
How to create column in DB with default value random string
Can I create column in DB table (PostgreSQL or MySQL) which have default value random string, and how ?
If is not possible, please let me know that.
8
votes
1answer
178 views
Disable explicit commits in JDBC, detect them in SQL, or put the database in a readonly state
Background: I'm working on http://sqlfiddle.com (my site), and am trying to prevent one avenue of abuse possible there. I'm hoping that by asking about a problem I'm currently addressing, I don't ...
3
votes
2answers
110 views
Migrating and normalizing data
We are rewriting a large Django application which uses a MySQL database, and the database schema needs to undergo major modifications. We're also porting the app to use PostgreSQL, for a couple of ...
0
votes
2answers
174 views
Creating a test database from Production database (different machines & servers)
I'd like to set up a test database on a separate server. Production database is MS SQL Server and the test server is a *nix box so I'd like to have the test server running either PostgreSQL or MySQL.
...
