Pythian Group

On first glance, it looks like TEXT and VARCHAR can store the same information. However, there are fundamental differences between the way TEXT fields and VARCHAR fields work, which are important to take into consideration.

Standard
VARCHAR is actually part of the ISO SQL:2003 standard; The TEXT data types, including TINYTEXT, are non-standard.

Storage
TEXT data types are stored as separate objects from the tables and result sets that contain them. This storage is transparent — there is no difference in how a query involving a TEXT field is written versus one involving a VARCHAR field. Since TEXT is not stored as part of a row, retrieval of TEXT fields requires extra [edited 1/22] memory overhead.

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This is the 137th edition of Log Buffer, the weekly review of database blogs. Dave Edwards is enjoying a week off, and so as part of my plot to take over the world, I am writing this week’s Log Buffer.

First, the fun stuff: Josh Berkus tells us that the American English Translation of the Manga Guide to Databases is available in Japanese Fairies and Third Normal Form.

Then, the basics:
Giri Mandalika points to an article on Using MySQL with Java Technology. This is a basic article on how to connect, and does not go into all the wonders that Connector/J can really do. Speaking of basics, Decipher Information Systems has an article on Back to the Basics: Refreshing a Regular View Definition in SQL Server and Oracle. Chet Justice, the Oracle Nerd, writes about transactions in ORA-8177 Can’t Serialize Access For this Transaction. There is theoretical information about isolation levels that applies to all database systems. Mats Kindahl explains some transactional theory when talking about why Mixing Engines in Transactions in MySQL can get you into trouble.

It’s hard to get more basic than what data type to use for a single character Read the rest of this entry . . .

Or, “Missing information in the MySQL Manual”.

Just earlier today, I was using POW(), which I’ve grown quite fond of, simply because it makes life easier. I prefer using it like SELECT 512*POW(1024,2) to find out the number of bytes to put in a variable, for example.

First, let’s take a look at the POW function:

Name: 'POW'
Description:
Syntax:
POW(X,Y)

Returns the value of X raised to the power of Y.

Okay, so it gives us a value; but what about the data type? Let’s take 512*POW(1024,2) as an example.

5067 (blogs) > SELECT 512*POW(1024,2) AS example;
+-----------+
| example   |
+-----------+
| 536870912 |
+-----------+
1 row in set (0.00 sec)

What is that? Well, it sure does look like an INT at this point, doesn’t it?

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