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Displaying posts with tag: text (reset)
Mar
14
2017
TEXT and VARCHAR inefficiencies in your db schema
Posted by Open Query on Tue 14 Mar 2017 00:59 UTC
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The TEXT and VARCHAR definitions in many db schemas are based on old information – that is, they appear to be presuming restrictions and behaviour from MySQL versions long ago. This has consequences for performance. To us, use of for instance VARCHAR(255) is a key indicator for this. Yep, an anti-pattern.

VARCHAR

In MySQL 4.0, VARCHAR used to be restricted to 255 max. In MySQL 4.1 character sets such as UTF8 were introduced and MySQL 5.1 supports VARCHARs up to 64K-1 in byte length. Thus, any occurrence of VARCHAR(255) indicates some old style logic that needs to be reviewed.

Why not just set the maximum length possible? Well…

A VARCHAR is subject to the character set it’s in, for UTF8 this means either 3 or 4 (utf8mb4) bytes per character can be used. So if one specifies VARCHAR(50) CHARSET utf8mb4, …

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Feb
08
2016
How to generate text representation of an image using PHP?
Posted by Satej Sahu on Mon 08 Feb 2016 04:28 UTC
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We will learn how to convert an image to its text representation using PHP that can be used in an html page (if any such requirement arises in your application or just for fun sake :) ).


The steps followed to convert the image to text representation are:

1. Get the width and height of the image to be converted.
2. Loop through every pixel value in the image.
3. At every pixel value, find the color at that position.
4. Apply that color to a # symbol we use to represent that pixel.
5. Finally we get the text representation of the image represented by # (hashes).

Code:

<html>
    <body style="background-color: #000000;">
…

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Feb
01
2013
MySQL: Large VARCHAR vs TEXT?
Posted by Gerrit on Fri 01 Feb 2013 12:20 UTC
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If you have to store big texts in MySQL you have to choose in between using a big VARCHAR column and the TEXT type. So what are the differences between using for example a VARCHAR(2000) and TEXT?

The difference between TEXT and the VARCHAR type is how MySQL is storing the data. TEXT (and BLOB) data is stored off the table, leaving only a pointer to the actual storage.

So using VARCHAR is faster when the size of the data is reasonable. How big the performance difference is depends on the data and the used hardware.

Due the row length limit of 65,535 bytes the data you can store in the table itself is limited (Using utf8 2000 chars could use up to 6000 bytes).

Sep
26
2011
Why a new memory engine may change everything ?
Posted by Cedric PEINTRE on Mon 26 Sep 2011 16:00 UTC
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I’m sure you are aware that the last Percona server release includes a new improved MEMORY storage engine for MySQL.
This new engine is based on Dynamic Row Format and offers some of great features, specialy for VARCHAR, VARBINARY, TEXT and BLOB fields in MEMORY tables.

But because this new MEMORY engine by Percona has some limitations and because Percona server hasn’t used it for its internal temporary tables yet, I would like to talk about what can be the real benefits to have a brand new MEMORY engine based on Dynamic row format specialy for internal memory tables.

Just remember or discover how MySQL uses …

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May
20
2011
Understanding MySQL binary and non-binary string data types
Posted by Ovais Tariq on Fri 20 May 2011 10:31 UTC
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Having reviewed different table structures designed by different people, I have come to the conclusion that binary and non-binary string data types are used without consideration of the consequences of choosing either one. The confusion stems from the fact that both non-binary and binary string data appear to store characters because they can be saved as quoted string.

Jan
20
2010
TEXT vs. VARCHAR
Posted by Sheeri K. Cabral on Wed 20 Jan 2010 18:31 UTC
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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.


Maximum VARCHAR length
The maximum row length of a VARCHAR is restricted by the maximum row length of a table. This is 65,535 bytes …

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Dec
02
2009
MySQL University: Practical Full-Text Search in MySQL
Posted by Stefan Hinz on Wed 02 Dec 2009 22:01 UTC
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This Thursday (December 3rd, 16:00 UTC – note the different time), Bill Karwin will talk about Practical Full-Text Search in MySQL. He'll introduce and compare five different approaches of full-text search with MySQL, using built-in functionality as well as third-party tools. It's interesting to see how vastly performance can vary, depending on which tools you use for which purposes.

For MySQL University sessions, point your browser to this page. You need a browser with a working Flash plugin. You may register for a Dimdim account, but you don't have to. (Dimdim is the conferencing system we're using for MySQL University sessions. It provides integrated voice …

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Dec
02
2009
MySQL University: Practical Full-Text Search in MySQL
Posted by Stefan Hinz on Wed 02 Dec 2009 14:01 UTC
Tags:

This Thursday (December 3rd, 16:00 UTC – note the different time), Bill Karwin will talk about Practical Full-Text Search in MySQL. He'll introduce and compare five different approaches of full-text search with MySQL, using built-in functionality as well as third-party tools. It's interesting to see how vastly performance can vary, depending on which tools you use for which purposes.

For MySQL University sessions, point your browser to this page. You need a browser with a working Flash plugin. You may register for a Dimdim account, but you don't have to. (Dimdim is the conferencing system we're using for MySQL University sessions. It provides integrated voice …

[Read more]
Dec
02
2009
MySQL University: Practical Full-Text Search in MySQL
Posted by Stefan Hinz on Wed 02 Dec 2009 14:01 UTC
Tags:

This Thursday (December 3rd, 16:00 UTC – note the different time), Bill Karwin will talk about Practical Full-Text Search in MySQL. He'll introduce and compare five different approaches of full-text search with MySQL, using built-in functionality as well as third-party tools. It's interesting to see how vastly performance can vary, depending on which tools you use for which purposes.

For MySQL University sessions, point your browser to this page. You need a browser with a working Flash plugin. You may register for a Dimdim account, but you don't have to. (Dimdim is the conferencing system we're using for MySQL University sessions. It provides integrated voice …

[Read more]
Sep
07
2009
How To – Change your ringtone on a Blackberry Curve
Posted by Adam Douglas on Mon 07 Sep 2009 04:11 UTC
Tags:
  1. Go to Profiles
  2. Click on Advanced
  3. Highlight Active profile
  4. Click on Menu and select Edit
  5. SMS Text/Phone/MMS etc.
  6. Select Tone
  7. Ring Tone: Change as desired
  8. Volume: High/Medium/Low
  9. Click back button
  10. Select Save
Showing entries 1 to 10