char vs. text

[Anon]

I am new to mySQL and have some questions:

1. Will the TEXT type receive the same size as the input or is it fixed? (If I input 1kb of text, will the db increase 1kb or 6,5kb which is the maximum of that type?)

2. Is the TEXT much slower than the CHAR. If I have 254 characters in a CHAR and 254 characters in a TEXT type, will the search take much longer in the TEXT type. (When searching several records).

3. Is the content in TEXT stored in another way than in the CHAR? (Will any characters stored look different, disappear or something like that?)

Thanks / Henrik

[ingooellers]

Hi,

Henrik Erlandsson wrote:

---

I am new to mySQL and have some questions:

1. Will the TEXT type receive the same size >as the input or is it fixed? (If I input >1kb of text, will the db increase 1kb or >6,5kb which is the maximum of that type?)
   TEXT is dynamic, but it uses only a little bit more than the data inside.

2. Is the TEXT much slower than the CHAR. >If I have 254 characters in a CHAR and 254 >characters in a TEXT type, will the search >take much longer in the TEXT type. (When >searching several records).
   Due its static character CHAR-Types (of maximum 256 characters or so (?)) are "more relational" than TEXT-Fields.
   Add a FULLTEXT index to your fields and get satisfied.

Performance difference you have to expect first, if the filesize is oversizing the internal memory-cache size of the mysql-server. Using indexes are a good choice and you will be lucky with much MBytes

3. Is the content in TEXT stored in another >way than in the CHAR? (Will any characters >stored look different, disappear or >something like that?)
   I think by experience: no. Standard character sets (ASCII ...) are supported.
   Look into your docs for localizing scandinavian fonts or test it with your local characters.

Regards
Ingo

[Anon]

Thank you for answers!

// Henrik