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Re: why size of table c united from table a and b are bigger than a+b ?
Posted by: Ingo Strüwing
Date: July 31, 2006 03:23AM

Well, I'm no expert in query optimization. You may get better replies in the "General" or "Optimizer" forums.

Without the table definition (SHOW CREATE TABLE) the question cannot be answered.

The size of c is bigger than a+b because there are more rows than a+b in it or the rows are longer. You insert five columns into c, but use thre from a and two from b only. But a or b can have more columns, as c can have. So it is difficult to make a good guess.

The conversion from latin1 to utf8 can enlarge the records if you have many non-ASCII characters in your tables.

I do not understand this question: "Will sql 'insert into .. select ' write temp data into table c". What do you mean with "temp data"? Data that is temporary and vanishes after some time? Probably not, but what is it?

Regards,
Ingo

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Re: why size of table c united from table a and b are bigger than a+b ?
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