be careful with size of keys being used in joins

[steve]

Hi, I want to share my experience with you. If you have large tables,
and you are doing joins, be extra careful that the keys in the joins
have exactly the same size (and type). Don’t mix mediumint and int
for example.

There is a huge performance hit if your join keys are not the same
size. This IS documented on mysql.com, but not everyone reads
everything :D

Just beware!

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[Thomas Bartkus]

"steve" <Us************@dbForumz.com> wrote in message
news:4_***************************************@dbf orumz.com...

Hi, I want to share my experience with you. If you have large tables,
and you are doing joins, be extra careful that the keys in the joins
have exactly the same size (and type). Don't mix mediumint and int
for example.

There is a huge performance hit if your join keys are not the same
size. This IS documented on mysql.com, but not everyone reads
everything :D

Just beware!

Owwwhhh! So that's it.
It is documented and I didn't read it.

Thank you Steve
Thomas Bartkus

[steve]

"" wrote:

"steve" <Us************@dbForumz.com> wrote in message
news:4_***************************************@dbf orumz.com...

Hi, I want to share my experience with you. If you have

large tables,

and you are doing joins, be extra careful that the keys in

the joins

have exactly the same size (and type). Don't mix mediumint

and int

for example.

There is a huge performance hit if your join keys are not

the same

size. This IS documented on mysql.com, but not everyone reads
everything :D

Just beware!

Owwwhhh! So that's it.
It is documented and I didn't read it.

Thank you Steve
Thomas Bartkus

I have spent AT LEAST A DAY dealing with all kind of weird mysql
errors (error .., mysql has gone away), which were solved by making
sure the join fields are the same. The problem is that there is no
way to tie the error to the this problem.

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