if one has a nested transaction does the outer-most transaction take precedence?

rubyonrails-talk
1

Hi,

Anyone know, if I have a nested transaction, will it be the outer most transaction (i.e. from outermost transaction start, to outermost transaction end) that will be used?

i.e. noting Rails doesn't currently support nested transactions. Another way to ask would be to say, if there was a database statement error between the end of the innermost transaction and the end of the outmost transaction, would the innermost transaction database statements be rolled back?

2

Hi,

Anyone know, if I have a nested transaction, will it be the outer most transaction (i.e. from outermost transaction start, to outermost transaction end) that will be used?

i.e. noting Rails doesn't currently support nested transactions. Another way to ask would be to say, if there was a database statement error between the end of the innermost transaction and the end of the outmost transaction, would the innermost transaction database statements be rolled back?

THis is probably database dependant but on mysql at least a nested
begin will commit the existing transaction and begin a new one (which
is why rails is careful not to start a new actual transaction in this
case). rails 2.3 supports savepoints for what it's worth.

Fred

3

thanks - so this means for the moment at least (until v2.3) one has to be careful re having a method with a transaction begin, that within may call another method that itself has a transaction begin. So really group your methods into ones that use & don't use transactions explicitly I guess...

4

thanks - so this means for the moment at least (until v2.3) one has to be careful re having a method with a transaction begin, that within may call another method that itself has a transaction begin. So really group your methods into ones that use & don't use transactions explicitly I guess...

You're ok if you're not doing things by hand: if you do

Foo.transaction do    Foo.transaction do      ...    end end

then the inner call to transaction is basically a no-op.

Fred

5

ok - so just to be clear then, statement A will rollback if there is an issue with the statement B? this is at least good then for me

Foo.transaction do   Foo.transaction do      statement A     ...   end   statement B end

6

ok - so just to be clear then, statement A will rollback if there is an issue with the statement B? this is at least good then for me

Foo.transaction do Foo.transaction do     statement A    ... end statement B end

Correct. The above is equivalent to

Foo.transaction do   statement A   statement B end

(Again assuming you're not using 2.3's savepoint support (which is
turned off by default I believe))

Fred