Re: CurrentMemoryContext and MemoryContextStrdup

I understand. Many thanks. I will try to modify my program to adapt it to
this.
Best regards,
Yessica Brinkmann

El mar., 26 nov. 2019 a las 15:11, Tom Lane (<tgl(at)sss(dot)pgh(dot)pa(dot)us>) escribió:

> Yessica Brinkmann <yessica(dot)brinkmann(at)gmail(dot)com> writes:
> > Now, as I understand it (I don't know if I'm right), what I would have to
> > do would be this:
> > 1. I save the CurrentMemoryContext, for example as follows:
> > MemoryContext oldcontext = CurrentMemoryContext;
> > 2. I make the call to SPI, which was what caused the context problem.
> > 3. I copy my variable in a different context, for example as follows:
> > MemoryContext newcontext;
> > char * copy = MemoryContextStrdup (newcontext, data);
> > 4. Then, at the end of my call to SPI, after SPI_finish () I would have
> in
> > the copy variable, the copy of the data variable, to use it as I want.
> > Is that so? I am correct at least to try to modify my program or is it
> > totally something else what should I do?
>
> IIRC, the real issue here is that SPI_connect creates and switches into
> a temporary context that SPI_finish will destroy; and the string you want
> is in that short-lived context. So what you want is to copy it out of
> that context, probably into the context that was current before you
> call SPI_connect. So what you want is to do this before calling
> SPI_connect:
>
> MemoryContext outer_context = CurrentMemoryContext;
>
> and then this, inside the SPI operation, will save your string safely:
>
> copy = MemoryContextStrdup(outer_context, data);
>
> regards, tom lane
>