Re: What is the maximum encoding-conversion growth rate, anyway?

Added to TODO:

* Change memory allocation for multi-byte functions so memory is allocated inside conversion functions
 Currently we preallocate memory based on worst-case usage.


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Tom Lane wrote:
> Tatsuo Ishii <ishii@postgresql.org> writes:
> > Thinking more, it striked me that users can define arbitarily growing
> > rate by using CFREATE CONVERSION. So it seems we need functionality to
> > define the growing rate anyway.
> 
> Seems to me that would be an argument for moving the palloc inside the
> conversion functions, as I suggested before.
> 
> In practice though, I find it hard to imagine a pair of encodings for
> which the growth rate is more than 3x.  You'd need something that
> translates a single-byte character into 4 or more bytes (pretty
> unlikely, especially considering we require all these encodings to be
> ASCII supersets); or something that translates a 2-byte character into
> more than 6 bytes.
> 
>             regards, tom lane
> 
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