Re: A dynamic SQL/ecpg question

Murphy Pope wrote:
> Can anyone explain the difference between the following descriptor members?
>
>
>
> LENGTH
>
> OCTET_LENGTH
>
> RETURNED_LENGTH
>
> RETURNED_OCTET_LENGTH
>
>
>
> From looking at the source code, the last two are identical and it
> looks like they return the length of an individual row/column value
> (i.e. for a varchar column, they would return the length of an actual
> varchar value).
>
>
>
> I think OCTET_LENGTH will return the size of the column as stored in the
> database.
>
>
>
> I can't quite figure out what LENGTH is supposed to do. It returns
> PQfmod( ) - VARHDRSZ. How is that different from the OCTET_LENGTH?

The problem is with pgsql's frontend/backend protocol (libpq). You only
get these two values, and I can't imagine a query which gives the
requested values. So you can't get/set any sensible values for two of them.
Christof