Re: SQL/MED - file_fdw

On Tue, Feb 8, 2011 at 00:30, Shigeru HANADA <hanada(at)metrosystems(dot)co(dot)jp> wrote:
> Fixed version is attached.

I reviewed your latest git version, that is a bit newer than the attached patch.
http://git.postgresql.org/gitweb?p=users/hanada/postgres.git;a=commit;h=0e1a1e1b0e168cb3d8ff4d637747d0ba8f7b8d55

The code still works with small adjustment, but needs to be rebased on the
latest master, especially for extension support and copy API changes.

Here are a list of comments and suggestions:

* You might forget some combination or unspecified options in
file_fdw_validator().
For example, format == NULL or !csv && header cases. I've not tested all
cases, but please recheck validations used in BeginCopy().

* estimate_costs() needs own row estimation rather than using baserel.
> > What value does baserel->tuples have?
> > Foreign tables are never analyzed for now. Is the number correct?
> No, baserel->tuples is always 0, and baserel->pages is 0 too.
> In addition, width and rows are set to 100 and 1, as default values.

It means baserel is not reliable at all, right? If so, we need alternative
solution in estimate_costs(). We adjust statistics with runtime relation
size in estimate_rel_size(). Also, we use get_rel_data_width() for not
analyzed tables. We could use similar technique in file_fdw, too.

* Should use int64 for file byte size (or, uint32 in blocks).
unsigned long might be 32bit. ulong is not portable.

* Oid List (list_make1_oid) might be more handy than Const to hold relid
in FdwPlan.fdw_private.

* I prefer FileFdwExecutionState to FileFdwPrivate, because there are
two different 'fdw_private' variables in FdwPlan and FdwExecutionState.

* The comment in fileIterate seems wrong. It should be
/* Store the next tuple as a virtual tuple. */ , right?

* #include <sys/stat.h> is needed.

--
Itagaki Takahiro