Re: Postgresql XML parsing

Hello,

> On 03/12/2014 09:36 AM, Ashoke wrote:
> > Hi,
> >
> >    I am working on adding a functionality to PostgreSQL. I need to parse
> >    the XML format query plan (produced by PostgreSQL v9.3) and save it in
> >    a simple data structure (say C structure). I was wondering if
...
> The only XML parsing we have is where Postgres is built with libxml,
> in which case we use its parser. But query plan XML is delivered to a
> client (or a log file, which means more or less the same thing
> here).

As a HACKERS' matter, explain output can be obtained from
ExplainPrintPlan() in any format in backend. I don't know if it
is the case though.

> If you want to parse it then it should be parsed in the client
> - that's why we provide it. Inside postgres I don't see a point in
> parsing the XML rather than handling the query plan directly.
> 
> The worst possible option would be to make a hand-cut XML parser,
> either in the client or the server - XML parsing has all sorts of
> wrinkles that can bite you badly.

I agree with it. If XML input is not essential, JSON format would
be parsed more easily than xml. 9.3 already intrinsically has a
JSON parser infrastructure available for the purpose.

regards,

-- 
Kyotaro Horiguchi
NTT Open Source Software Center