Re: remove contrib/xml2

On Mon, Feb 1, 2010 at 5:23 PM, Andrew Dunstan <andrew(at)dunslane(dot)net> wrote:
> Robert Haas wrote:
>> (2) add a very, very large warning that this will crash if you do
>> almost anything with it.
>
> I think that's an exaggeration. Certain people are known to be using it
> quite successfully.

Hmm. Well, all I know is that the first thing I tried crashed the server.

CREATE TABLE xpath_test (id integer NOT NULL, t xml);
INSERT INTO xpath_test VALUES (1, '<doc><int>1</int></doc>');
SELECT * FROM xpath_table('id', 't', 'xpath_test', '/doc/int', 'true')
as t(id int4);

It doesn't crash if you change the type of t from xml to text; instead
you get a warning about some sort of memory allocation problem.

DROP TABLE xpath_test;
CREATE TABLE xpath_test (id integer NOT NULL, t text);
INSERT INTO xpath_test VALUES (1, '<doc><int>1</int></doc>');
SELECT * FROM xpath_table('id', 't', 'xpath_test', '/doc/int', 'true')
as t(id int4);

yields:

WARNING: problem in alloc set ExprContext: bogus aset link in block
0x14645e0, chunk 0x14648b8

And then there's this (see also bug #5285):

DELETE FROM xpath_test;
INSERT INTO xpath_test VALUES (1, '<rowlist><row a="1"/><row a="2"
b="oops"/></rowlist>');
SELECT * FROM xpath_table('id', 't', 'xpath_test',
'/rowlist/row/@a|/rowlist/row/@b', 'true') as t(id int4, a text, b
text);

which yields an answer that is, at least, extremely surprising, if not
flat-out wrong:

id | a | b
----+---+------
1 | 1 | oops
1 | 2 |
(2 rows)

Bugs #4953 and #5079 can also be reproduced in CVS HEAD. Both crash the server.

...Robert