Обсуждение: CVS HEAD dumps core on simple tsvector input example

regression=# SELECT 'a very fat cat sat:4 on:5 a:6 mat:7'::tsvector;                  tsvector                    
-----------------------------------------------'a' 'on':5 'cat' 'fat' 'mat':7 'sat':4 'very'
(1 row)

regression=# SELECT 'a very fat cat sat:4 on:5 a:6 mat:7'::tsvector;
server closed the connection unexpectedly

Notice it's the same input both times --- only the second one crashes.
The coredump happens inside repalloc, making me suspect a memory clobber
is involved.

BTW, why does the 'a':6 lexeme disappear?  To the extent that I
understand how this should work, I'd have expected 'a' and 'a':6
to merge into 'a':6 not plain 'a'.
        regards, tom lane

Tom Lane wrote:

> BTW, why does the 'a':6 lexeme disappear?  To the extent that I
> understand how this should work, I'd have expected 'a' and 'a':6
> to merge into 'a':6 not plain 'a'.

'a':1,6 perhaps?

-- 
Alvaro Herrera                 http://www.amazon.com/gp/registry/DXLWNGRJD34J
We take risks not to escape from life, but to prevent life escaping from us.

Alvaro Herrera <alvherre@commandprompt.com> writes:
> Tom Lane wrote:
>> BTW, why does the 'a':6 lexeme disappear?  To the extent that I
>> understand how this should work, I'd have expected 'a' and 'a':6
>> to merge into 'a':6 not plain 'a'.

> 'a':1,6 perhaps?

No, it would be inappropriate to add a '1' that wasn't specified.

My reasoning is that 'a':1 and 'a':6 are distinct bits of information,
hence their combination is 'a':1,6.  But 'a' doesn't give any more
information than 'a':6 so it should be dropped by the
duplicate-elimination code.  It's not clear to me whether that's
what Oleg and Teodor think, though.

Hm, just found a variant of the bug:

regression=# select 'a a:6'::tsvector;tsvector 
----------'a'
(1 row)

regression=# select 'a a:6'::tsvector;                                tsvector                                 

--------------------------------------------------------------------------'a':6,16255C,0,12C,8C,2640,0,512,0,312,12C,400C,0,312,0,1,0,0,8448C,21,6
(1 row)

This makes it look even more like a memory-corruption issue.
        regards, tom lane