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Re: BUG #5793: tsquery error

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: "" <ms(at)instytut(dot)com(dot)pl>
Cc: pgsql-bugs(at)postgresql(dot)org
Subject: Re: BUG #5793: tsquery error
Date: 2010-12-19 04:51:06
Message-ID: 16079.1292734266@sss.pgh.pa.us (view raw or flat)
Thread:
Lists: pgsql-bugs
"" <ms(at)instytut(dot)com(dot)pl> writes:
> The expression 'a & !(c) | a & b' is interpreted as '( a | !c ) & a & b'.
> select 'a & !(c) | a & b'::tsquery;

> Subsequent "rewrites" of the same expression give inconsistent results:

> select '(a & !(c | d)) | (a & b)'::tsquery; -> 'a & !(c | d) | a & b'
> (correct)
> select 'a & !(c | d) | a & b'::tsquery; -> '(a | !(c | d)) & a & b' (not
> correct)

Hmm.  The immediate problem seems to be fixed by

diff --git a/src/backend/utils/adt/tsquery.c b/src/backend/utils/adt/tsquery.c
index db9236a474157a7851e2a80516e865c050543634..ba09b3b2ce7fcc0815edf4a4622663291d6f0b8f 100644
*** a/src/backend/utils/adt/tsquery.c
--- b/src/backend/utils/adt/tsquery.c
*************** makepol(TSQueryParserState state,
*** 371,378 ****
  			case PT_OPEN:
  				makepol(state, pushval, opaque);
  
! 				if (lenstack && (opstack[lenstack - 1] == OP_AND ||
! 								 opstack[lenstack - 1] == OP_NOT))
  				{
  					lenstack--;
  					pushOperator(state, opstack[lenstack]);
--- 371,378 ----
  			case PT_OPEN:
  				makepol(state, pushval, opaque);
  
! 				while (lenstack && (opstack[lenstack - 1] == OP_AND ||
! 									opstack[lenstack - 1] == OP_NOT))
  				{
  					lenstack--;
  					pushOperator(state, opstack[lenstack]);

but I can't say that I've got much confidence in the rest of that
function.  It's an utter kluge.

			regards, tom lane

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