Hackers,
The attached attempts to make comprehension of the code in
"TS_phrase_execute" a bit easier. I posted similar on the "typo patch"
thread of July 2nd/5th but my comments there reflected my mis-understanding
of the distance operator being exact as opposed to the expected
less-than-or-equal.
I had to make one assumption for the attached - that
"curitem->qoperator.distance" is always >= 0. In the presence of that
assumption the need for the OR goes away.
I don't follow why LposStart is needed so I removed it...
Not compiled or in any way tested...but its not major surgery either -
mostly code comments to make following the logic easier.
David J.
diff --git a/src/backend/utils/adt/tsvector_op.c
b/src/backend/utils/adt/tsvector_op.c
index ad5a254..215f58f 100644
--- a/src/backend/utils/adt/tsvector_op.c
+++ b/src/backend/utils/adt/tsvector_op.c
@@ -1474,14 +1474,14 @@ TS_phrase_execute(QueryItem *curitem,
*/
Rpos = Rdata.pos;
- LposStart = Ldata.pos;
while (Rpos < Rdata.pos + Rdata.npos)
{
/*
- * We need to check all possible distances, so reset
Lpos to
- * guaranteed not yet satisfied position.
+ * For each physically positioned right-side operand
iterate over each
+ * instance of the left-side operand to locate one at
exactly the specified
+ * distance. As soon as a match is found move onto the
next right-operand
+ * and continue searching starting with the next
left-operand.
*/
- Lpos = LposStart;
while (Lpos < Ldata.pos + Ldata.npos)
{
if (WEP_GETPOS(*Rpos) - WEP_GETPOS(*Lpos) ==
@@ -1490,16 +1490,16 @@ TS_phrase_execute(QueryItem *curitem,
/* MATCH! */
if (data)
{
- /* Store position for upper
phrase operator */
+ /* Store the position of the
right-operand */
*pos_iter = WEP_GETPOS(*Rpos);
pos_iter++;
/*
- * Set left start position to
next, because current
- * one could not satisfy
distance for any other right
- * position
+ * Move onto the next
right-operand, and also the next
+ * left-operand as the current
one cannot be a match
+ * for any other.
*/
- LposStart = Lpos + 1;
+ Lpos++
break;
}
else
@@ -1512,18 +1512,23 @@ TS_phrase_execute(QueryItem *curitem,
}
}
- else if (WEP_GETPOS(*Rpos) <= WEP_GETPOS(*Lpos)
||
- WEP_GETPOS(*Rpos) -
WEP_GETPOS(*Lpos) <
+ else if (WEP_GETPOS(*Rpos) - WEP_GETPOS(*Lpos) <
curitem->qoperator.distance)
{
/*
- * Go to the next Rpos, because Lpos is
ahead or on less
- * distance than required by current
operator
+ * We are now within the required
distance so
+ * continue onto the next right-operand
and retry
+ * the current left-operand to see if
the added
+ * distance causes it to match.
*/
break;
}
+ /*
+ * The current left-operand is too far away so
+ * try the next one.
+ */
Lpos++;
}
--
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