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Replace insertion sort in contrib/intarray with qsort().

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It's all very well to claim that a simplistic sort is fast in easy
cases, but O(N^2) in the worst case is not good ... especially if the
worst case is as easy to hit as "descending order input".  Replace that
bit with our standard qsort.

Per bug #12866 from Maksym Boguk.  Back-patch to all active branches.
This commit is contained in:
Tom Lane
2015-03-15 23:22:03 -04:00
parent 396ef6fd8d
commit 40b0c10b76
1 changed files with 24 additions and 25 deletions
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49
contrib/intarray/_int_tool.c
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@ -195,39 +195,38 @@ rt__int_size(ArrayType *a, float *size)
return;
}
/* qsort_arg comparison function for isort() */
static int
isort_cmp(const void *a, const void *b, void *arg)
{
int4 aval = *((const int4 *) a);
int4 bval = *((const int4 *) b);
/* len >= 2 */
if (aval < bval)
return -1;
if (aval > bval)
return 1;
/*
* Report if we have any duplicates. If there are equal keys, qsort must
* compare them at some point, else it wouldn't know whether one should go
* before or after the other.
*/
*((bool *) arg) = true;
return 0;
}
/* Sort the given data (len >= 2). Return true if any duplicates found */
bool
isort(int4 *a, int len)
{
int4 tmp,
index;
int4 *cur,
*end;
bool r = FALSE;
bool r = false;
end = a + len;
do
{
index = 0;
cur = a + 1;
while (cur < end)
{
if (*(cur - 1) > *cur)
{
tmp = *(cur - 1);
*(cur - 1) = *cur;
*cur = tmp;
index = 1;
}
else if (!r && *(cur - 1) == *cur)
r = TRUE;
cur++;
}
} while (index);
qsort_arg(a, len, sizeof(int4), isort_cmp, (void *) &r);
return r;
}
/* Create a new int array with room for "num" elements */
ArrayType *
new_intArrayType(int num)
{