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> The previous patch fixed an infinite recursion bug in

Browse Source 
> contrib/tablefunc/tablefunc.c:connectby. But, other unmanageable error
> seems to occur even if a table has commonplace tree data(see below).
>
> I would think the patch, ancestor check, should be
>
>   if (strstr(branch_delim || branchstr->data || branch_delim,
>                        branch_delim || current_key || branch_delim))
>
> This is my image, not a real code. However, if branchstr->data includes
> branch_delim, my image will not be perfect.

Good point. Thank you Masaru for the suggested fix.

Attached is a patch to fix the bug found by Masaru. His example now
produces:

regression=# SELECT * FROM connectby('connectby_tree', 'keyid',
'parent_keyid', '11', 0, '-') AS t(keyid int, parent_keyid int, level
int,
branch text);
  keyid | parent_keyid | level |  branch

-------+--------------+-------+----------
     11 |              |     0 | 11
     10 |           11 |     1 | 11-10
    111 |           11 |     1 | 11-111
      1 |          111 |     2 | 11-111-1
(4 rows)

While making the patch I also realized that the "no show branch" form of
the  function was not going to work very well for recursion detection.
Therefore  there is now a default branch delimiter ('~') that is used
internally, for  that case, to enable recursion detection to work. If
you need a different  delimiter for your specific data, you will have to
use the "show branch" form  of the function.

Joe Conway
This commit is contained in:
Bruce Momjian
2002-10-03 17:11:12 +00:00
parent a0bf2503ea
commit 620dddf88a
2 changed files with 29 additions and 7 deletions
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27
contrib/tablefunc/tablefunc.c
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@ -652,6 +652,9 @@ connectby_text(PG_FUNCTION_ARGS)
branch_delim = GET_STR(PG_GETARG_TEXT_P(5));
show_branch = true;
}
else
/* default is no show, tilde for the delimiter */
branch_delim = pstrdup("~");
per_query_ctx = rsinfo->econtext->ecxt_per_query_memory;
oldcontext = MemoryContextSwitchTo(per_query_ctx);
@ -798,10 +801,16 @@ build_tuplestore_recursively(char *key_fld,
char *current_branch;
char **values;
StringInfo branchstr = NULL;
StringInfo chk_branchstr = NULL;
StringInfo chk_current_key = NULL;
/* start a new branch */
branchstr = makeStringInfo();
/* need these to check for recursion */
chk_branchstr = makeStringInfo();
chk_current_key = makeStringInfo();
if (show_branch)
values = (char **) palloc(CONNECTBY_NCOLS * sizeof(char *));
else
@ -854,22 +863,24 @@ build_tuplestore_recursively(char *key_fld,
{
/* initialize branch for this pass */
appendStringInfo(branchstr, "%s", branch);
appendStringInfo(chk_branchstr, "%s%s%s", branch_delim, branch, branch_delim);
/* get the next sql result tuple */
spi_tuple = tuptable->vals[i];
/* get the current key and parent */
current_key = SPI_getvalue(spi_tuple, spi_tupdesc, 1);
appendStringInfo(chk_current_key, "%s%s%s", branch_delim, current_key, branch_delim);
current_key_parent = pstrdup(SPI_getvalue(spi_tuple, spi_tupdesc, 2));
/* check to see if this key is also an ancestor */
if (strstr(branchstr->data, current_key))
elog(ERROR, "infinite recursion detected");
/* get the current level */
sprintf(current_level, "%d", level);
/* extend the branch */
/* check to see if this key is also an ancestor */
if (strstr(chk_branchstr->data, chk_current_key->data))
elog(ERROR, "infinite recursion detected");
/* OK, extend the branch */
appendStringInfo(branchstr, "%s%s", branch_delim, current_key);
current_branch = branchstr->data;
@ -913,6 +924,12 @@ build_tuplestore_recursively(char *key_fld,
/* reset branch for next pass */
xpfree(branchstr->data);
initStringInfo(branchstr);
xpfree(chk_branchstr->data);
initStringInfo(chk_branchstr);
xpfree(chk_current_key->data);
initStringInfo(chk_current_key);
}
}