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> The previous patch fixed an infinite recursion bug in 

> 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
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
contrib/tablefunc/README.tablefunc
View File

@ -365,7 +365,9 @@ Inputs
branch_delim
if optional branch value is desired, this string is used as the delimiter
If optional branch value is desired, this string is used as the delimiter.
When not provided, a default value of '~' is used for internal
recursion detection only, and no "branch" field is returned.
Outputs
@ -388,7 +390,10 @@ Notes
the level value output
3. If the branch field is not desired, omit both the branch_delim input
parameter *and* the branch field in the query column definition
parameter *and* the branch field in the query column definition. Note
that when branch_delim is not provided, a default value of '~' is used
for branch_delim for internal recursion detection, even though the branch
field is not returned.
4. If the branch field is desired, it must be the forth column in the query
column definition, and it must be type TEXT

27
contrib/tablefunc/tablefunc.c
View File

@ -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);
}
}