Re: About connectby() again

Your patch has been added to the PostgreSQL unapplied patches list at:

http://candle.pha.pa.us/cgi-bin/pgpatches

I will try to apply it within the next 48 hours.

---------------------------------------------------------------------------

Joe Conway wrote:
> Masaru Sugawara wrote:
> > 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.
>
> If there are no objections, please apply. Thanks,
>
> Joe

> Index: contrib/tablefunc/README.tablefunc
> ===================================================================
> RCS file: /opt/src/cvs/pgsql-server/contrib/tablefunc/README.tablefunc,v
> retrieving revision 1.3
> diff -c -r1.3 README.tablefunc
> *** contrib/tablefunc/README.tablefunc 2 Sep 2002 05:44:04 -0000 1.3
> --- contrib/tablefunc/README.tablefunc 26 Sep 2002 22:57:27 -0000
> ***************
> *** 365,371 ****
>
> branch_delim
>
> ! if optional branch value is desired, this string is used as the delimiter
>
> Outputs
>
> --- 365,373 ----
>
> branch_delim
>
> ! 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
>
> ***************
> *** 388,394 ****
> 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
>
> 4. If the branch field is desired, it must be the forth column in the query
> column definition, and it must be type TEXT
> --- 390,399 ----
> 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. 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
> Index: contrib/tablefunc/tablefunc.c
> ===================================================================
> RCS file: /opt/src/cvs/pgsql-server/contrib/tablefunc/tablefunc.c,v
> retrieving revision 1.9
> diff -c -r1.9 tablefunc.c
> *** contrib/tablefunc/tablefunc.c 14 Sep 2002 19:32:54 -0000 1.9
> --- contrib/tablefunc/tablefunc.c 26 Sep 2002 23:09:27 -0000
> ***************
> *** 652,657 ****
> --- 652,660 ----
> 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);
> ***************
> *** 798,807 ****
> --- 801,816 ----
> 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
> ***************
> *** 854,875 ****
> {
> /* initialize branch for this pass */
> appendStringInfo(branchstr, "%s", branch);
>
> /* 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);
> 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 */
> appendStringInfo(branchstr, "%s%s", branch_delim, current_key);
> current_branch = branchstr->data;
>
> --- 863,886 ----
> {
> /* 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));
>
> /* get the current level */
> sprintf(current_level, "%d", level);
>
> ! /* 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;
>
> ***************
> *** 913,918 ****
> --- 924,935 ----
> /* 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);
> }
> }
>

>
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