Re: About connectby() again - Mailing list pgsql-hackers

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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