From f490dbe5946066d0e6741015f83bda12290fdc77 Mon Sep 17 00:00:00 2001
From: Bruce Momjian <bruce@momjian.us>
Date: Thu, 12 Sep 2002 00:19:44 +0000
Subject: [PATCH] > Now I'm testing connectby() in the /contrib/tablefunc in
7.3b1, which would > be a useful function for many users. However, I found
the fact that > if connectby_tree has the following data, connectby() tries
to search the end > of roots without knowing that the relations are
infinite(-5-9-10-11-9-10-11-) . > I hope connectby() supports a check routine
to find infinite relations. > > > CREATE TABLE connectby_tree(keyid int,
parent_keyid int); > INSERT INTO connectby_tree VALUES(1,NULL); > INSERT INTO
connectby_tree VALUES(2,1); > INSERT INTO connectby_tree VALUES(3,1); >
INSERT INTO connectby_tree VALUES(4,2); > INSERT INTO connectby_tree
VALUES(5,2); > INSERT INTO connectby_tree VALUES(6,4); > INSERT INTO
connectby_tree VALUES(7,3); > INSERT INTO connectby_tree VALUES(8,6); >
INSERT INTO connectby_tree VALUES(9,5); > > INSERT INTO connectby_tree
VALUES(10,9); > INSERT INTO connectby_tree VALUES(11,10); > INSERT INTO
connectby_tree VALUES(9,11); <-- infinite >
The attached patch fixes the infinite recursion bug in
contrib/tablefunc/tablefunc.c:connectby found by Masaru Sugawara.
test=# SELECT * FROM connectby('connectby_tree', 'keyid',
'parent_keyid', '2', 4, '~') AS t(keyid int, parent_keyid int, level
int, branch text);
keyid | parent_keyid | level | branch
-------+--------------+-------+-------------
2 | | 0 | 2
4 | 2 | 1 | 2~4
6 | 4 | 2 | 2~4~6
8 | 6 | 3 | 2~4~6~8
5 | 2 | 1 | 2~5
9 | 5 | 2 | 2~5~9
10 | 9 | 3 | 2~5~9~10
11 | 10 | 4 | 2~5~9~10~11
(8 rows)
test=# SELECT * FROM connectby('connectby_tree', 'keyid',
'parent_keyid', '2', 5, '~') AS t(keyid int, parent_keyid int, level
int, branch text);
ERROR: infinite recursion detected
I implemented it by checking the branch string for repeated keys
(whether or not the branch is returned). The performance hit was pretty
minimal -- about 1% for a moderately complex test case (220000 record
table, 9 level tree with 3800 members).
Joe Conway
---
contrib/tablefunc/tablefunc.c | 31 ++++++++++++++++---------------
1 file changed, 16 insertions(+), 15 deletions(-)
diff --git a/contrib/tablefunc/tablefunc.c b/contrib/tablefunc/tablefunc.c
index 254aa6c5c8..875e340c29 100644
--- a/contrib/tablefunc/tablefunc.c
+++ b/contrib/tablefunc/tablefunc.c
@@ -801,6 +801,10 @@ build_tuplestore_recursively(char *key_fld,
char current_level[INT32_STRLEN];
char *current_branch;
char **values;
+ StringInfo branchstr = NULL;
+
+ /* start a new branch */
+ branchstr = makeStringInfo();
if (show_branch)
values = (char **) palloc(CONNECTBY_NCOLS * sizeof(char *));
@@ -852,14 +856,8 @@ build_tuplestore_recursively(char *key_fld,
for (i = 0; i < proc; i++)
{
- StringInfo branchstr = NULL;
-
- /* start a new branch */
- if (show_branch)
- {
- branchstr = makeStringInfo();
- appendStringInfo(branchstr, "%s", branch);
- }
+ /* initialize branch for this pass */
+ appendStringInfo(branchstr, "%s", branch);
/* get the next sql result tuple */
spi_tuple = tuptable->vals[i];
@@ -868,17 +866,16 @@ build_tuplestore_recursively(char *key_fld,
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 */
- if (show_branch)
- {
- appendStringInfo(branchstr, "%s%s", branch_delim, current_key);
- current_branch = branchstr->data;
- }
- else
- current_branch = NULL;
+ appendStringInfo(branchstr, "%s%s", branch_delim, current_key);
+ current_branch = branchstr->data;
/* build a tuple */
values[0] = pstrdup(current_key);
@@ -916,6 +913,10 @@ build_tuplestore_recursively(char *key_fld,
per_query_ctx,
attinmeta,
tupstore);
+
+ /* reset branch for next pass */
+ xpfree(branchstr->data);
+ initStringInfo(branchstr);
}
}
--
2.24.1