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