Recursive PLPGSQL function?

[Mark Cave-Ayland]

Hi everyone,

I'm trying to write a recursive plpgsql function in PostgreSQL 7.4.2
that given a tree node id (ictid) will return all the nodes below it in
the tree, one row per node. When I try and execute the function I get
the following error message:

CONTEXT: PL/pgSQL function "findsubcategories" line 15 at for over
select rows
PL/pgSQL function "findsubcategories" line 15 at for over select rows
PL/pgSQL function "findsubcategories" line 15 at for over select rows
PL/pgSQL function "findsubcategories" line 15 at for over select rows
....repeated many many times...
Can anyone see where I am going wrong in my function? I found a
reference to "for over select rows" in pl_funcs.c but it appears to be
denoting a statement type? The code is given below:
CREATE OR REPLACE FUNCTION plpgsql.findsubcategories(int8) RETURNS SETOF
inventory.cattree AS '
DECLARE
_row inventory.cattree%ROWTYPE;
_nrow inventory.cattree%ROWTYPE;
_id ALIAS FOR $1;

BEGIN
-- Select the starting tree entry
FOR _row IN SELECT * FROM inventory.cattree WHERE parentictid =
_id LOOP

-- Return this category
RETURN NEXT _row;

-- Recurse for each child function
FOR _nrow IN SELECT * FROM
plpgsql.findsubcategories(_row.parentictid) LOOP
RETURN NEXT _nrow;
END LOOP;

END LOOP;

-- Return the entire set
RETURN;
END
' LANGUAGE 'plpgsql';
If this is not possible, can anyone else suggest a way of getting the
required result?
Many thanks,

Mark.

---

Mark Cave-Ayland
Webbased Ltd.
Tamar Science Park
Derriford
Plymouth
PL6 8BX
England

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[Tom Lane]

"Mark Cave-Ayland" <m.***********@webbased.co.uk> writes:

I'm trying to write a recursive plpgsql function in PostgreSQL 7.4.2
that given a tree node id (ictid) will return all the nodes below it in
the tree, one row per node. When I try and execute the function I get
the following error message:

You've got an infinite recursion there --- the function is calling
itself back with the original argument value.

regards, tom lane

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[DeJuan Jackson]

If I'm not mistaken you have an infinit recursion because you are always
pulling the same id (whatever _id starts at) throughout each function call.

Postgres is most likely killing the functions when it's hits some stack
or memory limit.

Mark Cave-Ayland wrote:

Hi everyone,

I'm trying to write a recursive plpgsql function in PostgreSQL 7.4.2
that given a tree node id (ictid) will return all the nodes below it in
the tree, one row per node. When I try and execute the function I get
the following error message:

CONTEXT: PL/pgSQL function "findsubcategories" line 15 at for over
select rows
PL/pgSQL function "findsubcategories" line 15 at for over select rows
PL/pgSQL function "findsubcategories" line 15 at for over select rows
PL/pgSQL function "findsubcategories" line 15 at for over select rows
...repeated many many times...
Can anyone see where I am going wrong in my function? I found a
reference to "for over select rows" in pl_funcs.c but it appears to be
denoting a statement type? The code is given below:
CREATE OR REPLACE FUNCTION plpgsql.findsubcategories(int8) RETURNS SETOF
inventory.cattree AS '
DECLARE
_row inventory.cattree%ROWTYPE;
_nrow inventory.cattree%ROWTYPE;
_id ALIAS FOR $1;

BEGIN
-- Select the starting tree entry
FOR _row IN SELECT * FROM inventory.cattree WHERE parentictid =
_id LOOP

-- Return this category
RETURN NEXT _row;

-- Recurse for each child function
FOR _nrow IN SELECT * FROM
plpgsql.findsubcategories(_row.parentictid) LOOP
RETURN NEXT _nrow;
END LOOP;

END LOOP;

-- Return the entire set
RETURN;
END
' LANGUAGE 'plpgsql';
If this is not possible, can anyone else suggest a way of getting the
required result?
Many thanks,

Mark.

---

Mark Cave-Ayland
Webbased Ltd.
Tamar Science Park
Derriford
Plymouth
PL6 8BX
England

Tel: [phone]
Fax: [phone]
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recipient and may also be privileged. If you are not the intended
recipient please delete it from your system and notify the sender. You
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its contents to any other person.

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