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Attached is an update to contrib/tablefunc. It introduces a new

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function, connectby(), which can serve as a reference implementation for

the changes made in the last few days -- namely the ability of a
function to return an entire tuplestore, and the ability of a function
to make use of the query provided "expected" tuple description.

Description:

   connectby(text relname, text keyid_fld, text parent_keyid_fld,
     text start_with, int max_depth [, text branch_delim])
   - returns keyid, parent_keyid, level, and an optional branch string
   - requires anonymous composite type syntax in the FROM clause. See
     the instructions in the documentation below.

Joe Conway
This commit is contained in:
Bruce Momjian
2002-09-02 05:44:05 +00:00
parent 9fd842c4b2
commit 6aa4482f2f
5 changed files with 602 additions and 12 deletions
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109
contrib/tablefunc/README.tablefunc
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@ -60,6 +60,12 @@ Installation:
- requires anonymous composite type syntax in the FROM clause. See
the instructions in the documentation below.
connectby(text relname, text keyid_fld, text parent_keyid_fld,
text start_with, int max_depth [, text branch_delim])
- returns keyid, parent_keyid, level, and an optional branch string
- requires anonymous composite type syntax in the FROM clause. See
the instructions in the documentation below.
Documentation
==================================================================
Name
@ -324,6 +330,109 @@ AS ct(row_name text, category_1 text, category_2 text, category_3 text);
test2 | val6 | val7 |
(2 rows)
==================================================================
Name
connectby(text, text, text, text, int[, text]) - returns a set
representing a hierarchy (tree structure)
Synopsis
connectby(text relname, text keyid_fld, text parent_keyid_fld,
text start_with, int max_depth [, text branch_delim])
Inputs
relname
Name of the source relation
keyid_fld
Name of the key field
parent_keyid_fld
Name of the key_parent field
start_with
root value of the tree input as a text value regardless of keyid_fld type
max_depth
zero (0) for unlimited depth, otherwise restrict level to this depth
branch_delim
if optional branch value is desired, this string is used as the delimiter
Outputs
Returns setof record, which must defined with a column definition
in the FROM clause of the SELECT statement, e.g.:
SELECT * FROM connectby('connectby_tree', 'keyid', 'parent_keyid', 'row2', 0, '~')
AS t(keyid text, parent_keyid text, level int, branch text);
- or -
SELECT * FROM connectby('connectby_tree', 'keyid', 'parent_keyid', 'row2', 0)
AS t(keyid text, parent_keyid text, level int);
Notes
1. keyid and parent_keyid must be the same data type
2. The column definition *must* include a third column of type INT4 for
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
Example usage
CREATE TABLE connectby_tree(keyid text, parent_keyid text);
INSERT INTO connectby_tree VALUES('row1',NULL);
INSERT INTO connectby_tree VALUES('row2','row1');
INSERT INTO connectby_tree VALUES('row3','row1');
INSERT INTO connectby_tree VALUES('row4','row2');
INSERT INTO connectby_tree VALUES('row5','row2');
INSERT INTO connectby_tree VALUES('row6','row4');
INSERT INTO connectby_tree VALUES('row7','row3');
INSERT INTO connectby_tree VALUES('row8','row6');
INSERT INTO connectby_tree VALUES('row9','row5');
-- with branch
SELECT * FROM connectby('connectby_tree', 'keyid', 'parent_keyid', 'row2', 0, '~')
AS t(keyid text, parent_keyid text, level int, branch text);
keyid | parent_keyid | level | branch
-------+--------------+-------+---------------------
row2 | | 0 | row2
row4 | row2 | 1 | row2~row4
row6 | row4 | 2 | row2~row4~row6
row8 | row6 | 3 | row2~row4~row6~row8
row5 | row2 | 1 | row2~row5
row9 | row5 | 2 | row2~row5~row9
(6 rows)
-- without branch
SELECT * FROM connectby('connectby_tree', 'keyid', 'parent_keyid', 'row2', 0)
AS t(keyid text, parent_keyid text, level int);
keyid | parent_keyid | level
-------+--------------+-------
row2 | | 0
row4 | row2 | 1
row6 | row4 | 2
row8 | row6 | 3
row5 | row2 | 1
row9 | row5 | 2
(6 rows)
==================================================================
-- Joe Conway