database.sarang.net
UserID
Passwd
Database
DBMS
MySQL
ㆍPostgreSQL
Firebird
Oracle
Informix
Sybase
MS-SQL
DB2
Cache
CUBRID
LDAP
ALTIBASE
Tibero
DB 문서들
스터디
Community
공지사항
자유게시판
구인|구직
DSN 갤러리
도움주신분들
Admin
운영게시판
최근게시물
PostgreSQL Tutorials 4098 게시물 읽기
 News | Q&A | Columns | Tutorials | Devel | Files | Links
No. 4098
OpenACS에 이용된 Category 구현에 대하여
작성자
송동수(namsanmo)
작성일
2002-03-21 14:52
조회수
4,607

OpenACS (http://www.openacs.org)에서 사용하는 트리구조형 카테고리 구현 부분입니다.

 

pl/pgSQL 은 모두 openacs4 의 ACS Kernel 4.2 의 postgresql.sql 에 있는 부분이고요 마지막의 category_insert_tr() 와 category_update_tr() 는 테이블 이름만 category 로 변경한 것입니다.

 

참고가 되었으면 합니다.

 

===================이하 sql 문 ==================

create table Category (

Category_ID SERIAL not null,

Category_Name VARCHAR null,

Parent_ID INT4 null,

SortKey VARBIT null,

constraint PK_CATEGORY primary key (Category_ID),

constraint FK_CATEGORY_REFERENCE_CATEGORY foreign key (Parent_ID)

references Category (Category_ID)

on delete restrict on update restrict

);

 

create index category_parent_id_idx on Category (

Parent_ID

);

 

create index category_sortkey_idx on Category (

SortKey

);

 

 

CREATE OR REPLACE FUNCTION int_to_tree_key ( integer )

RETURNS varbit

AS '

 

-- Convert an integer into the bit string format used to store

-- tree sort keys. Using 4 bytes for the long keys requires

-- using -2^31 rather than 2^31 to avoid a twos-complement

-- "integer out of range" error in PG - if for some reason you

-- want to use a smaller value use positive powers of two!

 

-- There was an "out of range" check in here when I was using 15

-- bit long keys but the only check that does anything with the long

-- keys is to check for negative numbers.

 

declare

p_intkey alias for ;

begin

if p_intkey < 0 then

raise exception ''int_to_tree_key: key must be a positive integer'';

end if;

 

if p_intkey < 2^7 then

return substring(bitfromint4(p_intkey), 25, 8);

else

return substring(bitfromint4(-2^31 + p_intkey), 1, 32);

end if;

 

end;'

LANGUAGE 'plpgsql' with (iscachable, isstrict)

;

 

 

CREATE OR REPLACE FUNCTION tree_key_to_int ( bit varying, integer )

RETURNS int4

AS '

 

-- Convert the compressed key for the node at the given level to an

-- integer.

 

declare

p_tree_key alias for ;

p_level alias for ;

v_level integer default 0;

v_parent_pos integer default 1;

v_pos integer default 1;

begin

 

-- Find the right key first

while v_pos < length(p_tree_key) and v_level < p_level loop

v_parent_pos := v_pos;

v_level := v_level + 1;

if substring(p_tree_key, v_pos, 1) = ''1'' then

v_pos := v_pos + 32;

else

v_pos := v_pos + 8;

end if;

end loop;

 

if v_level < p_level then

raise exception ''tree_key_to_int: key is at a level less than %'', p_level;

end if;

 

if substring(p_tree_key, v_parent_pos, 1) = ''1'' then

return bittoint4(substring(p_tree_key, v_parent_pos + 1, 31));

else

return bittoint4(substring(p_tree_key, v_parent_pos, 8));

end if;

 

end;'

LANGUAGE 'plpgsql' with (iscachable, isstrict)

;

 

CREATE OR REPLACE FUNCTION tree_ancestor_key ( bit varying, integer )

RETURNS varbit

AS '

 

-- Returns a key for the ancestor at the given level. The root is level

-- one.

 

declare

p_tree_key alias for ;

p_level alias for ;

v_level integer default 0;

v_pos integer default 1;

begin

 

if tree_level(p_tree_key) < p_level then

raise exception ''tree_ancestor_key: key is at a level less than %'', p_level;

end if;

 

while v_level < p_level loop

v_level := v_level + 1;

if substring(p_tree_key, v_pos, 1) = ''1'' then

v_pos := v_pos + 32;

else

v_pos := v_pos + 8;

end if;

end loop;

 

return substring(p_tree_key, 1, v_pos - 1);

 

end;'

LANGUAGE 'plpgsql' with (iscachable, isstrict)

;

 

 

CREATE OR REPLACE FUNCTION tree_root_key ( bit varying )

RETURNS varbit

AS '

 

-- Return the tree_sortkey for the root node of the node with the

-- given tree_sortkey.

 

declare

p_tree_key alias for ;

begin

 

if substring(p_tree_key, 1, 1) = ''1'' then

return substring(p_tree_key, 1, 32);

else

return substring(p_tree_key, 1, 8);

end if;

 

end;'

LANGUAGE 'plpgsql' with (iscachable, isstrict)

;

 

 

CREATE OR REPLACE FUNCTION tree_leaf_key_to_int ( bit varying )

RETURNS int4

AS '

 

-- Convert the bitstring for the last, or leaf, node represented by this key

-- to an integer.

 

declare

p_tree_key alias for ;

v_leaf_pos integer default 1;

v_pos integer default 1;

begin

 

-- Find the leaf key first

while v_pos < length(p_tree_key) loop

v_leaf_pos := v_pos;

if substring(p_tree_key, v_pos, 1) = ''1'' then

v_pos := v_pos + 32;

else

v_pos := v_pos + 8;

end if;

end loop;

 

if substring(p_tree_key, v_leaf_pos, 1) = ''1'' then

return bittoint4(substring(p_tree_key, v_leaf_pos + 1, 31));

else

return bittoint4(substring(p_tree_key, v_leaf_pos, 8));

end if;

 

end;'

LANGUAGE 'plpgsql' with (iscachable, isstrict)

;

 

 

CREATE OR REPLACE FUNCTION tree_next_key ( bit varying, integer )

RETURNS varbit

AS '

 

-- Create a new child of the given key with a leaf key number one greater than

-- the child value parameter. If the child value parameter is null, make the

-- child the first child of the parent.

 

declare

p_parent_key alias for ;

p_child_value alias for ;

v_child_value integer;

begin

 

if p_child_value is null then

v_child_value := 0;

else

v_child_value := p_child_value + 1;

end if;

 

if p_parent_key is null then

return int_to_tree_key(v_child_value);

else

return p_parent_key || int_to_tree_key(v_child_value);

end if;

 

end;'

LANGUAGE 'plpgsql' with (iscachable)

;

 

 

CREATE OR REPLACE FUNCTION tree_left ( bit varying )

RETURNS varbit

AS '

 

-- Create a key less than or equal to that of any child of the

-- current key.

 

declare

key alias for ;

begin

if key is null then

return ''X00'';

else

return key || ''X00'';

end if;

end;'

LANGUAGE 'plpgsql' with (iscachable)

;

 

 

CREATE OR REPLACE FUNCTION tree_right ( bit varying )

RETURNS varbit

AS '

 

-- Create a key greater or equal to that of any child of the current key.

-- Used in BETWEEN expressions to select the subtree rooted at the given

-- key.

 

declare

key alias for ;

begin

if key is null then

return ''XFFFFFFFF'';

else

return key || ''XFFFFFFFF'';

end if;

end;'

LANGUAGE 'plpgsql' with (iscachable)

;

 

 

CREATE OR REPLACE FUNCTION tree_level ( bit varying )

RETURNS int4

AS '

 

-- Return the tree level of the given key. The root level is defined

-- to be at level one.

 

declare

p_tree_key alias for ;

v_pos integer;

v_level integer;

 

begin

 

if p_tree_key is null then

return 0;

end if;

 

v_pos := 1;

v_level := 0;

 

while v_pos <= length(p_tree_key) loop

v_level := v_level + 1;

if substring(p_tree_key, v_pos, 1) = ''1'' then

v_pos := v_pos + 32;

else

v_pos := v_pos + 8;

end if;

end loop;

 

return v_level;

end;'

LANGUAGE 'plpgsql' with (iscachable)

;

 

 

CREATE OR REPLACE FUNCTION tree_ancestor_p ( bit varying, bit varying )

RETURNS bool

AS '

declare

p_potential_ancestor alias for ;

p_potential_child alias for ;

begin

return position(p_potential_ancestor in p_potential_child) = 1;

end;'

LANGUAGE 'plpgsql' with (iscachable)

;

 

 

CREATE OR REPLACE FUNCTION create_tree_ancestor_keys() returns boolean as '

 

-- PG 7.1 does not allow recursive SQL functions, but David Walker figured out how to

-- get around this with a truly inspired hack he posted to the OpenACS 4 Design Forum.

 

-- His solution involves a general "create and replace function" function written in

-- Tcl.

 

-- Rather than use the general solution I have just hacked up a PL/pgSQL function to

-- create the one recursive function we need: tree_ancestor_keys(varbit, integer).

 

-- PG 7.2 still does not allow recursive SQL functions during CREATE, but you can

-- fool it easily with CREATE OR REPLACE, a new feature in this version. Perhaps

-- someday the PG development group will see the light and just let us CREATE such

-- functions.

 

-- tree_ancestor_keys(varbit, integer) returns the set of ancestor keys starting at

-- the level passed in as the second parameter down to the key passed in as the first

 

-- This function should probably only be called from its overloaded cousin

-- tree_ancestor_keys(varbit), which returns the set of tree_sortkeys for all of the

-- ancestors of the given tree_sortkey...

 

begin

 

-- create tree_ancestor_keys with a dummy body

 

execute ''create function tree_ancestor_keys(varbit, integer) returns setof varbit as ''''

select

'''' language ''''sql'''' '';

 

if version() like ''%7.1%'' then

 

-- create another function with the body we want

 

execute ''create function __tree_ancestor_keys(varbit, integer) returns setof varbit as ''''

select tree_ancestor_key(, )

union

select tree_ancestor_keys(, + 1)

where < tree_level()

'''' language ''''sql'''' with (isstrict) '';

 

-- replace the body for tree_ancestor_keys with the body we want. Slick, eh?

 

update pg_proc

set prosrc = hack.prosrc, probin = hack.probin

from (select prosrc, probin

from pg_proc

where proname = ''__tree_ancestor_keys'') hack

where proname = ''tree_ancestor_keys'';

 

execute ''drop function __tree_ancestor_keys(varbit, integer)'';

 

else

 

-- The bootstrap installer has made certain that we are running a version >= 7.1 so it is safe

-- at this point to assume create or replace is supported.

 

execute ''create or replace function tree_ancestor_keys(varbit, integer) returns setof varbit as ''''

select tree_ancestor_key(, )

union

select tree_ancestor_keys(, + 1)

where < tree_level()

'''' language ''''sql'''' with (isstrict) '';

end if;

 

return true;

end;' language 'plpgsql';

 

select create_tree_ancestor_keys();

 

drop function create_tree_ancestor_keys();

 

 

CREATE OR REPLACE FUNCTION tree_ancestor_keys ( bit varying )

RETURNS varbit

AS '

 

-- Return the set of tree_sortkeys for all of the ancestors of the given

-- tree_sortkey ancestors.

 

-- Here is an example on acs_objects:

 

-- select o.*

-- from acs_objects o,

-- (select tree_ancestor_keys(acs_objects_get_tree_sortkey(:object_id)) as tree_sortkey) parents

-- where o.tree_sortkey = parents.tree_sortkey;

 

-- This query will use the index on tree_sortkey to scan acs_objects. The function to grab

-- the tree_sortkey for the node is necessary (and must be defined for each table that uses

-- our hierarchical query scheme) to avoid restrictions on the use of SQL functions that

-- return sets.

 

-- if you only want the ancestors for a node within a given subtree, do something like this and

-- cross your fingers that Postgres will figure out whether the join on parent or the root is

-- more restrictive and do the right one first:

 

-- select o.*

-- from acs_objects o,

-- (select tree_sortkey from acs_objects where object_id = :root_id) as root

-- (select tree_ancestor_keys(acs_objects_get_tree_sortkey(:object_id)) as tree_sortkey) parents

-- where o.tree_sortkey = parents.tree_sortkey

-- and o.tree_sortkey >= root.tree_sortkey;

 

-- DO NOT BE TEMPTED TO REWRITE THE ABOVE QUERIES LIKE THIS:

 

-- select *

-- from acs_objects

-- where object_id in (select tree_ancestor_keys(object_id)

-- from acs_objects

-- where object_id = :object_id);

 

-- This is more readable and is certainly cleaner BUT WILL NOT USE THE INDEX ON TREE_SORTKEY

-- when scanning the acs_objects instance referred to by the left operand of the "in" operator. Given

-- that acs_objects will become HUGE on real systems the resulting sequential scan would cripple

-- performance.

 

-- WARNING: subselects in where clauses that call this function and join on an outer table appear

-- to reliably kill PG 7.1.2, at least if "exists" is involved. PG 7.2 doesn''t die on my test

-- case, so it appears to have been fixed.

 

select tree_ancestor_keys(, 1)

 

'

LANGUAGE 'sql' with (isstrict)

;

 

 

CREATE OR REPLACE FUNCTION category_insert_tr ( )

RETURNS OPAQUE

AS '

declare

v_parent_sk varbit default null;

v_max_value integer;

begin

select max(tree_leaf_key_to_int(sortkey)) into v_max_value

from category

where parent_id = new.parent_id;

 

select sortkey into v_parent_sk

from category

where category_id = new.parent_id;

 

new.sortkey := tree_next_key(v_parent_sk ,v_max_value);

 

return new;

end;'

LANGUAGE 'plpgsql'

;

 

 

CREATE OR REPLACE FUNCTION category_update_tr ( )

RETURNS OPAQUE

AS '

declare

v_parent_sk varbit default null;

v_max_value integer;

v_rec record;

clr_keys_p boolean default ''t'';

begin

if new.category_id = old.category_id and

((new.parent_id = old.parent_id) or

(new.parent_id is null and old.parent_id is null)) then

 

return new;

 

end if;

 

for v_rec in select category_id, parent_id

from category

where sortkey between new.sortkey and tree_right(new.sortkey)

order by sortkey

LOOP

if clr_keys_p then

update category set sortkey = null

where sortkey between new.sortkey and tree_right(new.sortkey);

clr_keys_p := ''f'';

end if;

 

select max(tree_leaf_key_to_int(sortkey)) into v_max_value

from category

where parent_id = v_rec.parent_id;

 

select sortkey into v_parent_sk

from category

where category_id = v_rec.parent_id;

 

update category

set sortkey = tree_next_key(v_parent_sk, v_max_value)

where category_id = v_rec.category_id;

 

end LOOP;

 

return new;

 

end;'

LANGUAGE 'plpgsql'

;

 

 

create trigger category_update_tr after update on category

for each row execute procedure category_update_tr ( );

 

 

create trigger category_insert_tr before insert on category

for each row execute procedure category_insert_tr ( );

===================SQL 끝 =================

 

테스트....

 

select version();

                          version
-----------------------------------------------------------
 PostgreSQL 7.2 on i686-pc-linux-gnu, compiled by GCC 2.96

INSERT INTO category (category_name,parent_id) VALUES ('대한민국',NULL);

INSERT INTO category (category_name,parent_id) VALUES ('서울',1);

INSERT INTO category (category_name,parent_id) VALUES ('부산',1);

INSERT INTO category (category_name,parent_id) VALUES ('대전',1);

INSERT INTO category (category_name,parent_id) VALUES ('대구',1);

INSERT INTO category (category_name,parent_id) VALUES ('광주',1);

INSERT INTO category (category_name,parent_id) VALUES ('인천',1);

INSERT INTO category (category_name,parent_id) VALUES ('울산',1);

INSERT INTO category (category_name,parent_id) VALUES ('중구',8);

INSERT INTO category (category_name,parent_id) VALUES ('남구',8);

INSERT INTO category (category_name,parent_id) VALUES ('동구',8);

INSERT INTO category (category_name,parent_id) VALUES ('북구',8);

INSERT INTO category (category_name,parent_id) VALUES ('종로구',2);

INSERT INTO category (category_name,parent_id) VALUES ('강남구',2);

INSERT INTO category (category_name,parent_id) VALUES ('강서구',2);

INSERT INTO category (category_name,parent_id) VALUES ('강북구',2);

 

select * from category;

 category_id | category_name | parent_id |         sortkey
-------------+---------------+-----------+--------------------------
                 1 | 대한민국          |                | 00000000
                 2 | 서울                |         1 | 0000000000000000
                 3 | 부산                |         1 | 0000000000000001
                 4 | 대전                |         1 | 0000000000000010
                 5 | 대구                |         1 | 0000000000000011
                 6 | 광주                |         1 | 0000000000000100
                 7 | 인천                |         1 | 0000000000000101
                 8 | 울산                |         1 | 0000000000000110
                 9 | 중구                |         8 | 000000000000011000000000
               10 | 남구                |         8 | 000000000000011000000001
               11 | 동구                |         8 | 000000000000011000000010
               12 | 북구                |         8 | 000000000000011000000011
               13 | 종로구             |         2 | 000000000000000000000000
               14 | 강남구             |         2 | 000000000000000000000001
               15 | 강서구             |         2 | 000000000000000000000010
               16 | 강북구             |         2 | 000000000000000000000011

 

 

select * from category order by sortkey;

 

 category_id | category_name | parent_id |         sortkey
-------------+---------------+-----------+--------------------------
                 1 | 대한민국         |           | 00000000
                 2 | 서울               |         1 | 0000000000000000
               13 | 종로구            |         2 | 000000000000000000000000
               14 | 강남구            |         2 | 000000000000000000000001
               15 | 강서구            |         2 | 000000000000000000000010
               16 | 강북구            |         2 | 000000000000000000000011
                3 | 부산               |         1 | 0000000000000001
                4 | 대전               |         1 | 0000000000000010
                5 | 대구               |         1 | 0000000000000011
                6 | 광주               |         1 | 0000000000000100
                7 | 인천               |         1 | 0000000000000101
                8 | 울산               |         1 | 0000000000000110
                9 | 중구               |         8 | 000000000000011000000000
               10 | 남구              |         8 | 000000000000011000000001
               11 | 동구              |         8 | 000000000000011000000010
               12 | 북구              |         8 | 000000000000011000000011
[/color]
이 글에 대한 댓글이 총 1건 있습니다.

함수의 DECLARE 부분에서

alias for 뒷 부분은 차례로 $ 1, $ 2... 물론 $와 숫자 사이에는 공백문자가 없습니다.

송동수님이 2002-03-25 11:16에 작성한 댓글입니다.
[Top]
No.
제목
작성자
작성일
조회
4147PostgreSQL에서의 음력 날짜 자료형에 대해서.
김상기
2002-04-16
5528
4106\?+ 를 알고계십니까?
김상기
2002-03-26
5041
4103정수형 배열 자료형에서 인덱스 사용하기
김상기
2002-03-25
5198
4098OpenACS에 이용된 Category 구현에 대하여 [1]
송동수
2002-03-21
4607
4079[SQL] 재미난 RULE
김상기
2002-03-14
5154
3990PostgreSQL 7.2 설치하기
정재익
2002-02-11
6746
3910DB data directory 를 여러군데 이용하기.
정재익
2002-01-21
4715
Valid XHTML 1.0!
All about the DATABASE... Copyleft 1999-2020 DSN, All rights reserved.
작업시간: 0.034초, 이곳 서비스는
	PostgreSQL v13.0으로 자료를 관리합니다