鑑於mySQL前途不明決定轉向PostgreSQL。初步瞭解pgsql後發現其相當的強大,於是考慮把一個小項目遷移到pgsql上。對其中日誌表想玩玩pgsql的分區,最開始是參考pgsql手冊以規則(RULE)的方式來實現每一年一個日誌表
-- 禁止更新主表
CREATE RULE no_insert_on_tb_log AS ON INSERT TO tb_log
DO INSTEAD NOTHING;
DROP TABLE IF EXISTS tb_log_y2010 CASCADE;
CREATE TABLE tb_log_y2010 (
FOREIGN KEY (cid) REFERENCES tb_user ON DELETE CASCADE ON UPDATE CASCADE,
CHECK ( log_time >= '2010-01-01' AND log_time < '2010-12-31 24:0:0' )
) INHERITS (tb_log)
WITH (OIDS=FALSE);
CREATE OR REPLACE RULE insert_log_y2010 AS ON INSERT TO tb_log
WHERE ( ctime >= '2010-01-01' AND ctime < '2010-12-31 24:0:0' )
DO INSTEAD INSERT INTO tb_log_y2010 (log_code, log_stat, uid, log_ip, log_msg, log_time
) VALUES
( NEW.log_code, NEW.log_stat, NEW.uid, NEW.log_ip, NEW.log_msg, NEW.log_time ) ;
後來覺得每年需要生成新的日誌表以及相應的規則,用shell腳本來做不熟悉。於是決定換成觸發器的方式:
DROP TABLE IF EXISTS tb_log_y2010;
CREATE TABLE tb_log_y2010 (
FOREIGN KEY (uid) REFERENCES tb_users ON DELETE CASCADE ON UPDATE CASCADE,
CHECK ( log_time >= '2010-01-01' AND log_time < '2011-01-01' )
) INHERITS (tb_log)
WITH (OIDS=FALSE);
INSERT INTO row_counts VALUES ('tb_log_y2010', 0);
CREATE TRIGGER tb_log_y2010_count AFTER INSERT OR DELETE ON tb_log_y2010
FOR EACH ROW EXECUTE PROCEDURE count_trig();
CREATE OR REPLACE FUNCTION insert_log() RETURNS TRIGGER AS $$
-- 重定向對tb_log表寫入到相應年份分區表,如果目標表不存在則由common.php中 write_log() 自動創建
DECLARE
tbname TEXT := 'tb_log_y' || to_char(current_timestamp, 'YYYY');
BEGIN
EXECUTE 'INSERT INTO ' || tbname ||
' (log_code, log_stat, uid, log_ip, log_msg, log_time) ' ||
' VALUES ( ''' || NEW.log_code ||''','''|| NEW.log_stat ||''', '''|| NEW.uid ||
''','''|| NEW.log_ip ||''','''||
NEW.log_msg ||''','''|| NEW.log_time || ''' ) ';
RETURN NULL;
END;
$$ LANGUAGE plpgsql;
DROP TRIGGER IF EXISTS insert_log_trig ON tb_log CASCADE;
CREATE TRIGGER insert_log_trig BEFORE INSERT ON tb_log
FOR EACH ROW EXECUTE PROCEDURE public.insert_log() ;
然後在PHP寫日誌的函數裏面判斷錯誤代碼如果爲 ‘42P01’ 則表示(該年)日誌表不存在,於是就新建當年日誌表並且重新寫入出錯時的SQL語句。
接下來就寫PHP函數來遷移數據,但是遇上錯誤
仔細回憶原來log_user字段已經被uid字段替代,不過寫的觸發器、觸發器函數以及日誌表都已經更改了的啊。用Navicat Lite 查看觸發器函數也沒問題。後來用EMS查看就發現了問題,怎麼函數定義完全不相同呢?
一點擊Function name下拉列表發現具有有兩個地方存在同樣的名稱:
再回憶,想起最開始用規則方式時曾經試圖在日誌的重寫規則中判斷table是否存在並新建:
CREATE OR REPLACE FUNCTION insert_log () RETURNS trigger AS $BODY$
DECLARE
curryear TEXT := to_char(current_timestamp, 'YYYY');
yearbegin TEXT;
yearend TEXT;
tblname TEXT ;
q TEXT;
BEGIN
tblname := 'tb_log_y' || curryear ;
IF NOT EXISTS (SELECT relname FROM pg_class WHERE relname = tblname) THEN
yearbegin := curryear || '-01-01';
yearend := curryear || '-01-01 24:0:0';
q := $q$CREATE TABLE tblname (
FOREIGN KEY (log_user) REFERENCES tb_users ON DELETE CASCADE
ON UPDATE CASCADE,
CHECK ( log_time >= '$q$ || yearbegin || $q$' AND log_time < '$q$ ||
yearend || $q$' )
) INHERITS (tb_log)
WITH (OIDS=FALSE);
EXECUTE q;
END IF;
EXECUTE 'INSERT INTO tb_log_y' || || ' (log_code, log_stat, log_user,log_ip, log_msg,
log_time) ' || ' VALUES ( ''' || NEW.log_code ||''','''|| NEW.log_stat ||''','''||
NEW.log_user || ''','''|| NEW.log_ip ||''','''|| NEW.log_msg ||''','''||
NEW.log_time ||''' ) ';
RETURN NULL;
END;
$BODY$
LANGUAGE 'plpgsql' ;
不知怎麼地就跑到pg_catalog裏面去了,導致pg_catalog和pulic存在同名函數。前者是最開始的規則,後者是觸發器函數,結果在創建insert_log_trig()觸發器時就出了問題使用了pg_catalog中的過程函數。指定過程函數shema解決問題:
CREATE TRIGGER insert_log_trig BEFORE INSERT
ON tb_log FOR EACH ROW EXECUTE PROCEDURE public .insert_log() ;
再看看pg_catalog裏面那個的DDL,沒明白是怎麼創建到pg_catalog上面去的,因爲創建所有對象時都沒使用shema前綴
CREATE OR REPLACE FUNCTION "pg_catalog"."NewProc"()
RETURNS "pg_catalog"."trigger" AS $BODY$
DECLARE
curryear TEXT := to_char(current_timestamp, 'YYYY');
yearbegin TEXT;
yearend TEXT;
tblname TEXT ;
q TEXT;
BEGIN
tblname := 'tb_log_y' || curryear ;
IF NOT EXISTS (SELECT relname FROM pg_class WHERE relname = tblname) THEN
yearbegin := curryear || '-01-01';
yearend := curryear || '-01-01 24:0:0';
q := $q$CREATE TABLE tblname (
FOREIGN KEY (log_user) REFERENCES tb_user ON DELETE CASCADE ON UPDATE CASCADE,
CHECK ( log_time >= '$q$ || yearbegin || $q$' AND log_time < '$q$ || yearend || $q$' )
) INHERITS (tb_log)
WITH (OIDS=FALSE);
EXECUTE q;
END IF;
EXECUTE 'INSERT INTO tb_log_y' || || ' (log_code, log_stat, log_user,log_ip, log_msg, log_time) ' ||
' VALUES ( ''' || NEW.log_code ||''','''|| NEW.log_stat ||''','''|| NEW.log_user ||
''','''|| NEW.log_ip ||''','''|| NEW.log_msg ||''','''|| NEW.log_time ||''' ) ';
RETURN NULL;
END;
$BODY$
LANGUAGE 'plpgsql' ;
生命在於折騰。pgsql也挺好玩的
.