自我管理PostgreSQL分区表

Question

我正在尝试使用Postgres进行自我管理的分区表设置.这一切都围绕着这个功能,但我似乎无法让Postgres接受我的表名.自我管理分区表触发器功能的任何想法或示例？

我目前的职能:

DECLARE
day integer;
year integer;
tablename text;
startdate text;
enddate text;
BEGIN
day:=date_part('doy',to_timestamp(NEW.date));
year:=date_part('year',to_timestamp(NEW.date));
tablename:='pings_'||year||'_'||day||'_'||NEW.id;
-- RAISE EXCEPTION 'tablename=%',tablename;
PERFORM 'tablename' FROM pg_tables WHERE 'schemaname'=tablename;
-- RAISE EXCEPTION 'found=%',FOUND;
IF FOUND <> TRUE THEN
    startdate:=date_part('year',to_timestamp(NEW.date))||'-'||date_part('month',to_timestamp(NEW.date))||'-'||date_part('day',to_timestamp(NEW.date));
    enddate:=startdate::timestamp + INTERVAL '1 day';
    EXECUTE 'CREATE TABLE $1 (
        CHECK ( date >= DATE $2 AND date < DATE $3 )
    ) INHERITS (pings)' USING quote_ident(tablename),startdate,enddate;
END IF;
EXECUTE 'INSERT INTO $1 VALUES (NEW.*)' USING quote_ident(tablename);
RETURN NULL;
END;

我希望它自动创建一个名为的表,pings_YEAR_DOY_ID但它始终失败:

2011-10-24 13:39:04 CDT [15804]: [1-1] ERROR:  invalid input syntax for type double precision: "-" at character 45
2011-10-24 13:39:04 CDT [15804]: [2-1] QUERY:  SELECT date_part('year',to_timestamp( $1 ))+'-'+date_part('month',to_timestamp( $2 ))+'-'+date_part('day',to_timestamp( $3 ))
2011-10-24 13:39:04 CDT [15804]: [3-1] CONTEXT:  PL/pgSQL function "ping_partition" line 15 at assignment
2011-10-24 13:39:04 CDT [15804]: [4-1] STATEMENT:  INSERT INTO pings VALUES (0,0,5);

尝试2

在应用更改并修改它之后(date是unixtimestamp列,我的想法是选择时整数列比时间戳列快).我得到以下错误,不确定我是否使用正确的语法USING NEW？

更新功能:

CREATE FUNCTION ping_partition() RETURNS trigger
    LANGUAGE plpgsql
    AS $_$DECLARE
day integer;
year integer;
tablename text;
startdate text;
enddate text;
BEGIN
day:=date_part('doy',to_timestamp(NEW.date));
year:=date_part('year',to_timestamp(NEW.date));
tablename:='pings_'||year||'_'||day||'_'||NEW.id;
-- RAISE EXCEPTION 'tablename=%',tablename;
PERFORM 'tablename' FROM pg_tables WHERE 'schemaname'=tablename;
-- RAISE EXCEPTION 'found=%',FOUND;
IF FOUND <> TRUE THEN
    startdate := to_char(to_timestamp(NEW.date), 'YYYY-MM-DD');
    enddate:=startdate::timestamp + INTERVAL '1 day';
    EXECUTE 'CREATE TABLE ' || quote_ident(tablename) || ' (
        CHECK ( date >= EXTRACT(EPOCH FROM DATE ' || quote_literal(startdate) || ')
            AND date < EXTRACT(EPOCH FROM DATE ' || quote_literal(enddate) || ') )
    ) INHERITS (pings)';
END IF;
EXECUTE 'INSERT INTO ' || quote_ident(tablename) || ' SELECT $1' USING NEW; 
RETURN NULL;
END;
$_$;

我的声明:

INSERT INTO pings VALUES (0,0,5);

SQL错误:

ERROR:  column "date" is of type integer but expression is of type pings
LINE 1: INSERT INTO pings_1969_365_0 SELECT $1
                                            ^
HINT:  You will need to rewrite or cast the expression.
QUERY:  INSERT INTO pings_1969_365_0 SELECT $1
CONTEXT:  PL/pgSQL function "ping_partition" line 22 at EXECUTE statement

Answer 1

你是混合double precision的输出date_part数()用text '-'.这对Po​​stgreSQL没有意义.你需要一个明确的演员表text.但是有一种更简单的方法来完成所有这些:

startdate:=date_part('year',to_timestamp(NEW.date))
||'-'||date_part('month',to_timestamp(NEW.date))
||'-'||date_part('day',to_timestamp(NEW.date));

改为使用:

startdate := to_char(NEW.date, 'YYYY-MM-DD');

这没有任何意义:

EXECUTE 'CREATE TABLE $1 (
        CHECK (date >= DATE $2 AND date < DATE $3 )
    ) INHERITS (pings)' USING quote_ident(tablename),startdate,enddate;

您只能使用该USING子句提供值.请阅读此处的手册.尝试改为:

EXECUTE 'CREATE TABLE ' || quote_ident(tablename) || ' (
            CHECK ("date" >= ''' || startdate || ''' AND
                   "date" <  ''' || enddate   || '''))
            INHERITS (ping)';

或者更好的是,使用format().见下文.

另外,像@a_horse一样回答:您需要将文本值放在单引号中.

类似这里:

EXECUTE 'INSERT INTO $1 VALUES (NEW.*)' USING quote_ident(tablename);

代替:

EXECUTE 'INSERT INTO ' || quote_ident(tablename) || ' VALUES ($1.*)'
USING NEW;

相关回答:

• 如何在PostgreSQL 8.2中动态使用TG_TABLE_NAME？

旁白:虽然PostgreSQL中的列名允许"date",但它是每个SQL标准中的保留字.不要将列命名为"日期",这会导致语法错误混乱.

完整的工作演示

CREATE TABLE ping (ping_id integer, the_date date);

CREATE OR REPLACE FUNCTION trg_ping_partition()
  RETURNS trigger AS
$func$
DECLARE
   _tbl text := to_char(NEW.the_date, '"ping_"YYYY_DDD_') || NEW.ping_id;
BEGIN
   IF NOT EXISTS (
      SELECT 1
      FROM   pg_catalog.pg_class c
      JOIN   pg_catalog.pg_namespace n ON n.oid = c.relnamespace
      WHERE  n.nspname = 'public'  -- your schema
      AND    c.relname = _tbl
      AND    c.relkind = 'r') THEN

      EXECUTE format('CREATE TABLE %I (CHECK (the_date >= %L AND
                                              the_date <  %L)) INHERITS (ping)'
              , _tbl
              , to_char(NEW.the_date,     'YYYY-MM-DD')
              , to_char(NEW.the_date + 1, 'YYYY-MM-DD')
              );
   END IF;

   EXECUTE 'INSERT INTO ' || quote_ident(_tbl) || ' VALUES ($1.*)'
   USING NEW; 

   RETURN NULL;
END
$func$ LANGUAGE plpgsql SET search_path = public;

CREATE TRIGGER insbef
BEFORE INSERT ON ping
FOR EACH ROW EXECUTE PROCEDURE trg_ping_partition();

• 更新:后期版本的Postgres有更优雅的方法来检查表是否存在:

  • 如何检查给定模式中是否存在表

• to_char()可以采取date的$1.那是timestamp自动转换的.
  有关日期/时间功能的手册.

• (可选)SET将search_path您的函数的范围,以避免与改变的不当行为search_path设置.

• 多种其他简化和改进.比较代码.

测试:

INSERT INTO ping VALUES (1, now()::date);
INSERT INTO ping VALUES (2, now()::date);
INSERT INTO ping VALUES (2, now()::date + 1);
INSERT INTO ping VALUES (2, now()::date + 1);

SQL小提琴.