Question

我正在尝试在PostgreSQL数据库中创建与时间有关的分区。虽然下面的函数/触发器是我遇到服务器的大部分目的，但我仍然需要找到一种方法来将表名和模式名称设置为参数。因为我们计划通过更改参数值来为不同的表和模式运行相同的触发器。任何帮助都非常感谢，因为我几乎没有任何使用函数/触发器的经验。

CREATE OR REPLACE FUNCTION
myschema.server_partition_function()
RETURNS TRIGGER AS 
$BODY$
DECLARE
_new_time int;
_tablename text;
_startdate text;
_enddate text;
_result record;
BEGIN
--Takes the current inbound "time" value and determines when midnight is for the given date
_new_time := ((NEW."time"/86400)::int)*86400;
_startdate := to_char(to_timestamp(_new_time), 'YYYY-MM-DD');
_tablename := 'server_'||_startdate;

-- Check if the partition needed for the current record exists
PERFORM 1
FROM   pg_catalog.pg_class c
JOIN   pg_catalog.pg_namespace n ON n.oid = c.relnamespace
WHERE  c.relkind = 'r'
AND    c.relname = _tablename
AND    n.nspname = 'myschema';

-- If the partition needed does not yet exist, then we create it:
-- Note that || is string concatenation (joining two strings to make one)
IF NOT FOUND THEN
_enddate:=_startdate::timestamp + INTERVAL '1 day';
EXECUTE 'CREATE TABLE myschema.' || quote_ident(_tablename) || ' (
CHECK ( "time" >= EXTRACT(EPOCH FROM DATE ' || quote_literal(_startdate) || ')
AND "time" < EXTRACT(EPOCH FROM DATE ' || quote_literal(_enddate) || ')
)
) INHERITS (myschema.server_master)';

-- Table permissions are not inherited from the parent.
-- If permissions change on the master be sure to change them on the child also.
EXECUTE 'ALTER TABLE myschema.' || quote_ident(_tablename) || ' OWNER TO postgres';
EXECUTE 'GRANT ALL ON TABLE myschema.' || quote_ident(_tablename) || ' TO my_role';

-- Indexes are defined per child, so we assign a default index that uses the partition columns
EXECUTE 'CREATE INDEX ' || quote_ident(_tablename||'_indx1') || ' ON myschema.' || quote_ident(_tablename) || ' (time, id)';
END IF;

-- Insert the current record into the correct partition, which we are sure will now exist.
EXECUTE 'INSERT INTO myschema.' || quote_ident(_tablename) || ' VALUES ($1.*)' USING NEW;
RETURN NULL;
END;
$BODY$
LANGUAGE plpgsql;

Answer 1

您可能需要使用一些动态触发器特殊变量。调用触发器时，PostgreSQL会使用特殊变量自动提供一些值：Breeze's documentation page

_tablename  := TG_TABLE_NAME || '_' || _startdate;
_schemaname := TG_TABLE_SCHEMA || '_partitions';

在PostgreSQL函数/触发器

1 个答案: