Greenplum 生成加分区语句

在使用greenplum中会使用分区表，但同时分区表需要维护分区；比如加分区，这个过程比较痛苦，查询相关资料以后有了相应的解决办法，但是该办法也不是万能的，有诸多限制，关于限制有兴趣的同学可以查看我文章最后提到的参考资料。

创建2个表（range分区表和list分区表）

CREATE TABLE tb1_partition_list_yyyymmdd (
    id numeric,
    yyyymmdd character varying(128)
)
WITH (appendonly=true, compresslevel=5) DISTRIBUTED BY (id) PARTITION BY LIST(yyyymmdd)
          (
          PARTITION p20120811 VALUES('') WITH (tablename='tb1_partition_list_yyyymmdd_1_prt_p20120811', orientation=row , appendonly=true, compresslevel=5 ),
          PARTITION p20120812 VALUES('') WITH (tablename='tb1_partition_list_yyyymmdd_1_prt_p20120812', orientation=row , appendonly=true, compresslevel=5 )
          );

CREATE TABLE tb1_partition_range_yyyymmdd (
    id numeric,
    yyyymmdd date
)
WITH (appendonly=true, compresslevel=5) DISTRIBUTED BY (id) PARTITION BY RANGE(yyyymmdd)
          (
          PARTITION p20120811 START ('2012-08-11'::date) END ('2012-08-12'::date) WITH (tablename='tb1_partition_range_yyyymmdd_1_prt_p20120811', orientation=row , appendonly=true, compresslevel=5 ),
          PARTITION p20120812 START ('2012-08-12'::date) END ('2012-08-13'::date) WITH (tablename='tb1_partition_range_yyyymmdd_1_prt_p20120812', orientation=row , appendonly=true, compresslevel=5 )
          );

上面分别创建了list分区表和range分区表。

下面创建一个辅助视图：

CREATE VIEW v_pg_add_partitions AS
    SELECT pp.parrelid AS tableoid, prl.parchildrelid, prl.parname AS partitionname, CASE WHEN (pp.parkind = 'h'::"char") THEN 'hash'::text WHEN (pp.parkind = 'r'::"char") THEN 'range'::text WHEN (pp.parkind = '
l'::"char") THEN 'list'::text ELSE NULL::text END AS partitiontype, translate(pg_get_expr(prl.parlistvalues, prl.parchildrelid), '-'':date character varying bpchar numeric double precision timestamp without time
 zone'::text, ''::text) AS partitionlistvalue, "substring"(translate(pg_get_expr(prl.parrangestart, prl.parchildrelid), '-'':date character varying bpchar numeric double precision timestamp without time zone'::t
ext, ''::text), 1, 8) AS partitionrangestart, "substring"(translate(pg_get_expr(prl.parrangeend, prl.parchildrelid), '-'':date character varying bpchar numeric double precision timestamp without time zone'::text
, ''::text), 1, 8) AS partitionrangeend, prl.parruleord AS partitionposition, (("substring"(prl.parlistvalues, 'consttype ([0-9]+)'::text))::integer)::regtype AS listtype, (("substring"(prl.parrangeend, 'constty
pe ([0-9]+)'::text))::integer)::regtype AS rangetype FROM pg_partition pp, pg_partition_rule prl WHERE ((pp.paristemplate = false) AND (prl.paroid = pp.oid));

接下来创建生成添加分区表的命令的函数：

create or replace function add_partition_info(tableoid oid,days_from_now integer)
    returns setof text
as $$
    import datetime
    def now():
        d=datetime.datetime.now()
        format='%Y%m%d'
        return datetime.datetime.strftime(d,format)

    def add_day(d,n):
        format='%Y%m%d'
        d2=datetime.datetime.strptime(d,format)
        d3=d2+datetime.timedelta(days=n)
        return datetime.datetime.strftime(d3,format)

    def add_month(d,n):
        format='%Y%m%d'
        formatymd='%Y%m01'
        if d.__len__() == 6:
            format='%Y%m'
            formatymd='%Y%m'
        d2=datetime.datetime.strptime(d,format)
        d3=d2+datetime.timedelta(days=31*n)
        return datetime.datetime.strftime(d3,formatymd)

    relist=[]
    sql=""" select * from (select *,tableoid::regclass tablename,lead(case when partitionrangeend <> '' then partitionrangeend else partitionlistvalue end) over (partition by tableoid order by partitionposition desc) as pre_value,row_number() over (partition by tableoid order by partitionposition desc) rn from v_pg_add_partitions where substr(partitionname,1,3)='p20' and tableoid=%s) t where rn=1;""" % (tableoid);
    rv=plpy.execute(sql);
    sql_relation="select array_to_string(reloptions,',') reloptions from pg_class where oid=%s" % (tableoid)
    rv_relation=plpy.execute(sql_relation)

    if rv.nrows()!=1:
        return None
    else:
        reloptions = rv_relation[]['reloptions']
        tablename=rv[]['tablename']
        partitiontype=rv[]['partitiontype']
        partitionname=rv[]['partitionname']
        pre_value=rv[]['pre_value']
        now_add_7days=add_day(now(),days_from_now)

        if partitiontype=='range':
            rangetype=rv[]['rangetype']
            partitionrangestart=rv[]['partitionrangestart']
            partitionrangeend=rv[]['partitionrangeend']
            interval = int(partitionrangeend) - int(pre_value)

            if partitionname.__len__()==7:
                func_add=add_month
                interval=int(partitionrangeend[0:6]) - int(pre_value[0:6])

            elif partitionname.__len__()==9:
                func_add=add_day

            else:
                return None
            while partitionrangestart < now_add_7days:
                partitionrangestart = func_add(partitionrangestart,interval)
                partitionrangeend = func_add(partitionrangeend,interval)
                partitionname="p"+func_add(partitionname[1:],interval)
                add_sql = "alter table %s add partition %s start ('%s'::%s) end ('%s'::%s) " % (tablename,partitionname,partitionrangestart,rangetype,partitionrangeend,rangetype)
                if reloptions != None and reloptions != '':
                    add_sql+='with (%s);' % (reloptions)
                else:
                    add_sql+=";"
                relist.append(add_sql)

        if partitiontype=='list':
            listtype=rv[]['listtype']
            partitionlistvalue=rv[]['partitionlistvalue']
            interval=int(partitionlistvalue) - int(pre_value)

            if partitionname.__len__()==7:
                func_add = add_month

            elif partitionname.__len__()==9:
                func_add=add_day

            else:
                return None
            while partitionlistvalue < now_add_7days:
                partitionlistvalue=func_add(partitionlistvalue,interval)
                partitionname="p"+func_add(partitionname[1:],interval)
                add_sql="alter table %s add partition %s values ('%s'::%s)" % (tablename,partitionname,partitionlistvalue,listtype)
                if reloptions != None and reloptions != '':
                    add_sql +='with (%s);' % (reloptions)
                else:
                    add_sql+=";"
                relist.append(add_sql)
        return relist
$$ LANGUAGE plpythonu;

最后我们进行测试（增加当前时间3天内的分区）

test_db=# SELECT add_partition_info('tb1_partition_range_yyyymmdd'::regclass,3);
                                                                    add_partition_info
----------------------------------------------------------------------------------------------------------------------------------------------------------
 alter table tb1_partition_range_yyyymmdd add partition p20120813 start (''::date) end (''::date) with (appendonly=true,compresslevel=5);
 alter table tb1_partition_range_yyyymmdd add partition p20120814 start (''::date) end (''::date) with (appendonly=true,compresslevel=5);
 alter table tb1_partition_range_yyyymmdd add partition p20120815 start (''::date) end (''::date) with (appendonly=true,compresslevel=5);
 alter table tb1_partition_range_yyyymmdd add partition p20120816 start (''::date) end (''::date) with (appendonly=true,compresslevel=5);
 alter table tb1_partition_range_yyyymmdd add partition p20120817 start (''::date) end (''::date) with (appendonly=true,compresslevel=5);
 alter table tb1_partition_range_yyyymmdd add partition p20120818 start (''::date) end (''::date) with (appendonly=true,compresslevel=5);
 alter table tb1_partition_range_yyyymmdd add partition p20120819 start (''::date) end (''::date) with (appendonly=true,compresslevel=5);
 alter table tb1_partition_range_yyyymmdd add partition p20120820 start (''::date) end (''::date) with (appendonly=true,compresslevel=5);
 alter table tb1_partition_range_yyyymmdd add partition p20120821 start (''::date) end (''::date) with (appendonly=true,compresslevel=5);
 alter table tb1_partition_range_yyyymmdd add partition p20120822 start (''::date) end (''::date) with (appendonly=true,compresslevel=5);
 alter table tb1_partition_range_yyyymmdd add partition p20120823 start (''::date) end (''::date) with (appendonly=true,compresslevel=5);
 alter table tb1_partition_range_yyyymmdd add partition p20120824 start (''::date) end (''::date) with (appendonly=true,compresslevel=5);
 alter table tb1_partition_range_yyyymmdd add partition p20120825 start (''::date) end (''::date) with (appendonly=true,compresslevel=5);
 alter table tb1_partition_range_yyyymmdd add partition p20120826 start (''::date) end (''::date) with (appendonly=true,compresslevel=5);
 alter table tb1_partition_range_yyyymmdd add partition p20120827 start (''::date) end (''::date) with (appendonly=true,compresslevel=5);
 alter table tb1_partition_range_yyyymmdd add partition p20120828 start (''::date) end (''::date) with (appendonly=true,compresslevel=5);
 alter table tb1_partition_range_yyyymmdd add partition p20120829 start (''::date) end (''::date) with (appendonly=true,compresslevel=5);
 alter table tb1_partition_range_yyyymmdd add partition p20120830 start (''::date) end (''::date) with (appendonly=true,compresslevel=5);
 alter table tb1_partition_range_yyyymmdd add partition p20120831 start (''::date) end (''::date) with (appendonly=true,compresslevel=5);
 alter table tb1_partition_range_yyyymmdd add partition p20120901 start (''::date) end (''::date) with (appendonly=true,compresslevel=5);
 alter table tb1_partition_range_yyyymmdd add partition p20120902 start (''::date) end (''::date) with (appendonly=true,compresslevel=5);
 alter table tb1_partition_range_yyyymmdd add partition p20120903 start (''::date) end (''::date) with (appendonly=true,compresslevel=5);
 alter table tb1_partition_range_yyyymmdd add partition p20120904 start (''::date) end (''::date) with (appendonly=true,compresslevel=5);
 alter table tb1_partition_range_yyyymmdd add partition p20120905 start (''::date) end (''::date) with (appendonly=true,compresslevel=5);
 alter table tb1_partition_range_yyyymmdd add partition p20120906 start (''::date) end (''::date) with (appendonly=true,compresslevel=5);
 alter table tb1_partition_range_yyyymmdd add partition p20120907 start (''::date) end (''::date) with (appendonly=true,compresslevel=5);
 alter table tb1_partition_range_yyyymmdd add partition p20120908 start (''::date) end (''::date) with (appendonly=true,compresslevel=5);
 alter table tb1_partition_range_yyyymmdd add partition p20120909 start (''::date) end (''::date) with (appendonly=true,compresslevel=5);

再创建一个range分区且是按月分区的表

CREATE TABLE tb1(
    id numeric,
    yyyymmdd date
)DISTRIBUTED BY (id) PARTITION BY RANGE(yyyymmdd)
          (
          PARTITION p201208 START ('2012-08-01'::date) END ('2012-09-01'::date) ,
          PARTITION p201209 START ('2012-09-01'::date) END ('2012-10-01'::date)
          );

test_db=# SELECT add_partition_info('tb1'::regclass,1);
                                   add_partition_info
-----------------------------------------------------------------------------------------
 alter table tb1 add partition p201210 start (''::date) end (''::date) ;
 alter table tb1 add partition p201211 start (''::date) end (''::date) ;
 alter table tb1 add partition p201212 start (''::date) end (''::date) ;
 alter table tb1 add partition p201301 start (''::date) end (''::date) ;
 alter table tb1 add partition p201302 start (''::date) end (''::date) ;
 alter table tb1 add partition p201303 start (''::date) end (''::date) ;
 alter table tb1 add partition p201304 start (''::date) end (''::date) ;
 alter table tb1 add partition p201305 start (''::date) end (''::date) ;
 alter table tb1 add partition p201306 start (''::date) end (''::date) ;
 alter table tb1 add partition p201307 start (''::date) end (''::date) ;
 alter table tb1 add partition p201308 start (''::date) end (''::date) ;
 alter table tb1 add partition p201309 start (''::date) end (''::date) ;
 alter table tb1 add partition p201310 start (''::date) end (''::date) ;
 alter table tb1 add partition p201311 start (''::date) end (''::date) ;
 alter table tb1 add partition p201312 start (''::date) end (''::date) ;
 alter table tb1 add partition p201401 start (''::date) end (''::date) ;
 alter table tb1 add partition p201402 start (''::date) end (''::date) ;
 alter table tb1 add partition p201403 start (''::date) end (''::date) ;
 alter table tb1 add partition p201404 start (''::date) end (''::date) ;
 alter table tb1 add partition p201405 start (''::date) end (''::date) ;
 alter table tb1 add partition p201406 start (''::date) end (''::date) ;
 alter table tb1 add partition p201407 start (''::date) end (''::date) ;
 alter table tb1 add partition p201408 start (''::date) end (''::date) ;
 alter table tb1 add partition p201409 start (''::date) end (''::date) ;
 alter table tb1 add partition p201410 start (''::date) end (''::date) ;
 alter table tb1 add partition p201411 start (''::date) end (''::date) ;
 alter table tb1 add partition p201412 start (''::date) end (''::date) ;

可以看见也是没有问题的。

参考资料：

《greenplum企业应用实战》