pig中使用的一些实例语法
1：加载名用正则表达式：
LOAD '/user/wizad/data/wizad/raw/2014-0{6,7-0,7-1,7-2,7-3,8}*/3_1/adwords*'
2：filter的几种简单用法：
按值过滤
FILTER clickDate_all BY log_type=='2';
FILTER mapping_table BY mapping_ad_network_id=='3' AND mapping_type=='5';
test =FILTER allRow BY (ad_id=='14997' OR ad_id=='14998' OR ad_id=='14999') AND log_type==2;
test=FILTER allRow BY (INDEXOF(ad_id,'14997')==0 OR INDEXOF(ad_id,'14998')==0 OR INDEXOF(ad_id,'14999')==0) AND log_type==2;
配合size函数
FILTER count_imei BY (SIZE(cimei)>14 AND SIZE(cimei)<17);
正则表达式
FILTER cimei2 BY NOT cimei MATCHES '^[0-9]*$';
FILTER cmac2 BY cmac MATCHES '/[A-F\d]{2}:[A-F\d]{2}:[A-F\d]{2}:[A-F\d]{2}:[A-F\d]{2}:[A-F\d]{2}/';
3：排序
ORDER province_count BY $2 DESC;
4：CONCAT函数的使用。可用于生成独立的一列，如count了的一个数，前面加一列名称
FOREACH origin_cleaned_data GENERATE CONCAT('<-_','->') AS cou,guid,log_type;
read_social_14 =FOREACH metadata_social_14 GENERATE CONCAT('14','=='),guid_social;
all_id =FOREACH allRow GENERATE id,CONCAT('_','-') as cc;
5：值替换：过滤空值，改成取值为unknown。
origin_historical = FOREACH origin_cleaned_data GENERATE wizad_ad_id,guid,log_type,
((province_region_id == '') ? 'unknown' : province_region_id)
6:切分成不同子集，按值：
SPLIT geelyTuiGuang INTO Android IF os_id==1,ios IF os_id==2;
SPLIT ios INTO ios6 IF (INDEXOF(os_version,'7')!=0),ios7 IF INDEXOF(os_version,'7')==0;
7：replace函数替换值
FOREACH ios6 GENERATE imei,mac_address as cmac,REPLACE(idfa,'null','');
8： en_guid =STREAM duimei THROUGH `awk -F"," '{if($3 == "null") print $1","$2","; else print $0}'`;
Hadoop Pig进阶语法