FlinkSQL中【FULL OUTER JOIN】使用实例分析（坑）

news2025/5/24 1:07:38

Flink版本：flink1.14
最近有【FULL OUTER JOIN】场景的实时数据开发需求，想要的结果是，左右表来了数据都下发数据；左表存在的数据，右表进来可以关联下发（同样，右表存在的数据，左表进来也可以关联下发）。但在实际应用中遇到一些问题。

FlinkSQL demo


CREATE TABLE waybill_extend_kafka (
     mid bigint,
     db string,
     sch string,
     tab string,
     opt string,
     ts bigint,
     ddl string,
     err string,
     src map<string,string>,
     cur map<string,string>,
     cus map<string,string>,
     _proc  as proctime()
) WITH (
  'connector' = 'kafka',
  'topic' = 't1',
  'properties.bootstrap.servers' = 'xx.xx.xx.xx:9092',
  'properties.group.id' = 'g1',
  'scan.startup.mode' = 'earliest-offset',  --group-offsets/earliest-offset/latest-offset
  'format' = 'json'
);

CREATE TABLE package_state_kafka (
     mid bigint,
     db string,
     sch string,
     tab string,
     opt string,
     ts bigint,
     ddl string,
     err string,
     src map<string,string>,
     cur map<string,string>,
     cus map<string,string>,
     _proc  as proctime()
) WITH (
  'connector' = 'kafka',
  'topic' = 't2',
  'properties.bootstrap.servers' = 'xx.xx.xx.xx:9092',
  'properties.group.id' = 'g1',
  'scan.startup.mode' = 'earliest-offset',  --group-offsets/earliest-offset/latest-offset
  'format' = 'json'
);

CREATE TABLE es_dim(
    id                STRING,
    ts                STRING,
    waybill_code      STRING,
    pin               STRING,
    operater_ts       STRING,
    operater_type     STRING,
    is_enable         STRING,
    batch_no          STRING,
    activity_key      STRING,
    p_type            STRING,
    p_name            STRING,
    version            STRING,
    update_time            STRING
)
with (
    'connector' = 'elasticsearch-6',
    'index' = 'es_dim',
    'document-type' = 'es_dim',
    'hosts' = 'http://xxx:9200',
    'format' = 'json'
);

CREATE TABLE es_sink(
     waybill_code      STRING
    ,first_order       STRING -- 新客1，非新客0
    ,extend_update_time            STRING
    ,state       STRING -- 妥投150
    ,package_update_time            STRING
    ,pin              STRING
    ,coupon_use_time      STRING
    ,operater_type    STRING
    ,is_enable        STRING
    ,batch_no         STRING
    ,update_time         STRING
    ,PRIMARY KEY (waybill_code) NOT ENFORCED
)
with (
    'connector' = 'elasticsearch-6',
    'index' = 'es_sink',
    'document-type' = 'es_sink',
    'hosts' = 'http://xxx:9200',
    'format' = 'json',
    'filter.null-value'='true',
    'sink.bulk-flush.max-actions' = '1000',
    'sink.bulk-flush.max-size' = '10mb'
);

CREATE TABLE kafka_sink (
     waybill_code      STRING
    ,first_order       STRING 
    ,extend_update_time            STRING
    ,state       STRING -- 妥投150
    ,package_update_time            STRING
    ,pin              STRING
    ,coupon_use_time      STRING
    ,operater_type    STRING
    ,is_enable        STRING
    ,batch_no         STRING
    ,update_time         STRING
    ,PRIMARY KEY (waybill_code) NOT ENFORCED --注意 确保在 DDL 中定义主键。
) WITH (
  'connector' = 'upsert-kafka',
  'topic' = 't3',
  'properties.bootstrap.servers' = 'xx.xx.xx.xx:9092',
  'key.format' = 'json',
  'value.format' = 'json'
);

--新客
CREATE view  waybill_extend_temp as
select
    IF(cur['waybill_code'] IS NOT NULL , cur['waybill_code'], src ['waybill_code'])  AS waybill_code,
    IF(cur['data_key'] IS NOT NULL , cur['data_key'], src ['data_key'])  AS data_key,
    IF(cur['create_time'] IS NOT NULL , cur['create_time'], src ['create_time'])  AS create_time,
    opt,
    _proc
FROM waybill_extend_kafka
where UPPER(opt) = 'DELETE' OR UPPER(opt) = 'INSERT';

CREATE view  waybill_extend_temp_handle as
SELECT
    waybill_code,
    case when UPPER(opt) = 'INSERT'  then '1'
         when UPPER(opt) = 'DELETE'  then '0'
            end as first_order,
    create_time,
    _proc
from waybill_extend_temp
where data_key = 'firstOrder';

--妥投
CREATE view package_state_temp as
select
    IF(cur['WAYBILL_CODE'] IS NOT NULL , cur['WAYBILL_CODE'], src ['WAYBILL_CODE'])  AS waybill_code,
    IF(cur['STATE'] IS NOT NULL , cur['STATE'], src ['STATE'])  AS state,
    IF(cur['CREATE_TIME'] IS NOT NULL , cur['CREATE_TIME'], src ['CREATE_TIME'])  AS create_time,
    opt,
    _proc
FROM package_state_kafka
where UPPER(opt) = 'INSERT';

CREATE view package_state_temp_handle as
SELECT
    waybill_code,
    max(state) as state,
    min(create_time) as package_update_time,
    proctime() as _proc
from package_state_temp
where state = '150'
group by waybill_code;

--full join
-- flink1.14 注意：flinksql里面的FULL OUTER JOIN 只是分别下发左右数据，中间状态不关联下发，在流处理场景下相当于union all
CREATE view waybill_extend_package_state  as
SELECT
    COALESCE(a.waybill_code, b.waybill_code) as waybill_code,
    a.first_order,
    a.create_time as extend_update_time,
    b.state,
    b.package_update_time,
    COALESCE(a._proc, b._proc) as _proc
from waybill_extend_temp_handle as a
FULL OUTER JOIN package_state_temp_handle b
on a.waybill_code=b.waybill_code;

--result
CREATE VIEW res_view AS
SELECT
     a.waybill_code
    ,a.first_order
    ,a.extend_update_time
    ,a.state
    ,a.package_update_time
    ,b.pin
    ,b.operater_ts
    ,b.operater_type
    ,b.is_enable
    ,b.batch_no
    ,CAST(CAST(a._proc AS TIMESTAMP(3)) AS STRING) as update_time
    ,row_number() over(partition by a.waybill_code order by b.operater_ts desc) as rn 
from waybill_extend_package_state as a
JOIN es_dim FOR SYSTEM_TIME AS OF a._proc as b
on a.waybill_code=b.waybill_code;

INSERT INTO es_sink
SELECT
     waybill_code
    ,first_order
    ,extend_update_time
    ,state
    ,package_update_time
    ,pin
    ,operater_ts
    ,operater_type
    ,is_enable
    ,batch_no
    ,update_time
FROM res_view
where rn =1;

INSERT INTO kafka_sink
SELECT
     waybill_code
    ,first_order
    ,extend_update_time
    ,state
    ,package_update_time
    ,pin
    ,operater_ts 
    ,operater_type
    ,is_enable
    ,batch_no
    ,update_time
FROM res_view
where rn =1;

es_sink mapping:

POST es_sink/es_sink/_mapping
{
    "es_sink": {
        "properties": {
            "waybill_code": {
                "type": "keyword"
            },
            "pin": {
                "type": "keyword"
            },
            "operater_ts": {
                "type": "date",
                "format": "yyyy-MM-dd HH:mm:ss.SSS||yyyy-MM-dd HH:mm:ss||yyyy-MM-dd||epoch_millis"
            },
            "operater_type": {
                "type": "keyword"
            },
            "is_enable": {
                "type": "keyword"
            },
            "batch_no": {
                "type": "keyword"
            },
            "first_order": {
                "type": "keyword"
            },
            "extend_update_time": {
                "type": "date",
                "format": "yyyy-MM-dd HH:mm:ss.SSS||yyyy-MM-dd HH:mm:ss||yyyy-MM-dd||epoch_millis"
            },
            "state": {
                "type": "keyword"
            },
            "package_update_time": {
                "type": "date",
                "format": "yyyy-MM-dd HH:mm:ss.SSS||yyyy-MM-dd HH:mm:ss||yyyy-MM-dd||epoch_millis"
            },
            "update_time": {
                "type": "date",
                "format": "yyyy-MM-dd HH:mm:ss.SSS||yyyy-MM-dd HH:mm:ss||yyyy-MM-dd||epoch_millis"
            }
        }
    }
}

结果分析

从sink_es和sink_kafka获取数据都是同样的结果，部分结果如下：
在这里插入图片描述
但从结果中可以看出，FlinkSQL里面的【FULL OUTER JOIN】只是分别下发左右数据，中间状态（从FlinkUI中可以看到【FULL OUTER JOIN】状态也做了保存）不关联下发，在流处理场景下相当于【UNION ALL】，不知是否是FlinkSQL的bug。
【FULL OUTER JOIN】状态数据，如下：
在这里插入图片描述
此次用例分析只是针对于Flink1.14，对于其他版本尚不清楚。