好的。所以我想我可能錯過了顯而易見的,把自己在海裏。
這是場景:
- 批處理數據集到json格式的Azure數據湖
- 每一批是一套完整的“當前”記錄(完整的表)
- 這些處理中使用自動裝卸機流管道(因為我們有其他相關流程運行流數據管道,因為自動裝卸機使生活簡單)
- 重複數據刪除從提取行
- 變化捕獲通過內置的DLT SCD2處理
這都很好地工作。
現在,我需要確定當記錄已被刪除(刪除),不再出現在批次。
SCD表,這將導致記錄的狀態改變從“當前”到“前”
我不管理為實現這一目標。
這是有關管道代碼:
#自動裝卸機拿起文件導入dlt @dlt。表def currStudents_streamFiles():返回(spark.readStream.format .option (“cloudFiles (“cloudFiles”)。格式”、“json”) .option (“cloudFiles。在ferColumnTypes", "true") .load("abfss://*****@********.dfs.core.windows.net/current-students/restAPI") .select("*","_metadata", "_metadata.file_modification_time") ) -- extract the rows from the json (each file is a complete dataset with a few hundred rows) CREATE OR REFRESH STREAMING LIVE TABLE currStudents_ingest AS SELECT col.* ,"current" AS status ,file_modification_time FROM ( SELECT fi.file_modification_time, EXPLODE_OUTER (fi.students) FROM STREAM(LIVE.currStudents_streamFiles) AS fi ) WHERE col.id IS NOT NULL ; #run some de-duplication due to most records being identical each time import dlt from pyspark.sql.functions import lit @dlt.table def currStudents_dedup(): df = spark.readStream.format("delta").table("live.currStudents_ingest") return ( df.dropDuplicates([col for col in df.columns if col != "file_modification_time"]) .select('*') .withColumn('status', lit('current')) ) -- capture SCD2 change history CREATE OR REFRESH STREAMING LIVE TABLE students_SCD; APPLY CHANGES INTO live.currStudents_SCD FROM STREAM(live.currStudents_dedup) KEYS (id) SEQUENCE BY file_modification_time STORED AS SCD TYPE 2 TRACK HISTORY ON * EXCEPT (file_modification_time) -- match the latest batch (from json file) against "current" version and identify missing records -- attempt to push identified records back through SCD with a new status "former" -- DLT pipeline doesn't like INSERT in the apply changes into .... CREATE TEMPORARY LIVE VIEW former_students_view AS SELECT *, "former" AS status -- all records from the last batch processed FROM ( SELECT * FROM STREAM(live.currStudents_ingest) WHERE file_modification_time = ( SELECT MAX(file_modification_time) FROM STREAM(live.currstudents_streamfiles) ) ) t1 WHERE NOT EXISTS ( -- "current" version of the table held in Databricks SELECT 1 FROM ( SELECT schoolId FROM STREAM(live.students_SCD) WHERE `__END_AT` IS NULL AND status != "former" ) t2 WHERE t1.schoolId = t2.schoolId ); APPLY CHANGES INTO live.currStudents_dedup FROM former_students_view KEYS (schoolId) INSERT ALL
所有的幫助感激地接受。
我知道我可能會用錯誤的方式。
