I'm trying to read tables and columns and columns' type from Metastore DB. I checked "COLUMN_V2" table and it doesn't have TBL_ID, but it has CD_ID ! Then, I released that there is a table named CDS having one column which is "CD_ID" and the values are as the same as TBL_ID in TBLS table. I want to know if below query using CD_ID is a reliable query or not. Select tbls.TBL_NAME, cv2.COLUMN_NAME,cv2.TYPE_NAME from TBLS tbls JOIN COLUMNS_V2 cv2 on tbls.TBL_ID = cv2.CD_ID   And I would be grateful if I can know more about below concerns: 1. What is the purpose of CDS table? 2. why TBL_ID was not enough and CD_ID was needed? 3. What does "CD" stands for? 4. Does CD_ID has the same value as TBL_ID all the time? or there are scenarios that they can be different?   ... View more