Page History

...

2) any schema change will directly applied to this first id-schema and saved with commit file

let's give a exmaple:

Image Added

now rename operationTime to col1:Image Removed

Image Added

read operation:

once we have done schema change on old hudi table.  first id-schema will be created and all the old files are bound to the first id-schema. since old hudi table only support add/modify column type operation and avro/parquet support those change native. so use the first id-schema to represent the old data is completely fine.

...

1. when we read the old file, the first id-schema will be used as file-schema. lastest id-schema will be used as qurey-schema. then we use merge module to merge file-schema and query-schema to produce the final read-schema. once read-schema is produced, we can read the old files correctly.how to merge file-schema and query-schema pls see the chapter Data query process

Image RemovedImage Added

   2. when we read the new file, the lastest id-schema will be used as file-schema and qurey-schema the remaining process are same as (1)

...