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Hudi implements custom input formats to integrate with query engines. These existing custom input formats will recognize special bootstrap commit and performs column stitching between hudi record-level metadata fields in the skeleton hudi file and other columns present in external parquet file to provide same views as existing hudi tables. Note that only projected columns required by the query will be read from the physical parquet files. Please see below for a pictorial representation of how query engine integration is done

Caveats

• As with any Hudi datasets, the uniqueness constraint of record keys is expected for the dataset to be bootstrapped. Hence, care must be taken to select the columns in the original dataset to guarantee uniqueness. Otherwise, proper upsert for records corresponding to duplicate keys is not guaranteed.

Rollout/Adoption Plan

• This will be rolled out as an experimental feature in 0.5.1 
• Hudi Writers and Readers do not need special configuration to identify tables using this new bootstrap mechanism. The presence of special bootstrap commit and bootstrap index will automatically trigger correct handling of these tables.

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