We have some background on schema evolution in Parquet in the docs - https://docs.cloudera.com/runtime/7.2.2/impala-reference/topics/impala-parquet.html. See "Schema Evolution for Parquet Tables". Some of the details are specific to Impala but the concepts are the same across engines including Hive and Spark that use parquet tables. At a high level, you can think of the data files being immutable while the table schema evolves. If you add a new column at the end of the table, for example, that updates the table schema but leaves the parquet files unchanged. When the table is queried, the table schema and parquet file schema are reconciled and the new column's values will be all NULL.   If you want to modify the existing rows and include new non-NULL values, that would require rewriting the data, e.g. with an INSERT OVERWRITE statement for a partition or a CREATE TABLE .. AS SELECT to create an entirely new table. Keep in mind that traditional Parquet tables are not optimized for workloads with updates - Apache Kudu in particular and also transactional tables in Hive3+ have support for row-level updates that is more convenient/efficient.   We definitely don't require rewriting the whole table every time you want to add a column, that would be impractical for large tables! ... View more