IMO when Page V2 is present or PageIndex is enabled, the boundaries should be check[1]
[1] https://github.com/apache/arrow/blob/d10ebf055a393c94a693097db1dca08ff86745bd/cpp/src/parquet/column_writer.cc#L1235-L1237 Jan Finis <[email protected]> 于2024年5月11日周六 01:15写道： > Hey Parquet devs, > > I so far thought that Parquet mandates that records start at page > boundaries, i.e., at r-level 0, and we have relied on this fact in some > places of our engine. That means, there cannot be any data page for a > REPEATED column that starts at an r-level > 0, as this would mean that a > record would be split between multiple pages. > > I also found the two comments in parquet.thrift: > > /** Number of rows in this data page. which means pages change on record > > boundaries (r = 0) **/ > > 3: required i32 num_rows > > > /** > > * Index within the RowGroup of the first row of the page; this means > > pages > > * change on record boundaries (r = 0). > > */ > > 3: required i64 first_row_index > > > These comments seem to imply that my understanding is correct. However, > they are worded very weakly, not like a mandate but more like a "by the > way" comment. > > I haven't found any other mention of r-levels and page boundaries in the > parquet-format repo (maybe I missed them?). > > I recently noticed that pyarrow.parquet splits repeated fields over > multiple pages, so it violates this. This triggers assertions in our > engine, so I want to understand what's the right course of action here. > > So, can we please clarify: > *Does Parquet mandate that pages need to start at r-level 0?* > > - I.e., is a parquet file with a page that starts at an r-level > 0 ill > formed? I.e., is this a bug in pyarrow.parquet? > - Or can pages start at r-level 0? If so, then what is the significance > of the comments in parquet.thrift? > > > Cheers, > Jan >
