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Add summary table of encodings and supported types (in Encodings.md) #550
Description
Describe the enhancement requested
I propose adding an overview table to Encodings.md that lists each encoding, the supported data types and targets, and the applicable Parquet format versions. The goal is to provide a quick reference near the top of the page while keeping the detailed explanations further down.
Currently, encodings are explained one by one. While the detailed descriptions are useful, I believe a concise table will help users quickly identify which encodings are relevant for a given data type and format version.
The table will be placed before the explanation of the Plain encoding. It will highlight version-specific differences in supported types (e.g., which encodings and types are supported only in later format versions).
I have ensured that the terminology matches the existing documentation and verified the version information against past Thrift files and documentation.
If you have any comments or suggestions, please let me know — I’m happy to update the proposal. I can also open a PR with the table if the maintainers are comfortable with this approach. This is my first contribution here, so please let me know if there are any preferred formats or processes I should follow.
Example of the table:
Overview
Parquet Format 1.0.0+
| Encoding type | Encoding enum | Encoding targets |
|---|---|---|
| Plain | PLAIN = 0 | All physical types |
| Dictionary Encoding | PLAIN_DICTIONARY = 2 | All physical types |
| Run Length Encoding / Bit-Packing Hybrid | RLE = 3 | Definition and repetition levels |
| Bit-packed | BIT_PACKED = 4 | Definition and repetition levels |
Parquet Format 2.0.0+
| Encoding type | Encoding enum | Encoding Targets |
|---|---|---|
| Plain | PLAIN = 0 | All physical types, dictionary entries in dictionary page |
| Dictionary Encoding (Plain) | PLAIN_DICTIONARY = 2 (Deprecated) | All Physical Types |
| Run Length Encoding / Bit-Packing Hybrid | RLE = 3 | BOOLEAN |
| Bit-packed (Deprecated) | BIT_PACKED = 4 | N/A |
| Delta Encoding | DELTA_BINARY_PACKED = 5 | INT32, INT64 |
| Delta-length byte array | DELTA_LENGTH_BYTE_ARRAY = 6 | BYTE_ARRAY |
| Delta Strings | DELTA_BYTE_ARRAY = 7 | BYTE_ARRAY, FIXED_LEN_BYTE_ARRAY |
| Dictionary Encoding (RLE) | RLE_DICTIONARY = 8 | All physical types, repetition/definition levels, dictionary indices in data pages |
| Byte Stream Split (2.8.0+) | BYTE_STREAM_SPLIT = 9 | FLOAT (2.8.0+), DOUBLE (2.8.0+), INT32 (2.11.0+), INT64 (2.11.0+), FIXED_LEN_BYTE_ARRAY (2.11.0+) |
Activity
alamb commentedon Jan 23, 2026
This would be great -- thank you -- perhaps you can propose adding this table to Encodings.md as a sort of Table of contents and link to the relevant sections later in the doc?
MINOR: Add summary table of encodings and supported types (in Encodin…
MINOR: Add summary table of encodings and supported types (in Encodin…
nkaki commentedon Jan 29, 2026
@alamb
Thank you for the comment. I made a pull request with your feedback applied.
MINOR: Add summary table of encodings and supported types (in Encodin…
MINOR: Add summary table of encodings and supported types (in Encodin…
MINOR: Add summary table of encodings and supported types (in Encodin…