Multi-frame ZSTD data in Athena

Question

I've been trying to read some zstd data in Athena. The files are multi-frame, which is a feature that ZSTD format fully supports. In fact, a multi-frame file is simply a file created by concatenating individual ZSTD files. This approach works like a dream with GZ files, and Athena reads them without any hitches.

However, when I try the same with concatenated ZSTD files, I keep running into an error message that says, "GENERIC_INTERNAL_ERROR: Unknown frame descriptor."

These files are perfectly readable when I use a command-line tool.

```
smotrov@MacBook-Pro test_data % zstd -dvl default_US_YYY_bZfVhjMmdecpQew2wey8W.zst
*** Zstandard CLI (64-bit) v1.5.5, by Yann Collet ***
default_US_YYY_bZfVhjMmdecpQew2wey8W.zst 
# Zstandard Frames: 20
DictID: 0
Window Size: 4.00 MiB (4194304 B)
Compressed Size: 43.8 MiB (45957238 B)
Check: None
```

Has anyone encountered this issue before, and if so, any ideas on how to fix it?

Giovanni Lauria · Answer

Besides this being a well documented bug you can work around by ensuring that the ZSTD compressed files are stored in a format that Athena supports natively, such as Parquet or ORC. Athena supports reading ZSTD compressed data in these formats.

When creating the table in Athena, specify the ZSTD compression in the table properties.

Example Athena CREATE TABLE statement for a Parquet table with ZSTD compression:
```
CREATE TABLE my_table (
  col1 INT,
  col2 STRING
)
STORED AS PARQUET
LOCATION 's3://my-bucket/my-data/'
TBLPROPERTIES (
  'parquet.compression' = 'ZSTD',
  'compression_level' = '5'
);
```

Multi-frame ZSTD data in Athena

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