COMPRESSION_CODEC Query Option (Impala 2.0 or higher only)

When Impala writes Parquet data files using the INSERT statement, the underlying compression is controlled by the COMPRESSION_CODEC query option.

Note: Prior to Impala 2.0, this option was named PARQUET_COMPRESSION_CODEC. In Impala 2.0 and later, the PARQUET_COMPRESSION_CODEC name is not recognized. Use the more general name COMPRESSION_CODEC for new code.


SET COMPRESSION_CODEC=codec_name; // Supported for all codecs.
SET COMPRESSION_CODEC=codec_name:compression_level; // Only supported for ZSTD.

The allowed values for this query option are SNAPPY (the default), GZIP, ZSTD, LZ4, and NONE.

ZSTD also supports setting a compression level. The lower the level, the faster the speed at the cost of compression ratio. Compression levels from 1 up to 22 are supported for ZSTD. The default compression level 3 is used, if one is not passed using the compression_codec query option.

Note: A Parquet file created with COMPRESSION_CODEC=NONE is still typically smaller than the original data, due to encoding schemes such as run-length encoding and dictionary encoding that are applied separately from compression.

The option value is not case-sensitive.

If the option is set to an unrecognized value, all kinds of queries will fail due to the invalid option setting, not just queries involving Parquet tables. (The value BZIP2 is also recognized, but is not compatible with Parquet tables.)


Default: SNAPPY


set compression_codec=lz4;
insert into parquet_table_lz4_compressed select * from t1;

set compression_codec=zstd; // Default compression level 3.
insert into parquet_table_zstd_default_compressed select * from t1;

set compression_codec=zstd:12; // Compression level 12.
insert into parquet_table_zstd_highly_compressed select * from t1;

set compression_codec=gzip;
insert into parquet_table_highly_compressed select * from t1;

set compression_codec=snappy;
insert into parquet_table_compression_plus_fast_queries select * from t1;

set compression_codec=none;
insert into parquet_table_no_compression select * from t1;

set compression_codec=foo;
select * from t1 limit 5;
ERROR: Invalid compression codec: foo

Related information:

For information about how compressing Parquet data files affects query performance, see Compressions for Parquet Data Files.