ALTER TABLE ALTER COLUMN SET PARQUET

Sets or removes per-column Parquet encoding, compression, and bloom filter configuration on existing tables. These settings only affect Parquet partitions and are ignored for native partitions.

SET​

Override the default Parquet encoding, compression, bloom filter, or any combination for a column. The syntax is SET PARQUET(encoding [, compression[(level)]] [, BLOOM_FILTER]). Use default for the encoding when specifying compression only.

Set encoding only
ALTER TABLE trades ALTER COLUMN price SET PARQUET(rle_dictionary);
Set compression only (with optional level)
ALTER TABLE trades ALTER COLUMN price SET PARQUET(default, zstd(3));
Set both encoding and compression
ALTER TABLE trades ALTER COLUMN price SET PARQUET(rle_dictionary, zstd(3));

Reset per-column overrides back to the server defaults.

Reset to defaults
ALTER TABLE trades ALTER COLUMN price SET PARQUET(default);

Bloom filter​

The optional BLOOM_FILTER keyword enables bloom filter generation for the column when partitions are converted to Parquet. It can be combined with encoding and compression, and always appears as the last argument.

Enable bloom filter with default encoding
ALTER TABLE trades ALTER COLUMN symbol SET PARQUET(default, BLOOM_FILTER);
Enable bloom filter with encoding and compression
ALTER TABLE trades ALTER COLUMN symbol SET PARQUET(rle_dictionary, zstd(3), BLOOM_FILTER);

To remove the bloom filter from a column, re-issue SET PARQUET without the BLOOM_FILTER keyword:

Clear bloom filter, keep encoding
ALTER TABLE trades ALTER COLUMN symbol SET PARQUET(rle_dictionary);

The bloom filter false positive probability (FPP) is a global setting and cannot be configured per column. See the Configuration reference for details.

Supported encodings and codecs​

See the CREATE TABLE reference for the full list of supported encodings, compression codecs, and their valid column types.