@Rocky please tell me about relation between iceberg table property of write.parquet.compression-codec and starrocks session config of connector_sink_compression_codec when i using insert into files

The relationship between the Iceberg table property

write.parquet.compression-codec

and the StarRocks session variable

connector_sink_compression_codec

depends on whether you are sinking data into a managed Iceberg table or using the

INSERT INTO FILES

syntax. 1. Sinking into an Iceberg Table (via Catalog) When you use

INSERT INTO <iceberg_catalog>.<db>.<table>

, StarRocks determines the compression codec using the following priority: 1. Iceberg Table Property: StarRocks first checks the

write.parquet.compression-codec

property defined in the Iceberg table's metadata. 2. Session Variable: If the table property is not set, StarRocks uses the value of the session variable

connector_sink_compression_codec

. 3. Default: If neither is set, it defaults to

uncompressed

. 2. Using

INSERT INTO FILES

If you are specifically using the

INSERT INTO FILES

syntax (typically used to export data to a cloud storage path), the Iceberg table property does not apply because this operation bypasses Iceberg table metadata. The priority is: 1. Function Property: The

compression

property defined inside the

FILES()

table function (e.g.,

FILES("path"="..." , "compression"="snappy")

). 2. Session Variable: If the

compression

property is omitted in the

FILES()

call, StarRocks uses the

connector_sink_compression_codec

session variable. 3. Default: Defaults to

uncompressed

. Summary Table Method | Highest Priority | Fallback Catalog Sink (

INSERT INTO iceberg_table

) |

write.parquet.compression-codec

(Table Property) |

connector_sink_compression_codec

(Session Var) Direct Export (

INSERT INTO FILES

) |

compression

(Property in

FILES()

function) |

connector_sink_compression_codec

(Session Var) Note: The

connector_sink_compression_codec

variable was introduced in v3.2.3. Valid values include

uncompressed

,

snappy

,

lz4

,

zstd

, and

gzip

. References • sql-reference/System_variable.md • unloading/unload_using_insert_into_files.md • loading/loading_introduction/feature-support-loading-and-unloading.md • loading/Flink-connector-starrocks.md • sql-reference/sql-functions/table-functions/files.md • data_source/catalog/hive_catalog.md