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  • Shared session properties #

    Great Lakes connectivity supports a set of session properties that are shared among two or more table formats. In addition, each table format supports a unique set of session properties.

    The following table describes the session properties available with the Hive, Iceberg, and Delta Lake table formats:

    Session property Description
    dynamic_filtering_wait_timeout The duration to wait for completion of dynamic filtering during split generation. Dynamic filtering optimizations significantly improve the performance of queries with selective joins by avoiding reading of data that would be filtered by join conditions.This extra wait time can potentially result in significant overall savings in query and CPU time, if dynamic filtering is able to reduce the amount of scanned data.
    orc_bloom_filters_enabled Enable bloom filters for predicate pushdown. The default value is false.
    orc_lazy_read_small_ranges Read small file segments lazily. The default value is true.
    orc_max_buffer_size Maximum size of a single read. The default value is 8MB.
    orc_max_merge_distance Maximum size of gap between two reads to merge into a single read. The default value is 1MB.
    orc_max_read_block_size Soft maximum size of Trino blocks produced by ORC reader. The default value is 16MB.
    orc_native_zstd_ decompressor_enabled Enable using the native zstd library for faster decompression of ORC files. The default value is true.
    orc_nested_lazy_enabled Lazily read nested data. The default value is true.
    orc_stream_buffer_size Size of buffer for streaming reads. The default value is 8MB.
    orc_string_statistics_limit Maximum size of the string statistics. The default value is 64B.
    orc_tiny_stripe_threshold The Threshold below which an ORC stripe or file will read in its entirety. The default value is 8MB.
    parquet_use_bloom_filter Specifies whether Bloom filters are used for predicate pushdown when reading Parquet files.true.
    parquet_max_read_block_ row_count Sets the maximum number of rows read in a batch. The default value is 8192.
    parquet_max_read_block_size The maximum block size used when reading Parquet files. The default value is 16MB.
    parquet_native_snappy_ decompressor_enabled Enable using the native SNAPPY library for faster decompression of Parquet files. The default value is true.
    parquet_optimized_nested_ reader_enabled Specifies whether batched column readers are used when reading ARRAY, MAP, and ROW types from Parquet files for improved performance. Set this property to false to disable the optimized Parquet reader for structural data types. The default value is true.
    parquet_optimized_reader_ enabled Specifies whether batched column readers are used when reading Parquet files for improved performance. Set this property to false to disable the optimized Parquet reader The default value is true.
    parquet_vectorized_ decoding_enabled Enable the use of the Java Vector API for faster decoding of Parquet files. The default value is true.
    parquet_writer_batch_size Maximum number of rows processed by the Parquet writer in a batch. The default value is 10000.
    parquet_writer_block_size The maximum block size created by the Parquet writer. The default value is 128MB.
    parquet_writer_page_size The maximum page size created by the Parquet writer. The default value is 1MB.
    projection_pushdown_enabled Enable projection push down. The default value is true.
    sorted_writing_enabled Enable sorted writes. The default value is true.
    statistics_enabled Enables table statistics for performance improvements. The default value is true. If the value is set to false the following session property is disabled:
    • extended_statistics_enabled
    • extended_statistics_collect_on_write
    target_max_file_size Target maximum size of written files. The default value is 1GB.

    Format specific properties #

    Read more about the available session properties for each table format: