Configuration Parameters

This document lists the configuration parameters (GUC) of SynxDB Cloud database in alphabetical order.

cloud.enable_toast

  • Variable Type: Boolean

  • Default Value: on

  • Setting Category: user

  • Description: Controls whether Cloud storage uses TOAST (The Oversized-Attribute Storage Technique) for large attribute values. When enabled, the system stores values exceeding the configured thresholds separately, using either compression or external storage.

cloud.gp_segconfig_filter_warehouse

  • Variable Type: Boolean

  • Default Value: off

  • Setting Category: user

  • Description: Controls whether scans of gp_segment_configuration are restricted to the current warehouse. When set to on, the planner injects a warehouseid = current_warehouse OR content = -1 predicate into such scans before standard_planner. The filter recurses into subqueries and CTEs, so INSERT sub-selects and UDF SPI queries also see only the segments relevant to the current warehouse. Enable this parameter to keep tooling and regression behavior correct in multi-warehouse deployments that share a catalog.

cloud.pax_bloom_filter_work_memory_bytes

  • Variable Type: Integer

  • Default Value: 8192 (8 KB)

  • Unit: bytes

  • Value Range: [1024, 2147483647]

  • Setting Category: user

  • Description: Sets the work memory size (in bytes) for building bloom filters when writing data to Cloud tables. Sparse filtering uses bloom filters to quickly skip non-matching micro partitions during scans. Increasing this value improves bloom filter accuracy but consumes more memory during writes.

cloud.pax_enable_debug

  • Variable Type: Boolean

  • Default Value: off

  • Setting Category: user

  • Description: Enables Cloud storage debug mode. When you set this to on, the system outputs additional debug information during Cloud storage operations. Use this parameter for troubleshooting only, and keep it off in production environments.

cloud.pax_enable_row_filter

  • Variable Type: Boolean

  • Default Value: off

  • Setting Category: user

  • Description: Controls whether to enable row-level filtering for Cloud table scans. When enabled, the system applies row-level filter conditions during scanning to skip rows that do not match the query predicates, reducing unnecessary data processing.

cloud.pax_enable_sparse_filter

  • Variable Type: Boolean

  • Default Value: on

  • Setting Category: user

  • Description: Controls whether to enable sparse filtering for Cloud table scans. Sparse filtering uses min/max statistics and bloom filters at the micro partition and group level to skip data blocks that cannot contain matching rows. This feature can significantly reduce the amount of data read during scans.

cloud.pax_log_filter_tree

  • Variable Type: Boolean

  • Default Value: off

  • Setting Category: user

  • Description: Controls whether to log the filter tree structure during Cloud table scans. When enabled, the system outputs the filter tree to the server log to help diagnose filter pushdown behavior. Use this parameter for troubleshooting only.

cloud.pax_max_tuples_per_group

  • Variable Type: Integer

  • Default Value: 131072

  • Value Range: [5, 524288]

  • Setting Category: user

  • Description: Sets the maximum number of tuples in a single group within a Cloud micro partition file. Groups are the basic unit of data organization within a micro partition. Adjusting this parameter affects the granularity of data reading and filtering operations.

cloud.pax_min_size_of_compress_toast

  • Variable Type: Integer

  • Default Value: 524288 (512 KB)

  • Unit: bytes

  • Value Range: [32768, 1073741824]

  • Setting Category: user

  • Description: Sets the minimum attribute value size (in bytes) that triggers compressed TOAST storage in Cloud tables. The system compresses values larger than this threshold before storing them. This value must be less than cloud.pax_min_size_of_external_toast.

cloud.pax_min_size_of_external_toast

  • Variable Type: Integer

  • Default Value: 10485760 (10 MB)

  • Unit: bytes

  • Value Range: [1048576, 2147483647]

  • Setting Category: user

  • Description: Sets the minimum attribute value size (in bytes) that triggers external TOAST storage in Cloud tables. The system stores values larger than this threshold in a separate TOAST file. This value must be greater than cloud.pax_min_size_of_compress_toast.

cloud.pax_scan_reuse_buffer_size

  • Variable Type: Integer

  • Default Value: 8388608 (8 MB)

  • Unit: bytes

  • Value Range: [1048576, 33554432] (1 MB to 32 MB)

  • Setting Category: user

  • Description: Sets the size of the reusable buffer (in bytes) for Cloud table scan operations. The scan shares this buffer across micro partition reads to reduce memory allocation overhead.

datalake.enable_get_block_location

  • Variable Type: Boolean

  • Default Value: off

  • Value Range: on, off

  • Setting Category: user

  • Description: Controls whether HDFS block location information is retrieved during directory listing operations. When set to on, the system retrieves block location data, enabling data-locality-aware scheduling for HDFS-backed tables. This might improve scan performance when database segments and HDFS data nodes are co-located. This parameter applies only to HDFS directory listing operations.

max_locks_per_transaction

  • Variable Type: Integer

  • Default Value: 128

  • Value Range: [10, 2147483647]

  • Setting Category: postmaster

  • Description: Controls the average number of object locks allocated for each transaction; individual transactions can lock more objects as long as the locks of all transactions fit in the lock table. This is not the number of rows that can be locked; that value is unlimited. Increase this value if you get “out of shared memory” errors when performing operations that touch many different tables in a single transaction, such as DROP SCHEMA ... CASCADE on a schema containing many tables.

optimizer_valuescan_threshold

  • Variable Type: Integer

  • Default Value: 100

  • Value Range: [0, 2147483647]

  • Setting Category: user

  • Description: Sets the maximum number of tuples in a VALUES clause for GPORCA to plan directly. When the number of tuples in an INSERT INTO ... VALUES statement exceeds this threshold, GPORCA automatically falls back to the Postgres query planner.

    GPORCA’s Value Scan plan for bulk INSERT INTO ... VALUES statements can become very expensive when handling a large number of rows, causing the planning phase to dominate the total execution time. By falling back to the Postgres planner, this optimization achieves over 10x speed improvement for bulk data loading operations.

    Setting this parameter to 0 causes GPORCA to fall back to the Postgres planner for any VALUES clause. To have GPORCA always plan VALUES clauses directly, set this parameter to a large value such as 2147483647. This parameter is particularly beneficial for ETL and data ingestion pipelines that use bulk INSERT INTO ... VALUES as a common data loading pattern.

    For more details, see Bulk INSERT INTO…VALUES optimization.

pg_gophermeta.gopher_local_capacity_mb

  • Variable Type: Integer

  • Default Value: 1024000 (MB)

  • Value Range: [1024, 2147483647]

  • Unit: MB

  • Setting Category: user

  • Description: Controls how much local disk space (in MB) the GopherMeta process can use for caching. Setting this too low may degrade performance due to frequent cache evictions, while setting it too high may consume excessive disk space. A recommended starting point is approximately 30% of available disk space.