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4.1 System Variables

HeatWave maintains several variables that configure its operation. Variables are set when the HeatWave Cluster is enabled. Most HeatWave variable settings are managed by OCI and cannot be modified directly.

  • rapid_compression

    Introduced 8.0.29
    System Variable rapid_compression
    Scope Session
    Dynamic Yes
    SET_VAR Hint Applies No
    Type Boolean
    Default Value ON

    Whether to enable or disable data compression before loading data into HeatWave. Data compression is enabled by default. The setting does not affect data that is already loaded. See Section 2.2.6, “Data Compression”.

  • rapid_bootstrap

    Command-Line Format --rapid-bootstrap[={OFF|ON|IDLE}]
    Introduced 8.0.17
    System Variable rapid_bootstrap
    Scope Global
    Dynamic Yes
    SET_VAR Hint Applies No
    Type Enumeration
    Default Value OFF
    Valid Values

    IDLE

    SUSPEND

    ON

    The setting for this variable is managed by OCI and cannot be modified directly. Defines the HeatWave Cluster bootstrap state. States include:

    • OFF

      The HeatWave Cluster is not bootstrapped (not initialized).

    • IDLE

      The HeatWave Cluster is idle (stopped).

    • SUSPENDED

      The HeatWave Cluster is suspended. The SUSPENDED state is a transition state between IDLE and ON that facilitates planned restarts of the HeatWave Cluster.

    • ON

      The HeatWave Cluster is bootstrapped (started).

  • rapid_dmem_size

    Command-Line Format --rapid-dmem-size=#
    Introduced 8.0.17
    System Variable rapid_dmem_size
    Scope Global
    Dynamic Yes
    SET_VAR Hint Applies No
    Type Integer
    Default Value 2048
    Minimum Value 512
    Maximum Value 2097152

    The setting for this variable is managed by OCI and cannot be modified directly. Specifies the amount of DMEM available on each core of each node, in bytes.

  • rapid_memory_heap_size

    Command-Line Format --rapid-memory-heap-size=#
    Introduced 8.0.17
    System Variable rapid_memory_heap_size
    Scope Global
    Dynamic Yes
    SET_VAR Hint Applies No
    Type Integer
    Default Value unlimited
    Minimum Value 67108864
    Maximum Value unlimited

    The setting for this variable is managed by OCI and cannot be modified directly. Defines the amount of memory available for the HeatWave plugin, in bytes. Ensures that HeatWave does not use more memory than is allocated to it.

  • rapid_execution_strategy

    Command-Line Format --rapid_execution_strategy[={MIN_RUNTIME|MIN_MEM_CONSUMPTION}]
    Introduced 8.0.22
    System Variable rapid_execution_strategy
    Scope Session
    Dynamic No
    SET_VAR Hint Applies No
    Type Enumeration
    Default Value MIN_RUNTIME
    Valid Values

    MIN_RUNTIME

    MIN_MEM_CONSUMPTION

    Specifies the query execution strategy to use. Minimum runtime (MIN_RUNTIME) or minimum memory consumption (MIN_MEM_CONSUMPTION).

    HeatWave optimizes for network usage rather than memory. If you encounter out of memory errors when running a query, try running the query with the MIN_MEM_CONSUMPTION strategy by setting by setting rapid_execution_strategy prior to executing the query:

    SET SESSION rapid_execution_strategy = MIN_MEM_CONSUMPTION;

    See Section 2.14, “Troubleshooting”.

  • rapid_stats_cache_max_entries

    Command-Line Format --rapid-stats-cache-max-entries=#
    Introduced 8.0.25
    System Variable rapid_stats_cache_max_entries
    Scope Global
    Dynamic Yes
    SET_VAR Hint Applies No
    Type Integer
    Default Value 65536
    Minimum Value 0
    Maximum Value 1048576

    The setting for this variable is managed by OCI and cannot be modified directly. Specifies the maximum number of entries in the statistics cache.

    The number of entries permitted in the statistics cache by default is 65536, which is enough to store statistics for 4000 to 5000 unique queries of medium complexity.

    For more information, see Auto Query Plan Improvement.

  • show_create_table_skip_secondary_engine

    Command-Line Format --show-create-table-skip-secondary-engine[={OFF|ON}]
    Introduced 8.0.18
    System Variable show_create_table_skip_secondary_engine
    Scope Session
    Dynamic Yes
    SET_VAR Hint Applies Yes
    Type Boolean
    Default Value OFF

    Whether to exclude the SECONDARY ENGINE clause from SHOW CREATE TABLE output, and from CREATE TABLE statements dumped by the mysqldump utility.

    mysqldump provides the --show-create-skip-secondary-engine option. When specified, it enables the show_create_table_skip_secondary_engine system variable for the duration of the dump operation.

    Attempting a mysqldump operation with the --show-create-skip-secondary-engine option on a MySQL Server release prior to MySQL 8.0.18 that does not support the show_create_table_skip_secondary_engine variable causes an error.

  • use_secondary_engine

    Introduced 8.0.13
    System Variable use_secondary_engine
    Scope Session
    Dynamic Yes
    SET_VAR Hint Applies Yes
    Type Enumeration
    Default Value ON
    Valid Values

    OFF

    ON

    FORCED

    Whether to execute queries using the secondary engine. These values are permitted:

    • OFF: Queries execute using the primary storage (InnoDB) on the MySQL DB System. Execution using the secondary engine (RAPID) is disabled.

    • ON: Queries execute using the secondary engine (RAPID) when conditions warrant, falling back to the primary storage engine (InnoDB) otherwise. In the case of fallback to the primary engine, whenever that occurs during statement processing, the attempt to use the secondary engine is abandoned and execution is attempted using the primary engine.

    • FORCED: Queries always execute using the secondary engine (RAPID) or fail if that is not possible. Under this mode, a query returns an error if it cannot be executed using the secondary engine, regardless of whether the tables that are accessed have a secondary engine defined.