Monday, September 28, 2026

Hidden Parameters in Oracle AI Database 26ai H.13 Exadata smart scan (88)

 

NameTypeValueAt default?LevelPDBRAC inst.FlagsDescription
_cell_fast_file_createBooleanTRUEyesSESSIONYYAllow optimized file creation path for Cells
_cell_fast_file_restoreBooleanTRUEyesSESSIONYYAllow optimized rman restore for Cells
_cell_file_format_chunk_sizeInteger0yesSESSIONYYCell file format chunk size in MB
_cell_index_scan_enabledBooleanTRUEyesSESSIONYYenable CELL processing of index FFS
_cell_iot_scan_enabledBooleanTRUEyesSESSIONYYenable CELL processing of IOT FFS
_cell_materialize_all_expressionsBooleanFALSEyesSESSIONYYForce materialization of all offloadable expressions on the cells
_cell_materialize_virtual_columnsBooleanTRUEyesSESSIONYYenable offload of expressions underlying virtual columns to cells
_cell_metadata_compressionStringAUTOyesSESSIONYYCell metadata compression strategy
_cell_object_expiration_hoursInteger24yesSTATICNNflashcache object expiration timeout
_cell_offload_capabilities_enabledInteger1yesSESSIONYYspecifies capability table to load
_cell_offload_complex_processingBooleanTRUEyesSESSIONYYenable complex SQL processing offload to cells
_cell_offload_expressionsBooleanTRUEyesSESSIONYYenable offload of expressions to cells
_cell_offload_grand_totalBooleanTRUEyesSESSIONYYallow offload of grand total aggregations
_cell_offload_hybrid_processingBooleanTRUEyesSESSIONYYenable hybrid SQL processing offload to cells
_cell_offload_hybridcolumnarBooleanTRUEyesSESSIONYYQuery offloading of hybrid columnar compressed tables to exadata
_cell_offload_predicate_reordering_enabledBooleanFALSEyesSESSIONYYenable out-of-order SQL processing offload to cells
_cell_offload_sys_contextBooleanTRUEyesSESSIONYYenable offload of SYS_CONTEXT evaluation to cells
_cell_offload_timezoneBooleanTRUEyesSESSIONYYenable timezone related SQL processing offload to cells
_cell_offload_vectorBooleanTRUEyesSESSIONYYQuery offloading of vector operators to exadata
_cell_offload_vector_groupbyBooleanTRUEyesSESSIONYYenable SQL processing offload of vector group by
_cell_offload_vector_groupby_externalBooleanTRUEyesSESSIONYYenable cell offload of vector group by with external tables
_cell_offload_vector_groupby_fact_keyBooleanTRUEyesSESSIONYYenable cell offload of vector group by with fact grouping keys
_cell_offload_vector_groupby_forceBooleanFALSEyesSESSIONYYforce offload of vector group by
_cell_offload_vector_groupby_withnojoinBooleanTRUEyesSESSIONYYallow offload of vector group by without joins
_cell_offload_virtual_columnsBooleanTRUEyesSESSIONYYenable offload of predicates on virtual columns to cells
_cell_range_scan_enabledBooleanTRUEyesSESSIONYYenable CELL processing of index range scans
_cell_storidx_minmax_enabledBooleanTRUEyesSESSIONYYenable Storage Index Min/Max optimization on the cells
_cell_storidx_modeStringEVAyesSESSIONYYCell Storage Index mode
_cell_trace_sizeInteger0yesSESSIONYYmax trace size in bytes shipped back to server per filtering task
_cellcache_clause_defaultStringyesSESSIONYYDefault cellcache clause for new tables
_cellcache_default_flagsInteger2yesSESSIONYYDefault flags based on cellcache_clause_default
_cellcache_default_newBooleanFALSEyesSESSIONYYForce cellcache on new tables
_kcfis_automem_levelInteger1yesSESSIONYYSet auto memory management control for kcfis memory allocation
_kcfis_block_dump_levelInteger0yesSESSIONYYSmart IO block dump level
_kcfis_byteswap_opt_disabledBooleanFALSEyesSESSIONYYDon't use byte swapping optimization on the storage cell
_kcfis_caching_enabledBooleanTRUEyesSESSIONYYenable kcfis intra-scan session caching
_kcfis_cell_passthru_dataonlyBooleanTRUEyesSESSIONYYAllow dataonly passthru for smart scan
_kcfis_cell_passthru_enabledBooleanFALSEyesSESSIONYYDo not perform smart IO filtering on the cell
_kcfis_cell_passthru_fromcpu_enabledBooleanTRUEyesSESSIONYYEnable automatic passthru mode when cell CPU util is too high
_kcfis_cellcache_disabledBooleanFALSEyesSESSIONYYDon't use cellcache rewrite optimization on the storage cell
_kcfis_celloflsrv_passthru_enabledBooleanFALSEyesSESSIONYYEnable offload server usage for passthru operations
_kcfis_celloflsrv_usage_enabledBooleanTRUEyesSESSIONYYEnable offload server usage for offload operations
_kcfis_combine_md_maps_payloadInteger1yesSESSIONYYenable combining MD and MAPs in single payload
_kcfis_control1Integer0yesSESSIONYYKcfis control1
_kcfis_control2Integer0yesSESSIONYYKcfis control2
_kcfis_control3Integer0yesSESSIONYYKcfis control3
_kcfis_control4Integer0yesSESSIONYYKcfis control4
_kcfis_control5Integer0yesSESSIONYYKcfis control5
_kcfis_control6Integer0yesSESSIONYYKcfis control6
_kcfis_disable_platform_decryptionBooleanFALSEyesSESSIONYYDon't use platform-specific decryption on the storage cell
_kcfis_dump_corrupt_blockBooleanTRUEyesSESSIONYYDump any corrupt blocks found during smart IO
_kcfis_fast_response_enabledBooleanTRUEyesSESSIONYYEnable smart scan optimization for fast response (first rows)
_kcfis_fast_response_initiosizeInteger2yesSESSIONYYFast response - The size of the first IO in logical blocks
_kcfis_fast_response_iosizemultInteger4yesSESSIONYYFast response - (next IO size = current IO size * this parameter)
_kcfis_fast_response_thresholdInteger1048576yesSESSIONYYFast response - the number of IOs after which smartIO is used
_kcfis_fastfileinit_disabledBooleanFALSEyesSESSIONYYDon't use ffi during file creation
_kcfis_fault_controlInteger0yesSTATICNNFault Injection Control
_kcfis_fctempopt_modeInteger1yesSESSIONYYKCFIS FC Temp Drop FC Optimization Control
_kcfis_io_prefetch_sizeInteger8yesSESSIONYYSmart IO prefetch size for a cell
_kcfis_ioreqs_throttle_enabledBooleanTRUEyesSESSIONYYEnable Smart IO requests throttling
_kcfis_ivfscan_fd_max_cache_szInteger100yesSESSIONYYNumber of IVF scan FDs cached
_kcfis_ivfscan_fd_max_num_reuseInteger50yesSESSIONYYNumber of times IVF scan FDs are reused
_kcfis_ivfscan_opt_enabledBooleanTRUEyesSESSIONYYenable IVF scan optimizations
_kcfis_kept_in_cellfc_enabledBooleanTRUEyesSESSIONYYEnable usage of cellsrv flash cache for kept objects
_kcfis_large_payload_enabledBooleanFALSEyesSESSIONYYenable large payload to be passed to cellsrv
_kcfis_largemd_bfquota_kbInteger16384yesSESSIONYYSmart IO operation bloom filter metadata size in KBs
_kcfis_largemd_compressed_kbInteger20480yesSESSIONYYSmart IO operation maximum compressed metadata size in KBs
_kcfis_largemd_enabledBooleanTRUEyesSESSIONYYSmart IO operation large metadata supported enabled
_kcfis_max_cached_sessionsInteger10yesSESSIONYYSets the maximum number of kcfis sessions cached
_kcfis_max_ioctl_buffersInteger100yesSESSIONYYSets the maximum number of IOCTL buffers in kcfis
_kcfis_max_out_translationsInteger5000yesSESSIONYYSets the maximum number of outstanding translations in kcfis
_kcfis_nonkept_in_cellfc_enabledBooleanFALSEyesSESSIONYYEnable use of cellsrv flash cache for non-kept objects
_kcfis_oss_io_sizeInteger0yesSESSIONYYKCFIS OSS I/O size
_kcfis_partner_read_enabledBooleanTRUEyesSESSIONYYSmart IO operation partner read enabled
_kcfis_pmem_enabledBooleanTRUEyesSTATICNNRDMA Persistent Memory support enabled
_kcfis_qm_prioritize_sys_planBooleanTRUEyesSESSIONYYPrioritize Quarantine Manager system plan
_kcfis_qm_user_plan_nameStringyesSESSIONYYQuarantine Manager user plan name
_kcfis_rdbms_blockio_enabledBooleanFALSEyesSESSIONYYUse block IO instead of smart IO in the smart IO module on RDBMS
_kcfis_read_buffer_limitInteger0yesSESSIONYYKCFIS Read Buffer (per session) memory limit in bytes
_kcfis_spawn_debuggerBooleanFALSEyesSESSIONYYDecides whether to spawn the debugger at kcfis initialize
_kcfis_stats_levelInteger0yesSESSIONYYsets kcfis stats level
_kcfis_storageidx_diag_modeInteger0yesSESSIONYYDebug mode for storage index on the cell
_kcfis_storageidx_disabledBooleanFALSEyesSESSIONYYDon't use storage index optimization on the storage cell
_kcfis_storageidx_set_membership_disabledBooleanFALSEyesSESSIONYYDon't use set membership optimization on the storage cell
_kcfis_storageidx_xtss_disabledBooleanFALSEyesSESSIONYYDon't use storage index optimization on the storage cell for XTSS
_kcfis_test_control1Integer0yesSESSIONYYkcfis tst control1
_kcfis_trace_bucket_sizeInteger131072yesSESSIONYYKCFIS tracing bucket size in bytes
_kcfis_xtgran_prefetch_countInteger1yesSESSIONYYExternal Table Smart Scan granule prefetch count

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