data_conversion_compatibility_leveljson_compatibility_levelhighlight_allow_ascii_binary_stringsregexp_output_validation_modejson_extract_string_collationIncreasing this variable can allow segments with large sizes to be created, which can benefit full-text or vector search workloads, with the drawback of using more memory during merge and batch write operations.SingleStorerecommends that in a memory-constrained environment, the variable should not be set to a large value.This variable can sync to all nodes, including aggregator and leaf nodes.This engine variable is configurable onSingleStore Helios. | `536870912` | | `internal_max_cte_depth` | Specifies the maximum number of nested common table expressions (CTEs). For more information, refer to the[WITH](https://docs.singlestore.com/cloud/query-data/advanced-query-topics/with-common-table-expressions.md)topic. This is a session variable that can also be set globally. This variable can sync to all nodes, including aggregator and leaf nodes. | `128` | | `jwks_endpoint` | The endpoint to get JWKS updates from. If empty, JWKS update from the endpoint does not happen. This variable can sync to all nodes, including aggregator and leaf nodes. | | | `jwks_require_audience` | When set, specifies the value that must be present in JWT`aud`field. If JWT`aud`field is an array, then the value must be equal to one of array’s items. This variable can sync to all nodes, including aggregator and leaf nodes. | | | `jwks_ssl_ca_certificate` | The CA certificate file to be used for SSL JWKS endpoint host verification when HTTPS protocol is used. This variable can sync to all nodes, including aggregator and leaf nodes. | | | `jwks_update_interval` | The JWKS update interval in seconds. If set to 0, JWKS refresh does not happen. This variable can sync to all nodes, including aggregator and leaf nodes. | `3600` | | `jwks_username_field` | When set, specifies which JWT field contains username overriding other rules. This variable can sync to all nodes, including aggregator and leaf nodes. | | | `leaf_failure_detection` | Whether or not the master aggregator should detect leaf failures and trigger failovers.**WARNING**: Turning this variable`OFF`disables failover. This variable can sync to all aggregators. | `ON` | | `leaf_failover_fanout` | Specifies the placement of replica partitions in aworkspace. It can be set to the following modes:`paired`and`load_balanced`.This variable can sync to all nodes, including aggregator and leaf nodes. | `paired` | | `license_visibility` | Hides license-related variables from`SHOW`commands. This variable can sync to all nodes, including aggregator and leaf nodes. | `TRUE` | | `load_data_errors_retention_minutes` | The amount of time, in minutes, that a`LOAD DATA`error is stored on disk. This variable must be set to at least`0`. These errors are surfaced in[information\_schema.LOAD\_DATA\_ERRORS](https://docs.singlestore.com/cloud/reference/sql-reference/data-manipulation-language-dml/load-data.md)as long as they are stored on disk. This variable can sync to all nodes, including aggregator and leaf nodes.This engine variable is configurable onSingleStore Helios. | `1440` | | `load_data_internal_compression` | If this variable is set to`ON`and a network bottleneck is detected,`LOAD DATA`compresses data on the aggregator before forwarding it to the leaves. This variable can sync to all nodes, including aggregator and leaf nodes.This engine variable is configurable onSingleStore Helios. | `ON` | | `load_data_max_buffer_size` | Maximum number of unparsed bytes read by`LOAD DATA`before throwing an error. This variable can sync to all nodes, including aggregator and leaf nodes.This engine variable is configurable onSingleStore Helios. | `1073741823` | | `load_data_read_size` | Number of bytes read at a time by`LOAD DATA`. This variable can sync to all nodes, including aggregator and leaf nodes.This engine variable is configurable onSingleStore Helios. | `8192` | | `load_data_write_size` | Number of bytes written at a time by`LOAD DATA`. This variable can sync to all nodes, including aggregator and leaf nodes.This engine variable is configurable onSingleStore Helios. | `8192` | | `local_file_system_access_restricted` | Restricts access to the local file system. This variable can sync to all nodes, including aggregator and leaf nodes. | `FALSE` | | `lock_wait_timeout` | Time (in seconds) to wait for a row lock before returning an error. This is a session variable that can also be set globally. This variable can sync to all nodes, including aggregator and leaf nodes.This engine variable is configurable onSingleStore Helios. | `30` | | `log_file_size_partitions` | Specifies the log file size (in bytes) for partitions. Can be set to a minimum of 1 MB (in bytes) to a maximum of 1 TB (in bytes), in multiples of 1 MB. A MB contains 1048576 bytes. Each partition is pre-allocated to two log files. Each of these log files has the size`log_file_size_partitions`. By default,`log_file_size_partitions`is 256 MB. Changes in the log file size will not affect the sizes of the partitions that are used by existing databases. Use caution when adjusting this variable as it can result in large log files and thus consume more disk space. This variable can sync to all aggregators.This engine variable is configurable onSingleStore Helios. | `268435456` | | `log_file_size_ref_dbs` | Specifies the log file size (in bytes) for reference databases. Can be set to a minimum of 1 MB (in bytes) to maximum of 1 TB (in bytes), in multiples of 1 MB. A MB contains 1048576 bytes. Each reference database is pre-allocated two log files. Each of these log files has the size`log_file_size_ref_dbs`. By default,`log_file_size_ref_dbs`is 64 MB. Changes in the log file size will not affect existing databases. Use caution when adjusting this variable as it can result in large log files and thus consume more disk space. This variable can sync to all aggregators.This engine variable is configurable onSingleStore Helios. | `67108864` | | `managed_functions_batch_size` | Controls the batch size for managed external functions including Python UDFs and AI/ML Functions.This variable can sync to all nodes, including aggregator and leaf nodes. | `512` | | `managed_functions_connect_timeout_ms` | Controls the connection timeout for managed external functions including Python UDFs and AI/ML Functions.This variable can sync to all nodes, including aggregator and leaf nodes. | `60*1000` | | `managed_functions_credentials_reload_period_ms` | Specifies the grace period, in milliseconds, before expiration when the system proactively refreshes AWS IRSA (IAM Roles for Service Accounts) credentials.This setting ensures that managed external functions, including Python UDFs, AI functions, and ML functions, do not encounter authentication failures during long-running invocations.When the remaining time before credential expiration falls below this threshold, the system refreshes the credentials and re-signs requests for each batch or retry.This variable can sync to all nodes, including aggregator and leaf nodes. | `60000` | | `managed_functions_max_connections` | Maximum number of HTTP connections per node for managed external functions.This variable can sync to all nodes, including aggregator and leaf nodes. | `10000` | | `managed_functions_request_timeout_ms` | Controls the request timeout for managed external functions including Python UDFs and AI/ML Functions.This variable can sync to all nodes, including aggregator and leaf nodes. | `10*60*1000` | | `master_promote_kill_timeout_seconds` | Specifies the amount of time online failover will wait to drain open transactions on a master partition (whether running or idle) before killing them. This variable can sync to all nodes, including aggregator and leaf nodes. | `120` | | `max_allowed_packet` | Maximum allowed protocol packet size (in bytes). This is a session variable that is readable at the session level, but which must be set globally. The maximum value is`1`GB and the lowest allowable value is32KiB, though setting this to a value that low is not recommended. This variable can sync to all nodes, including aggregator and leaf nodes.This engine variable is configurable onSingleStore Helios. | `104857600` | | `max_async_compilation_concurrency` | The number of compiles that can run asynchronously at a given time on each node, when`interpreter_mode`is set to`interpret_first`. Its effective value is capped at the number of cores on the host machine. If set to 0, it takes the default value.This variable can sync to all nodes, including aggregator and leaf nodes.This engine variable is configurable onSingleStore Helios. | Half the number of cores on the host machine. | | `max_autostats_update_workers` | Sets the maximum number of merger threads that the autostats updater can run on.This variable can sync to all nodes, including aggregator and leaf nodes.This engine variable is configurable onSingleStore Helios. | `1` | | `max_compilation_memory_mb` | The maximum amount of memory (in megabytes) used to compile a query. An error is returned if the query reaches the specified memory limit. This variable can sync to all nodes, including aggregator and leaf nodes.This engine variable is configurable onSingleStore Helios. | `4096` | | `max_compilation_time_s` | The maximum time allowed (in seconds) to compile a query. An error is returned if the query reaches the specified compilation time limit, and any subsequent attempts to compile the query fail. This variable can sync to all nodes, including aggregator and leaf nodes.This engine variable is configurable onSingleStore Helios. | `600` | | `max_connect_errors` | If the number of interrupted connections from a host exceeds the value of`max_connect_errors`this host will be blocked from further connections. This variable can sync to all nodes, including aggregator and leaf nodes. | `10` | | `max_expression_item_limit` | This engine variable is configurable onSingleStore Helios. | Maximum unsigned`INT`value | | `max_expression_query_limit` | The maximum number of expressions within an entire query. The value can be set between 100 and the maximum unsigned`INT`value. The maximum unsigned`INT`value disables this feature. This is a session variable that can also be set globally. This engine variable can sync to all aggregators.This engine variable is configurable onSingleStore Helios. | Maximum unsigned`INT`value | | `max_pooled_connections` | The maximum number of stashed connections per leaf. For more information on this variable, see[In-Depth Variable Definitions](https://docs.singlestore.com/cloud/reference/configuration-reference/engine-variables/list-of-engine-variables/#in-depth-variable-definitions-3.md). This variable can sync to all nodes, including aggregator and leaf nodes.This engine variable is configurable onSingleStore Helios. | `1024` | | `max_prefetch_threads` | Sets the maximum number of threads to use for pre-fetching per scan. This variable can sync to all nodes, including aggregator and leaf nodes.This engine variable is configurable onSingleStore Helios. | `1` | | `max_prepared_stmt_count` | Sets the maximum number of simultaneous prepared statements. This variable can sync to all nodes, including aggregator and leaf nodes.This engine variable is configurable onSingleStore Helios. | `16382` | | `max_table_memory_room_mb` | Sets the maximum amount of memory (in bytes) required when creating or attaching a database. This variable can sync to all nodes, including aggregator and leaf nodes.This engine variable is configurable onSingleStore Helios. | `1024` | | `max_vector_index_cache_memory_percent` | Specifies the maximum percentage of available memory (`maximum_memory`) to be used by the vector index cache. Must be strictly between`0`and`100`.This variable can sync to all nodes, including aggregator and leaf nodes.This engine variable is configurable onSingleStore Helios. | `99` | | `max_vector_index_cache_memory_mb` | The maximum amount of memory that can be used by the vector index cache (in MB). This variable is calculated based on the value of`max_vector_index_cache_memory_percent`. The maximum value of this variable is (`maximum_memory`- 800MB). This variable is read-only and is provided for user convenience. | | | `maximum_blob_cache_shrink_percent_under_default_spilling_max` | The maximum percentage by which the blob cache can shrink from its original size, when`spilling_maximum_disk_percent = -1`.The value must be between 0 and 0.5.This variable can sync to all nodes, including aggregator and leaf nodes.This engine variable is configurable onSingleStore Helios. | `0.3` | | `maximum_blob_cache_size_percent` | Sets the maximum amount of space that can be used by the blob cache. It is a percent of the disk space and its value should be between 0 and 1.For example:`SET GLOBAL maximum_blob_cache_size_percent = 0.90`This variable can sync to all nodes, including aggregator and leaf nodes.This engine variable is configurable onSingleStore Helios. | `0` | | `memsql_original_server_version` | Displays the version ofSingleStoreinitially installed. This variable can sync to all nodes, including aggregator and leaf nodes. | | | `memsql_snapshot_trigger_size` | Indicates the size (in bytes) of theSingleStoredatabase log upon which a new snapshot will be kicked off. The minimum value this engine variable can be set is`65536`. This variable can sync to all nodes, including aggregator and leaf nodes. | `134217728` | | `monitoring_retention_period` | The period in minutes to keep historical monitoring data. Stored procedures reference this variable to purge values. This variable can sync to all aggregators. | `10080` | | `multi_insert_tuple_count` | Preferred number of tuples in multi-inserts that aggregators send to leaves. This variable can sync to all nodes, including aggregator and leaf nodes.This engine variable is configurable onSingleStore Helios. | `20000` | | `multi_statement_xact_idle_timeout` | Time (in seconds) that is allowed for a multi-statement transaction to remain idle while holding locks.This is a session variable that can be set via[SET SESSION](https://docs.singlestore.com/cloud/reference/sql-reference/operational-commands/set-and-set-session.md)onSingleStore Helios.This variable can sync to all aggregators. | `300` | | `node_degree_of_parallelism` | Controls the number of threads per leaf node for parallel columnstore scans. This variable can sync to all nodes, including aggregator and leaf nodes. | `0` | | `null_timestamps_for_testing` | Variable to write default`TIMESTAMP`columns during testing. This variable can sync to all nodes, including aggregator and leaf nodes. | `FALSE` | | `num_background_merger_threads` | Controls the number of background merger threads to start for each node. The default value of 2 implies two threads run on each node and the work is bound to 2 CPUs. On large nodes, with many CPUs, it is easier for nodes to outpace two merger threads. When there is a high-throughput ingest workload, the merger cannot keep up and query processing gets slower as the data is not well merged. Use the`mv_columnstore_merge_status`view to find out if the merger process is slow. If it gets behind, try increasing the value of this variable. For example, if with 32 core nodes, you find the merger is not keeping up then increase it from 2 to 8 and observe if the merger is keeping up with the ingest workload. Only 2 merger threads per partition per table are allowed at a time. Hence more partitions per node can use more threads. For one partition on one table increasing the value of this variable will not make any difference.The allowed values range between 2 and 64.This variable can sync to all nodes, including aggregator and leaf nodes.This engine variable is configurable onSingleStore Helios. | `2` | | `optimize_stmt_threshold` | A statement count threshold for a procedure or function. When the threshold is exceeded, the procedure or function compiles faster, but the highest level of code optimizations is not applied; however, SQL query optimizations are still in effect. This is a session variable that can also be set globally. This variable can sync to all nodes, including aggregator and leaf nodes.This engine variable is configurable onSingleStore Helios. | `50` | | `optimizer_beam_width` | Controls the beam search width. The default value is`10`. Setting this to`1`reverts to the previous behavior (prior to v7.5). Higher values (maximum is`1024`) will make the one-time query optimization time slower. This variable can sync to all nodes, including aggregator and leaf nodes.This engine variable is configurable onSingleStore Helios. | `10` | | `optimizer_cross_join_cost` | Increased the default value to reduce the chance of cartesian joins being included when there are incorrect estimations.This variable can sync to all nodes, including aggregator and leaf nodes.This engine variable is configurable onSingleStore Helios. | `1.0` | | `optimizer_disable_analyze_cardinality_on_json` | Controls if the cardinality of JSON columns is collected by[autostats](https://docs.singlestore.com/cloud/query-data/query-tuning/statistics-and-sampling/statistics-and-sampling-tasks.md)in`PERIODIC`mode.When`optimizer_disable_analyze_cardinality_on_json`is set to`On`, the engine does not collect cardinality on JSON columns during`ANALYZE`; instead the cardinality is estimated as the number of rows in the table.May be set to`Off`,`On`, or`Auto`.This variable can sync to all aggregators.This engine variable is configurable onSingleStore Helios. | `Auto (Off)` | | `optimizer_disable_cte_full_predicate_pushdown` | This variable disables optimizer Common Table Expression (CTE) predicate pushdown.This variable controls whether predicates are pushed into CTEs. Pushing predicates into CTEs typically improves performance; however, there are cases where this pushdown causes poor performance. For example if you have an`IN(...)`filter with many references on the Materialized Common Table Expression (MCTE), the engine is unable to recognize that the`IN(...)`filters are the same. As a result, the engine pushes an`OR`of all the`IN(...)`filters equal to the number of references.This is a session variable that can also be set globally.This variable can sync to all nodes, including aggregator and leaf nodes.This engine variable is configurable onSingleStore Helios. | `FALSE` | | `optimizer_disable_limit_pushdown_below_external_udf` | Disable the optimizer rewrite that pushes limits below external User Defined Functions (UDFs).This variable can sync to all nodes, including aggregator and leaf nodes.This engine variable is configurable onSingleStore Helios. | `FALSE` | | `optimizer_disable_subselect_to_join` | Setting this to`ON`disables the optimizer rewrite that converts subselect to joins automatically. Disabling this rewrite may cause queries to fail if they require the rewrite to run.This variable can sync to all nodes, including aggregator and leaf nodes. | `OFF` | | `optimizer_disable_transitive_predicates` | Disables predicate transitivity on query rewrites is set to`TRUE`. This is a session variable that can also be set globally.This variable can sync to all nodes, including aggregator and leaf nodes.This engine variable is configurable onSingleStore Helios. | `FALSE` | | `optimizer_disable_right_join` | Setting this variable to`TRUE`disables the right join in a query. This allows the left join to be used by the query plan, thereby allowing disk spilling to happen.This variable can sync to all nodes, including aggregator and leaf nodes.This engine variable is configurable onSingleStore Helios. | `FALSE` | | `optimizer_disable_subselect_to_join_cte_preprocess` | When set to`TRUE`, this variable disables the subselect to join rewrite for Common Table Expression (CTE) preprocessing before inlining or materialization.This variable can sync to all nodes, including aggregator and leaf nodes.This engine variable is configurable onSingleStore Helios. | `FALSE` | | `optimizer_empty_tables_limit` | Sets a threshold for the number of empty tables that must be present in a query before the optimizer falls back to being rule-based, instead of cost-based. This is a session variable that can also be set globally.This variable can sync to all nodes, including aggregator and leaf nodes.This engine variable is configurable onSingleStore Helios. | `0` | | `optimizer_enable_json_text_matching` | Applies to a computed column when matching`json_text`as a`json_col persisted text`. When the variable is enabled, a`json_text`computed column can use the following three text types:`TEXT`,`MEDIUM_TEXT`, and`LONG_TEXT`. Disabling this rewrite may cause queries to fail if they require the rewrite to run.This variable can sync to all nodes, including aggregator and leaf nodes.This engine variable is configurable onSingleStore Helios. | `FALSE` | | `optimizer_enable_merge_unioned_queries_rewrite` | Allows the optimizer to rewrite unioned queries into a single query.This variable can sync to all nodes, including aggregator and leaf nodes.This engine variable is configurable onSingleStore Helios. | `TRUE` | | `optimizer_enable_orderby_limit_self_join` | Allows the optimizer to rewrite leaf`ORDER BY LIMIT`queries using a self-join. Defaults to`TRUE`(enabled). Disabling this rewrite may cause queries to fail if they require the rewrite to run. This variable can sync to all nodes, including aggregator and leaf nodes.This engine variable is configurable onSingleStore Helios. | `TRUE` | | `optimizer_feedback_reoptimization_auto_marking` | Switch for whether to enable auto marking for feedback reoptimization.Values:`OFF`,`ON`,`AUTO`This is a session variable that can also be set globally.This variable can sync to all nodes, including aggregator and leaf nodes.This engine variable is configurable onSingleStore Helios. | `AUTO` | | `optimizer_histogram_multi_column_correlation_max_selectivity` | Controls an optimizer decision about when to use histograms in join estimates or not.SingleStorerecommends that customers adjust this variable only with guidance fromSingleStore.This is a session variable that can also be set globally.This variable can sync to all nodes, including aggregator and leaf nodes.This engine variable is configurable onSingleStore Helios. | `0.9` | | `optimizer_max_cross_joined_array_filters` | This variable controls the conditions under which an optimizer rewrite, which improves the performance of queries with`JOIN`conditions that use`JSON_ARRAY_CONTAINS`, will be performed. The rewrite may be disabled by setting the value to`0`.Refer to[optimizer\_max\_cross\_joined\_array\_filters](https://docs.singlestore.com/cloud/reference/configuration-reference/engine-variables/list-of-engine-variables/#in-depth-variable-definitions-4.md)for details.This is a session variable that can also be set globally.This variable can sync to all nodes, including aggregator and leaf nodes.This engine variable is configurable onSingleStore Helios. | `3` | | `optimizer_max_cross_joined_outer_tables_for_subselect_to_join` | Controls the maximum number of outer tables to cross join as part of a subselect to join optimizer rewrite.When joining subselects against outer tables with conditions other than AND/=, the engine needs to cross join all outer tables together. This variable limits the maximum number of outer tables that can be cross joined.This is a session variable that can also be set globally.This variable can sync to all nodes, including aggregator and leaf nodes.This engine variable is configurable onSingleStore Helios. | `3` | | `optimizer_max_table_row_count_as_default_cardinality` | This variable controls the maximum estimated table row count to be used as the per column cardinality when no column-level statistics exists.This is a session variable that can also be set globally.This variable can sync to all nodes, including aggregator and leaf nodes.This engine variable is configurable onSingleStore Helios. | `10` | | `optimizer_max_tpu_pushdown_table_rowcount` | This variable specifies the maximum row count for a**derived table**to be pushable to each branch of another union all table in the join list. By pushing down the table and doing joins earlier, more segments can potentially be eliminated earlier. One common case for this rewrite to be useful is when a subselect predicate gets transformed into a table in the join list by the optimizer and there is another union all table in the join list. By turning on this rewrite, the optimizer can pushdown the predicate to each branch of the union all table. Note that this rewrite can only work when force\_heuristic\_rewrites variable gets turned on. A value of`0`indicates to always try to push down table(s) to union, but the pushdown order is not guaranteed.This variable can sync to all nodes, including aggregator and leaf nodes.This engine variable is configurable onSingleStore Helios. | `100` | | `optimizer_min_reference_rows_for_gathered_join` | The minimum total number of rows estimates in joined reference tables for gathering non-reference tables to be considered. This variable can sync to all nodes, including aggregator and leaf nodes.This engine variable is configurable onSingleStore Helios. | `1000000` | | `optimizer_min_reference_tables_for_gathered_join` | The minimum number of reference tables joined in a query that will be considered before gathering non-reference tables. 0 disables this feature. This variable can sync to all nodes, including aggregator and leaf nodes.This engine variable is configurable onSingleStore Helios. | `0` | | `optimizer_not_null_filter_derivation` | Enable or disable the not null filter derivation rewrite in the optimizer. When enabled (`ON`), the optimizer can derive not null filters for base tables based on equality joins. If this filter can be pushed down to a table scan, query execution time for these subsequent joins may be significantly reduced.This variable is settable with an`enum {ON, OFF, AUTO}`and defaults to`AUTO`.Currently,`AUTO`has the same behavior as`OFF`.This variable can sync to all nodes, including aggregator and leaf nodes.This engine variable is configurable onSingleStore Helios. | `AUTO` | | `parametrizer_query_max_params` | The maximum number of scalar constants a single query can contain. Any query with more than`parametrizer_query_max_params`will be failed with an error. This variable can sync to all aggregators. | `1048576` | | `plan_expiration_minutes` | The interval in which a query plan must be reused at least once or it gets unloaded from the query plan cache. This variable can sync to all nodes, including aggregator and leaf nodes.This engine variable is configurable onSingleStore Helios. | `720` | | `plan_gc_max_plan_num_per_iteration` | Controls the number of plans that the engine attempts to evict during each iteration of the[plancache](https://docs.singlestore.com/cloud/user-and-workspace-administration/workspace-health-and-performance/managing-plancache-memory-and-disk-usage.md)garbage collection scan. The garbage collection scan frequency is determined as:`plan_expiration_minutes`/(`num_of_plans_in_plancache`/`plan_gc_max_plan_num_per_iteration`).This variable can sync to all nodes, including aggregator and leaf nodes.This engine variable is configurable onSingleStore Helios. | `10000` | | `preserve_original_colstore_json` | A global variable that preserves`NULL`values and empty arrays in a JSON object that is written to a columnstore table. Set this variable to`OFF`to disable this setting. For more information on this variable, see the[JSON Guide](https://docs.singlestore.com/cloud/create-a-database/using-json.md).This variable can sync to all nodes, including aggregator and leaf nodes. | `AUTO`(same as ON) | | `privilege_caches_update_mode` | This variable can be used to temporarily disable updating privilege caches while performing security operations such as: granting/revoking permissions to/from users, granting/revoking permissions to/from roles, adding/deleting roles to/from groups, adding/deleting users to/from groups, role deletion, group deletion. This can result in a performance gain.**IT IS IMPORTANT**that the privilege cache updates be reenabled (set back to`always`) once the administration work is finished.This variable can sync to all aggregators.To use this variable:⚠️ Warning:
It may take approximately up to 3 times the amount of memory specified in this variable to create a blob, for example during loading or columnstore merge process.
never.always.HARD mode, each pool’s HARD_CPU_LIMIT_PERCENTAGE reserves a share of the available CPU capacity for that pool.SOFT mode, each pool’s SOFT_CPU_LIMIT_PERCENTAGE sets a share of the available CPU capacity that can be temporarily exceeded when other pools are underutilizing their reservations.PRODQADEVSANDBOX| `ON` | | `wasm_alloc_max_flex_size` | Specifies the maximum memory (in bytes) that can be allocated to a Wasm module directly from the operating system in case of emergencies. This variable can sync to all nodes, including aggregator and leaf nodes.This engine variable is configurable onSingleStore Helios. | `2097152`(2MB) | | `wasm_alloc_retry_count` | Specifies the maximum number of timesSingleStoreretries memory allocation if an out-of-memory error occurs in the Wasm runtime. This variable can sync to all nodes, including aggregator and leaf nodes.This engine variable is configurable onSingleStore Helios. | `3` | | `wasm_alloc_retry_interval` | Specifies the time (in milliseconds) beforeSingleStoreretries memory allocation if an out-of-memory error occurs in the Wasm runtime. This variable can sync to all nodes, including aggregator and leaf nodes. | `1000` | | `wasm_create_from_url` | Enables creation of Wasm functions from a remote URL. Refer to[Wasm UDF Sources](https://docs.singlestore.com/cloud/reference/code-engine-powered-by-wasm/create-wasm-udfs/#section-idm4582794702529633102330989475.md)for more information. This variable can sync to all aggregators.This engine variable is configurable onSingleStore Helios. | `ON` | | `wasm_max_compiled_module_size` | Specifies the maximum size (in bytes) that a compiled Wasm module can use. This variable can sync to all aggregators.This engine variable is configurable onSingleStore Helios. | `26214400`(25MB) | | `wasm_max_image_cache_size` | Specifies the maximum size (in bytes) that is available for caching Wasm query object code images. This variable can sync to all nodes, including aggregator and leaf nodes. | `26214400`(25MB) | | `wasm_max_linear_memory_size` | Specifies the maximum linear memory (in bytes) that an individual Wasm module can use. This will further constrain UDF/TVF-specific`GROW TO`values. This variable can sync to all nodes, including aggregator and leaf nodes.This engine variable is configurable onSingleStore Helios. | `16777216`(16MB or 256 Wasm pages) | | `wasm_max_raw_module_size` | Specifies the maximum size (in bytes) of Wasm modules that may be loaded. The size is defined as the size of raw, uncompiled data passed in the`CREATE FUNCTION`statement. This variable can sync to all aggregators.This engine variable is configurable onSingleStore Helios. | `26214400`(25MB) | ## Workload Management Sync Variables | Name | Description | Default | | ------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ------- | | `resource_usage_model` | Whether to train or enable the resource usage model for workload management. When set to`ON`, workload management will estimate memory usage and queue queries that are estimated to use too much. When set to`TRAINONLY`,[PROFILE](https://docs.singlestore.com/cloud/reference/sql-reference/data-manipulation-language-dml/profile.md)can be run on queries to compare the estimated memory usage of queries with their actual use. This is recommended when upgrading from any version prior to 6.7, to allow for the workload manager to do the necessary machine learning for accurate estimates. Once estimated memory use in`PROFILE`begins matching actual use, consider setting this variable to`ON`.This variable can sync to all aggregators.This engine variable is configurable onSingleStore Helios. | `OFF` | | `workload_management` | Specifies whether to enable workload management for theworkspace. If this variable is set to`ON`, the other workload management engine variables will affect the way a query is executed. If set to`OFF`, the feature is disabled and no queueing or system resource optimization will occur.This variable can sync to all aggregators.This engine variable is configurable onSingleStore Helios. | `ON` | | `workload_management_available_leaf_memory_ratio` | Sets the ratio of the available leaf memory for workload\_management to use when queuing queries. Valid ranges are \[0.0 to 1.0]. The variable sets the ratio of the total amount of memory workload management uses when deciding to queue queries. For example, if it is set 0.9, thenSingleStorewill assume there is only 90% of the total leaf memory available, and will end up running fewer queries before hitting the limit and needing to queue. This variable can sync to all aggregators. | `1.0` | | `workload_management_dynamic_resource_allocation` | Enables/disables the dynamic reuse of WM queues feature. This variable can sync to all aggregators.This engine variable is configurable onSingleStore Helios. | `OFF` | | `workload_management_enable_large_memory_classification` | When enabled (set to`ON`), either memory usage or connections/threads usage can cause a query to be classified as large.When set to`OFF`, only connections/threads usage can classify a query as large.This variable can sync to all aggregators.This engine variable is configurable onSingleStore Helios. | `TRUE` | | `workload_management_enable_static_partitioning` | Enables static resource partitioning for deterministic behavior by workload management. This variable can sync to all aggregators.This engine variable is configurable onSingleStore Helios. | `FALSE` | | `workload_management_expected_aggregators` | The expected number of query aggregators (routers) that will be used to run a high volume of fully distributed queries in thisworkspace.Workload Management uses this value to divide leaf resources (threads, connections, memory) across those aggregators when deciding whether to queue a query.InSingleStore Helios, this is an advanced tuning setting. Do not change it unless explicitly directed by Support. For most workloads, leaving it at 0 gives the correct behavior, even at high concurrency. It represents a per-router share of leaf resources. With the default value of 0, the system automatically substitutes theworkspace’s actual number of query routers. You typically never need to set this manually. | `0` | | `workload_management_max_connections_per_leaf` | The maximum number of connections to use per leaf node in theworkspace. This variable can sync to all aggregators.This engine variable is configurable onSingleStore Helios. | `10000` | | `workload_management_max_queue_depth` | The maximum depth of the query queue, which is the maximum number of queries that can be queued. If this number is reached, additional queries will not execute, and an`ER_TOO_MANY_QUEUED_QUERIES`error will appear.This variable can sync to all aggregators.This engine variable is configurable onSingleStore Helios. | `100` | | `workload_management_max_threads_per_leaf` | The maximum number of threads to use per leaf. This number correlates with the`max_connection_threads`engine variable, and they should generally be set to the same value. This variable can sync to all aggregators.This engine variable is configurable onSingleStore Helios. | `8192` | | `workload_management_memory_queue_threshold` | Percentage of memory a query can use before it will get queued. If an individual query is projected to use more than`workload_management_memory_queue_threshold * (leaf_maximum_memory - leaf_current_table_memory) / workload_management_expected_aggregators`, then it will be queued.This variable can sync to all aggregators.This engine variable is configurable onSingleStore Helios. | `0.01` | | `workload_management_memory_queuing` | Whether to turn on queuing based on memory usage of queries. This variable can sync to all aggregators.This engine variable is configurable onSingleStore Helios. | `ON` | | `workload_management_queue_size_allow_upgrade` | Specifies how many large queries can be waiting for execution in the LARGE queue when we want to move to that queue a MEDIUM query from the MEDIUM queue. This variable can sync to all aggregators.This engine variable is configurable onSingleStore Helios. | `1` | | `workload_management_queue_time_warning_ratio` | Specifies when a warning will appear based on the ratio of time spent by a query in the queue versus the actual execution time of the query. For example, if a query waits in the queue for one second and it takes four seconds to execute, the ratio is 1:4 or 0.25. Once the specified ratio is reached for a query, a`ER_QUERY_QUEUED_WARNING`warning will appear.This variable can sync to all aggregators.This engine variable is configurable onSingleStore Helios. | `0.5` | | `workload_management_queue_timeout` | The time duration (in seconds) after which a query times out and is removed from the queue without being executed.This variable can sync to all aggregators.This engine variable is configurable onSingleStore Helios. | `3600` | | `workload_management_min_sample_based_memory_estimation_runs` | Minimum number of runs for workload management to use sample based rather than static row size based memory estimation. When disabled (set to 0), the first time query run will not be managed by workload management based on its memory.This variable can sync to all aggregators.This engine variable is configurable onSingleStore Helios | 1 | ## DR Replication Sync Variables SingleStore recommends contacting [Support](https://support.singlestore.com/) before changing the values of these variables. | Name | Description | Default | | ----------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ------- | | `repl_page_desc_limit_before_stall` | This limits the number of page descriptors in the page map that a 'ReplLog' can use before stalling new txs. The default 256K page desciptor limit means the hash table will not have load greater than 4. | 256K | | `repl_io_buffer_limit` | This limits the number of IO buffers that a 'ReplLog' can use before stalling new txs. 128 IO buffers is 16MB, since each IO buffer is 128K. | 16MB | | `[dr_]repl_network_buffer_size` | Replication tries to set both send and receive buffer sizes to reduce waits on TCP ack packets. 8MB is a sane battle-tested value. Can be set for both DR and non-DR replicas. | 8MB | | `[dr_]repl_max_chunk_size` | When sending logs or snapshots to a replica, limits chunk size to this value. Too long of a chunk increases the chance of timeout waiting for the replica's response packet (since the replica must process the entire chunk before acking). This defaults to 8MB - a sane, battle-tested value. Maximum value is 1GB, and it must be divisible by 128KB, so it's a multiple of IO buffer size. Can be set for both DR and non-DR replicas. | 8MB | ## Non-Sync Variables List See the [engine variables overview](https://docs.singlestore.com/cloud/reference/configuration-reference/engine-variables.md) to learn how non-sync variables work. > **📝 Note**: All of the non-sync variables listed in the following table are global variables, except when noted as a “session variable that can also be set globally” or “a session variable that can be set via SET SESSION” in the “Description” column. The variables listed in the following tables can be set to take effect on node startup and can be set to take effect while the node is running. Exceptions are noted in the fourth column. > **📝 Note**: The “Description” column will denote if an engine variable is configurable in SingleStore Helios. If not, they can be configured with the assistance of [SingleStoreDB Support](https://support.singlestore.com). ## Connection Management Variables | Name | Description | Default | Exceptions to When Variable can be Set | | --------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | -------- | -------------------------------------- | | `connect_timeout` | The number of seconds the node’sSingleStore Helioswaits for a connection packet before sending back a`Bad handshake`response. | `10` | | | `max_connections` | The number of simultaneous clients allowed. For more, see[In-Depth Variable Definitions](https://docs.singlestore.com/cloud/reference/configuration-reference/engine-variables/list-of-engine-variables/#in-depth-variable-definitions-9.md). | `100000` | | | `max_connection_threads` | The maximum number of kernel threads for processing queries. For more, see[In-Depth Variable Definitions](https://docs.singlestore.com/cloud/reference/configuration-reference/engine-variables/list-of-engine-variables/#in-depth-variable-definitions-10.md). | `8192` | | | `max_execution_time` | This variable exists only for backward compatibility with MySQL. | | | | `max_sys_mem_usage_for_load_data` | Sets the percentage of`maximum_memory`available for allocation to the`load_data_read_size`and`load_data_write_size`variables. This variable limits the memory usage by`LOAD DATA`read/write operations. | `20` | | ## Database Optimization Variables | Name | Description | Default | Exceptions to When Variable can be Set | | --------------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ------- | -------------------------------------- | | `columnstore_window_size` | This variable has been deprecated and is no longer operational inSingleStore Helios. | | | | `enable_idle_table_optimizations` | `enable_idle_table_optimizations`needs to be set at runtime and requires a restart for changes to take effect. It can be set to OFF or ON (default). The other related variable,`enable_idle_table_eviction`, can be set during a session (though a very small amount of overhead will remain until the server is restarted) and can be set to Full, SkipListsOnly, and Off. It defaults to SkipListsOnly, which meansSingleStorewill only evict skiplist indexes for idle tables on the cluster. Full means it will evict skiplists and table modules, and Off means no eviction. | `ON` | | | `enable_sort_on_load` | Whether to merge the newly loaded data segments (for`LOAD DATA`,`INSERT SELECT`, and`PIPELINE`statements) into a single sorted run. | `ON` | | | `net_read_timeout` | Number of seconds to wait for more data from a connection before aborting the read.This is a session variable that can be set via[SET SESSION](https://docs.singlestore.com/cloud/reference/sql-reference/operational-commands/set-and-set-session.md)onSingleStore Helios. | `3600` | | | `net_write_timeout` | Number of seconds to wait for a block to be written to a connection before aborting the write.This is a session variable that can be set via[SET SESSION](https://docs.singlestore.com/cloud/reference/sql-reference/operational-commands/set-and-set-session.md)onSingleStore Helios. | `3600` | | | `transaction_buffer` | This variable has been deprecated and is no longer operational inSingleStore Helios. | | | ## Full-Text Search Non-Sync Variables | Name | Description | Default | Exceptions to When Variable can be Set | | ---- | ----------- | ------- | -------------------------------------- | ## Logging Variables | Name | Description | Default | Exceptions to When Variable can be Set | | ------------------------ | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | --------------- | -------------------------------------- | | `core_file` | Turning`core_file`on or off determines whether or not full core dumps are produced upon a crash. | `ON` | | | `general_log` | If set to`ON`, every query will be logged to a table or log file. If set to`PARTIAL`, will only log when load is light.`OFF`turns off logging. | `OFF` | | | `general_log_file` | Log connections and queries to a given file. | `'./query.log'` | | | `tracelog_rotation_size` | Indicates the size threshold (in bytes) for tracelog file rotation. | | 65536> | | `tracelog_rotation_time` | Indicates the time threshold (in seconds) for tracelog file rotation. | | 60> | | `warn_level` | Defines howSingleStore Heliosbehaves when it encounters unsupported functionality. For more information, visit the Unsupported Feature List section of the[Unsupported MySQL Features](https://docs.singlestore.com/cloud/developer-resources/unsupported-mysql-features.md)topic. | `WARNINGS` | | ## Password Complexity Non-Sync Variables | Name | Description | Default | Exceptions to When Variable can be Set | | ----------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ----------- | -------------------------------------- | | `expire_root_password` | Specifies whether the root password can expire. If set to`ON`, the root password will expire after the`password_expiration_seconds`duration is reached. | `OFF` | | | `password_expiration_seconds` | The time (in seconds) before a password expires. The value`0`indicates that the password will never expire. | `0` | | | `password_expiration_mode` | Specifies what happens when a user's password expires. If set to`NO_ACCESS`, the user cannot login after the password expires. If set to`LIMITED_ACCESS`, the user can login after the password expires but can only update their password using`ALTER USER`or`SET PASSWORD`commands. Until the password is updated, no other commands can be executed except`SET SESSION`or`SET LOCAL`. | `NO_ACCESS` | | | `password_history_count` | The number of previous passwords per user thatSingleStore Helioswill store and disallow from reuse. The value`0`indicates that any previous password can be reused. The maximum is`10`. | `0` | | ## Pipelines Non-Sync Variables You cannot set a variable for a specific pipeline – each variable setting applies to all pipelines in the workspace. | Name | Description | Default Setting | Exceptions to When Variable can be Set | | -------------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | --------------- | -------------------------------------------------------------------------------------------------------------------------------------- | | `java_pipelines_java_home` | Specifies the value thatSingleStore Heliossets the node’s operating system environment variable`JAVA_HOME`to. If`java_pipelines_java_home`is not set,SingleStore Heliosdoes not set`JAVA_HOME`. | | You can only set this variable while the node is offline. The changes to this variable will take effect on the next start of the node. | | `java_pipelines_java_path` | Specifies the path that the HDFS extractor uses to run Java. | | | ## Query Plan Pinning Variables | Name | Description | Default | Exceptions to When Variable can be Set | | --------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | ------- | -------------------------------------- | | `pin_all_plans` | Writes a query plan pins when an un-planned pin is first optimized. The available values are`AUTO`,`OFF`,`ACTIVATED`, and`DEACTIVATED`. If set to`ACTIVATED`, all new plans are pinned in the activated state. If set to`DEACTIVATED`, all new plans are pinned in the deactivated state. If set to`OFF`, no plans are pinned automatically.`AUTO`is the same as`ACTIVATED`. | `OFF` | | | `plan_pin_read_timeout_ms` | This is used to enforce a maximum latency penalty that can be incurred when the server looks for a plan pin before proceeding with compiling a new plan. This behavior would become relevant if the cluster hosting the plan pins became severely overloaded or experienced networking issues. For commands that need to read pins by explicit user action -`ACTIVATE PIN`,`DEACTIVATE PIN`- usual RPC timeouts are used instead. | `2000` | | | `plan_pin_write_timeout_ms` | This is used to enforce a maximum latency penalty that can be incurred when the server writes a plan pin during compilation. This is only relevant for the case when a new query is being compiled without the presence of a pin, and defines the worst-case additional latency when`pin_all_plans`is set to`ACTIVATED`. For commands that need to write pins by explicit user action -`ACTIVATE PIN`,`DEACTIVATE PIN`- usual RPC timeouts are used instead. | `2000` | | | `use_plan_pins` | Loads query plan pins if one is found. The available values are`AUTO`,`TRUE`, and`FALSE`. When set to`TRUE`, if the`plan_pin_id`is not found in memory or on disk, the optimizer will search for the plan in the pinning database. If set to`FALSE`, the optimizer will not look in the plan\_pin\_id in the pinning database.`AUTO`is the same as`TRUE`. | `OFF` | | ## Other Variables | Name | Description | Default | Exceptions to When Variable can be Set | | ------------------------------------ | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------- | -------------------------------------------------------------------------------------------------------------------------------------- | | `activity_tracking_id` | An ID that can be used to identify the activities associated with a session. Configure the`activity_tracking_id`session engine variable to specify an ID for all the activities associated with the queries run in the current session. | | | | `activities_delta_sleep_s` | `activities_delta_sleep_s`specifies an interval of time (in seconds) which is used by the`mv_activities_cumulative`variable to determine recent resource usage. For more information, see[Management View Reference](https://docs.singlestore.com/cloud/reference/information-schema-reference/management.md).This is a session variable that can be set via[SET SESSION](https://docs.singlestore.com/cloud/reference/sql-reference/operational-commands/set-and-set-session.md)onSingleStore Helios. | `1` | | | `auditlogsdir` | Specifies the local or network directory to write log files. | `/📝 Note:
enable_wasmis a non-sync variable. It is listed with the Wasm sync variables for convenience sake.