# Copyright (C) 2019-present MongoDB, Inc. # # This program is free software: you can redistribute it and/or modify # it under the terms of the Server Side Public License, version 1, # as published by MongoDB, Inc. # # This program is distributed in the hope that it will be useful, # but WITHOUT ANY WARRANTY; without even the implied warranty of # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the # Server Side Public License for more details. # # You should have received a copy of the Server Side Public License # along with this program. If not, see # . # # As a special exception, the copyright holders give permission to link the # code of portions of this program with the OpenSSL library under certain # conditions as described in each individual source file and distribute # linked combinations including the program with the OpenSSL library. You # must comply with the Server Side Public License in all respects for # all of the code used other than as permitted herein. If you modify file(s) # with this exception, you may extend this exception to your version of the # file(s), but you are not obligated to do so. If you do not wish to do so, # delete this exception statement from your version. If you delete this # exception statement from all source files in the program, then also delete # it in the license file. # global: cpp_namespace: "mongo" cpp_includes: - "mongo/db/query/cost_model/cost_model_on_update.h" - "mongo/db/query/ce_mode_parameter.h" - "mongo/db/query/sbe_plan_cache_on_parameter_change.h" - "mongo/db/query/telemetry_util.h" - "mongo/platform/atomic_proxy.h" - "mongo/platform/atomic_word.h" enums: QueryFrameworkControl: description: "Enum for possible values of internalQueryFrameworkControl." type: string values: # Force the classic query engine for all queries. kForceClassicEngine: "forceClassicEngine" # Attempt to use SBE for eligible queries, otherwise fallback to the classic engine. kTrySbeEngine: "trySbeEngine" # Attempt to use the Bonsai optimizer and lower to SBE for eligible queries, otherwise # fallback to "trySbeEngine". kTryBonsai: "tryBonsai" # Force the Bonsai optimizer for all queries. kForceBonsai: "forceBonsai" QueryTelemetryFieldNameRedactionStrategy: description: "Enum for possible values of queryFieldNameRedactionStrategy." type: string values: kNoRedactionStrategy: "none" # Use the constant redaction strategy. kConstantRedactionStrategy: "constant" # Use a prefix of sha256 redaction strategy kSha256RedactionStrategy: "sha256" server_parameters: # # multi-plan ranking # internalQueryPlanEvaluationWorks: description: "For small collections, the max number of times we call work() on plans during the runtime plan selection trial period. Applies only to the classic execution engine. The complete formula for calculating the maximum trial period works depends on 'internalQueryPlanEvaluationCollFraction' as well as this parameter." set_at: [ startup, runtime ] cpp_varname: "internalQueryPlanEvaluationWorks" cpp_vartype: AtomicWord default: 10000 validator: gt: 0 internalQueryPlanEvaluationWorksSbe: description: "The maximum number of individual storage cursor reads performed by any candidate plan during the runtime plan selection trial period. Applies only to queries using the SBE execution engine. This is the analog of the 'internalQueryPlanEvaluationWorks' knob above but for SBE. When 'internalQueryPlanEvaluationCollFractionSbe' has its default value of 0, this parameter acts as a hard limit on trial period length regardless of collection size." set_at: [ startup, runtime ] cpp_varname: "internalQueryPlanEvaluationWorksSbe" cpp_vartype: AtomicWord default: 10000 validator: gt: 0 on_update: plan_cache_util::clearSbeCacheOnParameterChange internalQueryPlanEvaluationCollFraction: description: "For large collections, the ceiling for the number times we work() candidate plans is taken as this fraction of the collection size. Applies only to the classic execution engine." set_at: [ startup, runtime ] cpp_varname: "internalQueryPlanEvaluationCollFraction" cpp_vartype: AtomicDouble default: 0.3 validator: gte: 0.0 lte: 1.0 internalQueryPlanEvaluationCollFractionSbe: description: "For large collections, the ceiling for the number of individual storage cursor reads allowed during the multi-planning trial period is calculated based on this constant. Applies only for for queries using the SBE execution engine. This is the analog of the 'internalQueryPlanEvaluationCollFraction' knob above but for SBE." set_at: [ startup, runtime ] cpp_varname: "internalQueryPlanEvaluationCollFractionSbe" cpp_vartype: AtomicDouble default: 0.0 validator: gte: 0.0 lte: 1.0 on_update: plan_cache_util::clearSbeCacheOnParameterChange internalQueryPlanEvaluationMaxResults: description: "Stop working plans once a plan returns this many results." set_at: [ startup, runtime ] cpp_varname: "internalQueryPlanEvaluationMaxResults" cpp_vartype: AtomicWord default: 101 validator: gte: 0 on_update: plan_cache_util::clearSbeCacheOnParameterChange internalQueryForceIntersectionPlans: description: "Gives a large ranking bonus to index intersection plans, forcing intersection plans to be chosen when possible." set_at: [ startup, runtime ] cpp_varname: "internalQueryForceIntersectionPlans" cpp_vartype: AtomicWord default: false on_update: plan_cache_util::clearSbeCacheOnParameterChange internalQueryPlannerEnableIndexIntersection: description: "Controls whether the planner will generate and consider index intersection plans." set_at: [ startup, runtime ] cpp_varname: "internalQueryPlannerEnableIndexIntersection" cpp_vartype: AtomicWord default: true on_update: plan_cache_util::clearSbeCacheOnParameterChange internalQueryPlannerEnableHashIntersection: description: "Do we use hash-based intersection for rooted $and queries?" set_at: [ startup, runtime ] cpp_varname: "internalQueryPlannerEnableHashIntersection" cpp_vartype: AtomicWord default: false on_update: plan_cache_util::clearSbeCacheOnParameterChange # # Plan cache # internalQueryDisablePlanCache: description: "Disables caching of query plans for both classic and SBE engines." set_at: [ startup ] cpp_varname: "internalQueryDisablePlanCache" cpp_vartype: AtomicWord default: false internalQueryCacheMaxEntriesPerCollection: description: "The maximum number of entries allowed in a given collection's plan cache. Applies only to the classic plan cache, not to the SBE plan cache." set_at: [ startup, runtime ] cpp_varname: "internalQueryCacheMaxEntriesPerCollection" cpp_vartype: AtomicWord deprecated_name: "internalQueryCacheSize" default: 5000 validator: gte: 0 internalQueryCacheMaxSizeBytesBeforeStripDebugInfo: description: "Limits the amount of debug info stored across all plan caches in the system. Once the estimate of the number of bytes used across all plan caches exceeds this threshold, then debug info is not stored alongside new cache entries, in order to limit plan cache memory consumption. If plan cache entries are freed and the estimate once again dips below this threshold, then new cache entries will once again have debug info associated with them. Applies only to the classic plan cache, not to the SBE plan cache." set_at: [ startup, runtime ] cpp_varname: "internalQueryCacheMaxSizeBytesBeforeStripDebugInfo" cpp_vartype: AtomicWord default: expr: 512 * 1024 * 1024 validator: gte: 0 internalQueryCacheEvictionRatio: description: "How many times more works must we perform in order to justify plan cache eviction and replanning?" set_at: [ startup, runtime ] cpp_varname: "internalQueryCacheEvictionRatio" cpp_vartype: AtomicDouble default: 10.0 validator: gte: 0.0 on_update: plan_cache_util::clearSbeCacheOnParameterChange internalQueryCacheWorksGrowthCoefficient: description: "How quickly the the 'works' value in an inactive cache entry will grow. It grows exponentially. The value of this server parameter is the base." set_at: [ startup, runtime ] cpp_varname: "internalQueryCacheWorksGrowthCoefficient" cpp_vartype: AtomicDouble default: 2.0 validator: gt: 1.0 on_update: plan_cache_util::clearSbeCacheOnParameterChange internalQueryCacheDisableInactiveEntries: description: "Whether or not cache entries can be marked as 'inactive'." set_at: [ startup, runtime ] cpp_varname: "internalQueryCacheDisableInactiveEntries" cpp_vartype: AtomicWord default: false on_update: plan_cache_util::clearSbeCacheOnParameterChange planCacheSize: description: "The maximum amount of memory that the system will allocate for the plan cache. It takes value value in one of the two formats: 1. % indicates a percentage of the physical memory available to the process. E.g.: 15%. 2. (MB|GB), indicates the amount of memory in MB or GB. E.g.: 1.5GB, 100MB. The defualt value is 5% which means 5% of the physical memory available to the process." set_at: [ startup, runtime ] cpp_varname: "planCacheSize" cpp_vartype: synchronized_value default: "5%" on_update: plan_cache_util::onPlanCacheSizeUpdate validator: callback: plan_cache_util::validatePlanCacheSize # # Parsing # internalPipelineLengthLimit: description: "The maximum length allowed for an an aggregation pipeline." set_at: [ startup ] cpp_varname: "internalPipelineLengthLimit" cpp_vartype: int default: expr: 'kDebugBuild ? 200 : 1000' validator: gt: 0 internalMaxSubPipelineViewDepth: description: "The maximum length allowed for an an aggregation sub-pipeline view." set_at: [ startup, runtime ] cpp_varname: "internalMaxSubPipelineViewDepth" cpp_vartype: AtomicWord default: 20 test_only: true validator: gt: 0 internalPartialFilterExpressionMaxDepth: description: "The maximum depth allowed for a partialFilterExpression." set_at: [ startup, runtime ] cpp_varname: "internalPartialFilterExpressionMaxDepth" cpp_vartype: AtomicWord default: 4 validator: gt: 0 # # Planning and enumeration # internalQueryPlannerMaxIndexedSolutions: description: "How many indexed solutions will QueryPlanner::plan output?" set_at: [ startup, runtime ] cpp_varname: "internalQueryPlannerMaxIndexedSolutions" cpp_vartype: AtomicWord default: 64 validator: gte: 0 on_update: plan_cache_util::clearSbeCacheOnParameterChange internalQueryEnumerationPreferLockstepOrEnumeration: description: "If set to true, instructs the plan enumerator to enumerate contained $ors in a special order. $or enumeration can generate an exponential number of plans, and is therefore limited at some arbitrary cutoff controlled by a parameter. When this limit is hit, the order of enumeration is important. For example, a query like the following has a 'contained $or' (within an $and): {a: 1, $or: [{b: 1, c: 1}, {b: 2, c: 2}]} For this query if there are indexes a_b={a: 1, b: 1} and a_c={a: 1, c: 1}, the normal enumeration order would output assignments [a_b, a_b], [a_c, a_b], [a_b, a_c], then [a_c, a_c]. This flag will instruct the enumerator to instead prefer a different order. It's hard to summarize, but perhaps the phrases 'lockstep enumeration', 'simultaneous advancement', or 'parallel iteration' will help the reader. The effect is to give earlier enumeration to plans which use the same choice across all branches. In this order, we would get assignments [a_b, a_b], [a_c, a_c], [a_c, a_b], then [a_b, a_c]. This is thought to be helpful in general, but particularly in cases where all children of the $or use the same fields and have the same indexes available, as in this example." set_at: [ startup, runtime ] cpp_varname: "internalQueryEnumerationPreferLockstepOrEnumeration" cpp_vartype: AtomicWord default: false on_update: plan_cache_util::clearSbeCacheOnParameterChange internalQueryEnumerationMaxOrSolutions: description: "How many solutions will the enumerator consider at each OR?" set_at: [ startup, runtime ] cpp_varname: "internalQueryEnumerationMaxOrSolutions" cpp_vartype: AtomicWord default: 10 validator: gte: 0 on_update: plan_cache_util::clearSbeCacheOnParameterChange internalQueryEnumerationMaxIntersectPerAnd: description: "How many intersections will the enumerator consider at each AND?" set_at: [ startup, runtime ] cpp_varname: "internalQueryEnumerationMaxIntersectPerAnd" cpp_vartype: AtomicWord default: 3 validator: gte: 0 on_update: plan_cache_util::clearSbeCacheOnParameterChange internalQueryPlanOrChildrenIndependently: description: "Do we want to plan each child of the OR independently?" set_at: [ startup, runtime ] cpp_varname: "internalQueryPlanOrChildrenIndependently" cpp_vartype: AtomicWord default: true on_update: plan_cache_util::clearSbeCacheOnParameterChange internalQueryMaxScansToExplode: description: "How many index scans are we willing to produce in order to obtain a sort order during explodeForSort?" set_at: [ startup, runtime ] cpp_varname: "internalQueryMaxScansToExplode" cpp_vartype: AtomicWord default: 200 validator: gte: 0 on_update: plan_cache_util::clearSbeCacheOnParameterChange internalQueryPlannerGenerateCoveredWholeIndexScans: description: "Allow the planner to generate covered whole index scans, rather than falling back to a COLLSCAN." set_at: [ startup, runtime ] cpp_varname: "internalQueryPlannerGenerateCoveredWholeIndexScans" cpp_vartype: AtomicWord default: false on_update: plan_cache_util::clearSbeCacheOnParameterChange internalQueryIgnoreUnknownJSONSchemaKeywords: description: "Ignore unknown JSON Schema keywords." set_at: [ startup, runtime ] cpp_varname: "internalQueryIgnoreUnknownJSONSchemaKeywords" cpp_vartype: AtomicWord default: false # # Query execution # internalQueryMaxBlockingSortMemoryUsageBytes: description: "The maximum amount of memory a query (e.g. a find or aggregate command) is willing to use to execute a blocking sort, measured in bytes. If disk use is allowed, then it may be possible to sort more data, but this limit will still constrain the memory consumption." set_at: [ startup, runtime ] cpp_varname: "internalQueryMaxBlockingSortMemoryUsageBytes" cpp_vartype: AtomicWord default: expr: 100 * 1024 * 1024 validator: gte: 0 on_update: plan_cache_util::clearSbeCacheOnParameterChange internalQueryExecYieldIterations: description: "Yield after this many \"should yield?\" checks." set_at: [ startup, runtime ] cpp_varname: "internalQueryExecYieldIterations" cpp_vartype: AtomicWord default: 1000 internalQueryExecYieldPeriodMS: description: "Yield if it's been at least this many milliseconds since we last yielded." set_at: [ startup, runtime ] cpp_varname: "internalQueryExecYieldPeriodMS" cpp_vartype: AtomicWord default: 10 validator: gte: 0 internalQueryFacetBufferSizeBytes: description: "The number of bytes to buffer at once during a $facet stage." set_at: [ startup, runtime ] cpp_varname: "internalQueryFacetBufferSizeBytes" cpp_vartype: AtomicWord default: expr: 100 * 1024 * 1024 validator: gt: 0 internalQueryFacetMaxOutputDocSizeBytes: description: "The number of bytes to buffer at once during a $facet stage." set_at: [ startup, runtime ] cpp_varname: "internalQueryFacetMaxOutputDocSizeBytes" cpp_vartype: AtomicWord default: expr: 100 * 1024 * 1024 validator: gt: 0 internalLookupStageIntermediateDocumentMaxSizeBytes: description: "Maximum size of the result set that we cache from the foreign collection during a $lookup." set_at: [ startup, runtime ] cpp_varname: "internalLookupStageIntermediateDocumentMaxSizeBytes" cpp_vartype: AtomicWord default: expr: 100 * 1024 * 1024 validator: gte: { expr: BSONObjMaxInternalSize} internalDocumentSourceGroupMaxMemoryBytes: description: "Maximum size of the data that the $group aggregation stage will cache in-memory before spilling to disk." set_at: [ startup, runtime ] cpp_varname: "internalDocumentSourceGroupMaxMemoryBytes" cpp_vartype: AtomicWord default: expr: 100 * 1024 * 1024 validator: gt: 0 internalDocumentSourceSetWindowFieldsMaxMemoryBytes: description: "Maximum size of the data that the $setWindowFields aggregation stage will cache in-memory before throwing an error." set_at: [ startup, runtime ] cpp_varname: "internalDocumentSourceSetWindowFieldsMaxMemoryBytes" cpp_vartype: AtomicWord default: expr: 100 * 1024 * 1024 validator: gt: 0 internalInsertMaxBatchSize: description: "Maximum number of documents that we will insert in a single batch." set_at: [ startup, runtime ] cpp_varname: "internalInsertMaxBatchSize" cpp_vartype: AtomicWord default: expr: internalQueryExecYieldIterations.load() / 2 is_constexpr: false validator: gt: 0 internalDocumentSourceCursorBatchSizeBytes: description: "Maximum amount of data that DocumentSourceCursor will cache from the underlying PlanExecutor before pipeline processing." set_at: [ startup, runtime ] cpp_varname: "internalDocumentSourceCursorBatchSizeBytes" cpp_vartype: AtomicWord default: expr: 4 * 1024 * 1024 validator: gte: 0 internalDocumentSourceLookupCacheSizeBytes: description: "Maximum amount of non-correlated foreign-collection data that the $lookup stage will cache before abandoning the cache and executing the full pipeline on each iteration." set_at: [ startup, runtime ] cpp_varname: "internalDocumentSourceLookupCacheSizeBytes" cpp_vartype: AtomicWord default: expr: 100 * 1024 * 1024 validator: gte: 0 internalQueryProhibitBlockingMergeOnMongoS: description: "If true, blocking stages such as $group or non-merging $sort will be prohibited from running on mongoS." set_at: [ startup, runtime ] cpp_varname: "internalQueryProhibitBlockingMergeOnMongoS" cpp_vartype: AtomicWord default: false internalQueryMaxJsEmitBytes: description: "Limits the vector of values emitted from a single document's call to JsEmit to the given size in bytes." set_at: [ startup, runtime ] cpp_varname: "internalQueryMaxJsEmitBytes" cpp_vartype: AtomicWord default: expr: 100 * 1024 * 1024 validator: gt: 0 internalQueryMaxPushBytes: description: "Limits the vector of values pushed into a single array while grouping with the $push accumulator." set_at: [ startup, runtime ] cpp_varname: "internalQueryMaxPushBytes" cpp_vartype: AtomicWord default: expr: 100 * 1024 * 1024 validator: gt: 0 on_update: plan_cache_util::clearSbeCacheOnParameterChange internalQueryMaxRangeBytes: description: "Limits the vector of values pushed into a single array while generating $range result." set_at: [ startup, runtime ] cpp_varname: "internalQueryMaxRangeBytes" cpp_vartype: AtomicWord default: expr: 100 * 1024 * 1024 validator: gt: 0 internalQueryMaxAddToSetBytes: description: "Limits the vector of values pushed into a single array while grouping with the $addToSet accumulator." set_at: [ startup, runtime ] cpp_varname: "internalQueryMaxAddToSetBytes" cpp_vartype: AtomicWord default: expr: 100 * 1024 * 1024 validator: gt: 0 on_update: plan_cache_util::clearSbeCacheOnParameterChange internalQueryJavaScriptHeapSizeLimitMB: description: "Limits the JavaScript heap size used in aggregation. Will defer to the global 'jsHeapLimitMB' limit if the global limit is smaller." set_at: [ startup, runtime ] cpp_varname: "internalQueryJavaScriptHeapSizeLimitMB" cpp_vartype: AtomicWord default: 100 internalQueryJavaScriptFnTimeoutMillis: description: "Limits the maximum allowed time a user-defined javascript function can run in a query." set_at: [ startup, runtime ] cpp_varname: "internalQueryJavaScriptFnTimeoutMillis" cpp_vartype: AtomicWord default: expr: 60 * 1000 validator: gt: 0 internalQueryDesugarWhereToFunction: description: "When true, desugars $where to $expr/$function." set_at: [ startup, runtime ] cpp_varname: "internalQueryDesugarWhereToFunction" cpp_vartype: AtomicWord default: false internalQueryDefaultDOP: description: "Default degree of parallelism. This an internal experimental parameter and should not be changed on live systems." set_at: [ startup, runtime ] cpp_varname: "internalQueryDefaultDOP" cpp_vartype: AtomicWord default: 1 test_only: true validator: gt: 0 on_update: plan_cache_util::clearSbeCacheOnParameterChange internalQuerySlotBasedExecutionMaxStaticIndexScanIntervals: description: "Limits the number of statically known intervals that SBE can decompose index bounds into when possible." set_at: [ startup, runtime ] cpp_varname: "internalQuerySlotBasedExecutionMaxStaticIndexScanIntervals" cpp_vartype: AtomicWord default: 1000 validator: gt: 0 on_update: plan_cache_util::clearSbeCacheOnParameterChange internalQueryEnableCSTParser: description: "If true, use the grammar-based parser and CST to parse queries." set_at: [ startup, runtime ] cpp_varname: "internalQueryEnableCSTParser" cpp_vartype: AtomicWord default: false internalQueryMaxDocValidationErrorConsideredValues: description: "Limits the number of values reported in the 'consideredValues' array when generating a descriptive document validation error." set_at: [ startup, runtime ] cpp_varname: "internalQueryMaxDocValidationErrorConsideredValues" cpp_vartype: AtomicWord default: 10 validator: gt: 0 internalQueryExplainSizeThresholdBytes: description: "Number of bytes after which explain should start truncating portions of its output." set_at: [ startup, runtime ] cpp_varname: "internalQueryExplainSizeThresholdBytes" cpp_vartype: AtomicWord default: expr: 10 * 1024 * 1024 validator: gt: 0 lte: { expr: BSONObjMaxInternalSize } internalQuerySlotBasedExecutionHashAggMemoryUseCheckMargin: description: "The memory check in HashAgg stage is done on every T'th processed record, where T is calculated adaptively based on the estimated memory used and its recent growth. This setting defines the percent of the remaining available memory to be used before the next check, given the estimated growth speed per advance [see internalQuerySlotBasedExecutionHashAggApproxMemoryUseInBytesBeforeSpill]." set_at: [ startup, runtime ] cpp_varname: "internalQuerySBEAggMemoryUseCheckMargin" cpp_vartype: AtomicDouble default: 0.7 validator: gt: 0.0 lte: 1.0 internalQuerySlotBasedExecutionHashAggMemoryCheckPerAdvanceAtMost: description: "The memory check in HashAgg stage is done on every T'th processed record, where T is calculated adaptively based on the estimated memory used and its recent growth. This setting defines the lower bound for T [see internalQuerySlotBasedExecutionHashAggApproxMemoryUseInBytesBeforeSpill]." set_at: [ startup, runtime ] cpp_varname: "internalQuerySBEAggMemoryCheckPerAdvanceAtMost" cpp_vartype: AtomicWord default: 2 validator: gt: 0 internalQuerySlotBasedExecutionHashAggMemoryCheckPerAdvanceAtLeast: description: "The memory check in HashAgg stage is done on every T'th processed record, where T is calculated adaptively based on the estimated memory used and its recent growth. This setting defines the upper bound for T. If this setting is less than [see internalQuerySlotBasedExecutionHashAggMemoryCheckPerAdvanceAtMost], the check will be done on every internalQuerySlotBasedExecutionHashAggMemoryCheckPerAdvanceAtLeast'th processed record [see internalQuerySlotBasedExecutionHashAggApproxMemoryUseInBytesBeforeSpill]." set_at: [ startup, runtime ] cpp_varname: "internalQuerySBEAggMemoryCheckPerAdvanceAtLeast" cpp_vartype: AtomicWord default: 1024 validator: gt: 0 internalQuerySlotBasedExecutionHashAggApproxMemoryUseInBytesBeforeSpill: description: "The max size in bytes that the hash table in a HashAgg stage can be estimated to be before we spill to disk." set_at: [ startup, runtime ] cpp_varname: "internalQuerySBEAggApproxMemoryUseInBytesBeforeSpill" cpp_vartype: AtomicWord default: expr: 100 * 1024 * 1024 validator: gt: 0 internalQuerySlotBasedExecutionHashLookupApproxMemoryUseInBytesBeforeSpill: description: "The max size in bytes that the hash table in a HashLookup stage can be estimated to be before we spill to disk." set_at: [ startup, runtime ] cpp_varname: "internalQuerySBELookupApproxMemoryUseInBytesBeforeSpill" cpp_vartype: AtomicWord default: expr: 100 * 1024 * 1024 validator: gt: 0 internalQuerySlotBasedExecutionDisableLookupPushdown: description: "If true, the system will not push down $lookup to the SBE execution engine." set_at: [ startup, runtime ] cpp_varname: "internalQuerySlotBasedExecutionDisableLookupPushdown" cpp_vartype: AtomicWord default: false on_update: plan_cache_util::clearSbeCacheOnParameterChange internalQuerySlotBasedExecutionDisableGroupPushdown: description: "If true, the system will not push down $group to the SBE execution engine." set_at: [ startup, runtime ] cpp_varname: "internalQuerySlotBasedExecutionDisableGroupPushdown" cpp_vartype: AtomicWord default: false on_update: plan_cache_util::clearSbeCacheOnParameterChange internalQueryAppendIdToSetWindowFieldsSort: description: "If true, appends _id to the sort stage generated by desugaring $setWindowFields to ensure deterministic sort order." set_at: [startup, runtime] cpp_varname: "internalQueryAppendIdToSetWindowFieldsSort" cpp_vartype: AtomicWord default: false internalQueryTopNAccumulatorBytes: description: "Limits the vector of values pushed into a single array while grouping with the 'N' family of accumulators." set_at: [ startup, runtime ] cpp_varname: "internalQueryTopNAccumulatorBytes" cpp_vartype: AtomicWord default: expr: 100 * 1024 * 1024 validator: gt: 0 enableSearchMeta: description: "Exists for backwards compatibility in startup parameters, enabling this was required on 4.4 to access SEARCH_META variables. Does not do anything." set_at: [ startup, runtime ] cpp_varname: "enableSearchMeta" cpp_vartype: AtomicWord default: true enableTimeoutOfInactiveSessionCursors: description: "If true, cursors opened within sessions are eligible for inactive cursor timeout." set_at: [ startup, runtime ] cpp_varname: "enableTimeoutOfInactiveSessionCursors" cpp_vartype: AtomicWord default: false internalQueryMaxAllowedDensifyDocs: description: "Limits the number of documents that $densify is allowed to generate." set_at: [ startup, runtime ] cpp_varname: "internalQueryMaxAllowedDensifyDocs" cpp_vartype: AtomicWord default: 500000 validator: gt: 0 internalDocumentSourceDensifyMaxMemoryBytes: description: "Limits the number of bytes densification can use to store partition information." set_at: [ startup, runtime ] cpp_varname: "internalDocumentSourceDensifyMaxMemoryBytes" cpp_vartype: AtomicWord default: expr: 100 * 1024 * 1024 validator: gt: 0 internalQueryCardinalityEstimatorMode: description: "Set to select a method for estimating cardinality in the Cascades optimizer." set_at: [ startup, runtime ] cpp_varname: "internalQueryCardinalityEstimatorMode" cpp_vartype: std::string default: sampling validator: callback: optimizer::ce::validateCEMode internalCascadesOptimizerDisableScan: description: "Disable full collection scans in the Cascades optimizer." set_at: [ startup, runtime ] cpp_varname: "internalCascadesOptimizerDisableScan" cpp_vartype: AtomicWord default: false internalCascadesOptimizerDisableIndexes: description: "Disable index scan plans in the Cascades optimizer." set_at: [ startup, runtime ] cpp_varname: "internalCascadesOptimizerDisableIndexes" cpp_vartype: AtomicWord default: false internalCascadesOptimizerDisableMergeJoinRIDIntersect: description: "Disable index RID intersection via merge join in the Cascades optimizer." set_at: [ startup, runtime ] cpp_varname: "internalCascadesOptimizerDisableMergeJoinRIDIntersect" cpp_vartype: AtomicWord default: false internalCascadesOptimizerDisableHashJoinRIDIntersect: description: "Disable index RID intersection via hash join in the Cascades optimizer." set_at: [ startup, runtime ] cpp_varname: "internalCascadesOptimizerDisableHashJoinRIDIntersect" cpp_vartype: AtomicWord default: false internalCascadesOptimizerDisableGroupByAndUnionRIDIntersect: description: "Disable index RID intersection via group by and union in the Cascades optimizer." set_at: [ startup, runtime ] cpp_varname: "internalCascadesOptimizerDisableGroupByAndUnionRIDIntersect" cpp_vartype: AtomicWord default: false internalCascadesOptimizerKeepRejectedPlans: description: "Keep track of rejected plans in the memo. Applies only to the Cascades optimizer." set_at: [ startup, runtime ] cpp_varname: "internalCascadesOptimizerKeepRejectedPlans" cpp_vartype: AtomicWord default: false internalCascadesOptimizerDisableBranchAndBound: description: "Disable cascades branch-and-bound strategy, and fully evaluate all plans in the Cascades optimizer." set_at: [ startup, runtime ] cpp_varname: "internalCascadesOptimizerDisableBranchAndBound" cpp_vartype: AtomicWord default: false internalCascadesOptimizerFastIndexNullHandling: description: "Controls if we prefer to cover queries which may return nulls with indexes." set_at: [ startup, runtime ] cpp_varname: "internalCascadesOptimizerFastIndexNullHandling" cpp_vartype: AtomicWord default: false internalCascadesOptimizerDisableYieldingTolerantPlans: description: "Controls if we prefer to insert redundant index predicates on the Seek side in order to prevent issues arising from yielding." set_at: [ startup, runtime ] cpp_varname: "internalCascadesOptimizerDisableYieldingTolerantPlans" cpp_vartype: AtomicWord default: true internalCascadesOptimizerMinIndexEqPrefixes: description: "Controls the minimum number of equality prefixes in each candidate index." set_at: [ startup, runtime ] cpp_varname: "internalCascadesOptimizerMinIndexEqPrefixes" cpp_vartype: AtomicWord default: 1 internalCascadesOptimizerMaxIndexEqPrefixes: description: "Controls the maximum number of equality prefixes in each candidate index." set_at: [ startup, runtime ] cpp_varname: "internalCascadesOptimizerMaxIndexEqPrefixes" cpp_vartype: AtomicWord default: 1 internalCascadesOptimizerStdCoutDebugOutput: description: "Enables verbose, non-JSON, debug output for Cascades optimizer." set_at: [ startup, runtime ] cpp_varname: "internalCascadesOptimizerStdCoutDebugOutput" cpp_vartype: AtomicWord default: false test_only: true internalCascadesOptimizerUseDescriptiveVarNames: description: "Enables generation of descriptive variable names to aid debugging." set_at: [ startup, runtime ] cpp_varname: "internalCascadesOptimizerUseDescriptiveVarNames" cpp_vartype: AtomicWord default: false test_only: true internalQueryFrameworkControl: description: "Knob to control the optimizer/execution engine to use." set_at: [ startup, runtime ] cpp_class: name: QueryFrameworkControl data: synchronized_value default: expr: QueryFrameworkControlEnum::kTryBonsai internalQueryCollectionMaxNoOfDocumentsToChooseHashJoin: description: "Up to what number of documents do we choose the hash join algorithm when $lookup is translated to a SBE plan." set_at: [ startup, runtime ] cpp_varname: "internalQueryCollectionMaxNoOfDocumentsToChooseHashJoin" cpp_vartype: AtomicWord default: expr: 10 * 1000 validator: gt: 0 on_update: plan_cache_util::clearSbeCacheOnParameterChange internalQueryCollectionMaxDataSizeBytesToChooseHashJoin: description: "Up to what data size do we choose the hash join algorithm when $lookup is translated to a SBE plan." set_at: [ startup, runtime ] cpp_varname: "internalQueryCollectionMaxDataSizeBytesToChooseHashJoin" cpp_vartype: AtomicWord default: expr: 100 * 1024 * 1024 validator: gt: 0 on_update: plan_cache_util::clearSbeCacheOnParameterChange internalQueryCollectionMaxStorageSizeBytesToChooseHashJoin: description: "Up to what storage size do we choose the hash join algorithm when $lookup is translated to a SBE plan." set_at: [ startup, runtime ] cpp_varname: "internalQueryCollectionMaxStorageSizeBytesToChooseHashJoin" cpp_vartype: AtomicWord default: expr: 100 * 1024 * 1024 validator: gt: 0 on_update: plan_cache_util::clearSbeCacheOnParameterChange internalQueryDisableLookupExecutionUsingHashJoin: description: "Disable lookup execution using hash join algorithm, this will cause the plans, eligible for the hash join strategy, to fall back to using the nested loop join strategy." set_at: [ startup, runtime ] cpp_varname: "internalQueryDisableLookupExecutionUsingHashJoin" cpp_vartype: AtomicWord default: false on_update: plan_cache_util::clearSbeCacheOnParameterChange internalQueryMaxNumberOfFieldsToChooseUnfilteredColumnScan: description: "Up to what number of fields do we choose to use the column store index when there are no other indexed alternatives and no query predicates that can be applied during the column store index scan? Set to 0 to never use the column store, even if there is only one referenced field." set_at: [ startup, runtime ] cpp_varname: "internalQueryMaxNumberOfFieldsToChooseUnfilteredColumnScan" cpp_vartype: AtomicWord default: 5 validator: gte: 0 on_update: plan_cache_util::clearSbeCacheOnParameterChange internalQueryMaxNumberOfFieldsToChooseFilteredColumnScan: description: "Up to what number of fields do we choose to use the column store index when there are no other indexed alternatives but at least one query predicate that can be applied during the column store index scan? Set to 0 to never use the column store, even if there is only one referenced field." set_at: [ startup, runtime ] cpp_varname: "internalQueryMaxNumberOfFieldsToChooseFilteredColumnScan" cpp_vartype: AtomicWord default: 12 validator: gte: 0 on_update: plan_cache_util::clearSbeCacheOnParameterChange internalQueryFLERewriteMemoryLimit: description: "Maximum memory available for encrypted field query rewrites in bytes. Must be more than zero and less than 16Mb" set_at: [ startup, runtime ] cpp_varname: "internalQueryFLERewriteMemoryLimit" cpp_vartype: AtomicWord default: expr: 14 * 1024 * 1024 validator: gt: 0 lt: 16777216 internalMeasureQueryExecutionTimeInNanoseconds: description: "If true, the explain results include 'executionTimeMicros' and 'executionTimeNanos' fields to represent the execution time of each SBE plan stage in microseconds and in nanoseconds" set_at: [ startup ] cpp_varname: "internalMeasureQueryExecutionTimeInNanoseconds" cpp_vartype: AtomicWord default: false internalQueryFLEAlwaysUseEncryptedCollScanMode: description: "Boolean flag to force FLE to always use low selectivity mode" set_at: [ startup, runtime ] cpp_varname: "internalQueryFLEAlwaysUseEncryptedCollScanMode" cpp_vartype: AtomicWord default: expr: false internalCostModelCoefficients: description: "Cost Model Coefficients Override" set_at: [ startup, runtime ] cpp_varname: "internalCostModelCoefficients" cpp_vartype: "std::string" on_update: cost_model::updateCostCoefficientsOnUpdate # TODO SERVER-68341 Remove this query knob after tenancy is supported in the sharded cluster. internalChangeStreamUseTenantIdForTesting: description: "If true, then change streams will operate upon an internal tenant id for testing purposes if the actual tenant is not provided." set_at: [ startup ] cpp_varname: "internalChangeStreamUseTenantIdForTesting" cpp_vartype: AtomicWord default: false enableComputeMode: description: "Boolean flag to enable the compute mode in which mongod is used not as a persistent storage node, but as a worker node for executing queries." set_at: [ startup ] cpp_varname: "computeModeEnabled" cpp_vartype: bool default: false externalPipeDir: description: "Absolute path to the directory where external named pipes can be found. The trailing '/' must be included." set_at: [ startup ] cpp_varname: "externalPipeDir" cpp_vartype: std::string internalQueryDisableExclusionProjectionFastPath: description: "If true, then ExclusionProjectionExecutor won't use fast path implementation. This is needed for the generational fuzzers that are sensitive to field order and other corner cases when switching from Document to BSONObj." set_at: [ startup ] cpp_varname: "internalQueryDisableExclusionProjectionFastPath" cpp_vartype: bool default: false test_only: true internalQueryConfigureTelemetrySamplingRate: description: "The maximum number of queries per second that are sampled for query telemetry. If the rate of queries goes above this number, then rate limiting will kick in, and any further queries will not be sampled. To sample all queries, this can be set to the INT_MAX. This can be set to 0 to turn telemetry off completely." set_at: [ startup, runtime ] cpp_varname: "queryTelemetrySamplingRate" cpp_vartype: AtomicWord default: 0 internalQueryConfigureTelemetryCacheSize: description: "The maximum amount of memory that the system will allocate for the query telemetry cache. This will accept values in either of the following formats: 1. % indicates a percentage of the physical memory available to the process. E.g.: 15%. 2. (MB|GB), indicates the amount of memory in MB or GB. E.g.: 1.5GB, 100MB. The default value is 1%, which means 1% of the physical memory available to the process." set_at: [ startup, runtime ] cpp_varname: "queryTelemetryStoreSize" cpp_vartype: synchronized_value default: "1%" on_update: telemetry_util::onTelemetryStoreSizeUpdate validator: callback: telemetry_util::validateTelemetryStoreSize internalQueryColumnScanMinCollectionSizeBytes: description: "The min collection size threshold for which column scan will always be allowed. If the value is -1, decision will be made based on the size of available memory. If it is set to 0 column scan will always be allowed." set_at: [ startup, runtime ] cpp_varname: "internalQueryColumnScanMinCollectionSizeBytes" cpp_vartype: AtomicWord default: -1 validator: gte: -1 on_update: plan_cache_util::clearSbeCacheOnParameterChange internalQueryColumnScanMinAvgDocSizeBytes: description: "The min average document size threshold for which column scan will always be allowed. If it is set to 0 column scan will always be allowed." set_at: [ startup, runtime ] cpp_varname: "internalQueryColumnScanMinAvgDocSizeBytes" cpp_vartype: AtomicWord default: 1024 validator: gte: 0 on_update: plan_cache_util::clearSbeCacheOnParameterChange internalQueryColumnRowstoreScanMinBatchSize: description: "The minimum number of records that will be scanned from the row store after running into a record that cannot be served from the index and before attempting to use the index again. No preemptive scanning will be done if this setting is 0." set_at: [ startup, runtime ] cpp_varname: "internalQueryColumnRowstoreScanMinBatchSize" cpp_vartype: AtomicWord # The preemptive scan of the row store mitigates the situation when there is a range of records # that cannot be served from CSI. We increase the batch size exponentially as we keep seeing # 'bad' data so starting with a low minimum batch size is OK and allows to minimize scanning # if the 'bad' records are isolated. default: 1 validator: gte: 0 internalQueryColumnRowstoreScanMaxBatchSize: description: "The maximum number of records that can be scanned from the row store after running into a record that cannot be served from the index and before attempting to use the index again. If this setting is less than 'internalQueryColumnRowstoreScanMinBatchSize' the batch size will be fixed at 'internalQueryColumnRowstoreScanMinBatchSize'." set_at: [ startup, runtime ] cpp_varname: "internalQueryColumnRowstoreScanMaxBatchSize" cpp_vartype: AtomicWord # The sweet spot for scanning vs attempting to use the index would very much depend on the data # so there is no default setting that would work in all situations. Setting it relatively high # favors the case when all of the data would require reading from the row store. default: 10000 validator: gte: 0 internalQueryColumnScanMinNumColumnFilters: description: "The min number of column filters for which column scan will always be allowed. If it is set to 0 column scan will always be allowed." set_at: [ startup, runtime ] cpp_varname: "internalQueryColumnScanMinNumColumnFilters" cpp_vartype: AtomicWord default: 3 validator: gte: 0 on_update: plan_cache_util::clearSbeCacheOnParameterChange # Note for adding additional query knobs: # # When adding a new query knob, you should consider whether or not you need to add an 'on_update' # hook to flush the SBE plan cache. If your knob affects the contents of SBE plans which may be # cached, then the SBE cache should be flushed when the value of the knob changes. This will ensure # that the application actually starts to get plans which reflect the new value of the knob, rather # than continuing to use stale cached plans. # # When adding a new query knob which flushes the SBE plan cache on update, you should test this # behavior by including the name of the new knob in the list at the top of the jstest # 'sbe_plan_cache_clear_on_param_change.js'.