path: root/src/mongo/db/query/query_knobs.idl

# 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.
#
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# Server Side Public License for more details.
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# code of portions of this program with the OpenSSL library under certain
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global:
  cpp_namespace: "mongo"
  cpp_includes:
    - "mongo/platform/atomic_proxy.h"
    - "mongo/platform/atomic_word.h"

server_parameters:

  #
  # multi-plan ranking
  #
  internalQueryPlanEvaluationWorks:
    description: "Max number of times we call work() on plans before comparing them, for small collections."
    set_at: [ startup, runtime ]
    cpp_varname: "internalQueryPlanEvaluationWorks"
    cpp_vartype: AtomicWord<int>
    default: 10000
    validator: 
      gt: 0

  internalQueryPlanEvaluationCollFraction:
    description: "For large collections, the number times we work() candidate plans is taken as this fraction of the collection size."
    set_at: [ startup, runtime ]
    cpp_varname: "internalQueryPlanEvaluationCollFraction"
    cpp_vartype: AtomicDouble
    default: 0.3
    validator: 
      gte: 0.0
      lte: 1.0

  internalQueryPlanEvaluationMaxResults:
    description: "Stop working plans once a plan returns this many results."
    set_at: [ startup, runtime ]
    cpp_varname: "internalQueryPlanEvaluationMaxResults"
    cpp_vartype: AtomicWord<int>
    default: 101
    validator: 
      gte: 0
  
  internalQueryForceIntersectionPlans:
    description: "Do we give a big ranking bonus to intersection plans?"
    set_at: [ startup, runtime ]
    cpp_varname: "internalQueryForceIntersectionPlans"
    cpp_vartype: AtomicWord<bool>
    default: false
  
  internalQueryPlannerEnableIndexIntersection:
    description: "Do we have ixisect on at all?"
    set_at: [ startup, runtime ]
    cpp_varname: "internalQueryPlannerEnableIndexIntersection"
    cpp_vartype: AtomicWord<bool>
    default: true

  internalQueryPlannerEnableHashIntersection:
    description: "Do we use hash-based intersection for rooted $and queries?"
    set_at: [ startup, runtime ]
    cpp_varname: "internalQueryPlannerEnableHashIntersection"
    cpp_vartype: AtomicWord<bool>
    default: false
      
  #
  # Plan cache
  #
  internalQueryCacheSize:
    description: "How many entries in the cache?"
    set_at: [ startup, runtime ]
    cpp_varname: "internalQueryCacheSize"
    cpp_vartype: AtomicWord<int>
    default: 5000
    validator: 
      gte: 0

  internalQueryCacheFeedbacksStored:
    description: "How many feedback entries do we collect before possibly evicting from the cache based on bad performance?"
    set_at: [ startup, runtime ]
    cpp_varname: "internalQueryCacheFeedbacksStored"
    cpp_vartype: AtomicWord<int>
    default: 20
    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

  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
  
  internalQueryCacheDisableInactiveEntries:
    description: "Whether or not cache entries can be marked as 'inactive'."
    set_at: [ startup, runtime ]
    cpp_varname: "internalQueryCacheDisableInactiveEntries"
    cpp_vartype: AtomicWord<bool>
    default: false

  internalQueryCacheListPlansNewOutput:
    description: "Whether or not planCacheListPlans uses the new output format."
    set_at: [ startup, runtime ]
    cpp_varname: "internalQueryCacheListPlansNewOutput"
    cpp_vartype: AtomicWord<bool>
    default: false

  #
  # Planning and enumeration
  #
  internalQueryPlannerMaxIndexedSolutions:
    description: "How many indexed solutions will QueryPlanner::plan output?"
    set_at: [ startup, runtime ]
    cpp_varname: "internalQueryPlannerMaxIndexedSolutions"
    cpp_vartype: AtomicWord<int>
    default: 64
    validator: 
      gte: 0

  internalQueryEnumerationMaxOrSolutions:
    description: "How many solutions will the enumerator consider at each OR?"
    set_at: [ startup, runtime ]
    cpp_varname: "internalQueryEnumerationMaxOrSolutions"
    cpp_vartype: AtomicWord<int>
    default: 10
    validator: 
      gte: 0

  internalQueryEnumerationMaxIntersectPerAnd:
    description: "How many intersections will the enumerator consider at each AND?"
    set_at: [ startup, runtime ]
    cpp_varname: "internalQueryEnumerationMaxIntersectPerAnd"
    cpp_vartype: AtomicWord<int>
    default: 3
    validator: 
      gte: 0

  internalQueryPlanOrChildrenIndependently:
    description: "Do we want to plan each child of the OR independently?"
    set_at: [ startup, runtime ]
    cpp_varname: "internalQueryPlanOrChildrenIndependently"
    cpp_vartype: AtomicWord<bool>
    default: true

  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<int>
    default: 200
    validator: 
      gte: 0

  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<bool>
    default: false

  internalQueryIgnoreUnknownJSONSchemaKeywords:
    description: "Ignore unknown JSON Schema keywords."
    set_at: [ startup, runtime ]
    cpp_varname: "internalQueryIgnoreUnknownJSONSchemaKeywords"
    cpp_vartype: AtomicWord<bool>
    default: false

  #
  # Query execution
  #
  internalQueryExecMaxBlockingSortBytes:
    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: "internalQueryExecMaxBlockingSortBytes"
    cpp_vartype: AtomicWord<int>
    default: 
      expr: 100 * 1024 * 1024
    validator: 
      gte: 0

  internalQueryExecYieldIterations:
    description: "Yield after this many \"should yield?\" checks."
    set_at: [ startup, runtime ]
    cpp_varname: "internalQueryExecYieldIterations"
    cpp_vartype: AtomicWord<int>
    default: 128

  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<int>
    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<int>
    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<long long>
    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<long long>
    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<int>
    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<int>
    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<int>
    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<bool>
    default: false

  internalQueryAllowShardedLookup:
    description: "If true, activates the incomplete sharded $lookup feature."
    set_at: [ startup, runtime ]
    cpp_varname: "internalQueryAllowShardedLookup"
    cpp_vartype: AtomicWord<bool>
    default: false

  internalQueryUseAggMapReduce:
    description: "If true runs mapReduce in a pipeline instead of the mapReduce command."
    set_at: [ startup, runtime ]
    cpp_varname: "internalQueryUseAggMapReduce"
    cpp_vartype: AtomicWord<bool>
    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<int>
    default:
      expr: 100 * 1024 * 1024
    validator:
        gt: 0