CMDB Query Builder engine execution modes

  • Release version: Zurich
  • Updated March 26, 2026
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    Summary of CMDB Query Builder Engine Execution Modes

    The CMDB Query Builder engine in ServiceNow utilizes two execution modes—V2 (enhanced) and V1 (legacy)—to run queries against the Configuration Management Database (CMDB). By default, the system uses the V2 mode, which is optimized for higher performance and scalability, enabling faster execution of complex queries and handling larger result sets efficiently. However, certain query structures are not supported in V2 and will automatically fall back to V1 mode to ensure query success.

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    Execution Modes and Their Use

    • V2 Mode: The default and enhanced execution engine providing improved performance and scalability. It merges related results for queries with logical OR conditions, resulting in a consolidated output. It is suitable for most queries but does not support some specific structures.
    • V1 Mode: The legacy execution engine used either when explicitly configured or when the query structure is unsupported in V2. It presents results with separate items for OR conditions, maintaining legacy formatting important for some organizational reports.

    Handling Queries with 'OR' Operators

    Queries containing logical OR operators behave differently depending on the execution mode:

    • In V2 mode, OR results are merged into single result items for faster processing.
    • In V1 mode, OR results are shown as separate items, preserving legacy formatting.

    ServiceNow provides the glide.cmdb.query.orexecutionmode system property to control the execution mode specifically for queries with OR conditions, enabling customers to choose between performance and legacy result format based on business requirements.

    Configuring Execution Modes

    Execution mode determination follows a hierarchy of settings:

    • Query-level setting: The Query Execution Mode attribute in the Saved Queries table overrides system-wide settings.
    • Global settings: The glide.cmdb.query.executionmode system property sets the default execution mode for all queries without a query-level setting.
    • OR-specific global setting: The glide.cmdb.query.orexecutionmode property overrides the global execution mode for queries containing OR conditions.

    Unsupported Query Structures for V2

    Some query types are not supported by the V2 engine and will automatically run in V1 mode, including:

    • Queries with filters containing related list conditions.
    • Queries where nodes have no relationships but filters include configuration item conditions (e.g., Server NOT connected to a Router where Router status is Active).
    • Service Mapping queries involving related edges or specific service query properties like Find Related CIs, Find Unrelated CIs, or Does Not Belong to Service.

    Decision Flow for Execution Mode Selection

    The system follows a decision process to select the execution mode for each query:

    1. Check the query-level setting; if set to V1 or V2, use that mode or proceed accordingly.
    2. If no query-level setting, check global system properties for default execution mode and OR-specific execution mode.
    3. If V2 mode is selected, verify if the query structure is supported by V2.
    4. If unsupported in V2, automatically fall back to V1 mode.

    The Query Execution Mode field in the Query Status table reflects the final execution mode assigned to each query, helping customers monitor query execution behavior.

    Practical Implications for ServiceNow Customers

    • Use V2 mode by default for improved performance in most scenarios.
    • Be aware that complex or specific query structures may require or automatically use V1 mode.
    • Configure the execution mode at the query level when specific result formats or legacy support is necessary, especially for queries with OR conditions.
    • Leverage system properties to set global defaults and control behavior for OR queries according to organizational needs.

    The CMDB Query Builder engine uses two execution modes to run queries. By default, the system is configured to use the enhanced mode V2 which is designed for performance optimization. V2 is supported for most queries and enables running complex queries significantly quicker and process larger result sets without performance degradation.

    The CMDB Query Builder can be set with the following engine execution modes for running queries:
    V2

    An enhanced query execution engine designed for improved performance and scalability. This is the default execution engine. In V2 mode, compared to V1 mode, the CMDB Query Builder engine is capable of running complex queries significantly quicker and process larger result sets without performance degradation.

    However, some query structures aren't supported for the V2 mode, in which case such queries will automatically run using the legacy mode (V1).

    V1
    Legacy execution engine which is used when the system is explicitly configured to use V1. This mode is also used even if the system is configured to run in V2 mode, to run queries with a structure that isn't supported for the V2 mode.

    Considerations for the 'OR' operator

    Setting the execution mode for queries that contain 'OR' operators, such as the sample query below, require some special considerations:

    Query with 'OR' structure

    Running a query with 'OR' structures can be significantly faster in V2 mode than in V1, but the results are presented differently between V1 and V2 execution modes. The difference is because 'OR' operator nodes generate coalesced and cross-product result sets. In V2 mode, related results are merged into a single result item. In V1, the same results are represented by separate result items.

    Figure 1. Results for a query with an 'OR' structure, in V1 execution mode
    'OR' results in V1 execution mode
    Figure 2. Results for a query with an 'OR' structure, in V2 execution mode
    'OR' results in V2 execution mode

    In some situations, it might be important to run a query with an 'OR' structure, using the V1 engine mode to retain the legacy format of the results in support of existing organizational reports. You can use the glide.cmdb.query.or_execution_mode system property as described below to control execution mode for queries with 'OR' structures.

    Settings

    The system uses the following settings of execution mode to determine which execution mode to use to run a query:
    • Query-level setting:

      The Query Execution Mode attribute in the Saved Queries [qb_saved_query] table sets the engine mode for the respective query. For more information about this setting, see Set execution mode for running a query.

      The query-level setting has precedence over system property settings.

    • Global setting:

      System property glide.cmdb.query.execution_mode sets the system-wide default mode to use when a query's mode isn't set at the query level.

    • Global setting:

      System property glide.cmdb.query.or_execution_mode sets the system-wide default execution engine mode for queries that contain at least one logical OR condition. Because the results of a query with an 'OR' structure are formatted differently between V1 and V2 mode, this property setting also affects which format is used for the results.

      This property has precedence over the glide.cmdb.query.execution_mode system property.

    For more information about the engine mode system properties, see Property settings for CMDB Query Builder.

    Unsupported query structures for V2 mode

    The following query structures aren't supported in V2 and therefore are executed using V1 mode even if the system is configured to use V2 mode:
    • Queries with filters containing related list conditions.

    • No relationships combined with a filter containing configuration item conditions: Node that has no relationships configured and the target node's filter has configuration item conditions.

      For example: Server NOT connected to Router WHERE Router.status = Active.

    • Service Mapping query with related edges (Applicative flow, Not Applicative flow, Belongs To, Not belongs to). Service Mapping query with service query properties set to Find Related CIs or Find Unrelated CIs, or a combination query in which a service query connection property is set to Does Not Belong to Service.

    Decision flow

    The system uses a decision flow that checks all relevant settings and the query structure to determine which execution mode to use for running a query. First, the system checks the query-level and the system-level settings. Then, if the settings are configured for using V2 to run a query, the system checks the query structure to determine if the V2 execution mode supports the query's structure. If the query contains a structure that isn't supported in V2, execution automatically falls back to using V1 mode even though the settings are configured to using V2. This automatic fallback mechanism supports a successful execution of all queries while maximizing performance benefits where possible.

    Using default settings, if a query structure is supported by the V2 execution mode, the query executes using V2 mode.

    The following decision flow examines settings and query structures, to determine whether a query runs in V1 or V2 engine execution mode:
    1. Check the setting in the Query Execution Mode attribute in the query record in the Saved Queries [qb_saved_query] table:
      • If 'V1': Use V1
      • If 'V2': Skip to step #4 — Perform V2 support check
      • If 'None': Check system properties as described in the next step
    2. Check system property glide.cmdb.query.execution_mode:
      • If not set: Use V2 pending support check
      • If 'V1': Use V1
      • If 'V2':
        • If no logical OR conditions: Skip to step #4 — Perform V2 support check
        • If one or more logical OR conditions: Perform 'OR'-specific check as described in the next step
    3. Check the value of glide.cmdb.query.or_execution_mode:
      • If 'V1': Use V1
      • If 'V2': Skip to step #4 — Perform V2 support check
      • If empty: Use V2
    4. Perform V2 support check:
      • If the query contains a structure that isn't supported in V2: Use V1
      • If query structure is supported in V2: Use V2

    The Query Execution Mode attribute in table Query Status [qb_query_status] shows the execution mode assigned to each query.