# Execution Strategy Execution strategy allows you to change the outcome produced by the rule solver. \ There are several options for the execution strategy described below. ## How to Set Execution Strategy You can set the execution strategy in two ways: * [**Solver API**](/doc/api/rule-solver-api.md) → by adding the appropriate HTTP header. * [**Test Bench**](/doc/rules/common-rule-features/test-bench.md) → select the strategy from the dropdown.

Options for Decision Table

Options for Lookup Table

## Allowed Strategies per Rule Type | Rule Type | Allowed Strategies | | -------------------------------- | ------------------------------------------ | | Decision Table | Standard, Array, First Match, Evaluate All | | Decision Tree | Standard, Array | | Scripting Rule | Standard, Array | | Rule Flow | Standard, Array | | Decision Flow + Integration Flow | Standard | | Lookup Table | Lookup Exists, Lookup Value | ## Setting Strategy via API ### Standard Rules Header For all rule types except Lookup Tables, use the `X-Strategy` header to set the execution strategy: | HTTP Header | Possible value | | ----------- | -------------- | | X-Strategy | STANDARD | | X-Strategy | ARRAY | | X-Strategy | FIRST\_MATCH | | X-Strategy | EVALUATE\_ALL | {% hint style="warning" %} If the header is not specified or contains an invalid strategy, the system automatically uses the **STANDARD** strategy. {% endhint %} ### Lookup Table Header Lookup Tables use a dedicated header `X-Lookup-Method` instead of `X-Strategy` : | HTTP Header | Possible value | | --------------- | -------------- | | X-Lookup-Method | LOOKUP\_VALUE | | X-Lookup-Method | LOOKUP\_EXISTS | {% hint style="warning" %} If the header is not specified, the system automatically uses the **LOOKUP\_VALUE** strategy. {% endhint %} ## Strategy Behavior ### Standard Returns all matching rows in the same order as they appear in the rule. If 2 rows are matching the input, the output will contain all matching rows: ```json [ { "client": { "segment": "affluent" }, "profitability": 1 }, { "client": { "segment": "top affluent" }, "profitability": 1.6 } ] ``` #### **Useful for:** * Getting all possible matches for a given input. * Scenarios where multiple rules can apply simultaneously. ### First Match Returns only the first matching row from the rule. Evaluation stops after the first match is found. If 2 rows are matching the input, only the first match is returned: ```json { "client": { "segment": "affluent" }, "profitability": 1 } ``` #### **Useful for:** * Priority-based rules where order matters. * Decision scenarios where only one outcome should apply. {% hint style="info" %} Available for **Decision Tables only**. {% endhint %} ### Array Returns all matching outputs merged into a single object where each output field contains an array of all matched values. If 2 rows are matching the input, the outputs are returned in array format: ```json { "client": { "segment": [ "affluent", "top affluent" ] }, "profitability": [ 1, 1.6 ] } ``` #### **Useful for:** * Aggregating multiple matching results into a single response. * Building lists of applicable values from multiple matches. ### Evaluate All Returns a result for every row in the table regardless of whether it matched or not. Each result includes a `_match` field indicating whether that row was satisfied by the input. ```json [ { "client": { "segment": "affluent" }, "profitability": 1, "_match": true }, { "client": { "segment": "top affluent" }, "profitability": 1.6, "_match": false } ] ``` #### **Useful for:** * Auditing and compliance - see which rules applied and which didn't. * Debugging complex tables with many conditions. * Satisfiability analysis across all rows - table has N rows, the response will contain N objects. {% hint style="info" %} Available for **Decision Tables only**. {% endhint %} ### **Lookup Value** Returns the value found in the Lookup Table that match the input. This is the standard way to retrieve data from a Lookup Table. ```json { "output": "value 1" } // Can return entire row if no column is specified: { "output": { "Primary Key": "inputKey", "column 1": "value 1", "column 2": "value 2" } } ``` #### **Useful for:** * Retrieving actual data stored in the Lookup Table. * Any scenario where you need the actual stored value. For detailed information with examples see Lookup [Value function](/doc/rules/lookup-table/using-lookup-tables-in-rules.md#lookup_value). {% hint style="info" %} Available for **Lookup Table only**. {% endhint %} ### **Lookup Exists** Returns a boolean indicating whether a matching record exists in the Lookup Table, without returning the actual value. ```json { "output": true } ``` #### **Useful for:** * Validating if a value is in an allowed list. * Checking membership (e.g., is this customer in the VIP list?). * Input validation before processing. * Blacklist/whitelist verification. For detailed information with examples see [Lookup Exist function](/doc/rules/lookup-table/using-lookup-tables-in-rules.md#lookup_exists). {% hint style="info" %} Available for **Lookup Table only**. {% endhint %} --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://docs.decisionrules.io/doc/rules/common-rule-features/execution-strategy.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.