FunctionChain

This struct describes a named sequence of operations applied to search results, attached to a search request through SearchRequestBuilder::function_chains.

pub struct FunctionChain

PARAMETERS:

• name: String

  Name of the chain.

• stage: FunctionChainStage

  Execution stage of the chain. Must not be Unspecified when used for search.

• ops: Vec<FunctionChainOp>

  Ordered operations in the chain. Must contain at least one operation.

METHODS:

• new() - Creates a value initialized with its SDK defaults.
• name(value) / set_name(value) / get_name() - Sets or returns the chain name.
• stage(value) / set_stage(value) / get_stage() - Sets or returns the execution stage.
• ops(value) / set_ops(value) / get_ops() - Sets or returns the ordered operations.
• add_op(op) - Appends a raw FunctionChainOp, for operations the fluent conveniences do not expose, such as filter or merge.
• map(output, expr) - Appends a map operation that writes an expression result to an output column.
• sort(by, desc, tie_break_col) - Appends a sort operation by a column, optionally with a tie-break column.
• limit(limit, offset) - Appends a limit operation with an optional offset.
• validate() - Validates that the chain can be attached to a search request.

FunctionChainStage

pub enum FunctionChainStage {
    Unspecified,
    Ingestion,
    PreProcess,
    L0Rerank,
    L1Rerank,
    L2Rerank,
    PostProcess,
}

• Unspecified - Unset stage; the default. Not supported for search.
• Ingestion - Stage applied during data ingestion.
• PreProcess - Stage applied before search.
• L0Rerank / L1Rerank / L2Rerank - Rerank stages at increasing levels.
• PostProcess - Stage applied after search.

FunctionChainArg

pub enum FunctionChainArg {
    Column(String),
    Literal(FunctionParamValue),
}

• Column(String) - References an input column by name.
• Literal(FunctionParamValue) - Carries a literal parameter value.

The helper function col(name) builds a FunctionChainArg::Column.

FunctionParamValue

pub enum FunctionParamValue {
    Bool(bool),
    Int(i64),
    Double(f64),
    String(String),
    Bytes(Vec<u8>),
    Array(Vec<FunctionParamValue>),
    Object(HashMap<String, FunctionParamValue>),
}

• Bool(bool) / Int(i64) / Double(f64) / String(String) / Bytes(Vec<u8>) - Scalar parameter values.
• Array(Vec<FunctionParamValue>) - An array of parameter values, built with FunctionParamValue::array(...).
• Object(HashMap<String, FunctionParamValue>) - A map of parameter values, built with FunctionParamValue::object(...).

FunctionParamValue implements From conversions for bool, integer, float, string, byte-slice, array, and object types.

FunctionChainExpr

This struct describes a named expression with arguments and parameters used by a map operation.

pub struct FunctionChainExpr

PARAMETERS:

• name: String

  Name of the expression, for example num_combine.

• args: Vec<FunctionChainArg>

  Expression arguments, either column references or literals.

• params: HashMap<String, FunctionParamValue>

  Expression parameters.

METHODS:

• new() - Creates a value initialized with its SDK defaults.
• name(value) / set_name(value) - Sets the expression name.
• args(value) / set_args(value) / add_arg(value) - Sets, returns, or appends expression arguments.
• params(value) / set_params(value) / add_param(key, value) - Sets, returns, or adds expression parameters.
• get_name() / get_args() / get_params() - Returns the configured values.

FunctionChainOp

This struct describes one operation in a function chain.

pub struct FunctionChainOp

PARAMETERS:

• op: String

  Operation name, such as map, sort, or limit.

• expr: Option<FunctionChainExpr>

  Expression attached to the operation, required for map.

• inputs: Vec<String>

  Input columns of the operation.

• outputs: Vec<String>

  Output columns of the operation.

• params: HashMap<String, FunctionParamValue>

  Operation parameters.

METHODS:

• new() - Creates a value initialized with its SDK defaults.
• op(value) / set_op(value) / get_op() - Sets or returns the operation name.
• expr(value) / set_expr(value) / get_expr() - Sets or returns the expression.
• inputs(value) / set_inputs(value) / add_input(value) - Sets, returns, or appends input columns.
• outputs(value) / set_outputs(value) / add_output(value) - Sets, returns, or appends output columns.
• params(value) / set_params(value) / add_param(key, value) - Sets, returns, or adds operation parameters.

Example

let chain = FunctionChain::new()
    .name("post_process")
    .stage(FunctionChainStage::PostProcess)
    .map("score_boosted", FunctionChainExpr::new().name("num_combine").add_arg(col("score")).add_param("weight", 1.5))
    .limit(5, 0);