Struct Reducer

pub struct Reducer {
    transforms: Vec<Box<dyn Transform>>,
    checker: Checker,
    strategy: Strategy,
}

Fields

transforms: Vec<Box<dyn Transform>>

checker: Checker

strategy: Strategy

Implementations

impl Reducer

pub fn new(checker: Checker, strategy: Strategy) -> Self

pub async fn reduce(&mut self, sql: &str) -> Result<String>

Perform reduction on a SQL input containing multiple statements, where only the last statement is considered the failing one.

The reducer:

1. Executes all preceding statements using the checker client.
2. Verifies that the last statement indeed fails (self-check).
3. Applies transformation passes to simplify the failing query while preserving the failure behavior.
4. Returns the reduced failing SQL query as a string.

Arguments

• sql: A SQL script with multiple statements (e.g., setup + failing query).

Returns

• A simplified version of the last statement that still fails in the same way.
• The preceding statements are also returned as a string.

Errors

• Returns an error if SQL parsing fails or if no statements are found.
• Panics if the checker fails to validate failure preservation on the original failing query.

async fn reduce_until_fixed_point(&mut self, sql: &str) -> String

Apply all transformations in a fixed-point loop until no further reduction is possible.

For each transformation:

• Iterate over all applicable reduction points.
• If a smaller version of the query is found and passes the failure check, accept it and continue from that point.

The process continues until a global fixed point is reached (i.e., no transformation makes progress on any part of the SQL).

Arguments

• sql: The SQL string (usually the failing query) to reduce.

Returns

• A reduced SQL string (still failing) that is minimized w.r.t the current passes.