Struct PreparedQuery 

pub struct PreparedQuery {
    pub param_count: usize,
    /* private fields */
}

Mission C Phase 5: a pre-parsed, pre-planned query. The caller holds one of these and repeatedly executes it with fresh literal values via Engine::execute_prepared. This is PowDB’s equivalent of SQLite’s prepare_cached — the parse + plan cost is paid exactly once, and every subsequent execution skips the lexer, the canonicalise hash, and the plan-cache hashmap lookup.

The template plan still contains the literal values from the original query string. They’re overwritten on every call. See execute_prepared for the substitution walk order.

For PlanNode::Insert templates whose assignment values are all plain literals (the common case — insert T { id := 1, name := "a" }), we additionally resolve the column indices at prepare time and stash them in insert_col_indices. That lets execute_prepared skip the plan-clone + substitute walk entirely and build the row directly from the caller’s literal slice — the fastest possible insert through the query layer.

Fields

param_count: usize

Total number of Expr::Literal slots reachable from the plan. Callers must supply exactly this many literals per execution.

Trait Implementations

impl Clone for PreparedQuery

fn clone(&self) -> PreparedQuery

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.