Struct PgEngine 

pub struct PgEngine { /* private fields */ }

PostgreSQL query engine that implements the Prax QueryEngine trait.

Two modes, controlled by the tx_conn field:

• Pool mode (tx_conn == None, the default): each query acquires a fresh connection from PgPool and drops it after the call.
• Transaction mode (tx_conn == Some(conn)): each query routes through the single pinned deadpool_postgres::Object. The tx-bound engine is built by PgEngine::transaction, which issues a raw BEGIN; the outer future then runs COMMIT or ROLLBACK on the same connection based on the closure’s Ok / Err result.

We lean on raw BEGIN / COMMIT / ROLLBACK strings instead of tokio_postgres::Transaction<'_> because Transaction<'_> borrows from its owning Client, and bundling both into a heap cell requires mem::transmute gymnastics to launder the lifetime to 'static. Since Object implements Deref<Target = Client> and Client::query / execute take &self, an Arc<Object> is all we need — every engine clone can share it freely, and the last clone drops the Arc, which drops the Object back to the pool. This path is explicitly sanctioned by the task plan’s “fall back” guardrail.

Implementations

impl PgEngine

pub fn new(pool: PgPool) -> Self

Create a new PostgreSQL engine with the given connection pool.

pub fn pool(&self) -> &PgPool

Get a reference to the connection pool.

Trait Implementations

impl Clone for PgEngine

fn clone(&self) -> PgEngine

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl QueryEngine for PgEngine

fn dialect(&self) -> &dyn SqlDialect

The SQL dialect this engine targets.

fn query_many<T: Model + FromRow + Send + 'static>( &self, sql: &str, params: Vec<FilterValue>, ) -> BoxFuture<'_, QueryResult<Vec<T>>>

Execute a SELECT query and return rows.

fn query_one<T: Model + FromRow + Send + 'static>( &self, sql: &str, params: Vec<FilterValue>, ) -> BoxFuture<'_, QueryResult<T>>

Execute a SELECT query expecting one result.

fn query_optional<T: Model + FromRow + Send + 'static>( &self, sql: &str, params: Vec<FilterValue>, ) -> BoxFuture<'_, QueryResult<Option<T>>>

Execute a SELECT query expecting zero or one result.

fn execute_insert<T: Model + FromRow + Send + 'static>( &self, sql: &str, params: Vec<FilterValue>, ) -> BoxFuture<'_, QueryResult<T>>

Execute an INSERT query and return the created row.

fn execute_update<T: Model + FromRow + Send + 'static>( &self, sql: &str, params: Vec<FilterValue>, ) -> BoxFuture<'_, QueryResult<Vec<T>>>

Execute an UPDATE query and return affected rows.

fn execute_delete( &self, sql: &str, params: Vec<FilterValue>, ) -> BoxFuture<'_, QueryResult<u64>>

Execute a DELETE query and return affected rows count.

fn execute_raw( &self, sql: &str, params: Vec<FilterValue>, ) -> BoxFuture<'_, QueryResult<u64>>

Execute a raw SQL query.

fn count( &self, sql: &str, params: Vec<FilterValue>, ) -> BoxFuture<'_, QueryResult<u64>>

Get a count of records.

fn aggregate_query( &self, sql: &str, params: Vec<FilterValue>, ) -> BoxFuture<'_, QueryResult<Vec<HashMap<String, FilterValue>>>>

Execute an aggregate query (COUNT/SUM/AVG/MIN/MAX/GROUP BY) and return one map of column name → crate::filter::FilterValue per result row.

fn transaction<'a, R, Fut, F>(&'a self, f: F) -> BoxFuture<'a, QueryResult<R>>

where F: FnOnce(Self) -> Fut + Send + 'a, Fut: Future<Output = QueryResult<R>> + Send + 'a, R: Send + 'a, Self: Clone,

Run the closure inside a transaction.

fn refresh_materialized_view( &self, view_name: &str, concurrently: bool, ) -> Pin<Box<dyn Future<Output = Result<(), QueryError>> + Send + '_>>

Refresh a materialized view.