Trait StatementCacheStrategy

pub trait StatementCacheStrategy<DB, Statement>
where
    DB: Backend,
    StatementCacheKey<DB>: Hash + Eq,
{
    // Required methods
    fn cache_size(&self) -> CacheSize;
    fn get(
        &mut self,
        key: StatementCacheKey<DB>,
        backend: &DB,
        source: &dyn QueryFragmentForCachedStatement<DB>,
        prepare_fn: &mut dyn FnMut(&str, bool) -> Result<Statement, Error>,
    ) -> Result<MaybeCached<'_, Statement>, Error>;
}

Available on crate feature i-implement-a-third-party-backend-and-opt-into-breaking-changes only.

Implement this trait, in order to control statement caching.

Required Methods

fn cache_size(&self) -> CacheSize

Returns which prepared statement cache size is implemented by this trait

fn get( &mut self, key: StatementCacheKey<DB>, backend: &DB, source: &dyn QueryFragmentForCachedStatement<DB>, prepare_fn: &mut dyn FnMut(&str, bool) -> Result<Statement, Error>, ) -> Result<MaybeCached<'_, Statement>, Error>

Every query (which is safe to cache) will go through this function The implementation will decide whether to cache statement or not

• prepare_fn - will be invoked if prepared statement wasn’t cached already
  • first argument is sql query string
  • second argument specifies whether statement will be cached (true) or not (false).

Implementors

impl<DB, Statement> StatementCacheStrategy<DB, Statement> for WithCacheStrategy<DB, Statement>

where DB: Backend, StatementCacheKey<DB>: Hash + Eq, DB::TypeMetadata: Clone, DB::QueryBuilder: Default,

impl<DB, Statement> StatementCacheStrategy<DB, Statement> for WithoutCacheStrategy

where DB: Backend, StatementCacheKey<DB>: Hash + Eq, DB::TypeMetadata: Clone, DB::QueryBuilder: Default,