Struct headless_lms_server::prelude::Postgres

pub struct Postgres;

PostgreSQL database driver.

Trait Implementations

impl Database for Postgres

type Connection = PgConnection

The concrete Connection implementation for this database.

type TransactionManager = PgTransactionManager

The concrete TransactionManager implementation for this database.

type Row = PgRow

The concrete Row implementation for this database.

type QueryResult = PgQueryResult

The concrete QueryResult implementation for this database.

type Column = PgColumn

The concrete Column implementation for this database.

type TypeInfo = PgTypeInfo

The concrete TypeInfo implementation for this database.

type Value = PgValue

The concrete type used to hold an owned copy of the not-yet-decoded value that was received from the database.

const NAME: &'static str = "PostgreSQL"

The display name for this database driver.

const URL_SCHEMES: &'static [&'static str] = _

The schemes for database URLs that should match this driver.

impl Debug for Postgres

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl Decode<'_, Postgres> for Box<[u8]>

fn decode( value: PgValueRef<'_> ) -> Result<Box<[u8]>, Box<dyn Error + Send + Sync>>

Decode a new value of this type using a raw value from the database.

impl Decode<'_, Postgres> for String

fn decode(value: PgValueRef<'_>) -> Result<String, Box<dyn Error + Send + Sync>>

Decode a new value of this type using a raw value from the database.

impl Decode<'_, Postgres> for Uuid

fn decode(value: PgValueRef<'_>) -> Result<Uuid, Box<dyn Error + Send + Sync>>

Decode a new value of this type using a raw value from the database.

impl Decode<'_, Postgres> for Vec<u8>

fn decode( value: PgValueRef<'_> ) -> Result<Vec<u8>, Box<dyn Error + Send + Sync>>

Decode a new value of this type using a raw value from the database.

impl<'r> Decode<'r, Postgres> for &'r [u8]

fn decode( value: PgValueRef<'r> ) -> Result<&'r [u8], Box<dyn Error + Send + Sync>>

Decode a new value of this type using a raw value from the database.

impl<'r> Decode<'r, Postgres> for &'r str

fn decode( value: PgValueRef<'r> ) -> Result<&'r str, Box<dyn Error + Send + Sync>>

Decode a new value of this type using a raw value from the database.

impl<'r> Decode<'r, Postgres> for Box<str>

fn decode( value: PgValueRef<'r> ) -> Result<Box<str>, Box<dyn Error + Send + Sync>>

Decode a new value of this type using a raw value from the database.

impl<'r, T> Decode<'r, Postgres> for Vec<T>

where T: for<'a> Decode<'a, Postgres> + Type<Postgres>,

fn decode(value: PgValueRef<'r>) -> Result<Vec<T>, Box<dyn Error + Send + Sync>>

Decode a new value of this type using a raw value from the database.

impl Encode<'_, Postgres> for &[u8]

fn encode_by_ref(&self, buf: &mut PgArgumentBuffer) -> IsNull

Writes the value of self into buf without moving self.

fn encode(self, buf: &mut <DB as HasArguments<'q>>::ArgumentBuffer) -> IsNull

where Self: Sized,

Writes the value of self into buf in the expected format for the database.

fn produces(&self) -> Option<<DB as Database>::TypeInfo>

fn size_hint(&self) -> usize

impl Encode<'_, Postgres> for &str

fn encode_by_ref(&self, buf: &mut PgArgumentBuffer) -> IsNull

Writes the value of self into buf without moving self.

fn encode(self, buf: &mut <DB as HasArguments<'q>>::ArgumentBuffer) -> IsNull

where Self: Sized,

Writes the value of self into buf in the expected format for the database.

fn produces(&self) -> Option<<DB as Database>::TypeInfo>

fn size_hint(&self) -> usize

impl Encode<'_, Postgres> for Box<[u8]>

fn encode_by_ref(&self, buf: &mut PgArgumentBuffer) -> IsNull

Writes the value of self into buf without moving self.

fn encode(self, buf: &mut <DB as HasArguments<'q>>::ArgumentBuffer) -> IsNull

where Self: Sized,

Writes the value of self into buf in the expected format for the database.

fn produces(&self) -> Option<<DB as Database>::TypeInfo>

fn size_hint(&self) -> usize

impl Encode<'_, Postgres> for Box<str>

fn encode_by_ref(&self, buf: &mut PgArgumentBuffer) -> IsNull

Writes the value of self into buf without moving self.

fn encode(self, buf: &mut <DB as HasArguments<'q>>::ArgumentBuffer) -> IsNull

where Self: Sized,

Writes the value of self into buf in the expected format for the database.

fn produces(&self) -> Option<<DB as Database>::TypeInfo>

fn size_hint(&self) -> usize

impl Encode<'_, Postgres> for String

fn encode_by_ref(&self, buf: &mut PgArgumentBuffer) -> IsNull

Writes the value of self into buf without moving self.

fn encode(self, buf: &mut <DB as HasArguments<'q>>::ArgumentBuffer) -> IsNull

where Self: Sized,

Writes the value of self into buf in the expected format for the database.

fn produces(&self) -> Option<<DB as Database>::TypeInfo>

fn size_hint(&self) -> usize

impl Encode<'_, Postgres> for Uuid

fn encode_by_ref(&self, buf: &mut PgArgumentBuffer) -> IsNull

Writes the value of self into buf without moving self.

fn encode(self, buf: &mut <DB as HasArguments<'q>>::ArgumentBuffer) -> IsNull

where Self: Sized,

Writes the value of self into buf in the expected format for the database.

fn produces(&self) -> Option<<DB as Database>::TypeInfo>

fn size_hint(&self) -> usize

impl Encode<'_, Postgres> for Vec<u8>

fn encode_by_ref(&self, buf: &mut PgArgumentBuffer) -> IsNull

Writes the value of self into buf without moving self.

fn encode(self, buf: &mut <DB as HasArguments<'q>>::ArgumentBuffer) -> IsNull

where Self: Sized,

Writes the value of self into buf in the expected format for the database.

fn produces(&self) -> Option<<DB as Database>::TypeInfo>

fn size_hint(&self) -> usize

impl<'q, T> Encode<'q, Postgres> for &[T]

where T: Encode<'q, Postgres> + Type<Postgres>,

fn encode_by_ref(&self, buf: &mut PgArgumentBuffer) -> IsNull

Writes the value of self into buf without moving self.

fn encode(self, buf: &mut <DB as HasArguments<'q>>::ArgumentBuffer) -> IsNull

where Self: Sized,

Writes the value of self into buf in the expected format for the database.

fn produces(&self) -> Option<<DB as Database>::TypeInfo>

fn size_hint(&self) -> usize

impl<'q, T> Encode<'q, Postgres> for Vec<T>

where &'a [T]: for<'a> Encode<'q, Postgres>, T: Encode<'q, Postgres>,

fn encode_by_ref(&self, buf: &mut PgArgumentBuffer) -> IsNull

Writes the value of self into buf without moving self.

fn encode(self, buf: &mut <DB as HasArguments<'q>>::ArgumentBuffer) -> IsNull

where Self: Sized,

Writes the value of self into buf in the expected format for the database.

fn produces(&self) -> Option<<DB as Database>::TypeInfo>

fn size_hint(&self) -> usize

impl HasArguments<'_> for Postgres

type Database = Postgres

type Arguments = PgArguments

The concrete Arguments implementation for this database.

type ArgumentBuffer = PgArgumentBuffer

The concrete type used as a buffer for arguments while encoding.

impl<'q> HasStatement<'q> for Postgres

type Database = Postgres

type Statement = PgStatement<'q>

The concrete Statement implementation for this database.

impl<'r> HasValueRef<'r> for Postgres

type Database = Postgres

type ValueRef = PgValueRef<'r>

The concrete type used to hold a reference to the not-yet-decoded value that has just been received from the database.

impl MigrateDatabase for Postgres

fn create_database( url: &str ) -> Pin<Box<dyn Future<Output = Result<(), Error>> + Send + '_>>

fn database_exists( url: &str ) -> Pin<Box<dyn Future<Output = Result<bool, Error>> + Send + '_>>

fn drop_database( url: &str ) -> Pin<Box<dyn Future<Output = Result<(), Error>> + Send + '_>>

fn force_drop_database( url: &str ) -> Pin<Box<dyn Future<Output = Result<(), Error>> + Send + '_>>

impl TestSupport for Postgres

fn test_context( args: &TestArgs ) -> Pin<Box<dyn Future<Output = Result<TestContext<Postgres>, Error>> + Send + '_>>

Get parameters to construct a Pool suitable for testing.

fn cleanup_test( db_name: &str ) -> Pin<Box<dyn Future<Output = Result<(), Error>> + Send + '_>>

fn cleanup_test_dbs( ) -> Pin<Box<dyn Future<Output = Result<Option<usize>, Error>> + Send>>

Cleanup any test databases that are no longer in-use.

fn snapshot( _conn: &mut <Postgres as Database>::Connection ) -> Pin<Box<dyn Future<Output = Result<FixtureSnapshot<Postgres>, Error>> + Send + '_>>

Take a snapshot of the current state of the database (data only).

impl<T> Type<Postgres> for [T]

where T: PgHasArrayType,

fn type_info() -> PgTypeInfo

Returns the canonical SQL type for this Rust type.

fn compatible(ty: &PgTypeInfo) -> bool

Determines if this Rust type is compatible with the given SQL type.

impl<T, const N: usize> Type<Postgres> for [T; N]

where T: PgHasArrayType,

fn type_info() -> PgTypeInfo

Returns the canonical SQL type for this Rust type.

fn compatible(ty: &PgTypeInfo) -> bool

Determines if this Rust type is compatible with the given SQL type.

impl Type<Postgres> for ()

fn type_info() -> PgTypeInfo

Returns the canonical SQL type for this Rust type.

fn compatible(ty: &PgTypeInfo) -> bool

Determines if this Rust type is compatible with the given SQL type.

impl<T1> Type<Postgres> for (T1,)

fn type_info() -> PgTypeInfo

Returns the canonical SQL type for this Rust type.

fn compatible(ty: &<DB as Database>::TypeInfo) -> bool

Determines if this Rust type is compatible with the given SQL type.

impl<T1, T2> Type<Postgres> for (T1, T2)

fn type_info() -> PgTypeInfo

Returns the canonical SQL type for this Rust type.

fn compatible(ty: &<DB as Database>::TypeInfo) -> bool

Determines if this Rust type is compatible with the given SQL type.

impl<T1, T2, T3> Type<Postgres> for (T1, T2, T3)

fn type_info() -> PgTypeInfo

Returns the canonical SQL type for this Rust type.

fn compatible(ty: &<DB as Database>::TypeInfo) -> bool

Determines if this Rust type is compatible with the given SQL type.

impl<T1, T2, T3, T4> Type<Postgres> for (T1, T2, T3, T4)

fn type_info() -> PgTypeInfo

Returns the canonical SQL type for this Rust type.

fn compatible(ty: &<DB as Database>::TypeInfo) -> bool

Determines if this Rust type is compatible with the given SQL type.

impl<T1, T2, T3, T4, T5> Type<Postgres> for (T1, T2, T3, T4, T5)

fn type_info() -> PgTypeInfo

Returns the canonical SQL type for this Rust type.

fn compatible(ty: &<DB as Database>::TypeInfo) -> bool

Determines if this Rust type is compatible with the given SQL type.

impl<T1, T2, T3, T4, T5, T6> Type<Postgres> for (T1, T2, T3, T4, T5, T6)

fn type_info() -> PgTypeInfo

Returns the canonical SQL type for this Rust type.

fn compatible(ty: &<DB as Database>::TypeInfo) -> bool

Determines if this Rust type is compatible with the given SQL type.

impl<T1, T2, T3, T4, T5, T6, T7> Type<Postgres> for (T1, T2, T3, T4, T5, T6, T7)

fn type_info() -> PgTypeInfo

Returns the canonical SQL type for this Rust type.

fn compatible(ty: &<DB as Database>::TypeInfo) -> bool

Determines if this Rust type is compatible with the given SQL type.

impl<T1, T2, T3, T4, T5, T6, T7, T8> Type<Postgres> for (T1, T2, T3, T4, T5, T6, T7, T8)

fn type_info() -> PgTypeInfo

Returns the canonical SQL type for this Rust type.

fn compatible(ty: &<DB as Database>::TypeInfo) -> bool

Determines if this Rust type is compatible with the given SQL type.

impl<T1, T2, T3, T4, T5, T6, T7, T8, T9> Type<Postgres> for (T1, T2, T3, T4, T5, T6, T7, T8, T9)

fn type_info() -> PgTypeInfo

Returns the canonical SQL type for this Rust type.

fn compatible(ty: &<DB as Database>::TypeInfo) -> bool

Determines if this Rust type is compatible with the given SQL type.

impl Type<Postgres> for ActivityProgress

fn type_info() -> PgTypeInfo

Returns the canonical SQL type for this Rust type.

fn compatible(ty: &<DB as Database>::TypeInfo) -> bool

Determines if this Rust type is compatible with the given SQL type.

impl Type<Postgres> for Box<str>

fn type_info() -> PgTypeInfo

Returns the canonical SQL type for this Rust type.

fn compatible(ty: &PgTypeInfo) -> bool

Determines if this Rust type is compatible with the given SQL type.

impl Type<Postgres> for CertificateTextAnchor

fn type_info() -> PgTypeInfo

Returns the canonical SQL type for this Rust type.

fn compatible(ty: &<DB as Database>::TypeInfo) -> bool

Determines if this Rust type is compatible with the given SQL type.

impl Type<Postgres> for CourseBackgroundQuestionType

fn type_info() -> PgTypeInfo

Returns the canonical SQL type for this Rust type.

fn compatible(ty: &<DB as Database>::TypeInfo) -> bool

Determines if this Rust type is compatible with the given SQL type.

impl Type<Postgres> for Cow<'_, str>

fn type_info() -> PgTypeInfo

Returns the canonical SQL type for this Rust type.

fn compatible(ty: &PgTypeInfo) -> bool

Determines if this Rust type is compatible with the given SQL type.

impl<Tz> Type<Postgres> for DateTime<Tz>

where Tz: TimeZone,

fn type_info() -> PgTypeInfo

Returns the canonical SQL type for this Rust type.

fn compatible(ty: &<DB as Database>::TypeInfo) -> bool

Determines if this Rust type is compatible with the given SQL type.

impl Type<Postgres> for Duration

fn type_info() -> PgTypeInfo

Returns the canonical SQL type for this Rust type.

fn compatible(ty: &<DB as Database>::TypeInfo) -> bool

Determines if this Rust type is compatible with the given SQL type.

impl Type<Postgres> for ExerciseRepositoryStatus

fn type_info() -> PgTypeInfo

Returns the canonical SQL type for this Rust type.

fn compatible(ty: &<DB as Database>::TypeInfo) -> bool

Determines if this Rust type is compatible with the given SQL type.

impl Type<Postgres> for GradingProgress

fn type_info() -> PgTypeInfo

Returns the canonical SQL type for this Rust type.

fn compatible(ty: &<DB as Database>::TypeInfo) -> bool

Determines if this Rust type is compatible with the given SQL type.

impl Type<Postgres> for HistoryChangeReason

fn type_info() -> PgTypeInfo

Returns the canonical SQL type for this Rust type.

fn compatible(ty: &<DB as Database>::TypeInfo) -> bool

Determines if this Rust type is compatible with the given SQL type.

impl<T> Type<Postgres> for Json<T>

fn type_info() -> PgTypeInfo

Returns the canonical SQL type for this Rust type.

fn compatible(ty: &PgTypeInfo) -> bool

Determines if this Rust type is compatible with the given SQL type.

impl Type<Postgres> for NaiveDate

fn type_info() -> PgTypeInfo

Returns the canonical SQL type for this Rust type.

fn compatible(ty: &<DB as Database>::TypeInfo) -> bool

Determines if this Rust type is compatible with the given SQL type.

impl Type<Postgres> for NaiveDateTime

fn type_info() -> PgTypeInfo

Returns the canonical SQL type for this Rust type.

fn compatible(ty: &<DB as Database>::TypeInfo) -> bool

Determines if this Rust type is compatible with the given SQL type.

impl Type<Postgres> for NaiveTime

fn type_info() -> PgTypeInfo

Returns the canonical SQL type for this Rust type.

fn compatible(ty: &<DB as Database>::TypeInfo) -> bool

Determines if this Rust type is compatible with the given SQL type.

impl Type<Postgres> for Oid

fn type_info() -> PgTypeInfo

Returns the canonical SQL type for this Rust type.

fn compatible(ty: &<DB as Database>::TypeInfo) -> bool

Determines if this Rust type is compatible with the given SQL type.

impl Type<Postgres> for PaperSize

fn type_info() -> PgTypeInfo

Returns the canonical SQL type for this Rust type.

fn compatible(ty: &<DB as Database>::TypeInfo) -> bool

Determines if this Rust type is compatible with the given SQL type.

impl Type<Postgres> for PeerOrSelfReviewQuestionType

fn type_info() -> PgTypeInfo

Returns the canonical SQL type for this Rust type.

fn compatible(ty: &<DB as Database>::TypeInfo) -> bool

Determines if this Rust type is compatible with the given SQL type.

impl Type<Postgres> for PeerReviewProcessingStrategy

fn type_info() -> PgTypeInfo

Returns the canonical SQL type for this Rust type.

fn compatible(ty: &<DB as Database>::TypeInfo) -> bool

Determines if this Rust type is compatible with the given SQL type.

impl Type<Postgres> for PgCiText

fn type_info() -> PgTypeInfo

Returns the canonical SQL type for this Rust type.

fn compatible(ty: &PgTypeInfo) -> bool

Determines if this Rust type is compatible with the given SQL type.

impl Type<Postgres> for PgInterval

fn type_info() -> PgTypeInfo

Returns the canonical SQL type for this Rust type.

fn compatible(ty: &<DB as Database>::TypeInfo) -> bool

Determines if this Rust type is compatible with the given SQL type.

impl Type<Postgres> for PgLQuery

fn type_info() -> PgTypeInfo

Returns the canonical SQL type for this Rust type.

fn compatible(ty: &<DB as Database>::TypeInfo) -> bool

Determines if this Rust type is compatible with the given SQL type.

impl Type<Postgres> for PgLTree

fn type_info() -> PgTypeInfo

Returns the canonical SQL type for this Rust type.

fn compatible(ty: &<DB as Database>::TypeInfo) -> bool

Determines if this Rust type is compatible with the given SQL type.

impl Type<Postgres> for PgMoney

fn type_info() -> PgTypeInfo

Returns the canonical SQL type for this Rust type.

fn compatible(ty: &<DB as Database>::TypeInfo) -> bool

Determines if this Rust type is compatible with the given SQL type.

impl<Tz> Type<Postgres> for PgRange<DateTime<Tz>>

where Tz: TimeZone,

fn type_info() -> PgTypeInfo

Returns the canonical SQL type for this Rust type.

fn compatible(ty: &PgTypeInfo) -> bool

Determines if this Rust type is compatible with the given SQL type.

impl Type<Postgres> for PgRange<NaiveDate>

fn type_info() -> PgTypeInfo

Returns the canonical SQL type for this Rust type.

fn compatible(ty: &PgTypeInfo) -> bool

Determines if this Rust type is compatible with the given SQL type.

impl Type<Postgres> for PgRange<NaiveDateTime>

fn type_info() -> PgTypeInfo

Returns the canonical SQL type for this Rust type.

fn compatible(ty: &PgTypeInfo) -> bool

Determines if this Rust type is compatible with the given SQL type.

impl Type<Postgres> for PgRange<i32>

fn type_info() -> PgTypeInfo

Returns the canonical SQL type for this Rust type.

fn compatible(ty: &PgTypeInfo) -> bool

Determines if this Rust type is compatible with the given SQL type.

impl Type<Postgres> for PgRange<i64>

fn type_info() -> PgTypeInfo

Returns the canonical SQL type for this Rust type.

fn compatible(ty: &PgTypeInfo) -> bool

Determines if this Rust type is compatible with the given SQL type.

impl Type<Postgres> for PgTimeTz

fn type_info() -> PgTypeInfo

Returns the canonical SQL type for this Rust type.

fn compatible(ty: &<DB as Database>::TypeInfo) -> bool

Determines if this Rust type is compatible with the given SQL type.

impl Type<Postgres> for ProposalStatus

fn type_info() -> PgTypeInfo

Returns the canonical SQL type for this Rust type.

fn compatible(ty: &<DB as Database>::TypeInfo) -> bool

Determines if this Rust type is compatible with the given SQL type.

impl Type<Postgres> for ReviewingStage

fn type_info() -> PgTypeInfo

Returns the canonical SQL type for this Rust type.

fn compatible(ty: &<DB as Database>::TypeInfo) -> bool

Determines if this Rust type is compatible with the given SQL type.

impl Type<Postgres> for String

fn type_info() -> PgTypeInfo

Returns the canonical SQL type for this Rust type.

fn compatible(ty: &PgTypeInfo) -> bool

Determines if this Rust type is compatible with the given SQL type.

impl Type<Postgres> for TeacherDecisionType

fn type_info() -> PgTypeInfo

Returns the canonical SQL type for this Rust type.

fn compatible(ty: &<DB as Database>::TypeInfo) -> bool

Determines if this Rust type is compatible with the given SQL type.

impl<T> Type<Postgres> for Text<T>

fn type_info() -> PgTypeInfo

Returns the canonical SQL type for this Rust type.

fn compatible(ty: &PgTypeInfo) -> bool

Determines if this Rust type is compatible with the given SQL type.

impl Type<Postgres> for TimeDelta

fn type_info() -> PgTypeInfo

Returns the canonical SQL type for this Rust type.

fn compatible(ty: &<DB as Database>::TypeInfo) -> bool

Determines if this Rust type is compatible with the given SQL type.

impl Type<Postgres> for UserPointsUpdateStrategy

fn type_info() -> PgTypeInfo

Returns the canonical SQL type for this Rust type.

fn compatible(ty: &<DB as Database>::TypeInfo) -> bool

Determines if this Rust type is compatible with the given SQL type.

impl Type<Postgres> for UserRole

fn type_info() -> PgTypeInfo

Returns the canonical SQL type for this Rust type.

fn compatible(ty: &<DB as Database>::TypeInfo) -> bool

Determines if this Rust type is compatible with the given SQL type.

impl Type<Postgres> for Uuid

fn type_info() -> PgTypeInfo

Returns the canonical SQL type for this Rust type.

fn compatible(ty: &<DB as Database>::TypeInfo) -> bool

Determines if this Rust type is compatible with the given SQL type.

impl<T> Type<Postgres> for Vec<T>

where T: PgHasArrayType,

fn type_info() -> PgTypeInfo

Returns the canonical SQL type for this Rust type.

fn compatible(ty: &PgTypeInfo) -> bool

Determines if this Rust type is compatible with the given SQL type.

impl Type<Postgres> for bool

fn type_info() -> PgTypeInfo

Returns the canonical SQL type for this Rust type.

fn compatible(ty: &<DB as Database>::TypeInfo) -> bool

Determines if this Rust type is compatible with the given SQL type.

impl Type<Postgres> for f32

fn type_info() -> PgTypeInfo

Returns the canonical SQL type for this Rust type.

fn compatible(ty: &<DB as Database>::TypeInfo) -> bool

Determines if this Rust type is compatible with the given SQL type.

impl Type<Postgres> for f64

fn type_info() -> PgTypeInfo

Returns the canonical SQL type for this Rust type.

fn compatible(ty: &<DB as Database>::TypeInfo) -> bool

Determines if this Rust type is compatible with the given SQL type.

impl Type<Postgres> for i16

fn type_info() -> PgTypeInfo

Returns the canonical SQL type for this Rust type.

fn compatible(ty: &<DB as Database>::TypeInfo) -> bool

Determines if this Rust type is compatible with the given SQL type.

impl Type<Postgres> for i32

fn type_info() -> PgTypeInfo

Returns the canonical SQL type for this Rust type.

fn compatible(ty: &<DB as Database>::TypeInfo) -> bool

Determines if this Rust type is compatible with the given SQL type.

impl Type<Postgres> for i64

fn type_info() -> PgTypeInfo

Returns the canonical SQL type for this Rust type.

fn compatible(ty: &<DB as Database>::TypeInfo) -> bool

Determines if this Rust type is compatible with the given SQL type.

impl Type<Postgres> for i8

fn type_info() -> PgTypeInfo

Returns the canonical SQL type for this Rust type.

fn compatible(ty: &<DB as Database>::TypeInfo) -> bool

Determines if this Rust type is compatible with the given SQL type.

impl Type<Postgres> for str

fn type_info() -> PgTypeInfo

Returns the canonical SQL type for this Rust type.

fn compatible(ty: &PgTypeInfo) -> bool

Determines if this Rust type is compatible with the given SQL type.

impl HasStatementCache for Postgres