Data Type

The library intentionally rejects conversions that could silently lose data. For example, reading a BIGINT column as i8 will return an error rather than truncating the value. This ensures data integrity and makes bugs easier to catch.

Widening conversions (e.g., reading SMALLINT as i64) are allowed.

Parameter Types (Rust to PostgreSQL)

Rust Type	PostgreSQL Type	Notes
`bool`	`BOOL` (`BOOLEAN`)
`i8`	`INT2` (`SMALLINT`)	PostgreSQL has no 1-byte integer
`i16`	`INT2` (`SMALLINT`)
`i32`	`INT4` (`INTEGER`)
`i64`	`INT8` (`BIGINT`)
`u8`	`INT2` (`SMALLINT`)	PostgreSQL has no unsigned types
`u16`	`INT4` (`INTEGER`)	`u16` max exceeds `INT2` max
`u32`	`INT8` (`BIGINT`)	`u32` max exceeds `INT4` max
`u64`	`INT8` (`BIGINT`)	Overflow checked at runtime
`f32`	`FLOAT4` (`REAL`)
`f64`	`FLOAT8` (`DOUBLE PRECISION`)
`&str`	`TEXT`	Also works with `VARCHAR`, `CHAR`, `JSON`, `JSONB`
`String`	`TEXT`
`&[u8]`	`BYTEA`
`Vec<u8>`	`BYTEA`
`Option<T>`	Same as `T`	`None` encodes as `NULL`

Result Types (PostgreSQL to Rust)

PostgreSQL only has signed integer types. Decoding to unsigned Rust types (u8, u16, u32, u64) is not supported.

PostgreSQL Type	Rust Types
`BOOL` (`BOOLEAN`)	`bool`
`INT2` (`SMALLINT`)	`i16`, `i32`, `i64`
`INT4` (`INTEGER`)	`i32`, `i64`
`INT8` (`BIGINT`)	`i64`
`FLOAT4` (`REAL`)	`f32`, `f64`
`FLOAT8` (`DOUBLE PRECISION`)	`f64`
`NUMERIC`	`f32`, `f64`
`TEXT`, `VARCHAR`, `CHAR(n)`, `NAME`	`&str`, `String`
`BYTEA`	`&[u8]`, `Vec<u8>`
`NULL`	`Option<T>`

Feature-Gated Types

Additional type support is available through feature flags.

`with-chrono` (chrono crate)

Rust Type	PostgreSQL Type
`chrono::NaiveDate`	`DATE`
`chrono::NaiveTime`	`TIME`
`chrono::NaiveDateTime`	`TIMESTAMP`, `TIMESTAMPTZ`
`chrono::DateTime<Utc>`	`TIMESTAMPTZ`

PostgreSQL Type	Rust Types
`DATE`	`chrono::NaiveDate`
`TIME`	`chrono::NaiveTime`
`TIMESTAMP`	`chrono::NaiveDateTime`
`TIMESTAMPTZ`	`chrono::NaiveDateTime`, `chrono::DateTime<Utc>`

`with-time` (time crate)

Rust Type	PostgreSQL Type
`time::Date`	`DATE`
`time::Time`	`TIME`
`time::PrimitiveDateTime`	`TIMESTAMP`, `TIMESTAMPTZ`
`time::OffsetDateTime`	`TIMESTAMPTZ`

PostgreSQL Type	Rust Types
`DATE`	`time::Date`
`TIME`	`time::Time`
`TIMESTAMP`	`time::PrimitiveDateTime`
`TIMESTAMPTZ`	`time::PrimitiveDateTime`, `time::OffsetDateTime`

`with-uuid` (uuid crate)

Rust Type	PostgreSQL Type
`uuid::Uuid`	`UUID`

PostgreSQL Type	Rust Types
`UUID`	`uuid::Uuid`

`with-rust-decimal` (rust_decimal crate)

rust_decimal::Decimal uses 96-bit precision, not arbitrary precision like PostgreSQL’s NUMERIC.

Rust Type	PostgreSQL Type
`rust_decimal::Decimal`	`NUMERIC`

PostgreSQL Type	Rust Types
`NUMERIC`	`rust_decimal::Decimal`

Keyboard shortcuts

zero-postgres Documentation