Struct Held 

pub struct Held { /* private fields */ }

A literal with the one row column a comparison reads it through already built.

The comparison loops read both sides through a slice, so the constant side is turned into a one row column and read at position zero. That column is what carries a string’s four byte prefix, which is the thing the string comparison resolves almost every row from, and building it costs a couple of allocations. Doing that once for the query rather than once per chunk is what this is.

It matters least where a chunk is full and most where it is not. A second conjunct handed the eleven rows the first one kept pays the same setup as one handed two thousand, so on a selective filter the setup was a real part of the call rather than a rounding error on it.

Implementations

impl Held

pub fn of(ty: &LogicalType, value: &Value) -> Option<Self>

The one row column for value read as ty, or None for a type with no column layout.

A nested type answers None and the comparison does what it always did, which is decide per chunk and fall through to the row at a time path if it has to.

Trait Implementations

impl Debug for Held

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

Formats the value using the given formatter.