Module numeric_layout 

The values of NUMERIC, the decimal number of PostgreSQL with no fixed width and no fixed scale, as the bytes that a vector holds.

The number is the one NumericVar holds in src/backend/utils/adt/numeric.c: a sign, a weight, base-10000 digits and a display scale. crate::Numeric does the arithmetic, the input and the output on that form, and this module only packs it.

The first byte is the class of the value, in the order of the values: negative infinity, a negative number, zero, a positive number, positive infinity and NaN, as PostgreSQL sorts them. A number then has its weight and its digits, with no zero digit at either end. A negative number has them flipped and a last word of 0xffff, so that a longer negative number sorts first. The last two bytes are the display scale. Thus the bytes before the last two order as the numbers do, and 1.0 and 1.00 have the same key and different bytes.

Lifted from crates/rudb-common/src/numeric.rs of tamnd/rudb at f5f7065a (spec/04 section 4.9).

Structs

Unpacked

A value taken apart. A special value has no digits, a weight of 0 and a display scale of 0.

Constants

INFINITY

NAN

NEGATIVE

NEGATIVE_INFINITY

POSITIVE

NUMERIC_POS, NUMERIC_NEG, NUMERIC_NAN, NUMERIC_PINF and NUMERIC_NINF, the sign codes of PostgreSQL.

Functions

decode

The value of bytes that encode wrote. Bytes that it cannot have written read as NaN.

encode

The bytes of a value. Zero digits at either end are dropped, and a number with no digits left is zero.

key

The bytes that order and compare as the number does, which leave out the display scale.

to_text

The text of a value, as numeric_out writes it: the digits with exactly the display scale.