A binary format specification of PostgreSQL built-in types

Numeric

smallint - word16
integer  - word32
bigint   - word64
decimal - TODO
numeric - TODO
real - float32
double precision - float64

Monetary

Character

char - word8
text, varchar - text[n]

Binary

bytea - bytes[n]

Date/Times

TODO

Boolean

bool - word8(1 for True, 0 for False)

Enum

text[n]

Geometric

Network Address

Text Search

UUID

XML

JSON

json - text
jsonb - word8 - 1
        text

Array

word32 - dimension
word32 - 1 if array has NULL, 0 otherwise
oid - oid of element type
for each dimension:
  word32 - elements in dimension
  word32 - lower bound
for each element:
  word32 - elements length
  bytes[n] - encoded element

Composite

word32 - number of columns
for each column:
  oid - oid of element
  word32 - element length
  bytes[n] - encoded element

Range

word8 - flags(?)
if has lower bound:
  word32 - length
  bytes[n] - encoded lower bound as type
if has upper bound:
  word32 - length
  bytes[n] - encoded upper bound as type

Oid

oid