Module page 

See bufpage.h and bufpage.c.

Page layout

+--------+---------------+----------------+--------------+---------+
| header | line pointers |→  free space  ←| tuple data   | special |
+--------+---------------+----------------+--------------+---------+
0        24          pd_lower         pd_upper     pd_special    8192

Fields are little-endian. Postgres uses the machine’s byte order, which is little-endian on x86-64 and ARM64, so there the bytes match Postgres’s.

Structs

Header

LocationIndex

Offset of a byte within a page. Postgres’s LocationIndex.

Page

An 8 KB block, exactly as stored on disk.

PageFlags

The bits of pd_flags.

ValidatedPage

Enums

InvalidHeader

Why a header fails the checks Postgres runs before letting a page into the buffer pool.

PageError

Constants

HEADER_SIZE

PAGE_LAYOUT_VERSION

Version of this layout, kept in the low byte of pd_pagesize_version. Postgres’s PG_PAGE_LAYOUT_VERSION, which has been 4 since Postgres 8.3.