00d9c2d9a8
There were two issues with the test at page boundaries: 1. If the first logical message with 10 bytes payload crossed a page boundary, the calculated 'base_size' was too large because it included the page header. 2. If it was inserted near the end of a page so that there was not enough room for another one, we did "remaining_lsn += XLOG_BLCKSZ" but that didn't take into account the page headers either. As a result, the test would fail if the WAL insert position at the beginning of the test was too close to the end of a WAL page. Fix the calculations by repeating the 10-byte logical message if the starting position is not suitable. I bumped into this with PR #7377; it changed the arguments of a few SQL functions in neon_test_utils extension, which changed the WAL positions slightly, and caused a test failure. This is similar to https://github.com/neondatabase/neon/pull/7436, but for different test.
This module contains utilities for working with PostgreSQL file formats. It's a collection of structs that are auto-generated from the PostgreSQL header files using bindgen, and Rust functions to read and manipulate them.
There are also a bunch of constants in pg_constants.rs that are copied
from various PostgreSQL headers, rather than auto-generated. They mostly
should be auto-generated too, but that's a TODO.
The PostgreSQL on-disk file format is not portable across different
CPU architectures and operating systems. It is also subject to change
in each major PostgreSQL version. Currently, this module supports
PostgreSQL v14, v15 and v16: bindings and code that depends on them are
version-specific.
This code is organized in modules postgres_ffi::v14, postgres_ffi::v15 and
postgres_ffi::v16. Version independent code is explicitly exported into
shared postgres_ffi.
TODO: Currently, there is also some code that deals with WAL records in pageserver/src/waldecoder.rs. That should be moved into this module. The rest of the codebase should not have intimate knowledge of PostgreSQL file formats or WAL layout, that knowledge should be encapsulated in this module.