457e3a3ebc
Fix mx_offset_to_flags_offset() function Fixes issue #4774 Postgres `MXOffsetToFlagsOffset` was not correctly converted to Rust because cast to u16 is done before division by modulo. It is possible only if divider is power of two. Add a small rust unit test to check that the function produces same results as the PostgreSQL macro, and extend the existing python test to cover this bug. Co-authored-by: Konstantin Knizhnik <knizhnik@neon.tech> Co-authored-by: Heikki Linnakangas <heikki@neon.tech>
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 and v15: bindings and code that depends on them are version-specific.
This code is organized in modules: postgres_ffi::v14 and postgres_ffi::v15
Version independend 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.