37c87e63f9
For AIO, and also some other recent patches, we need the ability to call relpath() in a critical section. Until now that was not feasible, as it allocated memory. The fact that relpath() allocated memory also made it awkward to use in log messages because we had to take care to free the memory afterwards. Which we e.g. didn't do for when zeroing out an invalid buffer. We discussed other solutions, e.g. filling a pre-allocated buffer that's passed to relpath(), but they all came with plenty downsides or were larger projects. The easiest fix seems to be to make relpath() return the path by value. To be able to return the path by value we need to determine the maximum length of a relation path. This patch adds a long #define that computes the exact maximum, which is verified to be correct in a regression test. As this change the signature of relpath(), extensions using it will need to adapt their code. We discussed leaving a backward-compat shim in place, but decided it's not worth it given the use of relpath() doesn't seem widespread. Discussion: https://postgr.es/m/xeri5mla4b5syjd5a25nok5iez2kr3bm26j2qn4u7okzof2bmf@kwdh2vf7npra
PostgreSQL Database Management System
This directory contains the source code distribution of the PostgreSQL database management system.
PostgreSQL is an advanced object-relational database management system that supports an extended subset of the SQL standard, including transactions, foreign keys, subqueries, triggers, user-defined types and functions. This distribution also contains C language bindings.
Copyright and license information can be found in the file COPYRIGHT.
General documentation about this version of PostgreSQL can be found at https://www.postgresql.org/docs/devel/. In particular, information about building PostgreSQL from the source code can be found at https://www.postgresql.org/docs/devel/installation.html.
The latest version of this software, and related software, may be obtained at https://www.postgresql.org/download/. For more information look at our web site located at https://www.postgresql.org/.