Hello hackers, Here's a draft patch that teaches PostgreSQL how to ask for collation versions on Windows. It receives a pair of DWORDs, which, it displays as hex. The values probably have an internal structure that is displayed in a user-friendly way by software like Active Directory and SQL Server (I'm pretty sure they both track collation versions and reindex), but I don't know. It is based on the documentation at:
https://docs.microsoft.com/en-us/windows/win32/win7appqual/nls-sorting-changes My understanding of our OS and tool chain version strategy on that platform is limited, but it looks like we only allow ourselves to use Vista (and later) APIs if the compiler is Visual Studio 2015 (aka 14.0) or later. So I tested that this builds cleanly on AppVeyor using that compiler (see attached CI patch). The regression tests failed with Windows error code 87 before I added in the check to skip "C" and "POSIX", so I know the new code is reached. I don't have an environment to test it beyond that. The reason for returning an empty string for "C" and "POSIX" is the following comment for get_collation_actual_version(): * A particular provider must always either return a non-NULL string or return * NULL (if it doesn't support versions). It must not return NULL for some * collcollate and not NULL for others. I'm not sure why, or if that really makes sense. Do any Windows hackers want to help get it into shape? Some things to do: test it, verify that the _WIN32_WINNT >= 0x0600 stuff makes sense (why do we target such ancient Windows releases anyway?), see if there is way we could use GetNLSVersion() (no "Ex") to make this work on older Windows system, check if it makes sense to assume that collcollate is encoded with CP_ACP ("the system default Windows ANSI code page", used elsewhere in the PG source tree for a similar purpose, but this seems likely to go wrong for locale names that have non-ASCII characters, and indeed we see complaints on the lists involving the word "Bokmål"), and recommend a better way to display the collation version as text. I'll add this to the next commitfest to attract some eyeballs (but note that when cfbot compiles it, it will be using an older tool chain and Win32 target, so the new code will be ifdef'd out and regression test success means nothing). To test that it works, you'd need to look at the contents of pg_collation to confirm that you see the new version strings, create an index on a column that explicitly uses a collation that has a version, update the pg_collation table by hand to have a to a different value, and then open a new session and to access the index to check that you get a warning about the version changing. The warning can be cleared by using ALTER COLLATION ... REFRESH VERSION.
0001-Add-collation-versions-for-Windows.patch
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0002-CI.patch
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