On Mon, 23 Jul 2018 at 16:45, Michael Paquier <mich...@paquier.xyz> wrote:
> On Mon, Jul 23, 2018 at 08:16:52AM +0000, Tsunakawa, Takayuki wrote: > > I guess that is due to some missing files related to the libraries > > listed in shared_preload_library. If so, no, because this patch > > relates to failure before main(). > > No, I really mean a library dependency failure. For example, imagine > that Postgres is compiled on Windows dynamically, and that it depends on > libxml2.dll, which is itself compiled dynamically. Then imagine, in a > custom build echosystem, that a folk comes in and adds lz support to > libxml2 on Windows. If Postgres still consumes libxml2 but does not add > in its PATH a version of lz, then a backend in need of libxml2 would > fail to load, causing Postgres to not start properly. True, painful, > story. > What's super fun about this is the error message. Guess which error Windows will emit? (Some paraphrasing for exact wording): * "There was a problem starting C:\Program Files\PostgreSQL\11\bin\postgres.exe: The specified module could not be found." * "There was a problem starting C:\Program Files\PostgreSQL\11\bin\postgres.exe: module "libxml2.dll" could not be found." * "The program can't start because "libxml2.dll" is missing from your computer." * "The program "C:\Program Files\PostgreSQL\11\bin\postgres.exe" can't start because an error was encountered when loading required library "C:\Program Files\PostgreSQL\11\lib\libxml.dll": libxml.dll requires "liblz.dll" but it could not be found." Hint: not the last one. It'll at best complain about libxml.dll being missing, despite it being very obviously present. I had to go hunt around with Dependency Walker to figure out the actual missing DLL the last time I had to deal with this. -- Craig Ringer http://www.2ndQuadrant.com/ 2ndQuadrant - PostgreSQL Solutions for the Enterprise
