PostgreSQL overall design

Hi All,

Can anyone please tell/point me where I can get the postgresql system layout
(I've an interest to contribute). I would also like to know the files
involved for performing each task ( for eg when doing a select operation
what is exactly happening in postgres along with the files).

I was wandering inside the source for a while and I couldn't get a start
point to go with.

Need a clarification in copydir.c file of src/port directory, In the
following snippet the destination directory is created first then the source
directory is read. Suppose if I don't have permission to read the source,
even then the destination directory would be created.
I just want to know whether there is any reason for doing so?

if (mkdir(todir, S_IRUSR | S_IWUSR | S_IXUSR) != 0)
ereport(ERROR,
(errcode_for_file_access(),
errmsg("could not create directory \"%s\": %m", todir)));

xldir = AllocateDir(fromdir);
if (xldir == NULL)
ereport(ERROR,
(errcode_for_file_access(),
errmsg("could not open directory \"%s\": %m", fromdir)));

--
with thanks & regards,
S.Gnanavel
Satyam Computer Services Ltd.