Per previous convention (see
ace397e9d2), drop SQL:2008 and only keep
the latest two standards and SQL-92.
Note: SQL:2016-2 lists a large number of non-reserved keywords that
are really just information_schema column names related to new
features. Those kinds of thing have not previously been listed as
keywords, and this was apparently done here by mistake, since these
keywords have been removed again in post-2016 working drafts. So in
order to avoid bloating the keywords table unnecessarily, I have
omitted these erroneous keywords here.
The SQL keywords table in the documentation had until now been
generated by some ad hoc scripting outside the source tree once for
each major release. This changes it to an automated process.
We have the PostgreSQL keywords available in a parseable format in
parser/kwlist.h. For the relevant SQL standard versions, keep the
keyword lists in new text files. A new script
generate-keywords-table.pl pulls it all together and produces a
DocBook table.
The final output in the documentation should be identical after this
change.
Discussion: https://www.postgresql.org/message-id/flat/07daeadd-8c82-0d95-5e19-e350502cb749%402ndquadrant.com
