FOREIGN KEY and shift/reduce

Hi,

    I  just  committed  a  patch that turns on FOREIGN KEY. Thus,
    REFERENCES used in CREATE TABLE now automatically creates the
    appropriate  constraint  triggers.  The  implementation  also
    supports  omitting  the  PK   column   definition,   if   the
    corresponding  columns  should  be  the  PRIMARY  KEY  of the
    referenced table.

    Also I completed some more of the generic trigger procs.  For
    MATCH  FULL,  the  key  existence check in PK table and these
    actions are completed:

        ON DELETE RESTRICT
        ON DELETE CASCADE
        ON UPDATE RESTRICT
        ON UPDATE CASCADE

    Still missing are the SET NULL and SET DEFAULT  actions.  The
    former  is easy and will follow soon, the latter looks tricky
    if the  implementation  should  support  ALTER  TABLE/DEFAULT
    (what it IMHO must even if that ALTER TABLE isn't implemented
    yet).

    Anyway, I ran into some  shift/reduce  problem  in  the  main
    parser. The syntax according to SQL3 says

        <constraint attributes> ::=
              <constraint check time> [ [ NOT ] DEFERRABLE ]
            | [ NOT ] DEFERRABLE [ <constraint check time> ]

    <constraint  check time> defines INITIALLY DEFERRED/IMMEDIATE
    and defaults to IMMEDIATE.

    If I allow the <constraint attributes> in column constraints,
    I  get  2 shift/reduce conflicts. Seems the syntax interferes
    with NOT NULL.  Actually I commented that part  out,  so  the
    complete  syntax is available only for table constraints, not
    on the column level.

    Could some yacc-guru please take a look at it?

    Another interesting  question  is  about  inheritance.  If  a
    REFERENCES constraint exists for a table, must another table,
    inheriting this one, also get all the FK checks applied?


Jan

--

#======================================================================#
# It's easier to get forgiveness for being wrong than for being right. #
# Let's break this rule - forgive me.                                  #
#========================================= wieck@debis.com (Jan Wieck) #