• B
    This is the final state of the rule system for 6.4 after the · 15cb32d9
    Bruce Momjian 提交于
        patch is applied:
    
    	Rewrite rules on relation level work fine now.
    
    	Event qualifications on insert/update/delete  rules  work
    	fine now.
    
    	I  added  the  new  keyword  OLD to reference the CURRENT
    	tuple. CURRENT will be removed in 6.5.
    
    	Update rules can  reference  NEW  and  OLD  in  the  rule
    	qualification and the actions.
    
    	Insert/update/delete rules on views can be established to
    	let them behave like real tables.
    
    	For  insert/update/delete  rules  multiple  actions   are
    	supported  now.   The  actions  can also be surrounded by
    	parantheses to make psql  happy.   Multiple  actions  are
    	required if update to a view requires updates to multiple
    	tables.
    
    	Regular users  are  permitted  to  create/drop  rules  on
    	tables     they     have     RULE     permissions     for
    	(DefineQueryRewrite() is  now  able  to  get  around  the
    	access  restrictions  on  pg_rewrite).  This enables view
    	creation for regular users too. This  required  an  extra
    	boolean  parameter  to  pg_parse_and_plan() that tells to
    	set skipAcl on all rangetable entries  of  the  resulting
    	queries.       There      is      a      new     function
    	pg_exec_query_acl_override()  that  could  be   used   by
    	backend utilities to use this facility.
    
    	All rule actions (not only views) inherit the permissions
    	of the event relations  owner.  Sample:  User  A  creates
    	tables    T1    and    T2,   creates   rules   that   log
    	INSERT/UPDATE/DELETE on T1 in T2 (like in the  regression
    	tests  for rules I created) and grants ALL but RULE on T1
    	to user B.  User B  can  now  fully  access  T1  and  the
    	logging  happens  in  T2.  But user B cannot access T2 at
    	all, only the rule actions can. And due to  missing  RULE
    	permissions on T1, user B cannot disable logging.
    
    	Rules  on  the  attribute  level are disabled (they don't
    	work properly and since regular users are  now  permitted
    	to create rules I decided to disable them).
    
    	Rules  on  select  must have exactly one action that is a
    	select (so select rules must be a view definition).
    
    	UPDATE NEW/OLD rules  are  disabled  (still  broken,  but
    	triggers can do it).
    
    	There are two new system views (pg_rule and pg_view) that
    	show the definition of the rules or views so the db admin
    	can  see  what  the  users do. They use two new functions
    	pg_get_ruledef() and pg_get_viewdef() that are  builtins.
    
    	The functions pg_get_ruledef() and pg_get_viewdef() could
    	be used to implement rule and view support in pg_dump.
    
    	PostgreSQL is now the only database system I  know,  that
    	has rewrite rules on the query level. All others (where I
    	found a  rule  statement  at  all)  use  stored  database
    	procedures  or  the  like  (triggers as we call them) for
    	active rules (as some call them).
    
        Future of the rule system:
    
    	The now disabled parts  of  the  rule  system  (attribute
    	level,  multiple  actions on select and update new stuff)
    	require a complete new rewrite handler from scratch.  The
    	old one is too badly wired up.
    
    	After  6.4  I'll  start to work on a new rewrite handler,
    	that fully supports the attribute level  rules,  multiple
    	actions on select and update new.  This will be available
    	for 6.5 so we get full rewrite rule capabilities.
    
    Jan
    15cb32d9
initdb.sh 15.9 KB