>>>>> "Tom" == Tom Lane <tgl@sss.pgh.pa.us> writes:
>> - Why to read from a table, both a usage permission on the schema>> and a read access permission on the table is
needed?
Tom> Because the SQL standard says so.
You'd think, but in fact it doesn't; the spec (at least 2008 and the
2011 drafts) has no concept of grantable permissions on schemas, and
ties table ownership and schema ownership together.
(See the definition of <privileges> to see that there's nothing there
for schemas, and the definition of <table definition> for the fact that
it's the schema owner who also owns the table and gets the initial
grants on it, and <drop table statement> and <alter table statement> to
confirm that only the schema owner can alter or drop the table. The
access rules for <table reference> only require permission on a table
column, no mention of schemas.)
--
Andrew (irc:RhodiumToad)
