12-06-2005
Do you know about the /*+ parallel */ hint?
If you want to see what the query is doing, try EXPLAIN PLAN or use tkprof on a session with ALTER SESSION SET SQLTRACE TRUE;
For small tables joined against larger tables, parallel may not be part of the the possible optimizer choices.
Read Tom Kite's: 'Expert One on One ORACLE' or visit his website:
http://asktom.oracle.com/pls/ask
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LEARN ABOUT CENTOS
set_role
SET
ROLE(7) PostgreSQL 9.2.7 Documentation SET ROLE(7)
NAME
SET_ROLE - set the current user identifier of the current session
SYNOPSIS
SET [ SESSION | LOCAL ] ROLE role_name
SET [ SESSION | LOCAL ] ROLE NONE
RESET ROLE
DESCRIPTION
This command sets the current user identifier of the current SQL session to be role_name. The role name can be written as either an
identifier or a string literal. After SET ROLE, permissions checking for SQL commands is carried out as though the named role were the one
that had logged in originally.
The specified role_name must be a role that the current session user is a member of. (If the session user is a superuser, any role can be
selected.)
The SESSION and LOCAL modifiers act the same as for the regular SET(7) command.
The NONE and RESET forms reset the current user identifier to be the current session user identifier. These forms can be executed by any
user.
NOTES
Using this command, it is possible to either add privileges or restrict one's privileges. If the session user role has the INHERITS
attribute, then it automatically has all the privileges of every role that it could SET ROLE to; in this case SET ROLE effectively drops
all the privileges assigned directly to the session user and to the other roles it is a member of, leaving only the privileges available to
the named role. On the other hand, if the session user role has the NOINHERITS attribute, SET ROLE drops the privileges assigned directly
to the session user and instead acquires the privileges available to the named role.
In particular, when a superuser chooses to SET ROLE to a non-superuser role, she loses her superuser privileges.
SET ROLE has effects comparable to SET SESSION AUTHORIZATION (SET_SESSION_AUTHORIZATION(7)), but the privilege checks involved are quite
different. Also, SET SESSION AUTHORIZATION determines which roles are allowable for later SET ROLE commands, whereas changing roles with
SET ROLE does not change the set of roles allowed to a later SET ROLE.
SET ROLE does not process session variables as specified by the role's ALTER ROLE (ALTER_ROLE(7)) settings; this only happens during login.
SET ROLE cannot be used within a SECURITY DEFINER function.
EXAMPLES
SELECT SESSION_USER, CURRENT_USER;
session_user | current_user
--------------+--------------
peter | peter
SET ROLE 'paul';
SELECT SESSION_USER, CURRENT_USER;
session_user | current_user
--------------+--------------
peter | paul
COMPATIBILITY
PostgreSQL allows identifier syntax ("rolename"), while the SQL standard requires the role name to be written as a string literal. SQL does
not allow this command during a transaction; PostgreSQL does not make this restriction because there is no reason to. The SESSION and LOCAL
modifiers are a PostgreSQL extension, as is the RESET syntax.
SEE ALSO
SET SESSION AUTHORIZATION (SET_SESSION_AUTHORIZATION(7))
PostgreSQL 9.2.7 2014-02-17 SET ROLE(7)