Greenplum-数据库基础培训V1.2-2010-06-03.pptVIP

* All system catalog tables are in the pg_catalog schema. Greenplum uses the standard Postgres system catalog tables (such as pg_database, pg_inherits, pg_index, pg_class, etc). Greenplum has some additional tables used to store information about the array. these are all global tables, meaning they are shared across all databases on an instance. gp_configuration – GPDB array host and instance (segments and masters)gp_distribution_policy – GPDB distribution key columns for a table gp_id – each segment has a local copy of this table with its own dbid and contentid * Instructor Notes By default, the master host is configured to allow remote client connections from the default superuser account only. This is the user who initialized the Greenplum array. In this case, the OS user name and the Greenplum database user name are the same, but this may not always be the case for other users. Let’s go over each line of the pg_hba.conf file for the master host and explain what is happening: Lines 1 and 2 are saying that for local UNIX domain socket connections allow the gpadmin user (the superuser who bootstrapped the array, lab# in our training environment) and all users to connect to all databases. The ident authentication method works by obtaining the clients OS user name, then determining the allowed database user names using a map file. There is a predefined ident map named sameuser, which allows any operating system user to connect as the database user of the same name. Any other maps must be created manually using the pg_ident.conf file. Line 3 is saying that for TCP/IP connections allow only the gpadmin superuser to connect to all databases when the connection comes from the local host. Note that the CIDR address is in IPv4 format. trust means no authentication is performed. Line 4 is saying that for any remote host TCP/IP connections allow only the gpadmin superuser to connect to all databases. Note that the CIDR address is in IPv4 format. md5 means passw