文件名称：SQL语法-Greenplum 数据库基础培训V1.2
文件大小：7.92MB
文件格式：PPT
更新时间：2024-05-15 15:14:50
Greenplum 中文
SQL语法 具体参考《Gp sql language》： 注意事项： DELETE ,UPDATE在两表关联时，两个表的distribution必须一致。 如：delete from tablea using tableb where tablea.id=tableb.id UPDATE table a as a SET desc= b.desc FROM tableb as b WHERE a.id=b.id 以上操作 table a,table b 必须使用相同的分布，必要时可以使用 alter table set distribution 进行分布修改。 * 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 client's 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 password authentication is performed. If no password is provided at initialization time, the default password is mpparray.