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Greenplum 如何直連segment節點
直連greenplum segment節點的方法, utility模式 :
使用這種方式，不與其他節點通訊，隻操作當前節點。也沒有數據分布的概念。
如果使用utility模式連接的是master節點，寫入數據時，數據不會分布到segment，使用正常模式連接後，寫入master的數據也查不出來。
$ PGOPTIONS='-c gp_session_role=utility' psql -p 40005
psql (8.2.15)
Type "help" for help.
postgres=# \dt
List of relations
Schema | Name | Type | Owner | Storage
--------+------+-------+----------+---------
public | t | table | digoal | heap
public | test | table | digoal | heap
(2 rows)
postgres=# select * from pg_locks;
locktype | database | relation | page | tuple | transactionid | classid | objid | objsubid | transaction | pid | mode | granted | mppsessionid | mppiswriter | gp_segment_id
---------------+----------+----------+------+-------+---------------+---------+-------+----------+-------------+--------+-----------------+---------+--------------+-------------+---------------
transactionid | | | | | 136604 | | | | 136604 | 130724 | ExclusiveLock | t | 6 | t | -1
relation | 10899 | 10333 | | | | | | | 136604 | 130724 | AccessShareLock | t | 6 | t | -1
(2 rows)
注意使用PGOPTIONS='-c gp_session_role=utility'後，隻操作本地節點
$psql -p # master
psql (8.2.15)
Type "help" for help.
postgres=# select count(*) from test;
count
-------
0
(1 row)
postgres=# \q
$psql -p 40001 # segment
psql (8.2.15)
Type "help" for help.
postgres=# select count(*) from test;
count
---------
4166801
(1 row)
最後更新：2017-04-01 13:44:33