Greenplum Query Oracle via DLINK

Source: Internet
Author: User
Tags psql sqlplus

How to synchronize some configuration tables to GP library issues from Oracle database during the daily production process of the system.
First, the way you used it before:
0. Export plain text format from Oracle using 3rd party tools and store locally;
1. Loading the library with the GP external table
The advantage of this approach is that the performance is very high for a table that needs to synchronize large amounts of data, the disadvantage is a bit cumbersome, the main is real-time, there is a task scheduling cycle and export import time period.


My solution to this is to simplify the process and query in real time:
0. Querying Oracle data tables directly using the GP Web external table technology


Because it is a configuration table, the amount of data is generally very small, a few k to a few W records in this way is almost instantaneous consumption.


The first is the source table for Oracle:
[Email protected] ~]$ Sqlplus gtlions/gtlions


Sql*plus:release 10.2.0.5.0-production on Thu 8 15:41:06 2014


Copyright (c) 1982, Oracle. All rights Reserved.




Connected to:
Oracle Database 10g Enterprise Edition Release 10.2.0.5.0-64bit Production
With the partitioning, OLAP, Data Mining and Real application testing options


Sql> select * from test;


ID NAME
---------- -----
1 A
1 A
Then query the Oracle table directly in GP:
[Email protected] ~]$ Psql gtlions
Psql (8.2.15)
Type ' help ' for help.


gtlions=# drop External table if exists sqlplus_test;
DROP EXTERNAL TABLE
gtlions=# Create external Web table sqlplus_test (ID int,name varchar (5)) Execute ' sqlplus-s gtlions/[email protected] &lt ; <eof
Gtlions ' # set echo OFF;
Gtlions ' # set heading OFF;
Gtlions ' # set feedback off;
Gtlions ' # set linesize 32767;
Gtlions ' # set pagesize 0;
Gtlions ' # Select Id| | "," | | name from Test;
Gtlions ' # exit;
Gtlions ' # EOF ' on master format ' CSV ' (header);
Notice:header means that each one of the data files have a HEADER row.
CREATE EXTERNAL TABLE
gtlions=# select * from Sqlplus_test;
ID | Name
----+------
1 | A
2 | B
(2 rows)


So easy,bingo!
-eof

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