Updating a table with a conventional path load v16

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You can use EDB*Loader with a conventional path load to update the rows in a table, merging new data with the existing data. When you invoke EDB*Loader to perform an update, the server searches the table for an existing row with a matching primary key:

  • If the server locates a row with a matching key, it replaces the existing row with the new row.
  • If the server doesn't locate a row with a matching key, it adds the new row to the table.

To use EDB*Loader to update a table, the table must have a primary key. You can't use EDB*Loader to update a partitioned table.

Performing the update

To perform UPDATE, use the same steps as when performing a conventional path load:

  1. Create a data file that contains the rows you want to update or insert.
  2. Define a control file that uses the INFILE keyword to specify the name of the data file. For information about building the EDB*Loader control file, see Building the EDB*Loader control file.
  3. Invoke EDB*Loader, specifying the database name, connection information, and the name of the control file. For information about invoking EDB*Loader, see Invoking EDB*Loader.

This example uses the emp table that's distributed with the EDB Postgres Advanced Server sample data. By default, the table contains:

edb=# select * from emp;
Output
empno|ename |   job   |  mgr |       hiredate     |   sal    | comm  | deptno
-----+------+---------+------+--------------------+--------- +-------+--------
7369 |SMITH |CLERK    | 7902 | 17-DEC-80 00:00:00 | 800.00   |       |   20
7499 |ALLEN |SALESMAN | 7698 | 20-FEB-81 00:00:00 | 1600.00  |300.00 |   30
7521 |WARD  |SALESMAN | 7698 | 22-FEB-81 00:00:00 | 1250.00  |500.00 |   30
7566 |JONES |MANAGER  | 7839 | 02-APR-81 00:00:00 | 2975.00  |       |   20
7654 |MARTIN|SALESMAN | 7698 | 28-SEP-81 00:00:00 | 1250.00  |1400.00|   30
7698 |BLAKE |MANAGER  | 7839 | 01-MAY-81 00:00:00 | 2850.00  |       |   30
7782 |CLARK |MANAGER  | 7839 | 09-JUN-81 00:00:00 | 2450.00  |       |   10
7788 |SCOTT |ANALYST  | 7566 | 19-APR-87 00:00:00 | 3000.00  |       |   20
7839 |KING  |PRESIDENT|      | 17-NOV-81 00:00:00 | 5000.00  |       |   10
7844 |TURNER|SALESMAN | 7698 | 08-SEP-81 00:00:00 | 1500.00  | 0.00  |   30
7876 |ADAMS |CLERK    | 7788 | 23-MAY-87 00:00:00 | 1100.00  |       |   20
7900 |JAMES |CLERK    | 7698 | 03-DEC-81 00:00:00 | 950.00   |       |   30
7902 |FORD  |ANALYST  | 7566 | 03-DEC-81 00:00:00 | 3000.00  |       |   20
7934 |MILLER|CLERK    | 7782 | 23-JAN-82 00:00:00 | 1300.00  |       |   10
(14 rows)

This control file (emp_update.ctl) specifies the fields in the table in a comma-delimited list. The control file performs an UPDATE on the emp table.

LOAD DATA
  INFILE 'emp_update.dat'
  BADFILE 'emp_update.bad'
  DISCARDFILE 'emp_update.dsc'
UPDATE INTO TABLE emp
FIELDS TERMINATED BY ","
(empno, ename, job, mgr, hiredate, sal, comm, deptno)

The data that's being updated or inserted is saved in the emp_update.dat file. emp_update.dat contains:

7521,WARD,MANAGER,7839,22-FEB-81 00:00:00,3000.00,0.00,30
7566,JONES,MANAGER,7839,02-APR-81 00:00:00,3500.00,0.00,20
7903,BAKER,SALESMAN,7521,10-JUN-13 00:00:00,1800.00,500.00,20
7904,MILLS,SALESMAN,7839,13-JUN-13 00:00:00,1800.00,500.00,20
7654,MARTIN,SALESMAN,7698,28-SEP-81 00:00:00,1500.00,400.00,30

Invoke EDB*Loader, specifying the name of the database (edb), the name of a database user and their associated password, and the name of the control file (emp_update.ctl):

edbldr -d edb userid=user_name/password control=emp_update.ctl

Results of the update

After performing the update, the emp table contains:

edb=# select * from emp;
Output
empno|ename |   job   |  mgr |      hiredate      |   sal   |  comm  | deptno
-----+------+---------+------+--------------------+---------+--------+--------
7369 |SMITH |CLERK    | 7902 | 17-DEC-80 00:00:00 | 800.00  |        |  20
7499 |ALLEN |SALESMAN | 7698 | 20-FEB-81 00:00:00 | 1600.00 | 300.00 |  30
7521 |WARD  |MANAGER  | 7839 | 22-FEB-81 00:00:00 | 3000.00 | 0.00   |  30
7566 |JONES |MANAGER  | 7839 | 02-APR-81 00:00:00 | 3500.00 | 0.00   |  20
7654 |MARTIN|SALESMAN | 7698 | 28-SEP-81 00:00:00 | 1500.00 | 400.00 |  30
7698 |BLAKE |MANAGER  | 7839 | 01-MAY-81 00:00:00 | 2850.00 |        |  30
7782 |CLARK |MANAGER  | 7839 | 09-JUN-81 00:00:00 | 2450.00 |        |  10
7788 |SCOTT |ANALYST  | 7566 | 19-APR-87 00:00:00 | 3000.00 |        |  20
7839 |KING  |PRESIDENT|      | 17-NOV-81 00:00:00 | 5000.00 |        |  10
7844 |TURNER|SALESMAN | 7698 | 08-SEP-81 00:00:00 | 1500.00 | 0.00   |  30
7876 |ADAMS |CLERK    | 7788 | 23-MAY-87 00:00:00 | 1100.00 |        |  20
7900 |JAMES |CLERK    | 7698 | 03-DEC-81 00:00:00 | 950.00  |        |  30
7902 |FORD  |ANALYST  | 7566 | 03-DEC-81 00:00:00 | 3000.00 |        |  20
7903 |BAKER |SALESMAN | 7521 | 10-JUN-13 00:00:00 | 1800.00 | 500.00 |  20
7904 |MILLS |SALESMAN | 7839 | 13-JUN-13 00:00:00 | 1800.00 | 500.00 |  20
7934 |MILLER|CLERK    | 7782 | 23-JAN-82 00:00:00 | 1300.00 |        |  10
(16 rows)

The rows containing information for the three employees that are currently in the emp table are updated, while rows are added for the new employees (BAKER and MILLS).

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