How can we improve the performance of Cobol program in DB2?

1. Take advantage of the SQLERRD (3) out of the SQLCA.
2. Take advantage of fetching rowsets in your cursor processing.
3. Apply all calculations within the COBOL code and then move the value to a host variable.
4. Hard code any and all values known within an SQL statement.

How does cursor works in Cobol-DB2 program?

DB2 uses a cursor to make the rows, from the results table, available to the application program. A cursor identifies the current row of the results table. When you use a cursor, the program can retrieve each row sequentially from the results table until end-of-data (i.e the not found condition SQLCODE=100).

What happens if we don’t close cursor in Cobol?

If i didn’t code the close the cursor in a cobol-db2 prgoram means what it will happen? When program ended, it automatically closes the cursor. But in the case, where without closing the DB2 cursor, if you try to open the CURSOR again. OPen command will fail.

How does cursor work in Cobol?

Cursors in the application program are used to retrieve the multiple rows and process them one by one . Generally by using a singleton select statement in the application program, it is possible to retrieve only one row at a time as the host variable structure allows keeping one value at a time.

How do I optimize my Db2 database?

The Db2 optimizer can select the optimal query access plan if you have accurate catalog statistics and choose the best optimization class for your workload. Using the Db2 explain functionality to review potential query access plans and determine how to tune queries for best performance.

How do you optimize a program in Cobol?

Optimize IF statements by using a temporary field of a required size for the operation. Optimize operations on non-integer numbers by matching the decimal point alignment of the operands. Depending on the exponent, some exponential operations are optimized; for others, use MULTIPLY and DIVIDE operations.

What is cursor stability in Db2?

Cursor stability is the Db2 implementation of the SQL standard read committed isolation level. CS is perhaps the most common Db2 isolation level in use in production applications because it offers a good tradeoff between data integrity and concurrency.

What happens when we open a cursor in Db2?

When your program issues a row-positioned FETCH statement, Db2 uses the cursor to point to a row in the result table, making it the current row. Db2 then moves the current row contents into the program host variables that you specified in the INTO clause of the FETCH statement. The FETCH statement moves the cursor.

Is close cursor mandatory?

In your code example CURSOR is declared as part of procedure (not as part of package), which means, cursor is closed automatically when procedure executioin is complete. However it is best coding practice to CLOSE cursor statement if you have OPEN cursor statement in code.

Why do we use cursor in Db2?

In Db2, an application program uses a cursor to point to one or more rows in a set of rows that are retrieved from a table. You can also use a cursor to retrieve rows from a result set that is returned by a stored procedure. Your application program can use a cursor to retrieve rows from a table.

What is bottleneck in Db2?

Having any one resource constrained too much and everything slows down. You can have more CPU cycles available than you’ll ever need, but if your IO subsystem can’t keep up with the work, it becomes a bottleneck and you’ll never achieve your desired throughput.