Performance Analysis

Run-time analysis

• It is used to check load on each server.

• Run-time analysis is used to check the efficiency of a program or function module or t-code in terms of what is the load on the database server, application server, presentation server etc.
• The run-time analysis will display the load in a graph with %'s and the time in micro seconds.
• The graph will be displayed with either red color or green color.
• If the graph contains green color, then the program execution time is very good or very less.
• If the graph contains red color, the program execution time is very bad or very long.
• Always make sure the the load on database server should be less than 40% and should be green.
•  T-code for run-time analysis is SE30 or SAT (Latest Versions).

Steps

1. Goto SE30.

2.Click on Old SAT

3.Give program name and click on execute.

4.

5.

6. Go back

7. Click on evaluate

8. Execute the program & Click on Evaluate.

9. Execute the program & Click on Evaluate.

Performance Tunning:
It display the time taken by each SQL statement i.e. select, insert.
T-Code ST05.

Debugging

Debugging is a tool to check the program while execution to view how processor is working.

Selection-screen: /H in command screen.

Break points:

Set from within the debugger, the debugger interrupts the program when abap run time processor some across the specified keyword.

Watch point:

Set from within the debugger Watch point are field – specific to observe changes to a particular field or string.

Static break points: User independent

Dynamic break points: User specific.

Dynamic break points are more flexible than static break points because they can be removed or deactivated at run time.

In debugging we can keep up to 30 break points. At the same time we can keep up to 10 watch points in the debugging.

Code Inspector
The Code Inspector is a tool for checking static ABAP coding and DDIC objects (i.e. generally all objects of the Object Repository) under aspects of functional correctness, performance, security, reliability, and statistical information.

It helps developers to adhere to programming standards and guidelines by creating messages on less-than-optimal coding. The Code Inspector offers various possibilities to define object sets and to combine multiple single checks in so-called "check variants". 

Code inspectors t-codes.

SCID - code inspector for Specified Object 

SCII - code inspector: Inspection 

SIC - ABAP code inspector [Basis - ABAP Test Frameworks (ATC, Check Man, Code Inspector)]

Steps
1.

2.

3.Click on Results Table.

Extended program check
The extended program check performs a complete check that includes the interfaces of external procedures called from your program, for example, checking whether the number and type of the interface parameters in an external procedure call is correct.
The extended program check is also only a static check. It cannot eliminate all of the circumstances that could lead to exception situations or runtime errors.

SLIN is the ABAP Program Extended Syntax Check tool. It is basically used to perform a code reviewof the program. Its best practice to check the program in SLIN before transporting the program.

Steps
1.

OR

2.

3.Click on execute.

4.

5. Click on Display All Results.

Optimizing Performance In ABAP

Introduction

What is the need of optimizing performance?

In SAP programming, ABAP is the language used. Most of the projects focuses on getting a team of ABAP programmers as soon as possible and handing over the technical specifications to them and asking them to make out the ABAP programs within the "given deadlines".

Often due to this pressure of schedules and deliveries, the main focus of making a efficient program takes a back seat. An efficient ABAP program is one which delivers the required output to the user in a finite time as per the complexity of the program, rather than hearing the comment "I put the program to run, have my lunch and come back to check the results".

Leaving aside the hyperbole, a performance optimized ABAP program saves the time of the end user, thus increasing the productivity of the user, and in turn keeping the user and the management happy.

This tutorial focuses on presenting various performance tuning tips and tricks to make the ABAP programs efficient in doing their work. This tutorial also assumes that the reader is well versed in all the concepts and syntax of ABAP programming.

Performance of a program is also often limited due to hardware restrictions, which is out of the scope of this article.

Correct Way For Selection

Instead of selecting all the data and doing the processing during the selection, it is advisable to restrict the data to the selection criteria itself, rather than filtering it out using the ABAP code. 

Incorrect

            Select * from zflight.

             Check : zflight -airln = 'LF' and zflight-fligh = 'BW222'.

            Endselect.

Correct            Select * from zflight where airln = 'LF' and fligh = '222'.

            Endselect.

One more point to be noted here is of the select *. Often this is a lazy coding practice. When a programmer gives select * even if one or two fields are to be selected, this can significantly slow the program and put unnecessary load on the entire system. When the application server sends this request to the database server, and the database server has to pass on the entire structure for each row back to the application server. This consumes both CPU and networking resources, especially for large structures.

Thus it is advisable to select only those fields that are needed, so that the database server passes only a small amount of data back.

Also it is advisable to avoid selecting the data fields into local variables as this also puts unnecessary load on the server. Instead attempt must be made to select the fields into an internal table.

How To use aggregate functions

Using the already provided aggregate functions, instead of finding out the minimum/maximum values using ABAP code.

Incorrect             Maximum_numb = 0.

            Select * from zflight where airln = 'LF' and cntry = 'IN'.

             Check zflight -fligh > maximum_numb.

             Maximum_numb = zflight -fligh.

            Endselect.

Correct             Select max( field ) from ztable into maximum_numb where airln = 'LF' and cntry = 'IN'.

The other aggregate functions that can be used are min (to find the minimum value), avg (to find the average of a Data interval), sum (to add up a data interval) and count (counting the lines in a data selection).

Using Views in place of tables

Many times ABAP programmers deal with base tables and nested selects. Instead it is always advisable to see whether there is any view provided by SAP on those base tables, so that the data can be filtered out directly, rather than specially coding for it.

Incorrect

            Select * from zcntry where cntry like 'IN%'.

             Select single * from zflight where cntry = zcntry-cntry and airln = 'LF'.

            Endselect. 

Correct

            Select * from zcnfl where cntry like 'IN%' and airln = 'LF'.

            Endselect.

Use of the into table clause of select statement

Instead of appending one record at a time into an internal table, it is advisable to select all the records in a single shot.

 Incorrect

            Refresh: int_fligh.

            Select * from zflight into int_fligh.

             Append int_fligh. Clear int_fligh.

            Endselect.

 Correct

            Refresh: int_fligh.

            Select * from zflight into table int_fligh.

Modify cluster of lines

Use the variations of the modify command to speed up this kind of processing.

 Incorrect

            Loop at int_fligh.

             If int_fligh-flag is initial.

                        Int_fligh-flag = 'X'.

             Endif.

             Modify int_fligh.

            Endloop. 

Correct

            Int_fligh-flag = 'X'.

            Modify int_fligh transporting flag where flag is initial.

Binary Search

When a programmer uses the read command, the table is sequentially searched. This slows down the processing. Instead of this, use the binary search addition. The binary search algorithm helps faster search of a value in an internal table. It is advisable to sort the internal table before doing a binary search. Binary search repeatedly divides the search interval in half. If the value to be searched is less than the item in the middle of the interval, the search is narrowed to the lower half, otherwise the search is narrowed to the upper half. 

Incorrect

            Read table int_fligh with key  airln = 'LF'. 

Correct

            Read table int_fligh with key  airln = 'LF' binary search.

Appending 2 internal tables

Instead of using the normal loop-endloop approach for this kind of programming, use the variation of the append command. Care should be taken that the definition of both the internal tables should be identical. 

Incorrect

            Loop at int_fligh1.

             Append int_fligh1 to int_fligh2.

            Endloop. 

Correct

            Append lines of int_fligh1 to int_fligh2.

Table Buffering

Use of buffered tables is recommended to improve the performance considerably. The buffer is bypassed while using the following statements

1.     Select distinct

2.     Select ... for update

3.     Order by, group by, having clause

4.     Joins

Use the Bypass buffer addition to the select clause in order to explicitly bypass the buffer while selecting the data.

FOR ALL Entries

Outer join can be created using this addition to the where clause in a select statement. It speeds up the performance tremendously, but the cons of using this variation are listed below

1.     Duplicates are automatically removed from the resulting data set. Hence care should be taken that the unique key of the detail line items should be given in the select statement.

2.     If the table on which the For All Entries IN clause is based is empty, all rows are selected into the destination table. Hence it is advisable to check before-hand that the first table is not empty.

3.     If the table on which the For All Entries IN clause is based is very large, the performance will go down instead of improving. Hence attempt should be made to keep the table size to a moderate level.

Incorrect

            Loop at int_cntry.

             Select single * from zfligh into int_fligh

 where cntry = int_cntry-cntry.

 Append int_fligh.

            Endloop. 

Correct

            Select * from zfligh appending table int_fligh

            For all entries in int_cntry

            Where cntry = int_cntry-cntry.

Structure of Where Clause

When a base table has multiple indices, the where clause should be in the order of the index, either a primary or a secondary index.

To choose an index, the optimizer checks the field names specified in the where clause and then uses an index that has the same order of the fields. One more tip is that if a table begins with MANDT, while an index does not, there is a high possibility that the optimizer might not use that index.

In certain scenarios, it is advisable to check whether a new index can speed up the performance of a program. This will come handy in programs that access data from the finance tables.

Move Statement

Instead of using the move-corresponding clause it is advisable to use the move statement instead. Attempt should be made to move entire internal table headers in a single shot, rather than moving the fields one by one.

Inner Join

When multiple SAP tables are logically joined, it is always advisable to use inner join to read the data from them. This certainly reduces the load on the network. 

Let us take an example of 2 tables, zairln and zflight. The table zairln has the field airln, which is the airline code and the field lnnam, which is the name of the airline. The table zflight has the field airln, the airline code and other fields which hold the details of the flights that an airline operates.

Since these 2 tables a re logically joined by the airln field, it is advisable to use the inner join.

             Select a~airln a~lnnam b~fligh b~cntry into table int_airdet

            From zairln as a inner join zflight as b on a~airln = b~airln.

 In order to restrict the data as per the selection criteria, a where clause can be added to the above inner join.

Using ABAP Sort in place of Order By

The order by clause is executed on the database server, while the sort statement is executed on the application server. Thus instead of giving the order by in the select clause statement, it is better to collect the records in an internal table and then use the sort command to sort the resulting data set.