SAP ABAP Perfection - Fixing performance issues - The Read Table statement

Hello fellow ABAPers, this is the first post in the SAP ABAP Perfection series, aiming to help you fix those performance issues you face regularly.

Have you faced performance issues with your programs lately? 
Are you working with huge sets of data (usually not expected in test systems but proving to be a nuisance in productive ones) ? 
Do you have a lot of programs in your SAP system which regularly go into long run?

I, like the most of us, in our project or support life-cycle, have faced these situations. We spend loads of efforts and man hours trying to find out why and what caused this sudden performance problem. Sometimes the problem becomes so critical that entire production lines are required to stop due to job failures or long running jobs. This has serious financial consequences for your company or client. 

The Good News - 
Now that I have shared the worst of the situations with you, time for some good news. All these performance problems can be fixed  and avoided easily by using the following statements correctly - 

• The SELECT statement

and,

• The READ TABLE statement

Let's discuss the READ TABLE statement
In this discussion, I will give you a few hints on how to use the READ TABLE statement correctly. These hints can be applied to 90% of the times you use the statement. For the remaining 10%, please refer to the documentation of READ TABLE in the SAP documentation (F1 Help).
  
What does the Read Table statement do?
Put simply, the Read Table statement is used to read the contents of a single row of an internal table. Optionally, it can use user given conditions to pinpoint the exact row required by the user.

Which other ABAP statement has a similar functionality?
The LOOP AT statement (and it's modifications) in ABAP can also be used to read the contents of an internal table.

What is the difference between READ TABLE and LOOP AT statement? 
The LOOP AT statement will always do a linear search (read each entry one by one) to find the correct entry matching the user given conditions. While the READ TABLE statement can make use of the binary search technique (divide and search) to find the correct entry. The binary search option is substantially faster as the number of entries in the internal table grows. As a comparison of the speed: to search a list of one million items takes as many as one million iterations with linear search, but never more than twenty iterations with binary search.

What are the best ways to use READ TABLE?
Now that we already know that the Read Table statement is superior than the Loop At statement as far as searching is concerned, let us dwell on the best ways to use the Read Table statement.

• Always use the INDEX option or the BINARY SEARCH option wherever possible
• When using BINARY SEARCH, make sure that the internal table is sorted with those keys

e.g.: 

Read using INDEX option

READ TABLE [itab] INTO [variable] INDEX 1.

The above statement is going to read the contents of row 1 (as INDEX 1 is being read) of internal table [itab] and store it in the [variable]. This means that the user is requesting the Read Table to fetch the contents of row 1 directly without searching the internal table. This statement can be used in situations where we are sure that only the first (or any specific entry) is required to be read.

e.g.: We have a list of Sales Orders in internal table [itab_so] and we want to read the details of the latest Sales Order. In such a case, we can easily sort the [itab_so] in descending order of the creation date and read the first entry in it. This means that once we have sorted the [itab_so] in descending order, we are sure that we will require only the first entry (or INDEX 1) of the internal table.

Read using the BINARY SEARCH

SORT [itab] BY [key_1].

READ TABLE [itab] INTO [variable] WITH KEY [key_1] = [variable_1] BINARY SEARCH.

The above READ TABLE statement is going to search for the entry in [itab] where the field [key_1] matches the [variable_1] input given by the user. The search algorithm to be used here is binary search as specified by the final section of the statement. As already mentioned in a previous section, sorting is mandatory when using binary search.

Conclusion

If you keep these easy to use options in mind and implement them in your programs, then you will notice a definite increase in performance. The larger the data set you are working with, the greater the performance increase.

With these suggestions, I leave you to ponder over them and maybe try and implement them in one of your demo programs to see the difference.

DIY Series - Create Your Own Windows Dock

Do you keep going to your start menu to navigate to any folder on your computer?

Do your indispensable shortcuts cover your beautiful wallpaper?

Do you always keep going to your start menu for opening your programs?

Do you love docks on your desktop?

If you do any of the above, then today I will show you how to create your custom dock easily and without much hassle. 

The custom dock primarily has these advantages -

1. It will keep your desktop spic and span

2. You no longer have to search for your shortcuts in your overcrowded desktop

3. Its an easy way to keep your favorite programs and shortcuts handy and yet out of sight

Create your own windows dock

Requirements:

1. Any flavor of windows (Win XP, Win Vista, Win 7 etc.)

2. Memory (RAM) is not a problem

Step 1:

Create a folder anywhere in your computer. Name it 'Fav'. Of course you are free to name it anything you want.

Folder 'Fav' created

Step 2:

Choose your favorite shortcuts to folders, shortcuts to programs. Then copy and paste them to the folder 'Fav' which you created in step 1.

Shortcuts added to 'Fav' folder

Step 3:

Drag the folder 'Fav' to any ledge of the screen except the ledge where your Task bar is situated. Your dock has been created.

Folder dragged to window ledge

Step 4:

Right click on the dock and choose the options you like. You can choose to view large or small icons on your dock. Maybe, you want to show text and title of the shortcuts on the dock.

Step 5:

Right click again on the dock and select Auto-Hide. This will ensure that the dock does not get in your way once you are done with it.

That’s it. Your dock is now ready for use.

TMS_TM_GET_HISTORY

This article is for those of you who are interested in Transport Management in SAP systems. This article tells you how to get the import history that is displayed in T-code STMS.

Recently, I was developing a tool to count the modification of the objects which are in production.  

Now, for finding the objects you need a data source. There I found two options -

1.   The E070 table which would contain all the desired Transport Requests

2.   The Import History found in transaction STMS

After much thought, I decided on the Import History source. This decision was based on primarily two reasons. 

a.    The import history contained a practical and correct list of all the imports that happened in the system

b.    The import history could be fetched on the basis of start and end date of import and not just the creation date of the transports.

That was when I came across the FM  TMS_TM_GET_HISTORY

TMS_TM_GET_HISTORY

The basic functionality of the FM is to provide a unformatted data of the import history based on the start date time and end date and time provided to it. In addition it also needs the system name and domain name of the system to be provided to it. Following section talks about the import parameters.

Importing Parameters:

iv_system: The system name (Note: directly providing sy-sysid won't work as the types are different)

iv_domain: The domain name of the system. (Can be found from table  tmscsys; field domnam)

iv_allcli: To be put as 'X'

iv_imports: To be put as 'X'

Exporting Parameters:

et_tmstpalog: This is the table of the import history. Type is tmstpalogs table type.

Changing Parameters:

cv_start_date: This is the date from where you want the import history from

cv_start_time: This is the time of start for your search of the import history

cv_end_date: This is the date till which you want the import history of the system

cv_end_time: Similarly, this parameter defines the end time till which the import history should be fetched

Sample Code:

* Initialise the system
  l_sysname = sy-sysid.


* Get the domain
  SELECT SINGLE domnam
    FROM tmscsys
    INTO l_domain_p
   WHERE sysnam = l_sysname.


  IF sy-subrc = 0.


* Get the import history from the sytem provided


    CALL FUNCTION 'TMS_TM_GET_HISTORY'
     EXPORTING
       iv_system               = l_sysname
       iv_domain               = l_domain_p
       iv_allcli               = k_true
*        IV_TRCLI                =
*        IV_TRFUNCTION           =
*        iv_project              =
       iv_imports              = k_true
*        IV_EXPORTS              =
*        IV_ALL_STEPS            =
*        IV_ALL_ALOG_STEPS       =
*        IV_TPSTAT_KEY           =
       iv_monitor              = k_true
     IMPORTING
*        EV_ALOG_LINENR          =
       et_tmstpalog            = li_import_history_p
*        ES_EXCEPTION            =
     CHANGING
       cv_start_date           = l_strtdt_p
       cv_start_time           = l_start_time_p
       cv_end_date             = l_enddt_p
       cv_end_time             = l_end_time_p
     EXCEPTIONS
       alert                   = 1
       OTHERS                  = 2.


    IF sy-subrc <> 0.
      MESSAGE ID sy-msgid TYPE sy-msgty NUMBER sy-msgno
              WITH sy-msgv1 sy-msgv2 sy-msgv3 sy-msgv4.
    ENDIF.

ENDIF.

TR_OBJECT_JUMP_TO_TOOL

Have you ever wondered how any object that you want to view in the requests in se10 gets displayed ?

If your answer is yes, then read on to find an interesting function which you can use in your custom code to actually display any object in its own editor!

TR_OBJECT_JUMP_TO_TOOL

This Function Module (FM) is very simple to use. All you need to know  is the Object Name, Program ID and the Object Id.

Importing Parameters:

Object Name - The name of the object.

PGMID & OBJECT - These two fields together denote the type of object

The above data can be fetched from E071 table provided you know the Transport Request Number.

Once you pass these fields to the respective importing parameters of the FM, it will open the desired tool for you.

 Mode (iv_action):

Also,  you can control the way the object is opened in its tool, i.e. in display mode or in change mode.

This is easily done by passing the respective character strings in the importing parameter 'iv_action'.

Mode	Value
Display	'SHOW'
Change	'EDIT'

Example code:




CALL FUNCTION 'TR_OBJECT_JUMP_TO_TOOL'
            EXPORTING
              iv_pgmid           = e071-pgmid            " PGMID
              iv_object          = e071-object           " OBJECT
              iv_obj_name      = e071-obj_name       " Object Name
              iv_action          = 'SHOW'                  " Mode
            EXCEPTIONS
              jump_not_possible = 1
              OTHERS            = 2.

          IF sy-subrc <> 0.
            MESSAGE ID sy-msgid TYPE sy-msgty NUMBER sy-msgno
                    WITH sy-msgv1 sy-msgv2 sy-msgv3 sy-msgv4.
          ENDIF.

Any comments or suggestions are welcome!