SAP ABAP PERFORMENCE TIPS

ABAP/4 Optimization


Use the GET RUN TIME command to help evaluate performance. It's hard to know whether that optimization technique REALLY helps unless you test it out. Using this tool can help you know what is effective, under what kinds of conditions. The GET RUN TIME has problems under multiple CPUs, so you should use it to test small pieces of your program, rather than the whole program.

Avoid 'SELECT *', especially in tables that have a lot of fields. Use SELECT A B C INTO instead, so that fields are only read if they are used. This can make a very big difference.

Field-groups can be useful for multi-level sorting and displaying. However, they write their data to the system's paging space, rather than to memory (internal tables use memory). For this reason, field-groups are only appropriate for processing large lists (e.g. over 50,000 records).

If you have large lists, you should work with the systems administrator to decide the maximum amount of RAM your program should use, and from that, calculate how much space your lists will use. Then you can decide whether to write the data to memory or swap space. See the Fieldgroups ABAP example.


Use as many table keys as possible in the WHERE part of your select statements.

Whenever possible, design the program to access a relatively constant number of records (for instance, if you only access the transactions for one month, then there probably will be a reasonable range, like 1200-1800, for the number of transactions inputted within that month). Then use a SELECT A B C INTO TABLE ITAB statement.

Get a good idea of how many records you will be accessing. Log into your productive system, and use SE80 -> Dictionary Objects (press Edit), enter the table name you want to see, and press Display. Go To Utilities -> Table Contents to query the table contents and see the number of records. This is extremely useful in optimizing a program's memory allocation.

Try to make the user interface such that the program gradually unfolds more information to the user, rather than giving a huge list of information all at once to the user.

Declare your internal tables using OCCURS NUM_RECS, where NUM_RECS is the number of records you expect to be accessing. If the number of records exceeds NUM_RECS, the data will be kept in swap space (not memory).

Use SELECT A B C INTO TABLE ITAB whenever possible. This will read all of the records into the itab in one operation, rather than repeated operations that result from a SELECT A B C INTO ITAB... ENDSELECT statement. Make sure that ITAB is declared with OCCURS NUM_RECS, where NUM_RECS is the number of records you expect to access.

Many tables contain totals fields (such as monthly expense totals). Use these avoid wasting resources by calculating a total that has already been calculated and stored.

Program Analysis Utility


To determine the usage of variables and subroutines within a program, you can use the ABAP utility called ‘Program Analysis’ included in transaction SE38. To do so, execute transaction SE38, enter your program name, then use the path Utilities ->

Program Analysis

ABAP PERFORMANCE IMPROVEMENTS VIA DATA DICTIONARY

INDEX CREATION SUGGESTIONS RELATED TO DATABASE PERFORMANCE
The columns at the beginning of an index are the most “common”. The most “common” columns are those where reports are selecting columns with no ranges - the where clause for these columns is an “equal to” expression. Rearrange columns of an index to match the selection criteria. For example, if a select statement is written to include columns 1 and 2 with “equal to” expressions in the where clause and column 3 and 4 are selected with value ranges, then the index should be created with columns in the sequence of 1,2,3,4.


Columns towards the end of the index are either infrequently used in selects or are part of reporting selects that involve ranges of values.

TABLE TYPE SUGGESTIONS RELATED TO DATABASE PERFORMANCE

Use VIEW tables to effectively join and “denormalize” related tables that are taking large amounts of time to select for reporting. For example, at times where highly accessed tables normalize description text into one table and the header data into another table, it may make sense to create a view table that joins the relevant fields of the two associated with a poor performing ABAP.


For POOL tables that contain large amounts of data and are highly accessed, convert the pooled table into a transparent table and add an index. POOLED tables are supposed to be collections of smaller tables that are quickly accessed from the database or are completely buffered in memory.

Pooled tables containing more than a few hundred rows and are accessed many times in a report or transaction are candidates for POOL to TRANSPARENT Conversion. For example, table A053 contains tax jurisdiction condition information and are accessed more than ten times in the sales order create transaction.

If the entire United States tax codes are loaded into these condition tables, the time to save a sales order increases to unacceptable levels. Converting the tax condition table to transparent and creating an index based upon the key fields, decreases processing time from minutes to seconds.

Do not allow the use of LIKE in an SAP SQL statement accessing a large table.
Use internal tables in ABAPs to preselect values once and store values in memory for sorting and searching purposes (this is an assumption stated at the beginning of this discussion).



Avoid logical databases when not processing all row s of a table. In fact, a logical database is merely a group of nested SAP SQL SELECT statements. In general, when processing a small number of rows in a larger table is required, the use of internal tables and NOT using a logical database or nested selects will be much better for performance.