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If possible, convert the data in the driver table to ranges so a BETWEEN statement is used instead of and
OR statement:
FOR ALL ENTRIES IN i_tab
WHERE mykey >= i_tab-low and
mykey
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Very large amount of data
Similar to Nested selects - when the accesses are planned by the programmer
In some cases the fastest
Not so memory critical
The minus
Very difficult to program/understand
Mixing processing and reading of data not possible
Use the selection criteria
SELECT * FROM SBOOK.
CHECK: SBOOK-CARRID = 'LH' AND
SBOOK-CONNID = '0400'.
ENDSELECT.
SELECT * FROM SBOOK
WHERE CARRID = 'LH' AND
CONNID = '0400'.
ENDSELECT.
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Use the aggregated functions
C4A = '000'.
SELECT * FROM T100
WHERE SPRSL = 'D' AND
ARBGB = '00'.
CHECK: T100-MSGNR > C4A.
C4A = T100-MSGNR.
ENDSELECT.
SELECT MAX( MSGNR ) FROM T100 INTO C4A
WHERE SPRSL = 'D' AND
ARBGB = '00'.
Select with view
SELECT * FROM DD01L
WHERE DOMNAME LIKE 'CHAR%'
AND AS4LOCAL = 'A'.
SELECT SINGLE * FROM DD01T
WHERE DOMNAME = DD01L-DOMNAME
AND AS4LOCAL = 'A'
AND AS4VERS = DD01L-AS4VERS
AND DDLANGUAGE = SY-LANGU.
ENDSELECT.
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SELECT * FROM DD01V
WHERE DOMNAME LIKE 'CHAR%'
AND DDLANGUAGE = SY-LANGU.
ENDSELECT.
Select with index support
SELECT * FROM T100
WHERE ARBGB = '00'
AND MSGNR = '999'.
ENDSELECT.
SELECT * FROM T002.
SELECT * FROM T100
WHERE SPRSL = T002-SPRAS
AND ARBGB = '00'
AND MSGNR = '999'.
ENDSELECT.
ENDSELECT.
Select Into table
REFRESH X006.
SELECT * FROM T006 INTO X006.
APPEND X006.
ENDSELECT
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SELECT * FROM T006 INTO TABLE X006.
Select with selection list
SELECT * FROM DD01L
WHERE DOMNAME LIKE 'CHAR%'
AND AS4LOCAL = 'A'.
ENDSELECT
SELECT DOMNAME FROM DD01L
INTO DD01L-DOMNAME
WHERE DOMNAME LIKE 'CHAR%'
AND AS4LOCAL = 'A'.
ENDSELECT
Key access to multiple lines
LOOP AT TAB.
CHECK TAB-K = KVAL.
" ...
ENDLOOP.
LOOP AT TAB WHERE K = KVAL.
" ...
ENDLOOP.
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Copying internal tables
REFRESH TAB_DEST.
LOOP AT TAB_SRC INTO TAB_DEST.
APPEND TAB_DEST.
ENDLOOP.
TAB_DEST[] = TAB_SRC[].
Modifying a set of lines
LOOP AT TAB.
IF TAB-FLAG IS INITIAL.
TAB-FLAG = 'X'.
ENDIF.
MODIFY TAB.
ENDLOOP.
TAB-FLAG = 'X'.
MODIFY TAB TRANSPORTING FLAG
WHERE FLAG IS INITIAL.
Deleting a sequence of lines
DO 101 TIMES.
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DELETE TAB_DEST INDEX 450.
ENDDO.
DELETE TAB_DEST FROM 450 TO 550.
Linear search vs. binary
READ TABLE TAB WITH KEY K = 'X'.
READ TABLE TAB WITH KEY K = 'X' BINARY SEARCH.
Comparison of internal tables
DESCRIBE TABLE: TAB1 LINES L1,
TAB2 LINES L2.
IF L1 L2.
TAB_DIFFERENT = 'X'.
ELSE.
TAB_DIFFERENT = SPACE.
LOOP AT TAB1.
READ TABLE TAB2 INDEX SY-TABIX.
IF TAB1 TAB2.
TAB_DIFFERENT = 'X'. EXIT.
ENDIF.
ENDLOOP.
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ENDIF.
IF TAB_DIFFERENT = SPACE.
" ...
ENDIF.
IF TAB1[] = TAB2[].
" ...
ENDIF.
Modify selected components
LOOP AT TAB.
TAB-DATE = SY-DATUM.
MODIFY TAB.
ENDLOOP.
WA-DATE = SY-DATUM.
LOOP AT TAB.
MODIFY TAB FROM WA TRANSPORTING DATE.
ENDLOOP.
Appending two internal tables
LOOP AT TAB_SRC.
APPEND TAB_SRC TO TAB_DEST.
ENDLOOP
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APPEND LINES OF TAB_SRC TO TAB_DEST.
Deleting a set of lines
LOOP AT TAB_DEST WHERE K = KVAL.
DELETE TAB_DEST.
ENDLOOP
DELETE TAB_DEST WHERE K = KVAL.
Tools available in SAP to pin-point a performance problem
The runtime analysis (SE30)
SQL Trace (ST05)
Tips and Tricks tool
The performance database
Optimizing the load of the database
Using table buffering
Using buffered tables improves the performance considerably. Note that in some cases a stament can
not be used with a buffered table, so when using these staments the buffer will be bypassed. These
staments are:
Select DISTINCT
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ORDER BY / GROUP BY / HAVING clause
Any WHERE clasuse that contains a subquery or IS NULL expression
JOIN s
A SELECT... FOR UPDATE
If you wnat to explicitly bypass the bufer, use the BYPASS BUFFER addition to the SELECR clause.
Use the ABAP SORT Clause Instead of ORDER BY
The ORDER BY clause is executed on the database server while the ABAP SORT statement is executed on
the application server. The datbase server will usually be the bottleneck, so sometimes it is better to
move thje sort from the datsbase server to the application server.
If you are not sorting by the primary key ( E.g. using the ORDER BY PRIMARY key statement) but are
sorting by another key, it could be better to use the ABAP SORT stament to sort the data in an internaltable. Note however that for very large result sets it might not be a feasible solution and you would
want to let the datbase server sort it.
Avoid ther SELECT DISTINCT Statement
As with the ORDER BY clause it could be better to avoid using SELECT DISTINCT, if some of the fields are
not part of an index. Instead use ABAP SORT + DELETE ADJACENT DUPLICATES on an internal table, to
delete duplciate rows.
TIPS & TRICKS FOR 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
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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.
Generally, try to reduce I/O first, then memory, then CPU activity. I/O operations that read/write to hard
disk are always the most expensive operations. Memory, if not controlled, may have to be written to
swap space on the hard disk, which therefore increases your I/O read/writes to disk. CPU activity can be
reduced by careful program design, and by using commands such as SUM (SQL) and COLLECT (ABAP/4).
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.
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.
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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.
If the number of records you are reading is constantly growing, you may be able to break it into chunks
of relatively constant size. For instance, if you have to read all records from 1991 to present, you can
break it into quarters, and read all records one quarter at a time. This will reduce I/O operations. Test
extensively with GET RUN TIME when using this method.
Know how to use the 'collect' command. It can be very efficient.
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Use the SELECT SINGLE command whenever possible.
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.
ABAP/4 Development Code Efficiency Guidelines
ABAP/4 (Advanced Business Application Programming 4GL) language is an "event-driven", "top-down",
well-structured and powerful programming language. The ABAP/4 processor controls the execution of
an event. Because the ABAP/4 language incorporates many "event" keywords and these keywords need
not be in any specific order in the code, it is wise to implement in-house ABAP/4 coding standards.
SAP-recommended customer-specific ABAP/4 development guidelines can be found in the SAP-
documentation.
This page contains some general guidelines for efficient ABAP/4 Program Development that should be
considered to improve the systems performance on the following areas:-
Physical I/O - data must be read from and written into I/O devices. This can be a potential bottle neck. A
well configured system always runs 'I/O-bound' - the performance of the I/O dictates the overall
performance.
Memory consumption of the database resources eg. buffers, etc.
CPU consumption on the database and application servers
Network communication - not critical for little data volumes, becomes a bottle neck when large volumes
are transferred.
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Policies and procedures can also be put into place so that every SAP-customer development object is
thoroughly reviewed (qualityprogram correctness as well as code-efficiency) prior to promoting the
object to the SAP-production system. Information on the SAP R/3 ABAP/4 Development Workbench
programming tools and its features can be found on the SAP Public Web-Server.
-
-
CLASSIC GOOD 4GL PROGRAMMING CODE-PRACTICES GUIDELINES
Avoid dead-code
Remove unnecessary code and redundant processing
Spend time documenting and adopt good change control practices
Spend adequate time anayzing business requirements, process flows, data-structures and data-model
Quality assurance is key: plan and execute a good test plan and testing methodology
Experience counts
-
-
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SELECT * FROM
ENDSELECT
In order to keep the amount of data which is relevant to the query the hit set small, avoid using
SELECT+CHECK statements wherever possible. As a general rule of thumb, always specify all known
conditions in the WHERE clause (if possible). If there is no WHERE clause the DBMS has no chance to
make optimizations. Always specify your conditions in the Where-clause instead of checking them
yourself with check-statements. The database system can also potentially make use a database index (if
possible) for greater efficiency resulting in less load on the database server and considerably less load on
the network traffic as well.
Also, it is important to use EQ (=) in the WHERE clause wherever possible, and analyze the SQL-
statement for the optimum path the database optimizer will utilize via SQL-trace when necessary.
Also, ensure careful usage of "OR", "NOT" and value range tables (INTTAB) that are used
inappropriately in Open SQL statements.
-
-
SELECT *
vs.
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If you want to find the maximum, minimum, sum and average value or the count of a database column,
use a select list with aggregate functions instead of computing the aggregates within the program. The
RDBMS is responsible for aggregated computations instead of transferring large amount of data to the
application. Overall Network, Application-server and Database load is also considerably less.
-
-
SELECT INTO TABLE
.
ENDSELECT
If you process your data only once, use a SELECT-ENDSELECT loop instead of collecting data in an
internal table with SELECT ... INTO TABLE. Internal table handling takes up much more space
-
-
Nested SELECT statements:
SELECT * FROM
ENDSELECT
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To process a join, use a view wherever possible instead of nested SELECT statements.
Using nested selects is a technique with low performance. The inner select statement is executed
several times which might be an overhead. In addition, fewer data must be transferred if another
technique would be used eg. join implemented as a view in ABAP/4 Repository.
SELECT ... FORM ALL ENTRIES
Explicit cursor handling (for more information, goto Transaction SE30Tips & Tricks)
-
-
Nested select:
SELECT * FROM pers WHERE condition.
SELECT * FROM persproj WHERE person = pers-persnr.
... process ...
ENDSELECT.
ENDSELECT.
vs.
SELECT persnr FROM pers INTO TABLE ipers WHERE cond. .
SELECT * FROM persproj FOR ALL ENTRIES IN ipers
WHERE person = ipers-persnr
... process .
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ENDSELECT.
In the lower version the new Open SQL statement FOR ALL ENTRIES is used. Prior to the call, all
interesting records from 'pers' are read into an internal table. The second SELECT statement results in a
call looking like this (ipers containing: P01, P02, P03):
(SELECT * FROM persproj WHERE person = 'P01')
UNION
(SELECT * FROM persproj WHERE person = 'P02')
UNION
(SELECT * FROM persproj WHERE person = 'P03')
In case of large statements, the R/3's database interface divides the statement into several parts and
recombines the resulting set to one. The advantage here is that the number of transfers is minimized
and there is minimal restrictions due to the statement size (compare with range tables).
-
-
SELECT * FROM
Use a select list or a view instead of SELECT *, if you are only interested in specific columns of the table.
If only certain fields are needed then only those fields should be read from the database. Similarly, the
number of columns can also be restricted by using a view defined in ABAP/4 Dictionary. Overall
database and network load is considerably less.
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-
-
SELECT without table buffering support
vs.
SELECT with table buffering support
For all frequently used, read-only(few updates) tables, do attempt to use SAP-buffering for eimproved
performance response times. This would reduce the overall Database activity and Network traffic.
-
-
Single-line inserts
LOOP AT
ENDLOOP
vs.
Array inserts
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Whenever possible, use array operations instead of single-row operations to modify the database
tables.
Frequent communication between the application program and database system produces considerable
overhead.
-
-
Single-line updates
SELECT * FROM
Wherever possible, use column updates instead of single row updates to update your database tables
-
-
DO....ENDDO loop with Field-Symbol
vs.
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Using CA operator
Use the special operators CO, CA, CS instead of programming the operations yourself
If ABAP/4 statements are executed per character on long strings, CPU consumprion can rise substantially
-
-
Use of a CONCATENATE function module
vs.
Use of a CONCATENATE statement
Some function modules for string manipulation have become obsolete, and should be replaced by ABAP
statements or functions
STRING_CONCATENATE... ---> CONCATENATE
STRING_SPLIT... ---> SPLIT
STRING_LENGTH... ---> strlen()
STRING_CENTER... ---> WRITE..TO. ..CENTERED
STRING_MOVE_RIGHT ---> WRITE...TO...RIGHT-JUSTIFIED
-
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-
Moving with offset
vs.
Use of the CONCATENATE statement
Use the CONCATENATE statement instead of programming a string concatenation of your own
-
-
Use of SEARCH and MOVE with offset
vs.
Use of SPLIT statement
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Use the SPLIT statement instead of programming a string split yourself
-
-
Shifting by SY-FDPOS places
vs
Using SHIFT...LEFT DELETING LEADING...
If you want ot delete the leading spaces in a string use the ABAP/4 statements SHIFT...LEFT DELETING
LEADING... Other constructions (with CN and SHIFT... BY SY-FDPOS PLACES, with CONDENSE if possible,
with CN and ASSIGN CLA+SY-FDPOS(LEN) ...) are not as fast
-
-
Get a check-sum with field length
vs
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Get a check-sum with strlen ()
Use the strlen () function to restrict the DO loop to the relevant part of the field, eg. when determinating
a check-sum
2.Other Explanation
Performance Tuning
1.1 SELECT:
Always select the only the required fields from the database tables and give the filtering condition in
the select statement itself.
Recommended
Select * from zflight where airln = LF and fligh = 222.
Endselect.
Using select * fetches all the fields from the table and thus occupies more memory.
Not recommended
SELECT * FROM DD01L INTO DD01L_WA
WHERE DOMNAME LIKE 'CHAR%'
AND AS4LOCAL = 'A'.
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ENDSELECT.
Recommended
SELECT DOMNAME FROM DD01L
INTO DD01L_WA-DOMNAME
WHERE DOMNAME LIKE 'CHAR%'
AND AS4LOCAL = 'A'.
ENDSELECT.
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.
If all the fields of a table have to be selected then select * into table is better option then declaringexplicit work area.
SELECT * FROM T006 INTO TABLE X006.
Use of 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.
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1. Try to use aggregate functions.
Select max (fligh) from zflight into maxnu 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).
2. Try to use views instead of tables if provided by SAP.
3. Whenever reading internal table into a work area then try to mention key if possible.
To copy contents of one internal table into another use this syntax.
Instead of loop on one into work area and appending work area to another.
TAB_DEST[] = TAB_SRC[].
1.2 READ
Always try to read internal table by passing key and read by Binary search.
And before doing this always sort your internal table (This is the primary condition for binary search).
Not Recommended
Read table int_fligh with key airln = LF.
Recommended
Read table int_fligh with key airln = LF binary search.
Always read the required fields using TRANSPORTING f1 f2
read table i_vbap transporting posnr with key
vbeln = i_vbak-vbeln binary search.
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1.3 Sort Statement
A linear search on internal table with large record size or large record numbers is time consuming. It is
always a good practice to search a record by binary search after sorting. The difference is felt especially
in the production environment where the live data is usually huge.
When an internal table is sorted without specifying the keys the default is used. Hence specify the fields
to be sorted, which is more efficient than SORT ITAB.
Sorting an Internal Table, though done in the memory, is a unnecessary load on the processor. Try to fill
the table with sorted values. If the SORTED BY clause cannot be used in the select statement, then
sorting the Internal Table is inevitable.
Always try to sort by giving key.
Sort i_mara by matnr.
Or
Try to declare your table type sorted table of or type hashed table of
1.4 DELETE
Where appropriate using the following syntax, task of deleting a set of lines can be transferred to the
kernel.
DELETE itable [FROM ...] [TO ...] WHERE ...
If possible, WHERE should be used together with FROM... and/or TO... to enhance performance.
The performance gain when using
DELETE itable WHERE....
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Instead of
LOOP AT table WHERE ...
DELETE itable.
ENDLOOP.
Increases with the number of entries the internal table contains and the number of lines to be deleted.
When deleting adjacent duplicates use COMPARING fields as far as possible.
E.g. DELETE ADJACENT DUPLICATE ENTRIES from
COMPARING F1 F2
DELETE ADJACENT DUPLICATES FROM ITAB COMPARING K.
1.5 MOVE
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.
It is always advisable not to write move corresponding because in this the system looks for identical data
elements and then it assigns the value.
Always try to use move fields manually from one to other structure
1.6 NESTED LOOPS
Avoid nested looping on the internal tables. They eat up processor time.
If nested loops are unavoidable then,
Avoid the following:
SORT: I_vbak by vbeln, I_vbap by vbeln.
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Loop at I_vbak
Loop at I_vbap where vbeln = I_vbak-vbeln.
Endloop.
Endloop.
Instead use:
SORT: I_vbak by vbeln, I_vbap by vbeln.
Loop at I_vbak
Read table I_vbap with key vbeln = I_vbak-vbeln
binary search transporting no fields.
Loop at I_vbap from sy-tabix.
If I_vbap-vbeln I_vbak-vbeln.
Exit.
EndIf.
Endloop.
Endloop.
1.7 DESCRIBE
DESCRIBE TABLE [LINES ] [OCCURS ] [KIND ]
To find out how many entries are in an internal table use DESCRIBE.
DESCRIBE TABLE ITAB LINES CNTLNS.
Is more efficient than
LOOP AT ITAB.
CNTLNS = CNTLNS + 1.
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ENDLOOP.
1.8 FIELD CONVERSION
Use fields of type I for typical integral variables like indices.
Use numeric literals or named constants with a number type
instead of character strings if you are dealing with type-I
or integral type-P fields.
Use type-N fields only for pure
digit strings that are not intended for calculations, e.g.,
telephone numbers or parts of a date or time field.
1.9 CONTROL BREAK STATEMENTS
SAP recommends not to use control break events in loop statements which have a Where Clause.
The outcome of the results cannot be predicted correctly. However it is a general practice to use these
control break events even in loop statements, which have a Where Clause. It is always a good practice to
avoid control break events in such cases. If the logic is complicated without events then populate a new
internal table, which has the required records, and then use events with it.
In a LOOP which processes an internal table, you can use special control structures for control break
processing. All these structures begin with AT and end with ENDAT. The sequence of statements which
lies between them is then executed if a control break occurs.
You can use these key words for control break processing with internal tables only if a loop is actively
processing an internal table and reference is to the innermost currently active loop.
The control level structure with internal tables is static. It corresponds exactly to the sequence of
columns in the internal table (from left to right). In this context, the criteria according to which you sort
the internal table are unimportant.
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At the start of a new control level (i.e. immediately after AT), the following occurs in the output area of
the current LOOP statement:
All character type fields (on the right) are filled with "*" after the current control level key.
All other fields (on the right) are set to their initial values after the current control level key.
Between AT and ENDAT, you can use SUM to insert the appropriate control totals in the numeric fields
(see also ABAP Number Types) of the LOOP output area (on the right) after the current control level key.
Summing is supported both at the beginning of a control level (AT FIRST, AT NEW f) and also the end of a
control level (AT END OF f, AT LAST).
At the end of the control level processing (i.e. after ENDAT), the old contents of the LOOP output area
are restored.
The main purpose of control break statements is to :
To display headings (AT FIRST)
To display Subheading (AT NEW)
To display subtotals (AT END OF )
To get grand total and Footer(AT LAST)
On change of - it can be used in any loops like do, loop at,etc.
2 SUBROUTINES
Whenever values need to be passed in a subroutine have type declarations assigned to the formal
parameters. If no specific type declaration is possible then use TYPE ANY. This improves the
performance. It is also recommended by SAP and can be noticed during extended program check (EPC)
for the program.
When modularizing your program, use FORMS rather than FUNCTIONS whenever practical. A statement
of PERFORM FORM < > requires significantly less resources and time than does a CALL FUNCTION < >.
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2.1 EFFICIENT DATABASE SELECTION
The following basic guidelines need to be considered while retrieving data from the database:
Avoid unnecessary database accesses
Keep the number of data records small
Reduce information transfer to application server
Reduce the load on the database engine
Use database locks and SAP enqueue.
Basic thing to be kept in mind is:
Get the data in one single go as far as possible, thereby reducing the network traffic.
Always use the WHERE clause in the corresponding SQL statement. An application should read only
those lines of the table that are necessary for the processing. Therefore formulate filter condition not
through CHECK statements, rather through part of WHERE statements
Avoid using complex WHERE clauses since the system has to break them down into several individual
statements for the database system
If all you are interested in is retrieving all possible values for a given table field (i.e. you do not want
duplicates), then SELECT DISTINCT will provide that capability and will also restrict the amount of data
passed back to the application to only the set of unique values.
Instead of using DISTINCT, the application might remove the duplicates by itself, e.g. using DELETE
ADJACENT DUPLICATES. This should only be used if a small number of duplicates are expected.
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2.2 MISCELLANOUS
1. Avoid Use of validations between SELECT and ENDSELECT. Rather, retrieve the data into an internal
table and make your validations.
2. Use Aggregate functions along with the SELECT statement is better than looping through the entire
set of records.
3. Nested select is a No No, instead of that use Joins or Views. This improves the readability to some
extent also.
4. Always use INTO TABLE and FOR ALL ENTRIES where ever possible. While using FOR ALL ENTRIES,
check if the table contains any entries.
5. Modifying a group of lines. Do not loop at all the records, rather use the MODIFY statement on the
internal table as a whole.
6. READ TABLE always with BINARY SEARCH.
7. Try to align your WHERE clause in sync with the index.
8. Appropriate use of INNER JOIN
9. Use ABAP sort over ORDER BY.
10. Use simple tools like SE30 and ST05 to fine tune the programs.