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primary key-index-non-primary key

kiran_k8
Active Contributor
0 Kudos

Hi Folks,

SELECT VBELN

FKART

VBTYP

VKORG

VTWEG

FKDAT

ERDAT

KUNRG

FROM VBRK INTO TABLE ITAB1

<b> WHERE BUKRS = P_BUKRS AND

ERDAT IN S_ERDAT.</b>

The fields in the where clause are not primary keys,so it is taking time to fetch the data.How can I improve efficiency of the above select statement.

1.loop at itab1.

if itab1-erdat not in s_erdat.

delete itab1.

endif.

endloop.

2.delete itab1 where itab1-erdat not in s_erdat.

Out of the above two which one is efficient.

What if I can't avoid giving non-primary keys in the where clause,can I go ahead and create an index.

Kindly opine.

Thanks,

K.Kiran.

1 ACCEPTED SOLUTION

Former Member
0 Kudos

Hi

<b>Ways of Performance Tuning</b>

1. Selection Criteria

2. Select Statements

• Select Queries

• SQL Interface

• Aggregate Functions

• For all Entries

Select Over more than one Internal table

<b>Selection Criteria</b>

1. Restrict the data to the selection criteria itself, rather than filtering it out using the ABAP code using CHECK statement.

2. Select with selection list.

<b>Points # 1/2</b>

SELECT * FROM SBOOK INTO SBOOK_WA.

CHECK: SBOOK_WA-CARRID = 'LH' AND

SBOOK_WA-CONNID = '0400'.

ENDSELECT.

The above code can be much more optimized by the code written below which avoids CHECK, selects with selection list

SELECT CARRID CONNID FLDATE BOOKID FROM SBOOK INTO TABLE T_SBOOK

WHERE SBOOK_WA-CARRID = 'LH' AND

SBOOK_WA-CONNID = '0400'.

<b>Select Statements Select Queries</b>

1. Avoid nested selects

2. Select all the records in a single shot using into table clause of select statement rather than to use Append statements.

3. 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.

4. For testing existence , use Select.. Up to 1 rows statement instead of a Select-Endselect-loop with an Exit.

5. Use Select Single if all primary key fields are supplied in the Where condition .

<b>Point # 1</b>

SELECT * FROM EKKO INTO EKKO_WA.

SELECT * FROM EKAN INTO EKAN_WA

WHERE EBELN = EKKO_WA-EBELN.

ENDSELECT.

ENDSELECT.

The above code can be much more optimized by the code written below.

SELECT PF1 PF2 FF3 FF4 INTO TABLE ITAB

FROM EKKO AS P INNER JOIN EKAN AS F

ON PEBELN = FEBELN.

Note: A simple SELECT loop is a single database access whose result is passed to the ABAP program line by line. Nested SELECT loops mean that the number of accesses in the inner loop is multiplied by the number of accesses in the outer loop. One should therefore use nested SELECT loops only if the selection in the outer loop contains very few lines or the outer loop is a SELECT SINGLE statement.

<b>Point # 2</b>

SELECT * FROM SBOOK INTO SBOOK_WA.

CHECK: SBOOK_WA-CARRID = 'LH' AND

SBOOK_WA-CONNID = '0400'.

ENDSELECT.

The above code can be much more optimized by the code written below which avoids CHECK, selects with selection list and puts the data in one shot using into table

SELECT CARRID CONNID FLDATE BOOKID FROM SBOOK INTO TABLE T_SBOOK

WHERE SBOOK_WA-CARRID = 'LH' AND

SBOOK_WA-CONNID = '0400'.

<b>Point # 3</b>

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 . 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.

<b>Point # 4</b>

SELECT * FROM SBOOK INTO SBOOK_WA

UP TO 1 ROWS

WHERE CARRID = 'LH'.

ENDSELECT.

The above code is more optimized as compared to the code mentioned below for testing existence of a record.

SELECT * FROM SBOOK INTO SBOOK_WA

WHERE CARRID = 'LH'.

EXIT.

ENDSELECT.

<b>Point # 5</b>

If all primary key fields are supplied in the Where condition you can even use Select Single.

Select Single requires one communication with the database system, whereas Select-Endselect needs two.

<b>Select Statements contd.. SQL Interface</b>

1. Use column updates instead of single-row updates

to update your database tables.

2. For all frequently used Select statements, try to use an index.

3. Using buffered tables improves the performance considerably.

<b>

Point # 1</b>

SELECT * FROM SFLIGHT INTO SFLIGHT_WA.

SFLIGHT_WA-SEATSOCC =

SFLIGHT_WA-SEATSOCC - 1.

UPDATE SFLIGHT FROM SFLIGHT_WA.

ENDSELECT.

The above mentioned code can be more optimized by using the following code

UPDATE SFLIGHT

SET SEATSOCC = SEATSOCC - 1.

<b>Point # 2</b>

SELECT * FROM SBOOK CLIENT SPECIFIED INTO SBOOK_WA

WHERE CARRID = 'LH'

AND CONNID = '0400'.

ENDSELECT.

The above mentioned code can be more optimized by using the following code

SELECT * FROM SBOOK CLIENT SPECIFIED INTO SBOOK_WA

WHERE MANDT IN ( SELECT MANDT FROM T000 )

AND CARRID = 'LH'

AND CONNID = '0400'.

ENDSELECT.

<b>Point # 3</b>

Bypassing the buffer increases the network considerably

SELECT SINGLE * FROM T100 INTO T100_WA

BYPASSING BUFFER

WHERE SPRSL = 'D'

AND ARBGB = '00'

AND MSGNR = '999'.

The above mentioned code can be more optimized by using the following code

SELECT SINGLE * FROM T100 INTO T100_WA

WHERE SPRSL = 'D'

AND ARBGB = '00'

AND MSGNR = '999'.

<b>Select Statements contd… Aggregate Functions</b>

• 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 yourself.

Some of the Aggregate functions allowed in SAP are MAX, MIN, AVG, SUM, COUNT, COUNT( * )

Consider the following extract.

Maxno = 0.

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

Check zflight-fligh > maxno.

Maxno = zflight-fligh.

Endselect.

The above mentioned code can be much more optimized by using the following code.

Select max( fligh ) from zflight into maxno where airln = ‘LF’ and cntry = ‘IN’.

<b>Select Statements contd…For All Entries</b>

• The for all entries creates a where clause, where all the entries in the driver table are combined with OR. If the number of entries in the driver table is larger than rsdb/max_blocking_factor, several similar SQL statements are executed to limit the length of the WHERE clause.

The plus

• Large amount of data

• Mixing processing and reading of data

• Fast internal reprocessing of data

• Fast

The Minus

• Difficult to program/understand

• Memory could be critical (use FREE or PACKAGE size)

<u>Points to be must considered FOR ALL ENTRIES</u>

• Check that data is present in the driver table

• Sorting the driver table

• Removing duplicates from the driver table

Consider the following piece of extract

Loop at int_cntry.

Select single * from zfligh into int_fligh

where cntry = int_cntry-cntry.

Append int_fligh.

Endloop.

The above mentioned can be more optimized by using the following code.

Sort int_cntry by cntry.

Delete adjacent duplicates from int_cntry.

If NOT int_cntry[] is INITIAL.

Select * from zfligh appending table int_fligh

For all entries in int_cntry

Where cntry = int_cntry-cntry.

Endif.

<b>

Select Statements contd… Select Over more than one Internal table</b>

1. Its better to use a views instead of nested Select statements.

2. To read data from several logically connected tables use a join instead of nested Select statements. Joins are preferred only if all the primary key are available in WHERE clause for the tables that are joined. If the primary keys are not provided in join the Joining of tables itself takes time.

3. Instead of using nested Select loops it is often better to use subqueries.

<b>Point # 1</b>

SELECT * FROM DD01L INTO DD01L_WA

WHERE DOMNAME LIKE 'CHAR%'

AND AS4LOCAL = 'A'.

SELECT SINGLE * FROM DD01T INTO DD01T_WA

WHERE DOMNAME = DD01L_WA-DOMNAME

AND AS4LOCAL = 'A'

AND AS4VERS = DD01L_WA-AS4VERS

AND DDLANGUAGE = SY-LANGU.

ENDSELECT.

The above code can be more optimized by extracting all the data from view DD01V_WA

SELECT * FROM DD01V INTO DD01V_WA

WHERE DOMNAME LIKE 'CHAR%'

AND DDLANGUAGE = SY-LANGU.

ENDSELECT

<b>Point # 2</b>

SELECT * FROM EKKO INTO EKKO_WA.

SELECT * FROM EKAN INTO EKAN_WA

WHERE EBELN = EKKO_WA-EBELN.

ENDSELECT.

ENDSELECT.

The above code can be much more optimized by the code written below.

SELECT PF1 PF2 FF3 FF4 INTO TABLE ITAB

FROM EKKO AS P INNER JOIN EKAN AS F

ON PEBELN = FEBELN.

<b>Point # 3</b>

SELECT * FROM SPFLI

INTO TABLE T_SPFLI

WHERE CITYFROM = 'FRANKFURT'

AND CITYTO = 'NEW YORK'.

SELECT * FROM SFLIGHT AS F

INTO SFLIGHT_WA

FOR ALL ENTRIES IN T_SPFLI

WHERE SEATSOCC < F~SEATSMAX

AND CARRID = T_SPFLI-CARRID

AND CONNID = T_SPFLI-CONNID

AND FLDATE BETWEEN '19990101' AND '19990331'.

ENDSELECT.

The above mentioned code can be even more optimized by using subqueries instead of for all entries.

SELECT * FROM SFLIGHT AS F INTO SFLIGHT_WA

WHERE SEATSOCC < F~SEATSMAX

AND EXISTS ( SELECT * FROM SPFLI

WHERE CARRID = F~CARRID

AND CONNID = F~CONNID

AND CITYFROM = 'FRANKFURT'

AND CITYTO = 'NEW YORK' )

AND FLDATE BETWEEN '19990101' AND '19990331'.

ENDSELECT.

1. Table operations should be done using explicit work areas rather than via header lines.

2. Always try to use binary search instead of linear search. But don’t forget to sort your internal table before that.

3. A dynamic key access is slower than a static one, since the key specification must be evaluated at runtime.

4. A binary search using secondary index takes considerably less time.

5. LOOP ... WHERE is faster than LOOP/CHECK because LOOP ... WHERE evaluates the specified condition internally.

6. Modifying selected components using “ MODIFY itab …TRANSPORTING f1 f2.. “ accelerates the task of updating a line of an internal table.

<b>Point # 2</b>

READ TABLE ITAB INTO WA WITH KEY K = 'X‘ BINARY SEARCH.

IS MUCH FASTER THAN USING

READ TABLE ITAB INTO WA WITH KEY K = 'X'.

If TAB has n entries, linear search runs in O( n ) time, whereas binary search takes only O( log2( n ) ).

Point # 3

READ TABLE ITAB INTO WA WITH KEY K = 'X'. IS FASTER THAN USING

READ TABLE ITAB INTO WA WITH KEY (NAME) = 'X'.

<b>Point # 5</b>

LOOP AT ITAB INTO WA WHERE K = 'X'.

" ...

ENDLOOP.

The above code is much faster than using

LOOP AT ITAB INTO WA.

CHECK WA-K = 'X'.

" ...

ENDLOOP.

<b>Point # 6</b>

WA-DATE = SY-DATUM.

MODIFY ITAB FROM WA INDEX 1 TRANSPORTING DATE.

The above code is more optimized as compared to

WA-DATE = SY-DATUM.

MODIFY ITAB FROM WA INDEX 1.

7. Accessing the table entries directly in a "LOOP ... ASSIGNING ..." accelerates the task of updating a set of lines of an internal table considerably

8. If collect semantics is required, it is always better to use to COLLECT rather than READ BINARY and then ADD.

9. "APPEND LINES OF itab1 TO itab2" accelerates the task of appending a table to another table considerably as compared to “ LOOP-APPEND-ENDLOOP.”

10. “DELETE ADJACENT DUPLICATES“ accelerates the task of deleting duplicate entries considerably as compared to “ READ-LOOP-DELETE-ENDLOOP”.

11. "DELETE itab FROM ... TO ..." accelerates the task of deleting a sequence of lines considerably as compared to “ DO -DELETE-ENDDO”.

<b>Point # 7</b>

Modifying selected components only makes the program faster as compared to Modifying all lines completely.

e.g,

LOOP AT ITAB ASSIGNING <WA>.

I = SY-TABIX MOD 2.

IF I = 0.

<WA>-FLAG = 'X'.

ENDIF.

ENDLOOP.

The above code works faster as compared to

LOOP AT ITAB INTO WA.

I = SY-TABIX MOD 2.

IF I = 0.

WA-FLAG = 'X'.

MODIFY ITAB FROM WA.

ENDIF.

ENDLOOP.

<b>Point # 8</b>

LOOP AT ITAB1 INTO WA1.

READ TABLE ITAB2 INTO WA2 WITH KEY K = WA1-K BINARY SEARCH.

IF SY-SUBRC = 0.

ADD: WA1-VAL1 TO WA2-VAL1,

WA1-VAL2 TO WA2-VAL2.

MODIFY ITAB2 FROM WA2 INDEX SY-TABIX TRANSPORTING VAL1 VAL2.

ELSE.

INSERT WA1 INTO ITAB2 INDEX SY-TABIX.

ENDIF.

ENDLOOP.

The above code uses BINARY SEARCH for collect semantics. READ BINARY runs in O( log2(n) ) time. The above piece of code can be more optimized by

LOOP AT ITAB1 INTO WA.

COLLECT WA INTO ITAB2.

ENDLOOP.

SORT ITAB2 BY K.

COLLECT, however, uses a hash algorithm and is therefore independent

of the number of entries (i.e. O(1)) .

<b>Point # 9</b>

APPEND LINES OF ITAB1 TO ITAB2.

This is more optimized as compared to

LOOP AT ITAB1 INTO WA.

APPEND WA TO ITAB2.

ENDLOOP.

<b>Point # 10</b>

DELETE ADJACENT DUPLICATES FROM ITAB COMPARING K.

This is much more optimized as compared to

READ TABLE ITAB INDEX 1 INTO PREV_LINE.

LOOP AT ITAB FROM 2 INTO WA.

IF WA = PREV_LINE.

DELETE ITAB.

ELSE.

PREV_LINE = WA.

ENDIF.

ENDLOOP.

<b>Point # 11</b>

DELETE ITAB FROM 450 TO 550.

This is much more optimized as compared to

DO 101 TIMES.

DELETE ITAB INDEX 450.

ENDDO.

12. Copying internal tables by using “ITAB2[ ] = ITAB1[ ]” as compared to “LOOP-APPEND-ENDLOOP”.

13. Specify the sort key as restrictively as possible to run the program faster.

<b>Point # 12</b>

ITAB2[] = ITAB1[].

This is much more optimized as compared to

REFRESH ITAB2.

LOOP AT ITAB1 INTO WA.

APPEND WA TO ITAB2.

ENDLOOP.

<b>Point # 13</b>

“SORT ITAB BY K.” makes the program runs faster as compared to “SORT ITAB.”

<b>Internal Tables contd…

Hashed and Sorted tables</b>

1. For single read access hashed tables are more optimized as compared to sorted tables.

2. For partial sequential access sorted tables are more optimized as compared to hashed tables

Hashed And Sorted Tables

<b>Point # 1</b>

Consider the following example where HTAB is a hashed table and STAB is a sorted table

DO 250 TIMES.

N = 4 * SY-INDEX.

READ TABLE HTAB INTO WA WITH TABLE KEY K = N.

IF SY-SUBRC = 0.

" ...

ENDIF.

ENDDO.

This runs faster for single read access as compared to the following same code for sorted table

DO 250 TIMES.

N = 4 * SY-INDEX.

READ TABLE STAB INTO WA WITH TABLE KEY K = N.

IF SY-SUBRC = 0.

" ...

ENDIF.

ENDDO.

<b>Point # 2</b>

Similarly for Partial Sequential access the STAB runs faster as compared to HTAB

LOOP AT STAB INTO WA WHERE K = SUBKEY.

" ...

ENDLOOP.

This runs faster as compared to

LOOP AT HTAB INTO WA WHERE K = SUBKEY.

" ...

ENDLOOP.

Reward if usefull<b></b>

11 REPLIES 11

Former Member
0 Kudos

1.loop at itab1.

if itab1-erdat not in s_erdat.

delete itab1.

endif.

endloop.

2.delete itab1 where itab1-erdat not in s_erdat.

2 one is more efficient.

Creating secondary index depends on lot many factors, such as the table, its usage, the data in the table, benefits of secondary index in one program or multiple, etc. as the secondary index itself take space in the DB.

Regards,

Atish

0 Kudos

1.loop at itab1.

if itab1-erdat not in s_erdat.

delete itab1.

endif.

endloop.

2.delete itab1 where itab1-erdat not in s_erdat

Both will give the same output, right?

*****

What I am doing is a normal report,for this report how far it is advisable to create an index.Isn't thre any other way to improve perfornamce without creating an index.Only this select statement is not using the primary key,the rest are all written using primary keys.

Thanks,

K.Kiran.

0 Kudos

Hi Kiran,

Yes both will give same output but the perfomance of the second will be much better.

delete itab1 where itab1-erdat not in s_erdat

change to

<b>delete itab1 where erdat not in s_erdat</b>.

Regarding the index.->

1 What is the frequency of usage of your report,

2 Is it must to run the report in foreground

3 Can you convince to use the report in background?

4 how many users will be using this.

5 Can you provide more fields in WHERE clause.

Based on these questions and some more analysis you can decide whether to create index or not

Regards,

Atish

0 Kudos

1 What is the frequency of usage of your report.

Not sure.

2 Is it must to run the report in foreground.

Preferred.As it is a normal report I don't see any need to run it in the background.

3 Can you convince to use the report in background?

I got the ouput when run in the background.The thing is that it is working fine when run for an year but sleeps when executed for just 15 days,depending on the number of documents created during that period.Report is not yet moved to Production,if it is the case in quality,then it wil go for a toss in production,I guess.

4 how many users will be using this.

Not sure.

5 Can you provide more fields in WHERE clause

The same I asked the Funtcional consultant,VBRK is having only VBELN as the primary key,the purpose of the report is to get the VBELN's along with some other data for a particular period,hence I can't give VBELN in the selection screen.In such a case how to approach.

***

By ther way,After filtering the itab1 w.r.t to erdat not in s_erdat it is working fine,will get back to you.

***

Thanks,

K.Kiran

0 Kudos

Hi Kiran,

Based on the your answers, I think the best option is to use the report in background as creating index only for your report is not advisable.

Regards,

Atish

Former Member
0 Kudos

I would look into doing it differently. There are a number of dates in indexes for table BKPF. Try using your date to SELECT from BKPF instead. Then use BKPF-AWTYP and BKPF-AWKEY to go directly against VBRK.

I would never create an index on a standard SAP table to speed up a single SELECT in a single custom program - particularly if there's a way around it.

Rob

Former Member
0 Kudos

Hi,

For the select..use the billing date in the where clause which has the index..

WHERE

FKDAT IN S_ERDAT AND

BUKRS = P_BUKRS.

OR

Create an index for the field BUKRS & ERDAT ..

Thanks

Naren

Former Member
0 Kudos

Hi

<b>Ways of Performance Tuning</b>

1. Selection Criteria

2. Select Statements

• Select Queries

• SQL Interface

• Aggregate Functions

• For all Entries

Select Over more than one Internal table

<b>Selection Criteria</b>

1. Restrict the data to the selection criteria itself, rather than filtering it out using the ABAP code using CHECK statement.

2. Select with selection list.

<b>Points # 1/2</b>

SELECT * FROM SBOOK INTO SBOOK_WA.

CHECK: SBOOK_WA-CARRID = 'LH' AND

SBOOK_WA-CONNID = '0400'.

ENDSELECT.

The above code can be much more optimized by the code written below which avoids CHECK, selects with selection list

SELECT CARRID CONNID FLDATE BOOKID FROM SBOOK INTO TABLE T_SBOOK

WHERE SBOOK_WA-CARRID = 'LH' AND

SBOOK_WA-CONNID = '0400'.

<b>Select Statements Select Queries</b>

1. Avoid nested selects

2. Select all the records in a single shot using into table clause of select statement rather than to use Append statements.

3. 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.

4. For testing existence , use Select.. Up to 1 rows statement instead of a Select-Endselect-loop with an Exit.

5. Use Select Single if all primary key fields are supplied in the Where condition .

<b>Point # 1</b>

SELECT * FROM EKKO INTO EKKO_WA.

SELECT * FROM EKAN INTO EKAN_WA

WHERE EBELN = EKKO_WA-EBELN.

ENDSELECT.

ENDSELECT.

The above code can be much more optimized by the code written below.

SELECT PF1 PF2 FF3 FF4 INTO TABLE ITAB

FROM EKKO AS P INNER JOIN EKAN AS F

ON PEBELN = FEBELN.

Note: A simple SELECT loop is a single database access whose result is passed to the ABAP program line by line. Nested SELECT loops mean that the number of accesses in the inner loop is multiplied by the number of accesses in the outer loop. One should therefore use nested SELECT loops only if the selection in the outer loop contains very few lines or the outer loop is a SELECT SINGLE statement.

<b>Point # 2</b>

SELECT * FROM SBOOK INTO SBOOK_WA.

CHECK: SBOOK_WA-CARRID = 'LH' AND

SBOOK_WA-CONNID = '0400'.

ENDSELECT.

The above code can be much more optimized by the code written below which avoids CHECK, selects with selection list and puts the data in one shot using into table

SELECT CARRID CONNID FLDATE BOOKID FROM SBOOK INTO TABLE T_SBOOK

WHERE SBOOK_WA-CARRID = 'LH' AND

SBOOK_WA-CONNID = '0400'.

<b>Point # 3</b>

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 . 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.

<b>Point # 4</b>

SELECT * FROM SBOOK INTO SBOOK_WA

UP TO 1 ROWS

WHERE CARRID = 'LH'.

ENDSELECT.

The above code is more optimized as compared to the code mentioned below for testing existence of a record.

SELECT * FROM SBOOK INTO SBOOK_WA

WHERE CARRID = 'LH'.

EXIT.

ENDSELECT.

<b>Point # 5</b>

If all primary key fields are supplied in the Where condition you can even use Select Single.

Select Single requires one communication with the database system, whereas Select-Endselect needs two.

<b>Select Statements contd.. SQL Interface</b>

1. Use column updates instead of single-row updates

to update your database tables.

2. For all frequently used Select statements, try to use an index.

3. Using buffered tables improves the performance considerably.

<b>

Point # 1</b>

SELECT * FROM SFLIGHT INTO SFLIGHT_WA.

SFLIGHT_WA-SEATSOCC =

SFLIGHT_WA-SEATSOCC - 1.

UPDATE SFLIGHT FROM SFLIGHT_WA.

ENDSELECT.

The above mentioned code can be more optimized by using the following code

UPDATE SFLIGHT

SET SEATSOCC = SEATSOCC - 1.

<b>Point # 2</b>

SELECT * FROM SBOOK CLIENT SPECIFIED INTO SBOOK_WA

WHERE CARRID = 'LH'

AND CONNID = '0400'.

ENDSELECT.

The above mentioned code can be more optimized by using the following code

SELECT * FROM SBOOK CLIENT SPECIFIED INTO SBOOK_WA

WHERE MANDT IN ( SELECT MANDT FROM T000 )

AND CARRID = 'LH'

AND CONNID = '0400'.

ENDSELECT.

<b>Point # 3</b>

Bypassing the buffer increases the network considerably

SELECT SINGLE * FROM T100 INTO T100_WA

BYPASSING BUFFER

WHERE SPRSL = 'D'

AND ARBGB = '00'

AND MSGNR = '999'.

The above mentioned code can be more optimized by using the following code

SELECT SINGLE * FROM T100 INTO T100_WA

WHERE SPRSL = 'D'

AND ARBGB = '00'

AND MSGNR = '999'.

<b>Select Statements contd… Aggregate Functions</b>

• 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 yourself.

Some of the Aggregate functions allowed in SAP are MAX, MIN, AVG, SUM, COUNT, COUNT( * )

Consider the following extract.

Maxno = 0.

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

Check zflight-fligh > maxno.

Maxno = zflight-fligh.

Endselect.

The above mentioned code can be much more optimized by using the following code.

Select max( fligh ) from zflight into maxno where airln = ‘LF’ and cntry = ‘IN’.

<b>Select Statements contd…For All Entries</b>

• The for all entries creates a where clause, where all the entries in the driver table are combined with OR. If the number of entries in the driver table is larger than rsdb/max_blocking_factor, several similar SQL statements are executed to limit the length of the WHERE clause.

The plus

• Large amount of data

• Mixing processing and reading of data

• Fast internal reprocessing of data

• Fast

The Minus

• Difficult to program/understand

• Memory could be critical (use FREE or PACKAGE size)

<u>Points to be must considered FOR ALL ENTRIES</u>

• Check that data is present in the driver table

• Sorting the driver table

• Removing duplicates from the driver table

Consider the following piece of extract

Loop at int_cntry.

Select single * from zfligh into int_fligh

where cntry = int_cntry-cntry.

Append int_fligh.

Endloop.

The above mentioned can be more optimized by using the following code.

Sort int_cntry by cntry.

Delete adjacent duplicates from int_cntry.

If NOT int_cntry[] is INITIAL.

Select * from zfligh appending table int_fligh

For all entries in int_cntry

Where cntry = int_cntry-cntry.

Endif.

<b>

Select Statements contd… Select Over more than one Internal table</b>

1. Its better to use a views instead of nested Select statements.

2. To read data from several logically connected tables use a join instead of nested Select statements. Joins are preferred only if all the primary key are available in WHERE clause for the tables that are joined. If the primary keys are not provided in join the Joining of tables itself takes time.

3. Instead of using nested Select loops it is often better to use subqueries.

<b>Point # 1</b>

SELECT * FROM DD01L INTO DD01L_WA

WHERE DOMNAME LIKE 'CHAR%'

AND AS4LOCAL = 'A'.

SELECT SINGLE * FROM DD01T INTO DD01T_WA

WHERE DOMNAME = DD01L_WA-DOMNAME

AND AS4LOCAL = 'A'

AND AS4VERS = DD01L_WA-AS4VERS

AND DDLANGUAGE = SY-LANGU.

ENDSELECT.

The above code can be more optimized by extracting all the data from view DD01V_WA

SELECT * FROM DD01V INTO DD01V_WA

WHERE DOMNAME LIKE 'CHAR%'

AND DDLANGUAGE = SY-LANGU.

ENDSELECT

<b>Point # 2</b>

SELECT * FROM EKKO INTO EKKO_WA.

SELECT * FROM EKAN INTO EKAN_WA

WHERE EBELN = EKKO_WA-EBELN.

ENDSELECT.

ENDSELECT.

The above code can be much more optimized by the code written below.

SELECT PF1 PF2 FF3 FF4 INTO TABLE ITAB

FROM EKKO AS P INNER JOIN EKAN AS F

ON PEBELN = FEBELN.

<b>Point # 3</b>

SELECT * FROM SPFLI

INTO TABLE T_SPFLI

WHERE CITYFROM = 'FRANKFURT'

AND CITYTO = 'NEW YORK'.

SELECT * FROM SFLIGHT AS F

INTO SFLIGHT_WA

FOR ALL ENTRIES IN T_SPFLI

WHERE SEATSOCC < F~SEATSMAX

AND CARRID = T_SPFLI-CARRID

AND CONNID = T_SPFLI-CONNID

AND FLDATE BETWEEN '19990101' AND '19990331'.

ENDSELECT.

The above mentioned code can be even more optimized by using subqueries instead of for all entries.

SELECT * FROM SFLIGHT AS F INTO SFLIGHT_WA

WHERE SEATSOCC < F~SEATSMAX

AND EXISTS ( SELECT * FROM SPFLI

WHERE CARRID = F~CARRID

AND CONNID = F~CONNID

AND CITYFROM = 'FRANKFURT'

AND CITYTO = 'NEW YORK' )

AND FLDATE BETWEEN '19990101' AND '19990331'.

ENDSELECT.

1. Table operations should be done using explicit work areas rather than via header lines.

2. Always try to use binary search instead of linear search. But don’t forget to sort your internal table before that.

3. A dynamic key access is slower than a static one, since the key specification must be evaluated at runtime.

4. A binary search using secondary index takes considerably less time.

5. LOOP ... WHERE is faster than LOOP/CHECK because LOOP ... WHERE evaluates the specified condition internally.

6. Modifying selected components using “ MODIFY itab …TRANSPORTING f1 f2.. “ accelerates the task of updating a line of an internal table.

<b>Point # 2</b>

READ TABLE ITAB INTO WA WITH KEY K = 'X‘ BINARY SEARCH.

IS MUCH FASTER THAN USING

READ TABLE ITAB INTO WA WITH KEY K = 'X'.

If TAB has n entries, linear search runs in O( n ) time, whereas binary search takes only O( log2( n ) ).

Point # 3

READ TABLE ITAB INTO WA WITH KEY K = 'X'. IS FASTER THAN USING

READ TABLE ITAB INTO WA WITH KEY (NAME) = 'X'.

<b>Point # 5</b>

LOOP AT ITAB INTO WA WHERE K = 'X'.

" ...

ENDLOOP.

The above code is much faster than using

LOOP AT ITAB INTO WA.

CHECK WA-K = 'X'.

" ...

ENDLOOP.

<b>Point # 6</b>

WA-DATE = SY-DATUM.

MODIFY ITAB FROM WA INDEX 1 TRANSPORTING DATE.

The above code is more optimized as compared to

WA-DATE = SY-DATUM.

MODIFY ITAB FROM WA INDEX 1.

7. Accessing the table entries directly in a "LOOP ... ASSIGNING ..." accelerates the task of updating a set of lines of an internal table considerably

8. If collect semantics is required, it is always better to use to COLLECT rather than READ BINARY and then ADD.

9. "APPEND LINES OF itab1 TO itab2" accelerates the task of appending a table to another table considerably as compared to “ LOOP-APPEND-ENDLOOP.”

10. “DELETE ADJACENT DUPLICATES“ accelerates the task of deleting duplicate entries considerably as compared to “ READ-LOOP-DELETE-ENDLOOP”.

11. "DELETE itab FROM ... TO ..." accelerates the task of deleting a sequence of lines considerably as compared to “ DO -DELETE-ENDDO”.

<b>Point # 7</b>

Modifying selected components only makes the program faster as compared to Modifying all lines completely.

e.g,

LOOP AT ITAB ASSIGNING <WA>.

I = SY-TABIX MOD 2.

IF I = 0.

<WA>-FLAG = 'X'.

ENDIF.

ENDLOOP.

The above code works faster as compared to

LOOP AT ITAB INTO WA.

I = SY-TABIX MOD 2.

IF I = 0.

WA-FLAG = 'X'.

MODIFY ITAB FROM WA.

ENDIF.

ENDLOOP.

<b>Point # 8</b>

LOOP AT ITAB1 INTO WA1.

READ TABLE ITAB2 INTO WA2 WITH KEY K = WA1-K BINARY SEARCH.

IF SY-SUBRC = 0.

ADD: WA1-VAL1 TO WA2-VAL1,

WA1-VAL2 TO WA2-VAL2.

MODIFY ITAB2 FROM WA2 INDEX SY-TABIX TRANSPORTING VAL1 VAL2.

ELSE.

INSERT WA1 INTO ITAB2 INDEX SY-TABIX.

ENDIF.

ENDLOOP.

The above code uses BINARY SEARCH for collect semantics. READ BINARY runs in O( log2(n) ) time. The above piece of code can be more optimized by

LOOP AT ITAB1 INTO WA.

COLLECT WA INTO ITAB2.

ENDLOOP.

SORT ITAB2 BY K.

COLLECT, however, uses a hash algorithm and is therefore independent

of the number of entries (i.e. O(1)) .

<b>Point # 9</b>

APPEND LINES OF ITAB1 TO ITAB2.

This is more optimized as compared to

LOOP AT ITAB1 INTO WA.

APPEND WA TO ITAB2.

ENDLOOP.

<b>Point # 10</b>

DELETE ADJACENT DUPLICATES FROM ITAB COMPARING K.

This is much more optimized as compared to

READ TABLE ITAB INDEX 1 INTO PREV_LINE.

LOOP AT ITAB FROM 2 INTO WA.

IF WA = PREV_LINE.

DELETE ITAB.

ELSE.

PREV_LINE = WA.

ENDIF.

ENDLOOP.

<b>Point # 11</b>

DELETE ITAB FROM 450 TO 550.

This is much more optimized as compared to

DO 101 TIMES.

DELETE ITAB INDEX 450.

ENDDO.

12. Copying internal tables by using “ITAB2[ ] = ITAB1[ ]” as compared to “LOOP-APPEND-ENDLOOP”.

13. Specify the sort key as restrictively as possible to run the program faster.

<b>Point # 12</b>

ITAB2[] = ITAB1[].

This is much more optimized as compared to

REFRESH ITAB2.

LOOP AT ITAB1 INTO WA.

APPEND WA TO ITAB2.

ENDLOOP.

<b>Point # 13</b>

“SORT ITAB BY K.” makes the program runs faster as compared to “SORT ITAB.”

<b>Internal Tables contd…

Hashed and Sorted tables</b>

1. For single read access hashed tables are more optimized as compared to sorted tables.

2. For partial sequential access sorted tables are more optimized as compared to hashed tables

Hashed And Sorted Tables

<b>Point # 1</b>

Consider the following example where HTAB is a hashed table and STAB is a sorted table

DO 250 TIMES.

N = 4 * SY-INDEX.

READ TABLE HTAB INTO WA WITH TABLE KEY K = N.

IF SY-SUBRC = 0.

" ...

ENDIF.

ENDDO.

This runs faster for single read access as compared to the following same code for sorted table

DO 250 TIMES.

N = 4 * SY-INDEX.

READ TABLE STAB INTO WA WITH TABLE KEY K = N.

IF SY-SUBRC = 0.

" ...

ENDIF.

ENDDO.

<b>Point # 2</b>

Similarly for Partial Sequential access the STAB runs faster as compared to HTAB

LOOP AT STAB INTO WA WHERE K = SUBKEY.

" ...

ENDLOOP.

This runs faster as compared to

LOOP AT HTAB INTO WA WHERE K = SUBKEY.

" ...

ENDLOOP.

Reward if usefull<b></b>

0 Kudos

Hi Folks,

This is the way the select statements in the prog are,how can we optimise this.

SELECT VBELN

FKART

VBTYP

VKORG

VTWEG

FKDAT

ERDAT

KUNRG

FROM VBRK INTO TABLE ITAB1

WHERE BUKRS = P_BUKRS.

DELETE ITAB1 WHERE ERDAT NOT IN S_ERDAT.

LOOP AT ITAB1.

MOVE-CORRESPONDING ITAB1 TO ITFINAL.

SELECT POSNR

FKIMG

MATNR

ARKTX

WERKS

BWTAR

FROM VBRP INTO CORRESPONDING FIELDS OF ITFINAL

WHERE VBELN = ITAB1-VBELN.

SELECT NAME1

FROM KNA1 INTO (ITFINAL-NAME1)

WHERE KUNNR = ITAB1-KUNRG.

ENDSELECT.

*Description of the Billing Type

SELECT SINGLE

VTEXT

FROM TVFKT INTO (ITFINAL-BTYPE)

WHERE FKART = ITAB1-FKART AND

SPRAS = SY-LANGU.

APPEND ITFINAL.

ENDSELECT.

CLEAR ITAB1.

CLEAR ITFINAL.

ENDLOOP.

*Condition Records

SELECT KSCHL

VKORG

VTWEG

MATNR

DATBI

DATAB

KNUMH

FROM A304 INTO TABLE ITAB2

WHERE KFRST = ' '.

LOOP AT ITAB2.

IF ITAB2-KSCHL <> 'ZPR0' AND

ITAB2-KSCHL <> 'ZPR1'.

DELETE ITAB2.

ENDIF.

ENDLOOP.

LOOP AT ITAB2 INTO WAITAB2.

READ TABLE ITFINAL WITH KEY VKORG = WAITAB2-VKORG

VTWEG = WAITAB2-VTWEG

MATNR = WAITAB2-MATNR.

IF ITFINAL-MATNR NE WAITAB2-MATNR.

DELETE ITAB2.

ENDIF.

ENDLOOP.

LOOP AT ITAB2.

SELECT SINGLE

KBETR

FROM KONP

INTO ITAB2-KBETR

WHERE KNUMH = ITAB2-KNUMH.

MODIFY ITAB2.

ENDLOOP.

LOOP AT ITFINAL.

LOOP AT ITAB2 WHERE MATNR = ITFINAL-MATNR.

IF ITAB2-DATAB LE ITFINAL-ERDAT AND

ITFINAL-ERDAT LE ITAB2-DATBI.

MOVE ITAB2-KNUMH TO ITFINAL-KNUMH.

IF ITAB2-KSCHL = 'ZPR0'.

MOVE ITAB2-KBETR TO ITFINAL-KBETR1.

ELSE.

MOVE ITAB2-KBETR TO ITFINAL-KBETR2.

ENDIF.

MODIFY ITFINAL.

ENDIF.

ENDLOOP.

ENDLOOP.

ENDFORM. " GETDATA

Thanks,

K.Kiran.

0 Kudos

Hi Kiran,

SELECT VBELN

FKART

VBTYP

VKORG

VTWEG

FKDAT

ERDAT

KUNRG

FROM VBRK INTO TABLE ITAB1

WHERE BUKRS = P_BUKRS.

DELETE ITAB1 WHERE ERDAT NOT IN S_ERDAT.

LOOP AT ITAB1.

MOVE-CORRESPONDING ITAB1 TO ITFINAL.

SELECT POSNR

FKIMG

MATNR

ARKTX

WERKS

BWTAR

FROM VBRP INTO CORRESPONDING FIELDS OF ITFINAL

WHERE VBELN = ITAB1-VBELN.

SELECT NAME1

FROM KNA1 INTO (ITFINAL-NAME1)

WHERE KUNNR = ITAB1-KUNRG.

ENDSELECT.

*Description of the Billing Type

SELECT SINGLE

VTEXT

FROM TVFKT INTO (ITFINAL-BTYPE)

WHERE FKART = ITAB1-FKART AND

SPRAS = SY-LANGU.

APPEND ITFINAL.

ENDSELECT.

CLEAR ITAB1.

CLEAR ITFINAL.

ENDLOOP.

<b>REPLACE THIS WHOLE LOOP ENDLOOP WITH FOR ALL ENTRIES</b>

*Condition Records

SELECT KSCHL

VKORG

VTWEG

MATNR

DATBI

DATAB

KNUMH

FROM A304 INTO TABLE ITAB2

WHERE KFRST = ' '.

LOOP AT ITAB2.

IF ITAB2-KSCHL <> 'ZPR0' AND

ITAB2-KSCHL <> 'ZPR1'.

DELETE ITAB2.

ENDIF.

ENDLOOP.

<b>REPLACE WITH DELETE ITAB2 WHERE..</b>

LOOP AT ITAB2 INTO WAITAB2.

READ TABLE ITFINAL WITH KEY VKORG = WAITAB2-VKORG

VTWEG = WAITAB2-VTWEG

MATNR = WAITAB2-MATNR.

IF ITFINAL-MATNR NE WAITAB2-MATNR.

DELETE ITAB2.

ENDIF.

ENDLOOP.

LOOP AT ITAB2.

SELECT SINGLE

KBETR

FROM KONP

INTO ITAB2-KBETR

WHERE KNUMH = ITAB2-KNUMH.

MODIFY ITAB2.

ENDLOOP.

<b>REPLACE WITH FOR ALL ENTRIES</b>

LOOP AT ITFINAL.

LOOP AT ITAB2 WHERE MATNR = ITFINAL-MATNR.

IF ITAB2-DATAB LE ITFINAL-ERDAT AND

ITFINAL-ERDAT LE ITAB2-DATBI.

MOVE ITAB2-KNUMH TO ITFINAL-KNUMH.

IF ITAB2-KSCHL = 'ZPR0'.

MOVE ITAB2-KBETR TO ITFINAL-KBETR1.

ELSE.

MOVE ITAB2-KBETR TO ITFINAL-KBETR2.

ENDIF.

MODIFY ITFINAL.

ENDIF.

ENDLOOP.

ENDLOOP.

ENDFORM. " GETDATA<b></b>

0 Kudos

Atish,

I will try as you said.But I have to display both the prices w.r.t ZPRO AND ZPR1,moreover for a particular invoice document there can be n no.of line items and n.no.of condition record numbers w.r.t the line items.I have to consider all the condition records numbers w.r.t to date and get the valid prices.

I am getting the output right,but the only thing is optimisation.

Thanks,

K.Kiran.