Restrict user SELECT query time on a particular VIEW
Hi - I am trying to restrict user SELECT statemnet time on a particular view.There is a user called ABC and he is accessing many objects in database.All SELECT statments are fine execept when he query a particular VIEW.That view SELECT causing performance problem.So I am trying to restrict the SELECT query time on a VIEW.
Can you please help me to achive this task through some SQL command like ALTER USER etc...
Thanks for your help.
user2538196 wrote:
Hi - I am trying to restrict user SELECT statemnet time on a particular view.There is a user called ABC and he is accessing many objects in database.All SELECT statments are fine execept when he query a particular VIEW.That view SELECT causing performance problem.So I am trying to restrict the SELECT query time on a VIEW.
Can you please help me to achive this task through some SQL command like ALTER USER etc...
Thanks for your help.It sounds like you are really trying to solve a performance problem with the view. I agree with Justin that the solution to restrict access to the view dynamically sounds unwieldy.
Consider tuning the view, or perhaps the query using the view. Post the view and see if anyone can help you tune it.
Similar Messages
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Restricting a characteristic & query time out problem
Hi. We have the follwoing problem:
Before our BI upgrade, we have had a number of users querying different info areas, that are now having difficulty restricting on a characteristic in a query. This was performed with no problems before the upgrade.
Many times, the list of records for the particular characteristic is quite small. Either it takes 20-30 minutes for the list to appear, or the query times out (after 6000 seconds).
Any ideas?Any time you have an existing query that has been running quickly in production, and it suddenly starts to run much longer, you should be suspicious of some change to DB statisitics and or indexes.
So the first thing to do is work with your DBA to make sure the DB statistics are current for the tables involved in the query, then get an Explain Plan for the query which will show you how the DB is trying to execute the query, what indexes it uses, etc. Perhaps stats are not being refreshed after the upgrade, or something happened to an index -
I'm using SQL Server 2008 R2 (10.50.4033) and I'm troubleshooting an issue that a select query against a specific view is taking more than 30 seconds consistently. The issue just starts happening this week and there is no mass changes in data.
The problem only occur if the query is issued from an IIS application but not from SSMS. One thing I noticed is that sys.dm_exec_cached_plans is returning 2 Parse Tree rows for the view - one created when the select query is issued
1st time from the IIS application and another one created when the same select query is issued 1st time from SSMS. The usecounts of the Parse Tree row for the view (the IIS one) is increasing whenever the select query is issued. The
usecounts of the Parse Tree row for the view (the SSMS one) does not increase when the select query is issued again.
There seems to be a correlation between the slowness of the query and the increasing of the usecounts of the Parse Tree row for the view.
I don't know why there is 2 Parse Tree rows for the view. There is also 2 Compiled Plan rows for the select query.
What does the Parse Tree row mean especially the usecounts column?>> The issue just starts happening this week and there is no mass changes in data.
There might be a mass changes in the execution plan for several reason without mass changes in data
If you have the old version and a way to check the old execution plan, and compare to the new one, that this should be your starting point. In most cases you don't have this option and we need to monitor from scratch.
>> The problem only occur if the query is issued from an IIS application but not from SSMS.
This mean that we know exactly what is the different and you can compare both execution plan. once you do it, you will find that they are no the same. But this is very common issue and we can know that it is a result of different SETting while connecting
from different application. SSMS is an external app like any app that you develop in Visual studio but the SSMS dose not use the Dot.Net default options.
Please check this link, to find the full explanation and solutions:
http://www.sommarskog.se/query-plan-mysteries.html
Take a look at sys.dm_exec_sessions for your ASP.Net application and for your SSMS session.
If you need more specific help, then we need more information and less stories :-)
We need to see the DDL+DML+Query and both execution plans
>> What does the Parse Tree row mean
I am not sure what you mean but the parse tree represents the logical steps necessary to execute the query that has been requested. you can check this tutorial about the execution plan: https://www.simple-talk.com/sql/performance/execution-plan-basics/ or
this one: http://www.developer.com/db/understanding-a-sql-server-query-execution-plan.html
>> regarding the usecount column or any other column check this link:
https://msdn.microsoft.com/en-us/library/ms187404.aspx?f=255&MSPPError=-2147217396.
Ronen Ariely
[Personal Site] [Blog] [Facebook] -
Hello Experts,
Please help me this below query. If I ran the program, it will take so much time to execute the below query and its goes to time out.
Please help me.
SELECT mvgr1 "Line of Business
werks "Plant
lgort "Storage Location
charg "Batch
matnr "Material Number
kwmeng "Ordered quantity
posnr "Item
vbeln "Sales Order Number
FROM vbap
INTO TABLE gt_salesdatatemp
FOR ALL ENTRIES IN gt_matmerge
WHERE matnr EQ gt_matmerge-matnr
AND werks EQ gt_matmerge-werks
AND mvgr1 EQ gt_matmerge-mvgr1
AND lgort EQ gt_matmerge-lgort
AND charg EQ gt_matmerge-charg
AND abgru EQ space.
Thanks in advance.Hi,
If the number of records to be fetched is very very high then you can use the cursor concept.
Please see the below code.
=====
OPEN CURSOR dbcur FOR SELECT .... FROM ....... WHERE ...... .
DO.
FETCH NEXT CURSOR dbcur INTO TABLE itab PACKAGE SIZE 10000.
IF sy-subrc NE 0.
EXIT.
ENDIF.
ENDDO.
CLOSE CURSOR dbcur.
=====
Using this concept you can fetch the data in packets.
Additionally, you can take care of the following points to have better performance.
a. Check that your query is using the index.
b. Check that the internal table is not initial. If it is initial then the select will happen for all records in the DB.
Regards,
Saurabh -
Select Query info req for ZMKPFMSEG: View of MSEG and MKPF table
Hi
I am fetching 7-8 records frm ZMKPFMSEG: View of MSEG and MKPF table,which based on matnr,werks & budut,which is taking a large time,there is no index in the table,so can nay one tell me how to fetch the data,to make code more effictient.
SELECT budat
matnr
menge
bwart
meins
bwtar
waers
dmbtr
shkzg
matkl
FROM zmkpfmseg
INTO CORRESPONDING FIELDS OF TABLE it_mseg
WHERE budat GE r_ytd-low
AND matnr IN so_matnr
AND werks = p_werks
AND lgort IN so_lgort
AND matkl IN so_matkl.
plz tell me what changes have to be done in where condtion to make it run fast.
regdsHi,
Try the alternate Methods,
ACCESS VIA SUBQUERY.
SELECT * FROM MKPF AS M INTO CORRESPONDING FIELDS OF SWAP
WHERE BUDAT IN BUDAT AND
MBLNR IN MBLNR AND
VGART = 'WA' AND
EXISTS ( SELECT * FROM MSEG
WHERE MBLNR = M~MBLNR
AND MJAHR = M~MJAHR
AND WERKS = P_WERKS
AND matnr IN so_matnr
AND lgort IN so_lgort
AND matkl IN so_matkl.
APPEND SWAP.CLEAR SWAP.
ENDSELECT.
LOOP AT SWAP.
SELECT * FROM MSEG
WHERE MBLNR = SWAP-MBLNR AND
MJAHR = SWAP-MJAHR AND
IF SY-SUBRC EQ 0.
MOVE-CORRESPONDING SWAP TO ITAB.
MOVE-CORRESPONDING MSEG TO ITAB.
APPEND ITAB.CLEAR ITAB.
CLEAR MSEG.
ENDIF.
ENDSELECT.
CLEAR : SWAP,ITAB.
ENDLOOP.
Try this,
SELECT budat
matnr
menge
bwart
meins
bwtar
waers
dmbtr
shkzg
matkl
FROM zmkpfmseg
INTO CORRESPONDING FIELDS OF TABLE it_mseg
WHERE budat GE r_ytd-low
AND matnr IN so_matnr
AND lgort IN so_lgort
AND matkl IN so_matkl.
delete it_mseg where WERKS NE p_WERKS .
Reward Points if helpful.
Regards,
Balakumar.G -
Is there any way to prevent users from ship confirming on a particular date?
Hello All,
We have a requirement to prevent users from ship confirming on a particular date. This is due to they are performing Annual Physical Inventory.
Is it possible to restrict users performing shipping transactions on this particular date?
I have tried adding exception to the existing Calendar set at org level and there is no customer specific Calendar defined, however it is still allowing me to perform ship confirm.
Please let me know if you have any suggestion on this requirement.
ThanksHi,
Yes is Possible.
You can add An Exception in Your Shipping Calender.
So when Some one tries to ship an Order on that date Oracle will automatically select Next possible date.
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RichI updatee a BI App Workstream to include a few fields, Request Dimension mapplet to be specific.
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Is their any way to restrict user from overriding the graphs in SAP APO?
Dear All,
As we know, we can copy the graphs to other users using /n/sapapo/sdp_graph. But is their any way to restrict user from overriding the graph to particular user.
Scenarios:
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Can we handle exceptions for the expressions in select query?
Hi all,
Can we handle exceptions for the expressions in select query.
I created a view, there I am extracting a substring from a character data and expected that as a number.
For example consider the following query.
SQL> select to_number( substr('r01',2,2) ) from dual;
TO_NUMBER(SUBSTR('R01',2,2))
1
Here we got the value as "1".
Consider the following query.
SQL> select to_number( substr('rr1',2,2) ) from dual;
select to_number( substr('rr1',2,2) ) from dual
ORA-01722: invalid number
For this I got error. Because the substr returns "r1" which is expected to be as number. So it returns "Invalid number".
So, without using procedures or functions can we handle these type of exceptions?
I am using Oracle 10 G.
Thanks in advance.
Thank you,
Regards,
Gowtham Sen.SQL> select decode(ltrim(rtrim(translate(substr('r21', 2, 2), '0123456789', ' ' ), ' '), ' '), null, (substr('r21', 2, 2)), null) from dual;
DE
21
SQL> ed a
SQL> select decode(ltrim(rtrim(translate(substr('rr1', 2, 2), '0123456789', ' ' ), ' '), ' '), null, (substr('rr1', 2, 2)), null) from dual;
D
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How to write XSJS Select Query with input parameters
Hello Experts,
I am creating a xsjs file and in that file I am trying to write a Select Query based on a Calculation View
I have tried it the following way:
var query = 'SELECT TOP 100 \"Name\", \"Address\", \"City\", \"Country\" FROM \"_SYS_BIC\".\"Test.HL/AddressView\"'
+ 'WITH PARAMETERS(\'PLACEHOLDER\' = (\'$$P_Name$$\', \' Akhil \'),'
+ '\'PLACEHOLDER\' = (\'$$P_City$$\', \' Lucknow \'))';
But it gives me the "Mixed spaces and tabs error".
How should I write XSJS Select Query with input parameters?
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Rohit>But it gives me the "Mixed spaces and tabs error".
Mixed spaces and tabs has nothing to do with the syntax of the statement. You used both spaces and the tab in the content - which JSLint doesn't like. Remove the beginning spaces of each line and use only one or the other.
The actual syntax of your statement doesn't look right. The problem is that you are escaping the \ when you don't need to if you are using ' instead of " for your string. You escape with \" in the first line but then escape with \' in the 2nd and 3rd line. That is going to cause serious parsing problems with the command. -
In oracle rac, If user query a select query and in processing data is fetched but in the duration of fetching the particular node is evicted then how failover to another node internally?
The query is re-issued as a flashback query and the client process can continue to fetch from the cursor. This is described in the Net Services Administrators Guide, the section on Transparent Application Failover.
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How to restrict user marking same events in multiple times.
Hi,
In my online exam system, I am displaying the questions and related answer in jsp page. Once user fill all this questions, the result of these stored in final table containing column questonNo, userid, answer, testname.
Now in my application if any user goes back to the question displaying page after submitting same questions, he can change the answer selected in first attempt and submitting again the test, the result are stored in final table. I.e. for same question no. user is now able to answer in two times. I want to restrict user for answering test in second times.
How can I achieve this?
Any suggestion is highly appreciated?
Thanks and Regards
HarshalHi Hari,
with you suggested logic can i restrict user marking one question in multiple times,
My target is once user submit any questions teh control will be transferred to the next page.Now he/she could not able to submit the same questions with another answer or the same answer also which is possible in my application by going back to these page using back button .so that i can get only one record for particular questions in table final.
Thanks and Regards
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Edited by: HARSHAL_GURAV on Aug 20, 2008 12:15 AM -
SELECT query takes too much time! Y?
Plz find my SELECT query below:
select w~mandt
wvbeln wposnr wmeins wmatnr wwerks wnetwr
wkwmeng wvrkme wmatwa wcharg w~pstyv
wposar wprodh wgrkor wantlf wkztlf wlprio
wvstel wroute wumvkz wumvkn wabgru wuntto
wawahr werdat werzet wfixmg wprctr wvpmat
wvpwrk wmvgr1 wmvgr2 wmvgr3 wmvgr4 wmvgr5
wbedae wcuobj w~mtvfp
xetenr xwmeng xbmeng xettyp xwepos xabart
x~edatu
xtddat xmbdat xlddat xwadat xabruf xetart
x~ezeit
into table t_vbap
from vbap as w
inner join vbep as x on xvbeln = wvbeln and
xposnr = wposnr and
xmandt = wmandt
where
( ( werdat > pre_dat ) and ( werdat <= w_date ) ) and
( ( ( erdat > pre_dat and erdat < p_syndt ) or
( erdat = p_syndt and erzet <= p_syntm ) ) ) and
w~matnr in s_matnr and
w~pstyv in s_itmcat and
w~lfrel in s_lfrel and
w~abgru = ' ' and
w~kwmeng > 0 and
w~mtvfp in w_mtvfp and
x~ettyp in w_ettyp and
x~bdart in s_req_tp and
x~plart in s_pln_tp and
x~etart in s_etart and
x~abart in s_abart and
( ( xlifsp in s_lifsp ) or ( xlifsp = ' ' ) ).
The problem: It takes too much time while executing this statement.
Could anybody change this statement and help me out to reduce the DB Access time?
ThxWays of Performance Tuning
1. Selection Criteria
2. Select Statements
Select Queries
SQL Interface
Aggregate Functions
For all Entries
Select Over more than one internal table
Selection Criteria
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.
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'.
Select Statements Select Queries
1. Avoid nested selects
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.
2. Select all the records in a single shot using into table clause of select statement rather than to use Append statements.
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'.
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.
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.
4. For testing existence, use Select.. Up to 1 rows statement instead of a Select-Endselect-loop with an Exit.
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.
5. Use Select Single if all primary key fields are supplied in the Where condition .
If all primary key fields are supplied in the Where conditions you can even use Select Single.
Select Single requires one communication with the database system, whereas Select-Endselect needs two.
Select Statements SQL Interface
1. Use column updates instead of single-row updates
to update your database tables.
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.
2. For all frequently used Select statements, try to use an index.
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.
3. Using buffered tables improves the performance considerably.
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'.
Select Statements Aggregate Functions
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.
Select Statements For All Entries
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)
Points to be must considered FOR ALL ENTRIES
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.
Select Statements Select Over more than one Internal table
1. Its better to use a views instead of nested Select statements.
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
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.
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.
3. Instead of using nested Select loops it is often better to use subqueries.
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.
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 ) ).
2. Always try to use binary search instead of linear search. But dont forget to sort your internal table before that.
READ TABLE ITAB INTO WA WITH KEY K = 'X'. IS FASTER THAN USING
READ TABLE ITAB INTO WA WITH KEY (NAME) = 'X'.
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.
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.
6. Modifying selected components using MODIFY itab TRANSPORTING f1 f2.. accelerates the task of updating a line of an internal table.
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
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.
8. If collect semantics is required, it is always better to use to COLLECT rather than READ BINARY and then ADD.
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)) .
9. "APPEND LINES OF itab1 TO itab2" accelerates the task of appending a table to another table considerably as compared to LOOP-APPEND-ENDLOOP.
APPEND LINES OF ITAB1 TO ITAB2.
This is more optimized as compared to
LOOP AT ITAB1 INTO WA.
APPEND WA TO ITAB2.
ENDLOOP.
10. DELETE ADJACENT DUPLICATES accelerates the task of deleting duplicate entries considerably as compared to READ-LOOP-DELETE-ENDLOOP.
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.
11. "DELETE itab FROM ... TO ..." accelerates the task of deleting a sequence of lines considerably as compared to DO -DELETE-ENDDO.
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.
ITAB2[] = ITAB1[].
This is much more optimized as compared to
REFRESH ITAB2.
LOOP AT ITAB1 INTO WA.
APPEND WA TO ITAB2.
ENDLOOP.
13. Specify the sort key as restrictively as possible to run the program faster.
SORT ITAB BY K. makes the program runs faster as compared to SORT ITAB.
Internal Tables contd
Hashed and Sorted tables
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
Point # 1
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.
Point # 2
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.
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