hai gurus...

[Former Member]

hello guru's...

in select single and select upto one row which one is best performance wise and which one will take less time and also which one will give us the correct result and also can i know how these is related to the BUFFERING concept....

[Former Member]

hello guru's...

in select single and select upto one row which one is best performance wise and which one will take less time and also which one will give us the correct result and also can i know how these is related to the BUFFERING concept....

[Former Member]

hi,

Select single is better than select upto one row.

[Simha_]

Hi,

According to SAP Performance course the SELECT UP TO 1 ROWS is faster than SELECT SINGLE because you are not using all the primary key fields.

select single is a construct designed to read database records with primary key. In the absence of the primary key, it might end up doing a sequential search, whereas the select up to 1 rows may assume that there is no primary key supplied and will try to find most suitable index.

The best way to find out is through sql trace or runtime analysis.

Use "select up to 1 rows" only if you are sure that all the records returned will have the same value for the field(s) you are interested in. If not, you will be reading only the first record which matches the criteria, but may be the second or the third record has the value you are looking for.

The System test result showed that the variant Single * takes less time than Up to 1 rows as there is an additional level for COUNT STOP KEY for SELECT ENDSELECT UP TO 1 ROWS.

The 'SELECT SINGLE' statement selects the first row in the database that it finds that fulfils the 'WHERE' clause If this results in multiple records then only the first one will be returned and therefore may not be unique.

Mainly: to read data from

The 'SELECT .... UP TO 1 ROWS' statement is subtly different. The database selects all of the relevant records that are defined by the WHERE clause, applies any aggregate, ordering or grouping functions to them and then returns the first record of the result set.

Mainly: to check if entries exist.

Cheers,

Simha.

Reward if helpfu...

[Former Member]

Hi

Select single is better to use when u know the complete key.

Regards

Suresh

[Former Member]

Hi Pavan

You are asking question not rewarding points which i observed in your previous threads also which boosts us to help you more

here comes your answer

The Major difference between Select Single and Select UPTO 1 rows is The Usage Of Buffer for each.

Select Single will search for all the satisfied data and bring all that data into Buffer and later it will give to that data to the program.

Select UPTO 1 Rows will end the search after getting the 1st satisfied record and gives that record to the program.

Thus Select Single will take much processing time when compare with Select UPTO 1 rows.

According to SAP Performance course the SELECT UP TO 1 ROWS is faster than SELECT SINGLE because you are not using all the primary key fields.

select single is a construct designed to read database records with primary key. In the absence of the primary key, it might end up doing a sequential search, whereas the select up to 1 rows may assume that there is no primary key supplied and will try to find most suitable index.

The best way to find out is through sql trace or runtime analysis.

Use "select up to 1 rows" only if you are sure that all the records returned will have the same value for the field(s) you are interested in. If not, you will be reading only the first record which matches the criteria, but may be the second or the third record has the value you are looking for.

The System test result showed that the variant Single * takes less time than Up to 1 rows as there is an additional level for COUNT STOP KEY for SELECT ENDSELECT UP TO 1 ROWS.

The 'SELECT SINGLE' statement selects the first row in the database that it finds that fulfils the 'WHERE' clause If this results in multiple records then only the first one will be returned and therefore may not be unique.

Mainly: to read data from

The 'SELECT .... UP TO 1 ROWS' statement is subtly different. The database selects all of the relevant records that are defined by the WHERE clause, applies any aggregate, ordering or grouping functions to them and then returns the first record of the result set.

Mainly: to check if entries exist.

<b>Select single is performance wise more Better then select upto one row.</b>

Reward all helpfull answers

Regards

Pavan

[Former Member]

hi

good

According to SAP Performance course the SELECT UP TO 1 ROWS is faster than SELECT SINGLE because you are not using all the primary key fields.

select single is a construct designed to read database records with primary key. In the absence of the primary key, it might end up doing a sequential search, whereas the select up to 1 rows may assume that there is no primary key supplied and will try to find most suitable index.

The best way to find out is through sql trace or runtime analysis.

Use "select up to 1 rows" only if you are sure that all the records returned will have the same value for the field(s) you are interested in. If not, you will be reading only the first record which matches the criteria, but may be the second or the third record has the value you are looking for.

The System test result showed that the variant Single * takes less time than Up to 1 rows as there is an additional level for COUNT STOP KEY for SELECT ENDSELECT UP TO 1 ROWS.

The 'SELECT SINGLE' statement selects the first row in the database that it finds that fulfils the 'WHERE' clause If this results in multiple records then only the first one will be returned and therefore may not be unique.

Mainly: to read data from

The 'SELECT .... UP TO 1 ROWS' statement is subtly different. The database selects all of the relevant records that are defined by the WHERE clause, applies any aggregate, ordering or grouping functions to them and then returns the first record of the result set.

thanks

mrutyun^

[Former Member]

hi,

select single * , select upto works similar but when we consider performance issue select up to is superior to select single * as

select single * selects all records from database table and it buffers all but displays only one record to user based on given condition.

select up to selects only n records from database and buffers them only n displays the top most record based on given condition.

selectup to works faster than select single *

if helpful reward some points,

with regrads,

suresh.