tables

[Former Member]

while creating table we will go to technical settings there we find options for buffering ->buffering not allowed 2->buffering allowed what does it mean may u plz explain clearly the difference points will be rewarded.

thanks in advance.

[Former Member]

Check this link to learn more about buffering

http://help.sap.com/saphelp_erp2004/helpdata/en/cf/21f244446011d189700000e8322d00/content.htm

[Former Member]

Hi

We have 3 types of buffering

There are the following types of buffering:

o single-record buffering

o generic area buffering

o full buffering

Single-record buffering should be selected when :

o For large tables where there are frequent single-record accesses (using SELECT SINGLE ...). The size of the records being accessed should be between 100-200 KB.

o For comparatively small tables for which the access range is large, it is normally advisable to opt for full buffering. Only one database access is required to load such a table for full buffering,

while single-record buffering calls for a very large number of table accesses.

And also check this matter.

Single-record buffering: Only the records of a table that are really accessed are loaded into the buffer

Single-record buffering should be used particularly for large tables where only a few records are accessed with SELECT SINGLE. The size of the records being accessed should be between 100 and 200 KB.

Full buffering is usually more suitable for smaller tables that are accessed frequently. This is because only one database access is necessary to load such a table with full buffering, whereas several database accesses are necessary for single-record buffering.

Check this link :

http://help.sap.com/saphelp_nw04/helpdata/en/f7/e4c5a8a84a11d194eb00a0c929b3c3/content.htm

reward points if useful

regards,

Anji

[Former Member]

Buffering not permitted: Table buffering is not permitted, for example because application programs always need the most recent data from the table or the table is changed too frequently.

Buffering permitted but not activated: Buffering is permitted from the business and technical points of view. Applications which access the table execute correctly with and without table buffering. Whether or not table buffering will result in a gain in performance depends on the table size and access profile of the table (frequency of the different types of table access). Table buffering is deactivated because it is not possible to know what these values will be in the customer system. If table buffering would be advantageous for the table size and access profile of the table, you can activate it in the customer system at any time.

Buffering activated: The table should be buffered. In this case you must specify a buffering type

Check the following link also:

http://help.sap.com/saphelp_nw04/helpdata/en/cf/21ebc9446011d189700000e8322d00/frameset.htm

Warm Regards,

Vijay

[Former Member]

The <b>buffering status</b> specifies whether or not a table may be buffered.

This depends on how the table is used, for example on the expected

volume of data in the table or on the type of access to a table. (mainly

read or mainly write access to the table. In the latter case, for

example, one would not select buffering).

You should therefore select

- <b>Buffering not allowed</b> if a table may not be buffered.

- <b>Buffering allowed but not activated</b> if buffering is

principally allowed for a table, but at the moment no buffering

should be active. The

buffering type specified in this case is only

a suggestion.

- <b>Buffering allowed</b> if the table should be buffered. In this

case a buffering type

must be specified.

[Former Member]

Hi Naga,

if you select option buffering allowed....

this will buffer the data that is fetched from database server to application server. means for further similar fetching of data it will get it from application server itself and will not have to get the load onto database table.

but if you have selected Buffering not allowed...

it will not buffer data on application server and thats y it will always fetch the data from database server though the same data was fetched earlier from same table.

This is the very basic and simple difference between the two options that you have asked for.

<b>Reward points if helpful,</b>

Regards,

Tejas

[Former Member]

while buffering the records will get stored locally in the application server itself,so it

1) improves the performance

2)time consuming

because it will not refer the database every time once it is buffered

Message was edited by:

varalakshmi kannan

[satykumar]

The buffering status specifies whether or not a table may be buffered.

This depends on how the table is used, for example on the expected volume of data in the table or on the type of access to a table. (mainly read or mainly write access to the table. In the latter case, for example, one would not select buffering).

You should therefore select

- Buffering not allowed if a table may not be buffered.

- Buffering allowed but not activated if buffering is

principally allowed for a table, but at the moment no buffering

should be active. The

buffering type specified in this case is only

a suggestion.

- Buffering allowed if the table should be buffered. In this

case a buffering type

must be specified.

Types:

<b>Single-record buffering</b>

With this kind of buffering, only the records of a table which are actually accessed are loaded into the buffer.

This kind of buffering requires less storage space in the buffer than full buffering. However, greater organization is necessary and considerably more database accesses are necessary for loading.

If an as yet unbuffered record is accessed using SELECT SINGLE, a database access occurs to load the record. If the table does not contain a record for the specified key ('no record found'), this record is noted as nonexistent in the buffer. If a further attempt is made to access this record using SELECT SINGLE, a renewed database access can be avoided.

When should single-record buffering be selected?

For large tables where there are frequent single-record accesses (using SELECT SINGLE ...). The size of the records being accessed should be between 100-200 KB.

For comparatively small tables for which the access range is large, it is normally advisable to opt for full buffering. Only one database access is required to load such a table for full buffering, while single-record buffering calls for a very large number of table accesses.

<b>Generic buffering</b>

In a read access to a record of a generically buffered table, all the records whose left-justified part of the key (generic area) corresponds are loaded into the buffer.

If this type of buffering is selected, the generic area must be defined by specifying a number n of key fields. The first n key fields of the table then define the generic key.

The number of key fields to be entered must lie between 1 and the number of key fields -1. For example, only values between 1 and 5 are permitted for a table with 6 key fields. The client field is included here.

When should generic buffering be selected?

A table should be buffered generically if usually only certain areas of the table are required. The individual generic areas are treated like independent tables that are fully buffered. Refer also to the text on complete buffering.

The generic key area should be selected so that the generic areas are not too small to prevent too may generic areas being produced. If there are only a few records for each generic area, it is more efficient to use full buffering.

Generic buffering only makes sense if the table is accessed by a specified generic key. If, when an access takes place, a field of the generic key is not supplied with a value, the buffer is ignored and the records are read directly from the database.

Language-specific tables are an example of good use of generic buffering (with the language key field as generic key area).

<b>Full buffering</b>

With full buffering, either the complete table or none of the table is in the buffer. If a read access is made to a record, all records of the table are transferred to the buffer.

When should you select full buffering?

For tables up to 30 KB in size. If a table is accessed frequently, but all accesses are read accesses, this value can be exceeded.

For larger tables where large numbers of records are frequently accessed. However, if the application program is able to formulate an extremely selective WHERE condition using a database index, it may be advisable to dispense with full buffering.

For tables with frequent accesses to data not contained in the table. Since all records are contained in the buffer, a quick decision can be made as to whether or not the table contains a record for a specific key.

When considering whether a table should be fully buffered, you should take three aspects into account: the size of the table, the number of read accesses, and the number of write accesses. Tables best suited to full buffering are small, frequently read, and rarely updated.