topic about the buffring in Application Development and Automation Discussions

about the buffring

Former Member — Mon, 16 Apr 2007 08:58:01 GMT

plz anybody tell me about the buffring types.

i will give good points.

Re: about the buffring

Former Member — Mon, 16 Apr 2007 08:59:09 GMT

Hi rangamma,

Buffering

You must define whether and how a table is buffered in the

technical settings for the table. There are three possibilities

here:

1> 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.

2> 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.

3> Buffering activated: The table should be buffered. In this

case you must specify a buffering type.

Buffering types:

1> Single-Record buffering

With single-record buffering, only the records that are actually

read are loaded into the buffer. Single-record buffering therefore

requires less storage space in the buffer than generic and full

buffering. The administrative costs in the buffer, however, are

greater than for generic or full buffering. Considerably more

database accesses are necessary to load the records than for

the other buffering types.

When Should you Use Single-Record Buffering?

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.

2> Generic buffering

With generic buffering, all the records in the buffer whose

generic key fields match this record are loaded when one

record of the table is accessed. The generic key is a part of

the primary key of the table that is left-justified.

3> Full buffering

With full buffering, either the entire table is in the

buffer or the table is not in the buffer at all. All the

records of the table are loaded into the buffer when

one record of the table is read.

When Should you Use Full Buffering?

When deciding whether a table should be fully buffered, you

should take 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, read frequently, and rarely written.

Full buffering is recommended in the following cases:

Tables up to 30 KB in size. If a table is accessed frequently, but

allaccesses are read accesses, this value can be exceeded.

However, youshould always pay attention to the buffer

utilization.

Larger tables where large numbers of records are frequently

Provide some points if it is helpful.

Rgds,

P.Nag

Re: about the buffring

Former Member — Mon, 16 Apr 2007 08:59:59 GMT

The buffering type defines which table records are loaded into the buffer of the application server when a table record is accessed. There are the following buffering types:

Full buffering: All the records of the table are loaded into the buffer when one record of the table is accessed.

Generic buffering: When a record of the table is accessed, all the records having this record in the generic key fields (part of the table key that is left-justified, identified by specifying a number of key fields) are loaded into the buffer.

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

Full buffering is recommended in the following cases:

Tables up to 30 KB in size. If a table is accessed frequently, but all accesses are read accesses, this value can be exceeded. However, you should always pay attention to the buffer utilization.

Larger tables where large numbers of records are frequently accessed. If these mass accesses can be formulated with a very selective WHERE condition using a database index, it could be better to dispense with buffering.

Tables for which accesses to non-existent records are frequently submitted. Since all the table records reside in the buffer, the system can determine directly in the buffer whether or not a record exists.

Regards rk

Re: about the buffring

Former Member — Mon, 16 Apr 2007 09:01:09 GMT

Buffering type

The buffering type defines whether and how the table should be buffered.

There are the following types of buffering:

o single-record buffering

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.

o generic area buffering

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.

o full buffering

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.

In generic area buffering, a number of key fields between 1 and no. of

key fields-1 must be specified.

Re: about the buffring

Former Member — Mon, 16 Apr 2007 09:01:49 GMT

hi Rangamma,

Full buffering: All the records of the table are loaded into the buffer when one record of the table is accessed.

Generic buffering: When a record of the table is accessed, all the records having this record in the generic key fields (part of the table key that is left-justified, identified by specifying a number of key fields) are loaded into the buffer.

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

Hope this helps,

Sajan Joseph.

Re: about the buffring

Former Member — Mon, 16 Apr 2007 09:03:44 GMT

Hi....

Buffering a table improves the performance when accessing the data records contained in the table

The buffering type defines which table records are loaded into the buffer of the application server when a table record is accessed. There are the following buffering types:

Full buffering: All the records of the table are loaded into the buffer when one record of the table is accessed.

Generic buffering: When a record of the table is accessed, all the records having this record in the generic key fields (part of the table key that is left-justified, identified by specifying a number of key fields) are loaded into the buffer.

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

also see the following link:

http://help.sap.com/saphelp_nw04/helpdata/en/cf/21eaec446011d189700000e8322d00/frameset.htm

It helps you a lot.......

Reward points if useful.....

Suresh.....