Database table and cluster table

Former Member — Tue, 31 Oct 2006 12:24:30 GMT

What is databese table and cluster table. what is the differnce between them. which table do we use very frequently.

Re: Database table and cluster table

Former Member — Tue, 31 Oct 2006 13:00:33 GMT

database table is that which gets created in database finally after activating table from data dictionary workbench. in sap tables are like follows:

1. transparent table

2. cluster table

3. pooled table

normally transparent table are quite often used to hold transactional data whereas cluster table / pooled table are used to hold control data / system data / customization data. for example screen numbers...

normally you will get to use transparent tables quite often.

shane

Re: Database table and cluster table

anversha_s — Tue, 31 Oct 2006 13:19:25 GMT

Hi Abhay,

The following are the table types used in SAP :

I. Transparent tables (BKPF, VBAK, VBAP, KNA1, COEP)

Allows secondary indexes (SE11->Display Table->Indexes)

Can be buffered (SE11->Display Table->technical settings) Heavily updated tables should not be buffered.

II. Pool Tables (match codes, look up tables)

Should be accessed via primary key or

Should be buffered (SE11->Display Table->technical settings)

No secondary indexes

Select * is Ok because all columns retrieved anyway

III. Cluster Tables (BSEG,BSEC)

Should be accessed via primary key - very fast retrieval otherwise very slow

No secondary indexes

Select * is Ok because all columns retrieved anyway. Performing an operation on multiple rows is more efficient than single row operations. Therefore you still want to select into an internal table. If many rows are being selected into the internal table, you might still like to retrieve specific columns to cut down on the memory required.

Statistical SQL functions (SUM, AVG, MIN, MAX, etc) not supported

Can not be buffered

IV. Buffered Tables (includes both Transparent & Pool Tables)

While buffering database tables in program memory (SELECT into internal table) is generally a good idea for performance, it is not always necessary. Some tables are already buffered in memory. These are mostly configuration tables. If a table is already buffered, then a select statement against it is very fast. To determine if a table is buffered, choose the 'technical settings' soft button from the data dictionary display of a table (SE12). Pool tables should all be buffered.

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Database table and cluster table

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