ARTICLE
Processing Large Datasets in Release 4.0
General
You can manage large datasets in ABAP either as internal tables or
extract datasets .
Internal tables are dynamic sequential datasets whose rows all have the
same structure and a key.
Extracts are dynamic sequential datasets
whose rows can be structured differently. Extracts cannot be accessed
using indexes or keys. They are always processed in a loop.
From Release 4.5A , the performance of some crucial operations on
internal tables and extracts has improved significantly.
Description of Functions
New Index Management in Internal Tables
Until now, the cost of manipulating indexes increased in linear relation
to the number of entries being inserted or deleted from
standard and
sorted tables . From Release 4.5A ,
these index manipulation costs will only increase in logarithmic
relation to the number of entries, mainly due to the fact that table
indexes are now managed in tree form. This allows for more efficient
insertion and deletion in very large standard and sorted tables.
Internal Tables
Accessing Individual Internal Table Entries Using Field Symbols
Until now, individual entries in internal tables could only be processed
indirectly using separate work areas. From Release 4.5A , you can
use field symbols to display internal table entries. You can now both
read internal table entries and write to them as well. This allows for
better performance when working with large and complex tables and makes
processing nested internal tables considerably easier.
To assign a table row to a field symbol, use the following statements:
LOOP AT itab ASSIGNING fs .
READ TABLE itab ASSIGNING fs .
New Repository for Extracts
Until now, extracts were stored in SAP
paging. In an effort to improve sorting and sequential processing
performance, extracts of more than 500 kBytes are now stored
directly in the file system.
Extracts
New External Sort Process for Internal Tables and Extracts
The main memory cannot sort large datasets all at once. Until now large
datasets were sorted by the operating system's own platform-specific
sort function. Now SAP's own platform-independent sort procedure is
used. This reduces the costs of some sorting operations considerably.
Extracts stored in the file system are always resorted physically.
Internal tables are sorted physically if they are longer than
2^19
rows or larger than 12 MB . Physical sorting reduces the costs
of any follow-on sequential processing.
Documentation extract taken from SAP system, � Copyright SAP AG. All rights reserved