SAP NEWS-71-ITAB documentation, setup help and example usage

Internal Tables in Release 7.0, EhP2

1 Dynamic WHERE Condition
2 Definition of Secondary Table Keys
3 Use of Secondary Table Keys
4 Updating of Secondary Table Keys
5 Streaming for Internal Tables


ABAP_MODIFICATION_1 Dynamic WHERE Condition

As of Release 7.0, EhP2 , the LOOP AT itab , MODIFY itab , and DELETE itab statements allow you to dynamically specify the WHERE condition in a cond_syntax data object.


ABAP_MODIFICATION_2 Definition of Secondary Table Keys

Previously, each internal table had just one table key . Any search key could be entered when accessing internal tables, but this was not very efficient. Also, standard tables were always searched linearly during key access. To be able to efficiently access an internal table with different keys, and to also allow efficient key access to standard tables, secondary table keys were introduced.
As of Release 7.0, EhP2 ,
secondary table keys can be defined for internal tables with TYPES and DATA
as well as in ABAP Dictionary. An internal table can have up to 15 secondary table keys with different names. At the same time, what was previously the table key became the primary table key, and a predefined name for it, primary_key , was introduced. This can be replaced with an alias name in the enhanced definition
of the primary table key in Release 7.0, EhP2 .
Secondary table keys can be hash keys or sorted keys . A secondary table index is created for each sorted secondary key of an internal table. The previous table index, which exists only for index tables, becomes the primary table index .
Secondary table keys belong to the technical type properties of an internal table. The specification of secondary keys can be generic for standalone table types.


ABAP_MODIFICATION_3 Using Secondary Keys

The following additions have been introduced for statements that access rows of internal tables:
WITH [TABLE] KEY keyname COMPONENTS ...
USING KEY keyname
You can use keyname to specify the name of the key to be used statically or dynamically.
At the same time, statements that previously only accessed the primary key have been enhanced so that access to secondary keys is also possible. The table index to be used can now also be explicitly specified with a table key in index specifications. The sy-tabix system field is now filled with reference to the table index used. It is set to 0 for access via a hash key.
The enhanced statements are:
READ TABLE itab
The rows to be read can be specified using a secondary key.

LOOP AT itab
The processing sequence and conditions can be controlled using a secondary table key.

INSERT itab
Only a secondary key for the source table can be specified here, from which multiple rows are copied. The position they are inserted at is determined solely using the primary key and the primary index.

APPEND
Only a secondary key for the source table can be specified here, onto which multiple rows are appended.

MODIFY itab
The rows to be modified can be specified using a secondary key.

DELETE itab
The rows to be deleted can be specified using a secondary key.
In statements where these additions have not been introduced, such as SORT , COLLECT , or PROVIDE , secondary keys are not explicitly supported.


ABAP_MODIFICATION_4 Updating Secondary Keys

In all statements that change the content or structure of an internal table, the internal administration of the secondary table key (hash administration or secondary table index) is updated automatically as follows:
In inserting operations, such as INSERT or APPEND , and in change operations using MODIFY , the secondary table key administration of unique keys is updated immediately (
direct update ), while for non-unique table keys it is updated upon the next explicit use of the secondary table key ( lazy update ). If an update infringes the uniqueness of a secondary key, an exception is raised immediately.

For block operations, such as statements between internal tables, or when internal tables are filled using SELECT , the behavior is the same as with inserting operations.

When individual rows are modified using using field symbols or data references that point to table rows, the secondary key administration of unique keys is updated upon the next access to the internal table (
delayed update ), and the secondary key administration of non-unique keys is updated upon the next explicit use of the secondary table key (
lazy update ). A uniqueness check is also run when the update is made. An internal table might therefore be in an inconsistent state with respect to the secondary key after individual rows are modified. An exception is not raised until the table is next used.
Class CL_ABAP_ITAB_UTILITIES contains methods that can be used to update single secondary keys or all secondary keys for an internal table in exceptional situations.


ABAP_MODIFICATION_5 Streaming for internal tables

The new streaming concept supports
internal tables .