topic Re: about internal tables in Application Development and Automation Discussions

about internal tables

Former Member — Tue, 25 Mar 2008 10:36:26 GMT

can u tell me how many types of internal tables?

regards,

geeta sanku

Re: about internal tables

Former Member — Tue, 25 Mar 2008 10:38:50 GMT

Table type

The table type determines how ABAP will access individual table entries. Internal tables can be divided into three types:

Standard tables have an internal linear index. From a particular size upwards, the indexes of internal tables are administered as trees. In this case, the index administration overhead increases in logarithmic and not linear relation to the number of lines. The system can access records either by using the table index or the key. The response time for key access is proportional to the number of entries in the table. The key of a standard table is always non-unique. You cannot specify a unique key. This means that standard tables can always be filled very quickly, since the system does not have to check whether there are already existing entries.

Sorted tables are always saved sorted by the key. They also have an internal index. The system can access records either by using the table index or the key. The response time for key access is logarithmically proportional to the number of table entries, since the system uses a binary search. The key of a sorted table can be either unique or non-unique. When you define the table, you must specify whether the key is to be unique or not. Standard tables and sorted tables are known generically as index tables.

Hashed tables have no linear index. You can only access a hashed table using its key. The response time is independent of the number of table entries, and is constant, since the system access the table entries using a hash algorithm. The key of a hashed table must be unique. When you define the table, you must specify the key as UNIQUE.

Regards

Aditya

Re: about internal tables

Former Member — Tue, 25 Mar 2008 10:39:44 GMT

HI,

Standard tables

Sorted tables

Hashed tables

Regards,

S.Nehru

Re: about internal tables

Former Member — Tue, 25 Mar 2008 10:41:11 GMT

Explore this site:

http://help.sap.com/saphelp_erp2005vp/helpdata/en/fc/eb35de358411d1829f0000e829fbfe/content.htm

Hope this helps.

Regards

Vinayak

Re: about internal tables

Former Member — Tue, 25 Mar 2008 10:41:15 GMT

Hi,

Standard Internal Tables

Standard tables have a linear index. You can access them using either the index or the key. If you use the key, the response time is in linear relationship to the number of table entries. The key of a standard table is always non-unique, and you may not include any specification for the uniqueness in the table definition.

This table type is particularly appropriate if you want to address individual table entries using the index. This is the quickest way to access table entries. To fill a standard table, append lines using the (APPEND) statement. You should read, modify and delete lines by referring to the index (INDEX option with the relevant ABAP command). The response time for accessing a standard table is in linear relation to the number of table entries. If you need to use key access, standard tables are appropriate if you can fill and process the table in separate steps. For example, you can fill a standard table by appending records and then sort it. If you then use key access with the binary search option (BINARY), the response time is in logarithmic relation to

the number of table entries.

Sorted Internal Tables

Sorted tables are always saved correctly sorted by key. They also have a linear key, and, like standard tables, you can access them using either the table index or the key. When you use the key, the response time is in logarithmic relationship to the number of table entries, since the system uses a binary search. The key of a sorted table can be either unique, or non-unique, and you must specify either UNIQUE or NON-UNIQUE in the table definition. Standard tables and sorted tables both belong to the generic group index tables.

This table type is particularly suitable if you want the table to be sorted while you are still adding entries to it. You fill the table using the (INSERT) statement, according to the sort sequence defined in the table key. Table entries that do not fit are recognised before they are inserted. The response time for access using the key is in logarithmic relation to the number of

table entries, since the system automatically uses a binary search. Sorted tables are appropriate for partially sequential processing in a LOOP, as long as the WHERE condition contains the beginning of the table key.

Hashed Internal Tables

Hashes tables have no internal linear index. You can only access hashed tables by specifying the key. The response time is constant, regardless of the number of table entries, since the search uses a hash algorithm. The key of a hashed table must be unique, and you must specify UNIQUE in the table definition.

This table type is particularly suitable if you want mainly to use key access for table entries. You cannot access hashed tables using the index. When you use key access, the response time remains constant, regardless of the number of table entries. As with database tables, the key of a hashed table is always unique. Hashed tables are therefore a useful way of constructing and

using internal tables that are similar to database tables.

Hope this helps.

Reward points if useful.

Regards

Rose

Re: about internal tables

Former Member — Tue, 25 Mar 2008 10:42:03 GMT

there are 3 types

1.Standard Internal Tables: These tables have a linear index and can be accessed using the index or the key. The response time is in linear relationship with number of table entries. These tables are useful when user wants to address individual table entries using the index.

2.Sorted Internal Tables: These tables also have an index and the key. But, the response time is in logarithmic relationship with number of table entries, since it uses binary search algorithm instead of linear search. These tables are useful when user wants the table to be sorted while additional entries have to be added.

3.Hashed Internal Tables: These tables have no index, but have the key. The response time is constant irrespective of number of table entries, since it uses a Hash algorithm. These tables are useful when user wants to access the entries with key only.

Re: about internal tables

Former Member — Tue, 25 Mar 2008 10:43:20 GMT

Hi,

The table type determines how ABAP will access individual table entries. Internal tables can be divided into three types:

Generic Internal Tables

Unlike other local data types in programs, you do not have to specify the data type of an internal table fully. Instead, you can specify a generic construction, that is, the key or key and line type of an internal table data type may remain unspecified. You can use generic internal tables to specify the types of field symbols and the interface parameters of procedures. You cannot use them to declare data objects.

Regards,

Bhaskar

Re: about internal tables

Former Member — Wed, 26 Mar 2008 07:19:20 GMT

hi,

Internal tables are of 3 types:

1. Standard internal table

2. Sorted internal table

3. Hashed internal table.

STANDARD table Key access to a standard table uses a linear search. This means that the time required for a search is in linear relation to the number of table entries. You should use index operations to access standard tables.

SORTED table Defines the table as one that is always saved correctly sorted. Key access to a sorted table uses a binary key. If the key is not unique, the system takes the entry with the lowest index. The runtime required for key access is logarithmically related to the number of table entries.

HASHED table Defines the table as one that is managed with an internal hash procedure You can only access a hashed table using the generic key operations or other generic operations ( SORT, LOOP, and so on). Explicit or implicit index operations (such as LOOP ... FROM INSERT itab within a LOOP) are not allowed.

Index Tables

Index table is only used to specify the type of generic parameters in a FORM or FUNCTION. That means that you can't create a table of type INDEX.

Internal tables are not DB tables. Standard and Sorted tables in combined are basically called as Index tables and there nothing else. Here is the hierarchy

ANY TABLE

| |

Index Tables Hashed Table

| |

Standard Table Sorted Table