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what is the diff b/w standard and sorted and hashed tables

Hi All,

I want to kno wthe basic diff b/w standard table and sorted table and hashed table.

Can any body give the solution for this with expand code.

Thanks in advance

JD

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    author's profile photo Former Member
    Former Member
    Posted on May 31, 2007 at 10:54 AM

    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.

    Thanks,

    Anitha

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  • author's profile photo Former Member
    Former Member
    Posted on May 31, 2007 at 10:52 AM

    Hi

    Standard table:

    The key access to a standard table uses a sequential search. The time required for an access is linearly dependent on the number of entries in the internal table.

    You should usually access a standard table with index operations.

    Sorted table:

    The table is always stored internally sorted by its key. Key access to a sorted table can therefore use a binary search. If the key is not unique, the entry with the lowest index is accessed. The time required for an access is logarithmically dependent on the number of entries in the internal table.

    Index accesses to sorted tables are also allowed. You should usually access a sorted table using its key.

    Hash table:

    The table is internally managed with a hash procedure. All the entries must have a unique key. The time required for a key access is constant, that is it does not depend on the number of entries in the internal table.

    You cannot access a hash table with an index. Accesses must use generic key operations (SORT, LOOP, etc.).

    Reward points if useful

    Regards

    Anji

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  • author's profile photo Former Member
    Former Member
    Posted on May 31, 2007 at 10:54 AM

    Hi,

    Standard tables

    This is the most appropriate type if you are going to address the individual table entries using the index. Index access is the quickest possible access. You should fill a standard table by appending lines (ABAP APPEND statement), and read, modify and delete entries by specifying the index (INDEX option with the relevant ABAP command). The access time for a standard table increases in a linear relationship with the number of table entries. If you need key access, standard tables are particularly useful if you can fill and process the table in separate steps. For example, you could fill the table by appending entries, and then sort it. If you use the binary search option with key access, the response time is logarithmically proportional to the number of table entries.

    Sorted tables

    This is the most appropriate type if you need a table which is sorted as you fill it. You fill sorted tables using the INSERT statement. Entries are inserted according to the sort sequence defined through the table key. Any illegal entries are recognized as soon as you try to add them to the table. The response time for key access is logarithmically proportional to the number of table entries, since the system always uses a binary search. Sorted tables are particularly useful for partially sequential processing in a LOOP if you specify the beginning of the table key in the WHERE condition.

    Hashed tables

    This is the most appropriate type for any table where the main operation is key access. You cannot access a hashed table using its index. The response time for key access remains constant, regardless of the number of table entries. Like database tables, hashed tables always have a unique key. Hashed tables are useful if you want to construct and use an internal table which resembles a database table or for processing large amounts of data.

    paste this example..and test various cases...

    Note:

    u can not use append to HASH / SORT....

    data:

    begin of fs_data,

    f1 type i,

    f2 type c,

    end of fs_data.

    data:

    t_std like standard table of fs_data,

    t_srt like sorted table of fs_data with non-unique key f1,

    t_hsh like hashed table of fs_data with unique key f1.

    fs_data-f1 = 1.

    fs_data-f2 = 'A'.

    append fs_data to : t_std.

    insert fs_data into table: t_srt,t_hsh.

    fs_data-f1 = 4.

    fs_data-f2 = 'B'.

    append fs_data to : t_std.

    insert fs_data into table : t_srt,t_hsh.

    fs_data-f1 = 2.

    fs_data-f2 = 'A'.

    append fs_data to : t_std.

    insert fs_data into table : t_srt,t_hsh.

    fs_data-f1 = 3.

    fs_data-f2 = 'D'.

    append fs_data to : t_std.

    insert fs_data into table : t_srt,t_hsh.

    loop at t_std into fs_data.

    write: / fs_data-f1,fs_data-f2.

    endloop.

    skip 2.

    loop at t_srt into fs_data.

    write: / fs_data-f1,fs_data-f2.

    endloop.

    skip.

    loop at t_hsh into fs_data.

    write: / fs_data-f1,fs_data-f2.

    endloop.

    Regards,

    Priyanka.

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  • author's profile photo Former Member
    Former Member
    Posted on May 31, 2007 at 10:55 AM

    Standard table will use Linear Search.

    Sorted tables will use Binary search.

    Hashed Tables will use Hashing Alogorithms

    /people/harry.dietz/blog/2005/10/28/performance-improvement-hints-3-internal-table--fill-and-read

    http://www.sap-img.com/abap/what-are-different-types-of-internal-tables-and-their-usage.htm

    http://help.sap.com/saphelp_erp2005/helpdata/en/fc/eb35de358411d1829f0000e829fbfe/frameset.htm

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  • author's profile photo Former Member
    Former Member
    Posted on May 31, 2007 at 11:01 AM

    hi jagadish,

    Hi

    Standard table:

    The key access to a standard table uses a sequential search. The time required for an access is linearly dependent on the number of entries in the internal table.

    You should usually access a standard table with index operations.

    Sorted table:

    The table is always stored internally sorted by its key. Key access to a sorted table can therefore use a binary search. If the key is not unique, the entry with the lowest index is accessed. The time required for an access is logarithmically dependent on the number of entries in the internal table.Index accesses to sorted tables are also allowed. You should usually access a sorted table using its key.

    sorted tables are mainly useful in areas where u need to have data in order whether its ascending or decending.

    Hash table:

    The table is internally managed with a hash procedure. All the entries must have a unique key. The time required for a key access is constant, that is it does not depend on the number of entries in the internal table. hash tables are faster than other two when it comes to performance as it uses hash algorithms.

    in hash tables we cant search with indexes as in standard or sorted tables do.

    if helpful reward some points.

    with regards,

    suresh bbau aluri.

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  • author's profile photo Former Member
    Former Member
    Posted on May 31, 2007 at 11:02 AM

    hi,

    following are the defination of the three type of internal table.

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

    <b>Standard tables</b>--> 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 nonBC 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.

    <b>Sorted tables</b>--> 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.

    <b>Hashed tables</b>-->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.

    for more information please go through these links,

    /people/harry.dietz/blog/2005/10/28/performance-improvement-hints-3-internal-table--fill-and-read

    http://www.sap-img.com/abap/what-are-different-types-of-internal-tables-and-their-usage.htm

    http://help.sap.com/saphelp_erp2005/helpdata/en/fc/eb35de358411d1829f0000e829fbfe/frameset.htm

    hope this will solve your problem and please don't forget to reward points for all the helpful answer.

    regards,

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