Cluster tables , pool tables ,hashed tables?

give me the examles of cluster and pool tables & hashed tables ?

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.
regards,
srinivas
*reward for useful answers*

Similar Messages

How to use one hash table inside another hash table

Hi everyone,
Any example of hash table inside another hash table.
Can one here help me how to write one hash table inside another with repeating keys for the first hash table.
Thanks,
kanty.

Do you mean you want the 'value' entries in a hash table to themselves be hash tables? Easy but this often indicates a design flaw.
Hashtable<String,<Hashtable<String,Value>> fred = new Hashtable<String,<Hashtable<String,Value>> ();But what do you mean by "with repeating keys for the first hash table"?
Edited by: sabre150 on Jul 2, 2010 10:11 PM
Looks like you have already handled the declaration side in your other thread. I suspect you should be writing your own beans that hold the information and these beans would then be stored in a Map. The problem I have is that your description is too vague so I can't be certain.

Reg cluster and pooled tables

hi experts..
can u pls give the names of some cluster and pooled tables?
regards
Sellavel

Hello,
Pooled tables can be used to store control data (e.g. screen sequences, program parameters or temporary data). Several pooled tables can be combined to form a table pool. The table pool corresponds to a physical table on the database in which all the records of the allocated pooled tables are stored.
A001
A004
A005
A006
A007
A009
A010
A012
A015
A016
A017
A018
A019
A021
A022
Cluster tables contain continuous text, for example, documentation. Several cluster tables can be combined to form a table cluster. Several logical lines of different tables are combined to form a physical record in this table type. This permits object-by-object storage or object-by-object access. In order to combine tables in clusters, at least parts of the keys must agree. Several cluster tables are stored in one corresponding table on the database.
AUAA
AUAB
AUAO
AUAS
AUAT
AUAV
AUAW
AUAY
BSEC
BSED
BSEG
BSES
BSET
CDPOS
Vasanth

Hash tables in combination with data references to the line type.

I'm having an issue with hash tables - in combination with reference variables.
Consider the following: (Which is part of a class) - it attempts to see if a particular id exists in a table; if not add it; if yes change it.
types: BEGIN OF TY_MEASUREMENT,
 perfid TYPE zgz_perf_metric_id,
 rtime TYPE zgz_perf_runtime,
 execount TYPE zgz_perf_execount,
 last_start TYPE timestampl,
 END OF TY_MEASUREMENT.
METHOD START.
DATA: ls_measurement TYPE REF TO ty_measurement.
READ TABLE gt_measurements WITH TABLE KEY perfid = i_perfid reference into ls_measurement.
if sy-subrc <> 0.
 "Didn't find it.
 create data ls_measurement.
 ls_measurement->perfid = i_perfid.
 insert ls_measurement->* into gt_measurements.
endif.
GET TIME STAMP FIELD ls_measurements-last_start.
ls_measurement->execount = ls_measurement->execount + 1.
ENDMETHOD.
I get compile errors on the insert statement - either "You cannot use explicit index operations on tables with types HASHED TABLE" or "ANY TABLE". It is possible that.
If I don't dereference the type then I get the error LS_MEASUREMENT cannot be converted to the line type of GT_MEASUREMENTS.
I'm not looking to solve this with a combination of references and work ares - want a reference solution.
Thanks!
_Ryan
Moderator message - Moved to the correct forum
Edited by: Rob Burbank on Apr 22, 2010 4:43 PM

I think it might work when you change it for
insert ls_measurement->* into TABLE gt_measurements.
For hashed table a new line here will be inserted according to given table key.
Regards
Marcin

How to define a hashed table?

Hi..
I want to know that how we can define a hash table in ABAB.
And what are the advantages of that table?
Thanks

once you have data in your internal table, there is not much of a performance issue...unless of course it contains a huge number of entries...
i m not aware of such a possibility that an internal table can behave as both sorted and hashed...
if you go for a hashed table, the response time for your search will always be constant, regardless of the number of table entries....this is because the search uses a hash algorithm...u must specify the UNIQUE key for hashed tables.
just go thru this link for some more information...
http://www.sap-img.com/abap/what-are-different-types-of-internal-tables-and-their-usage.htm
read this...
Standard tables are managed system-internally by a logical index. New rows are either attached to the table or added at certain positions. The table key or the index identify individual rows.
Sorted tables are managed by a logical index (like standard tables). The entries are listed in ascending order according to table key.
Hashed tables are managed by a hash algorithm. There is no logical index. The entries are not ordered in the memory. The position of a row is calculated by specifying a key using a hash function.
Sorted tables store records in a "sorted" fashion at all times. It is faster to search through a sorted table vs a standard table. But performance is dictated by the amount of records in the internal table.
A hashed table's performance in reads is NOT dependent on the number of records. However, it is intended for reads that will return only and only one record. It uses a "side-table" with a hash algorithm to store off the physical location of the record in the actual internal table. It is not NECESSARILY sorted/organized in an meaningful order (like a sorted table is). Please note that changes to a hashed tables records must be managed carefully. Review SAP's on-help in SE38/80 about managing hashed tables.
TYPES: BEGIN OF TY_ITAB,
FIELD1 TYPE I,
FIELD2 TYPE I,
END OF TY_ITAB.
TYPES ITAB TYPE SORTED TABLE OF TY_ITAB WITH UNIQUE KEY FIELD1.....
FOR PROPER SYNTEX F1 HELP....

Urgent: how to add additional records to hashed table

Hi,
I want to add records to a hashed table.
my code is:
data: ipn_pc_zoba type hashed table of tpn_pc_zoba with unique key vbeln.
loop at izoba into wzoba.
clear wpn_pc_zoba .
read table ipn_pc_zoba into wpn_pc_zoba with key vbeln = wzoba-LS_KDAUF.
if sy-subrc ne 0.
wpn_pc_zoba-vbeln = wzoba-LS_KDAUF.
append wpn_pc_zoba to ipn_pc_zoba.
endif.
endloop.
The Error is : You cannot use explicit or implicit index operations on tables with types "HASHED TABLE" or "ANY TABLE". "IPN_PC_ZOBA" has the type "HASHED TABLE". It is possible that .
How to solve this?
Please reply ASAP.
Regards,
SRI

In your code you should use
INSERT WPN_PC_ZOBA INTO IPN_PC_ZOBA.
This is the only way to append data to a hashed table. It will also only work as long as wpn_pc_zoba-vbeln is unique in the hashed table.
If you are getting an error, what does the error say?
Michael

Isuue in adding additional records to hashed table

Hi,
I want to add records to a hashed table.
my code is:
data: ipn_pc_zoba type hashed table of tpn_pc_zoba with unique key vbeln,
wpn_pc_zoba like line of ipn_pc_zoba.
loop at izoba into wzoba.
clear wpn_pc_zoba .
read table ipn_pc_zoba into wpn_pc_zoba with key vbeln = wzoba-LS_KDAUF.
if sy-subrc ne 0.
wpn_pc_zoba-vbeln = wzoba-LS_KDAUF.
append wpn_pc_zoba to ipn_pc_zoba.
endif.
endloop.
The Error is : You cannot use explicit or implicit index operations on tables with types "HASHED TABLE" or "ANY TABLE". "IPN_PC_ZOBA" has the type "HASHED TABLE". It is possible that .
How to solve this?
Please reply ASAP.
Regards,
SRI

Hi,
use
insert wpn_pc_zoba into table ipn_pc_zoba.
to insert the new record into the hashed table.
Regards,
Thomas Langen

Select for a hashed table

Hi All,
This is a repost but this time Ill be specific.
How do I select from a table into a hashed table faster without using "select distinct"? my primary concern is the speed of the select statement, and im afraid I cannot get rid of the hashed table destination.
Thanks,
Kenny

HI Kenny,
HASHED TABLE:
There is no default setting for hashed tables. However, you must define a UNIQUE key. The NON-UNIQUE addition is not permitted.
You cannot avoid this statement. May be the alternative is You have to use SORTED table with NON-UNIQUE option and then apply DELETE ADJACENT DUPLICATES, in this way you can have unique values for your itab.
Regards,
Raghav

Question about Hash Tables

I would like to know if there is a method of class Hashtable to update values in a Hash Table. I know about methods "put", "get", "remove" and "contains", but what I need is to modify the field "quantity" of a certain row (element) in the Hash Table.
Do Hash Tables allow to update? I'm surprised my book does not mention any method for updating a Hash Table.
Thank you in advance for any information.

put() will replace whatever exists under the specified key, if anything, with whatever new value you put. If you want to modify the contents of an object stored in the hashtable, you'd have to get the object, modify it, and put it back. At least for non-immutable objects you could just get and modify. The modify will modify that object, the reference to it would already exist in the table, so the put is kinda redundant, and would affect performance somewhat (although not noticeable for many apps). This wouldn't work for String or Integer, for example, you'd really just be putting a new String or Integer, so no need for get, just do put. Get it?

SORTED & HASHED tables

Hi all
what exactly are the SORTED & HASHED tables??
Regards
Srini

Internal tables are the core of ABAP. They are like soul of a body. For any program we use
internal tables extensively. We can use Internal tables like normal data base tables only, but the
basic difference is the memory allocated for internal tables is temporary. Once the program is
closed the memory allocated for internal tables will also be out of memory.
But while using the internal tables, there are many performance issues to be considered. i.e which
type of internal table to be used for the program..like standard internal table, hashed internal
table or sorted internal table etc..
Internal tables
Internal tables provide a means of taking data from a fixed structure and storing it in working memory in ABAP. The data is stored line by
line in memory, and each line has the same structure. In ABAP, internal tables fulfill the function of arrays. Since they are dynamic data
objects, they save the programmer the task of dynamic memory management in his or her programs. You should use internal tables
whenever you want to process a dataset with a fixed structure within a program. A particularly important use for internal tables is for
storing and formatting data from a database table within a program. They are also a good way of including very complicated data
structures in an ABAP program.
Like all elements in the ABAP type concept, internal tables can exist both as data types and as data objects A data type is the abstract
description of an internal table, either in a program or centrally in the ABAP Dictionary, that you use to create a concrete data object. The
data type is also an attribute of an existing data object.
Internal Tables as Data Types
Internal tables and structures are the two structured data types in ABAP. The data type of an internal table is fully specified by its line type,
key, and table type.
Line type
The line type of an internal table can be any data type. The data type of an internal table is normally a structure. Each component of the
structure is a column in the internal table. However, the line type may also be elementary or another internal table.
Key
The key identifies table rows. There are two kinds of key for internal tables - the standard key and a user-defined key. You can specify
whether the key should be UNIQUE or NON-UNIQUE. Internal tables with a unique key cannot contain duplicate entries. The uniqueness
depends on the table access method.
If a table has a structured line type, its default key consists of all of its non-numerical columns that are not references or themselves
internal tables. If a table has an elementary line type, the default key is the entire line. The default key of an internal table whose line type
is an internal table, the default key is empty.
The user-defined key can contain any columns of the internal table that are not references or themselves internal tables. Internal tables
with a user-defined key are called key tables. When you define the key, the sequence of the key fields is significant. You should remember
this, for example, if you intend to sort the table according to the key.
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.
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.
Internal Tables as Dynamic Data Objects
Data objects that are defined either with the data type of an internal table, or directly as an internal table, are always fully defined in
respect of their line type, key and access method. However, the number of lines is not fixed. Thus internal tables are dynamic data objects,
since they can contain any number of lines of a particular type. The only restriction on the number of lines an internal table may contain are
the limits of your system installation. The maximum memory that can be occupied by an internal table (including its internal administration)
is 2 gigabytes. A more realistic figure is up to 500 megabytes. An additional restriction for hashed tables is that they may not contain more
than 2 million entries. The line types of internal tables can be any ABAP data types - elementary, structured, or internal tables. The
individual lines of an internal table are called table lines or table entries. Each component of a structured line is called a column in the
internal table.
Choosing a Table Type
The table type (and particularly the access method) that you will use depends on how the typical internal table operations will be most
frequently executed.
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.
Creating Internal Tables
Like other elements in the ABAP type concept, you can declare internal tables as abstract data
types in programs or in the ABAP Dictionary, and then use them to define data objects.
Alternatively, you can define them directly as data objects. When you create an internal table as a
data object, you should ensure that only the administration entry which belongs to an internal
table is declared statically. The minimum size of an internal table is 256 bytes. This is important if an
internal table occurs as a component of an aggregated data object, since even empty internal
tables within tables can lead to high memory usage. (In the next functional release, the size of the
table header for an initial table will be reduced to 8 bytes). Unlike all other ABAP data objects, you
do not have to specify the memory required for an internal table. Table rows are added to and
deleted from the table dynamically at runtime by the various statements for adding and deleting
records.
You can create internal tables in different types.
You can create standard internal table and then make it sort in side the program.
The same way you can change to hashed internal tables also.
There will be some performance issues with regard to standard internal tables/ hashed internal
tables/ sorted internal tables.
Internal table types
This section describes how to define internal tables locally in a program. You can also define internal tables globally as data types in the
ABAP Dictionary.
Like all local data types in programs , you define internal tables using the TYPES statement. If you do not refer to an existing table type
using the TYPE or LIKE addition, you can use the TYPES statement to construct a new local internal table in your program.
TYPES <t> TYPE|LIKE <tabkind> OF <linetype> [WITH <key>]
[INITIAL SIZE <n>].
After TYPE or LIKE, there is no reference to an existing data type. Instead, the type constructor occurs:
<tabkind> OF <linetype> [WITH <key>]
The type constructor defines the table type <tabkind>, the line type <linetype>, and the key <key> of the internal table <t>.
You can, if you wish, allocate an initial amount of memory to the internal table using the INITIAL SIZE addition.
Table type
You can specify the table type <tabkind> as follows:
Generic table types
INDEX TABLE
For creating a generic table type with index access.
ANY TABLE
For creating a fully-generic table type.
Data types defined using generic types can currently only be used for field symbols and for interface parameters in procedures . The generic
type INDEX TABLE includes standard tables and sorted tables. These are the two table types for which index access is allowed. You cannot
pass hashed tables to field symbols or interface parameters defined in this way. The generic type ANY TABLE can represent any table. You
can pass tables of all three types to field symbols and interface parameters defined in this way. However, these field symbols and
parameters will then only allow operations that are possible for all tables, that is, index operations are not allowed.
Fully-Specified Table Types
STANDARD TABLE or TABLE
For creating standard tables.
SORTED TABLE
For creating sorted tables.
HASHED TABLE
For creating hashed tables.
Fully-specified table types determine how the system will access the entries in the table in key operations. It uses a linear search for
standard tables, a binary search for sorted tables, and a search using a hash algorithm for hashed tables.
Line type
For the line type <linetype>, you can specify:
Any data type if you are using the TYPE addition. This can be a predefined ABAP type, a local type in the program, or a data type from the
ABAP Dictionary. If you specify any of the generic elementary types C, N, P, or X, any attributes that you fail to specify (field length, number
of decimal places) are automatically filled with the default values. You cannot specify any other generic types.
Any data object recognized within the program at that point if you are using the LIKE addition. The line type adopts the fully-specified data
type of the data object to which you refer. Except for within classes, you can still use the LIKE addition to refer to database tables and
structures in the ABAP Dictionary (for compatibility reasons).
All of the lines in the internal table have the fully-specified technical attributes of the specified data type.
Key
You can specify the key <key> of an internal table as follows:
[UNIQUE|NON-UNIQUE] KEY <col1> ... <col n>
In tables with a structured line type, all of the components <coli> belong to the key as long as they are not internal tables or references,
and do not contain internal tables or references. Key fields can be nested structures. The substructures are expanded component by
component when you access the table using the key. The system follows the sequence of the key fields.
[UNIQUE|NON-UNIQUE] KEY TABLE LINE
If a table has an elementary line type (C, D, F, I, N, P, T, X), you can define the entire line as the key. If you try this for a table whose line
type is itself a table, a syntax error occurs. If a table has a structured line type, it is possible to specify the entire line as the key. However,
you should remember that this is often not suitable.
[UNIQUE|NON-UNIQUE] DEFAULT KEY
This declares the fields of the default key as the key fields. If the table has a structured line type, the default key contains all non-numeric
columns of the internal table that are not and do not contain references or internal tables. If the table has an elementary line type, the
default key is the entire line. The default key of an internal table whose line type is an internal table, the default key is empty.
Specifying a key is optional. If you do not specify a key, the system defines a table type with an arbitrary key. You can only use this to
define the types of field symbols and the interface parameters of procedures . For exceptions, refer to Special Features of Standard Tables.
The optional additions UNIQUE or NON-UNIQUE determine whether the key is to be unique or non-unique, that is, whether the table can
accept duplicate entries. If you do not specify UNIQUE or NON-UNIQUE for the key, the table type is generic in this respect. As such, it can
only be used for specifying types. When you specify the table type simultaneously, you must note the following restrictions:
You cannot use the UNIQUE addition for standard tables. The system always generates the NON-UNIQUE addition automatically.
You must always specify the UNIQUE option when you create a hashed table.
Initial Memory Requirement
You can specify the initial amount of main memory assigned to an internal table object when you define the data type using the following
addition:
INITIAL SIZE <n>
This size does not belong to the data type of the internal table, and does not affect the type check. You can use the above addition to
reserve memory space for <n> table lines when you declare the table object.
When this initial area is full, the system makes twice as much extra space available up to a limit of 8KB. Further memory areas of 12KB each
are then allocated.
You can usually leave it to the system to work out the initial memory requirement. The first time you fill the table, little memory is used. The
space occupied, depending on the line width, is 16 <= <n> <= 100.
It only makes sense to specify a concrete value of <n> if you can specify a precise number of table entries when you create the table and
need to allocate exactly that amount of memory (exception: Appending table lines to ranked lists). This can be particularly important for
deep-structured internal tables where the inner table only has a few entries (less than 5, for example).
To avoid excessive requests for memory, large values of <n> are treated as follows: The largest possible value of <n> is 8KB divided by the
length of the line. If you specify a larger value of <n>, the system calculates a new value so that n times the line width is around 12KB.
Examples
TYPES: BEGIN OF LINE,
COLUMN1 TYPE I,
COLUMN2 TYPE I,
COLUMN3 TYPE I,
END OF LINE.
TYPES ITAB TYPE SORTED TABLE OF LINE WITH UNIQUE KEY COLUMN1.
The program defines a table type ITAB. It is a sorted table, with line type of the structure LINE and a unique key of the component
COLUMN1.
TYPES VECTOR TYPE HASHED TABLE OF I WITH UNIQUE KEY TABLE LINE.
TYPES: BEGIN OF LINE,
COLUMN1 TYPE I,
COLUMN2 TYPE I,
COLUMN3 TYPE I,
END OF LINE.
TYPES ITAB TYPE SORTED TABLE OF LINE WITH UNIQUE KEY COLUMN1.
TYPES: BEGIN OF DEEPLINE,
FIELD TYPE C,
TABLE1 TYPE VECTOR,
TABLE2 TYPE ITAB,
END OF DEEPLINE.
TYPES DEEPTABLE TYPE STANDARD TABLE OF DEEPLINE
WITH DEFAULT KEY.
The program defines a table type VECTOR with type hashed table, the elementary line type I and a unique key of the entire table line. The
second table type is the same as in the previous example. The structure DEEPLINE contains the internal table as a component. The table
type DEEPTABLE has the line type DEEPLINE. Therefore, the elements of this internal table are themselves internal tables. The key is the
default key - in this case the column FIELD. The key is non-unique, since the table is a standard table.
Internal table objects
Internal tables are dynamic variable data objects. Like all variables, you declare them using the DATA statement. You can also declare static
internal tables in procedures using the STATICS statement, and static internal tables in classes using the CLASS-DATA statement. This
description is restricted to the DATA statement. However, it applies equally to the STATICS and CLASS-DATA statements.
Reference to Declared Internal Table Types
Like all other data objects, you can declare internal table objects using the LIKE or TYPE addition of the DATA statement.
DATA <itab> TYPE <type>|LIKE <obj> [WITH HEADER LINE].
Here, the LIKE addition refers to an existing table object in the same program. The TYPE addition can refer to an internal type in the
program declared using the TYPES statement, or a table type in the ABAP Dictionary.
You must ensure that you only refer to tables that are fully typed. Referring to generic table types (ANY TABLE, INDEX TABLE) or not
specifying the key fully is not allowed (for exceptions, refer to Special Features of Standard Tables).
The optional addition WITH HEADER line declares an extra data object with the same name and line type as the internal table. This data
object is known as the header line of the internal table. You use it as a work area when working with the internal table (see Using the
Header Line as a Work Area). When you use internal tables with header lines, you must remember that the header line and the body of the
table have the same name. If you have an internal table with header line and you want to address the body of the table, you must indicate
this by placing brackets after the table name (<itab>[]). Otherwise, ABAP interprets the name as the name of the header line and not of the
body of the table. You can avoid this potential confusion by using internal tables without header lines. In particular, internal tables nested
in structures or other internal tables must not have a header line, since this can lead to ambiguous expressions.
TYPES VECTOR TYPE SORTED TABLE OF I WITH UNIQUE KEY TABLE LINE.
DATA: ITAB TYPE VECTOR,
JTAB LIKE ITAB WITH HEADER LINE.
MOVE ITAB TO JTAB. <- Syntax error!
MOVE ITAB TO JTAB[].
The table object ITAB is created with reference to the table type VECTOR. The table object JTAB has the same data type as ITAB. JTAB also
has a header line. In the first MOVE statement, JTAB addresses the header line. Since this has the data type I, and the table type of ITAB
cannot be converted into an elementary type, the MOVE statement causes a syntax error. The second MOVE statement is correct, since
both operands are table objects.
Declaring New Internal Tables
You can use the DATA statement to construct new internal tables as well as using the LIKE or TYPE addition to refer to existing types or
objects. The table type that you construct does not exist in its own right; instead, it is only an attribute of the table object. You can refer to
it using the LIKE addition, but not using TYPE. The syntax for constructing a table object in the DATA statement is similar to that for defining
a table type in the TYPES statement.
DATA <itab> TYPE|LIKE <tabkind> OF <linetype> WITH <key>
[INITIAL SIZE <n>]
[WITH HEADER LINE].
As when you define a table type , the type constructor
<tabkind> OF <linetype> WITH <key>
defines the table type <tabkind>, the line type <linekind>, and the key <key> of the internal table <itab>. Since the technical attributes of
data objects are always fully specified, the table must be fully specified in the DATA statement. You cannot create generic table types (ANY
TABLE, INDEX TABLE), only fully-typed tables (STANDARD TABLE, SORTED TABLE, HASHED TABLE). You must also specify the key and whether
it is to be unique (for exceptions, refer to Special Features of Standard Tables).
As in the TYPES statement, you can, if you wish, allocate an initial amount of memory to the internal table using the INITIAL SIZE addition.
You can create an internal table with a header line using the WITH HEADER LINE addition. The header line is created under the same
conditions as apply when you refer to an existing table type.
DATA ITAB TYPE HASHED TABLE OF SPFLI
WITH UNIQUE KEY CARRID CONNID.
The table object ITAB has the type hashed table, a line type corresponding to the flat structure SPFLI from the ABAP Dictionary, and a
unique key with the key fields CARRID and CONNID. The internal table ITAB can be regarded as an internal template for the database table
SPFLI. It is therefore particularly suitable for working with data from this database table as long as you only access it using the key.

What is the difference between standard,sorted and hash table

can anyone say what is the difference between standard,sorted and hash tabl

Hi,
Standard 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 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 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.
Regards,
Ferry Lianto

Standard & hashed tables

hello every one,
This is rahul
when we are declaring internal table by default it takes as standard table
but y don't we take hashed table they can get performance very well
hashed can perform very well than standard na

hI
READ THIS POINTS
Internal tables are the core of ABAP. They are like soul of a body. For any program we use
internal tables extensively. We can use Internal tables like normal data base tables only, but the
basic difference is the memory allocated for internal tables is temporary. Once the program is
closed the memory allocated for internal tables will also be out of memory.
But while using the internal tables, there are many performance issues to be considered. i.e which
type of internal table to be used for the program..like standard internal table, hashed internal
table or sorted internal table etc..
Internal tables
Internal tables provide a means of taking data from a fixed structure and storing it in working memory in ABAP. The data is stored line by
line in memory, and each line has the same structure. In ABAP, internal tables fulfill the function of arrays. Since they are dynamic data
objects, they save the programmer the task of dynamic memory management in his or her programs. You should use internal tables
whenever you want to process a dataset with a fixed structure within a program. A particularly important use for internal tables is for
storing and formatting data from a database table within a program. They are also a good way of including very complicated data
structures in an ABAP program.
Like all elements in the ABAP type concept, internal tables can exist both as data types and as data objects A data type is the abstract
description of an internal table, either in a program or centrally in the ABAP Dictionary, that you use to create a concrete data object. The
data type is also an attribute of an existing data object.
Internal Tables as Data Types
Internal tables and structures are the two structured data types in ABAP. The data type of an internal table is fully specified by its line type,
key, and table type.
Line type
The line type of an internal table can be any data type. The data type of an internal table is normally a structure. Each component of the
structure is a column in the internal table. However, the line type may also be elementary or another internal table.
Key
The key identifies table rows. There are two kinds of key for internal tables - the standard key and a user-defined key. You can specify
whether the key should be UNIQUE or NON-UNIQUE. Internal tables with a unique key cannot contain duplicate entries. The uniqueness
depends on the table access method.
If a table has a structured line type, its default key consists of all of its non-numerical columns that are not references or themselves
internal tables. If a table has an elementary line type, the default key is the entire line. The default key of an internal table whose line type
is an internal table, the default key is empty.
The user-defined key can contain any columns of the internal table that are not references or themselves internal tables. Internal tables
with a user-defined key are called key tables. When you define the key, the sequence of the key fields is significant. You should remember
this, for example, if you intend to sort the table according to the key.
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.
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.
Internal Tables as Dynamic Data Objects
Data objects that are defined either with the data type of an internal table, or directly as an internal table, are always fully defined in
respect of their line type, key and access method. However, the number of lines is not fixed. Thus internal tables are dynamic data objects,
since they can contain any number of lines of a particular type. The only restriction on the number of lines an internal table may contain are
the limits of your system installation. The maximum memory that can be occupied by an internal table (including its internal administration)
is 2 gigabytes. A more realistic figure is up to 500 megabytes. An additional restriction for hashed tables is that they may not contain more
than 2 million entries. The line types of internal tables can be any ABAP data types - elementary, structured, or internal tables. The
individual lines of an internal table are called table lines or table entries. Each component of a structured line is called a column in the
internal table.
Choosing a Table Type
The table type (and particularly the access method) that you will use depends on how the typical internal table operations will be most
frequently executed.
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.
Creating Internal Tables
Like other elements in the ABAP type concept, you can declare internal tables as abstract data
types in programs or in the ABAP Dictionary, and then use them to define data objects.
Alternatively, you can define them directly as data objects. When you create an internal table as a
data object, you should ensure that only the administration entry which belongs to an internal
table is declared statically. The minimum size of an internal table is 256 bytes. This is important if an
internal table occurs as a component of an aggregated data object, since even empty internal
tables within tables can lead to high memory usage. (In the next functional release, the size of the
table header for an initial table will be reduced to 8 bytes). Unlike all other ABAP data objects, you
do not have to specify the memory required for an internal table. Table rows are added to and
deleted from the table dynamically at runtime by the various statements for adding and deleting
records.
You can create internal tables in different types.
You can create standard internal table and then make it sort in side the program.
The same way you can change to hashed internal tables also.
There will be some performance issues with regard to standard internal tables/ hashed internal
tables/ sorted internal tables.
Internal table types
This section describes how to define internal tables locally in a program. You can also define internal tables globally as data types in the
ABAP Dictionary.
Like all local data types in programs , you define internal tables using the TYPES statement. If you do not refer to an existing table type
using the TYPE or LIKE addition, you can use the TYPES statement to construct a new local internal table in your program.
TYPES <t> TYPE|LIKE <tabkind> OF <linetype> [WITH <key>]
[INITIAL SIZE <n>].
After TYPE or LIKE, there is no reference to an existing data type. Instead, the type constructor occurs:
<tabkind> OF <linetype> [WITH <key>]
The type constructor defines the table type <tabkind>, the line type <linetype>, and the key <key> of the internal table <t>.
You can, if you wish, allocate an initial amount of memory to the internal table using the INITIAL SIZE addition.
Table type
You can specify the table type <tabkind> as follows:
Generic table types
INDEX TABLE
For creating a generic table type with index access.
ANY TABLE
For creating a fully-generic table type.
Data types defined using generic types can currently only be used for field symbols and for interface parameters in procedures . The generic
type INDEX TABLE includes standard tables and sorted tables. These are the two table types for which index access is allowed. You cannot
pass hashed tables to field symbols or interface parameters defined in this way. The generic type ANY TABLE can represent any table. You
can pass tables of all three types to field symbols and interface parameters defined in this way. However, these field symbols and
parameters will then only allow operations that are possible for all tables, that is, index operations are not allowed.
Fully-Specified Table Types
STANDARD TABLE or TABLE
For creating standard tables.
SORTED TABLE
For creating sorted tables.
HASHED TABLE
For creating hashed tables.
Fully-specified table types determine how the system will access the entries in the table in key operations. It uses a linear search for
standard tables, a binary search for sorted tables, and a search using a hash algorithm for hashed tables.
Line type
For the line type <linetype>, you can specify:
Any data type if you are using the TYPE addition. This can be a predefined ABAP type, a local type in the program, or a data type from the
ABAP Dictionary. If you specify any of the generic elementary types C, N, P, or X, any attributes that you fail to specify (field length, number
of decimal places) are automatically filled with the default values. You cannot specify any other generic types.
Any data object recognized within the program at that point if you are using the LIKE addition. The line type adopts the fully-specified data
type of the data object to which you refer. Except for within classes, you can still use the LIKE addition to refer to database tables and
structures in the ABAP Dictionary (for compatibility reasons).
All of the lines in the internal table have the fully-specified technical attributes of the specified data type.
Key
You can specify the key <key> of an internal table as follows:
[UNIQUE|NON-UNIQUE] KEY <col1> ... <col n>
In tables with a structured line type, all of the components <coli> belong to the key as long as they are not internal tables or references,
and do not contain internal tables or references. Key fields can be nested structures. The substructures are expanded component by
component when you access the table using the key. The system follows the sequence of the key fields.
[UNIQUE|NON-UNIQUE] KEY TABLE LINE
If a table has an elementary line type (C, D, F, I, N, P, T, X), you can define the entire line as the key. If you try this for a table whose line
type is itself a table, a syntax error occurs. If a table has a structured line type, it is possible to specify the entire line as the key. However,
you should remember that this is often not suitable.
[UNIQUE|NON-UNIQUE] DEFAULT KEY
This declares the fields of the default key as the key fields. If the table has a structured line type, the default key contains all non-numeric
columns of the internal table that are not and do not contain references or internal tables. If the table has an elementary line type, the
default key is the entire line. The default key of an internal table whose line type is an internal table, the default key is empty.
Specifying a key is optional. If you do not specify a key, the system defines a table type with an arbitrary key. You can only use this to
define the types of field symbols and the interface parameters of procedures . For exceptions, refer to Special Features of Standard Tables.
The optional additions UNIQUE or NON-UNIQUE determine whether the key is to be unique or non-unique, that is, whether the table can
accept duplicate entries. If you do not specify UNIQUE or NON-UNIQUE for the key, the table type is generic in this respect. As such, it can
only be used for specifying types. When you specify the table type simultaneously, you must note the following restrictions:
You cannot use the UNIQUE addition for standard tables. The system always generates the NON-UNIQUE addition automatically.
You must always specify the UNIQUE option when you create a hashed table.
Initial Memory Requirement
You can specify the initial amount of main memory assigned to an internal table object when you define the data type using the following
addition:
INITIAL SIZE <n>
This size does not belong to the data type of the internal table, and does not affect the type check. You can use the above addition to
reserve memory space for <n> table lines when you declare the table object.
When this initial area is full, the system makes twice as much extra space available up to a limit of 8KB. Further memory areas of 12KB each
are then allocated.
You can usually leave it to the system to work out the initial memory requirement. The first time you fill the table, little memory is used. The
space occupied, depending on the line width, is 16 <= <n> <= 100.
It only makes sense to specify a concrete value of <n> if you can specify a precise number of table entries when you create the table and
need to allocate exactly that amount of memory (exception: Appending table lines to ranked lists). This can be particularly important for
deep-structured internal tables where the inner table only has a few entries (less than 5, for example).
To avoid excessive requests for memory, large values of <n> are treated as follows: The largest possible value of <n> is 8KB divided by the
length of the line. If you specify a larger value of <n>, the system calculates a new value so that n times the line width is around 12KB.
Examples
TYPES: BEGIN OF LINE,
COLUMN1 TYPE I,
COLUMN2 TYPE I,
COLUMN3 TYPE I,
END OF LINE.
TYPES ITAB TYPE SORTED TABLE OF LINE WITH UNIQUE KEY COLUMN1.
The program defines a table type ITAB. It is a sorted table, with line type of the structure LINE and a unique key of the component
COLUMN1.
TYPES VECTOR TYPE HASHED TABLE OF I WITH UNIQUE KEY TABLE LINE.
TYPES: BEGIN OF LINE,
COLUMN1 TYPE I,
COLUMN2 TYPE I,
COLUMN3 TYPE I,
END OF LINE.
TYPES ITAB TYPE SORTED TABLE OF LINE WITH UNIQUE KEY COLUMN1.
TYPES: BEGIN OF DEEPLINE,
FIELD TYPE C,
TABLE1 TYPE VECTOR,
TABLE2 TYPE ITAB,
END OF DEEPLINE.
TYPES DEEPTABLE TYPE STANDARD TABLE OF DEEPLINE
WITH DEFAULT KEY.
The program defines a table type VECTOR with type hashed table, the elementary line type I and a unique key of the entire table line. The
second table type is the same as in the previous example. The structure DEEPLINE contains the internal table as a component. The table
type DEEPTABLE has the line type DEEPLINE. Therefore, the elements of this internal table are themselves internal tables. The key is the
default key - in this case the column FIELD. The key is non-unique, since the table is a standard table.
Internal table objects
Internal tables are dynamic variable data objects. Like all variables, you declare them using the DATA statement. You can also declare static
internal tables in procedures using the STATICS statement, and static internal tables in classes using the CLASS-DATA statement. This
description is restricted to the DATA statement. However, it applies equally to the STATICS and CLASS-DATA statements.
Reference to Declared Internal Table Types
Like all other data objects, you can declare internal table objects using the LIKE or TYPE addition of the DATA statement.
DATA <itab> TYPE <type>|LIKE <obj> [WITH HEADER LINE].
Here, the LIKE addition refers to an existing table object in the same program. The TYPE addition can refer to an internal type in the
program declared using the TYPES statement, or a table type in the ABAP Dictionary.
You must ensure that you only refer to tables that are fully typed. Referring to generic table types (ANY TABLE, INDEX TABLE) or not
specifying the key fully is not allowed (for exceptions, refer to Special Features of Standard Tables).
The optional addition WITH HEADER line declares an extra data object with the same name and line type as the internal table. This data
object is known as the header line of the internal table. You use it as a work area when working with the internal table (see Using the
Header Line as a Work Area). When you use internal tables with header lines, you must remember that the header line and the body of the
table have the same name. If you have an internal table with header line and you want to address the body of the table, you must indicate
this by placing brackets after the table name (<itab>[]). Otherwise, ABAP interprets the name as the name of the header line and not of the
body of the table. You can avoid this potential confusion by using internal tables without header lines. In particular, internal tables nested
in structures or other internal tables must not have a header line, since this can lead to ambiguous expressions.
TYPES VECTOR TYPE SORTED TABLE OF I WITH UNIQUE KEY TABLE LINE.
DATA: ITAB TYPE VECTOR,
JTAB LIKE ITAB WITH HEADER LINE.
MOVE ITAB TO JTAB. <- Syntax error!
MOVE ITAB TO JTAB[].
The table object ITAB is created with reference to the table type VECTOR. The table object JTAB has the same data type as ITAB. JTAB also
has a header line. In the first MOVE statement, JTAB addresses the header line. Since this has the data type I, and the table type of ITAB
cannot be converted into an elementary type, the MOVE statement causes a syntax error. The second MOVE statement is correct, since
both operands are table objects.
Declaring New Internal Tables
You can use the DATA statement to construct new internal tables as well as using the LIKE or TYPE addition to refer to existing types or
objects. The table type that you construct does not exist in its own right; instead, it is only an attribute of the table object. You can refer to
it using the LIKE addition, but not using TYPE. The syntax for constructing a table object in the DATA statement is similar to that for defining
a table type in the TYPES statement.
DATA <itab> TYPE|LIKE <tabkind> OF <linetype> WITH <key>
[INITIAL SIZE <n>]
[WITH HEADER LINE].
As when you define a table type , the type constructor
<tabkind> OF <linetype> WITH <key>
defines the table type <tabkind>, the line type <linekind>, and the key <key> of the internal table <itab>. Since the technical attributes of
data objects are always fully specified, the table must be fully specified in the DATA statement. You cannot create generic table types (ANY
TABLE, INDEX TABLE), only fully-typed tables (STANDARD TABLE, SORTED TABLE, HASHED TABLE). You must also specify the key and whether
it is to be unique (for exceptions, refer to Special Features of Standard Tables).
As in the TYPES statement, you can, if you wish, allocate an initial amount of memory to the internal table using the INITIAL SIZE addition.
You can create an internal table with a header line using the WITH HEADER LINE addition. The header line is created under the same
conditions as apply when you refer to an existing table type.
DATA ITAB TYPE HASHED TABLE OF SPFLI
WITH UNIQUE KEY CARRID CONNID.
The table object ITAB has the type hashed table, a line type corresponding to the flat structure SPFLI from the ABAP Dictionary, and a
unique key with the key fields CARRID and CONNID. The internal table ITAB can be regarded as an internal template for the database table
SPFLI. It is therefore particularly suitable for working with data from this database table as long as you only access it using the key.

Modify Syntax on Internal table of type ANY TABLE

Hi,
I have declared one internal table which is of type ANY TABLE.
In the Loop statement, I am trying to Modify that Internal table from WA.
Then I am getting one Error message
"You cannot use explicit or implicit index operations on tables with types "HASHED TABLE" or "ANY TABLE". "C_T_DATA" has the type "ANY TABLE".
Above code I have placed in method of a corresponding Class.
Can u please advise me on this..How to modify the Intenal table .
Thanks and Regards,
K.Krishna Chaitanya.

Hi Krishna,
the modify statement is obsolete.
You can always LOOP AT [itab] ASSIGNING <field-symbol>.
This makes the loop never slower, depending on the table structure faster or much faster.
If you know the table structure at run time, you can use a field-symbol of that type. If not, you can use a field-symbol TYPE any. Then you have to assign the components to field-symbol to modify them, i.e.
field-symbols:
<table_line> type any,
<matnr> type mara-matnr.
loop at itab assigning <table_line>.
assign component 'MATNR' of structure <table_line> to <matnr>.
clear <matnr>.
endloop.
This technique (available more than ten years) works incredibly fast. My estimate is that if SAP would change all the old standard programs that way and use it consequently in the new ones, the whole system would be 20 % faster because myriads of unnecessary copy operations of LOOP INTO would not happen.
Regards,
Clemens.

Cluster and pooled tables

when we will use cluster table , pooled table and transparent tables...

FOr Tables
http://www.erpgenie.com/abap/tables.htm
For Tables
Pooled Tables, Table Pools, Cluster Tables, and Table Clusters
These types of tables are not transparent in the sense that they are not legible or manageable directly using the underlying database system tools. They are managed from within the R/3 environment from the ABAP dictionary and also at runtime when they are loaded into application memory.Pool and cluster tables are logical tables. Physically, these logical tables are arranged as records of transparent tables. The pool and cluster tables are grouped together in other tables, which are of the transparent type. The tables that group together pool tables are known as table pools, or just pools; similarly, table clusters, or just
clusters, are the tables which group cluster tables.Not all operations that can be performed over transparent tables can be executed over pool or cluster tables.
For instance, you can manage these tables using Open SQL calls from ABAP, but not Native SQL.These tables are meant to be buffered and loaded in memory, because they are commonly used for storing internal control information and other types of data with no external (business) relevance. SAP recommends that tables of pool or cluster type be used exclusively for control information such as
program parameters, documentation, and so on. Transaction and application data should be stored in transparent tables.
Table Pools
From the point of view of the underlying DBMS as from the point of view of the ABAP dictionary, a table pool is a transparent table containing a group of pooled tables which, when created, were assigned to this table pool.
Field Type Description
TABNAME CHAR(10) Table name
VARKEY CHAR(n) Maximum key length n =< 110
DATALN INT2(5) Length of the VARDATA record returned
VARDATA RAW(m) Maximum length of the data varies according to DBMS
Table Clusters
Similarly to pooled tables, cluster tables are logical tables which, when created, are assigned to a table cluster. Therefore, a table cluster, or just cluster, groups together several tables of type clusters.Several logical rows from different cluster tables are brought together in a single physical record. The records
from the cluster tables assigned to a cluster are thus stored in a single common table in the database.A cluster contains a transparent cluster key which must be located at the start of the key of all logical cluster tables to be included in the cluster. As well, a cluster contains a long field (VARDATA), which contains the
data of the cluster tables for this key. If the data does not fit into a field, continuation records are created.
Field Type Description
CLKEY1 CHAR(*) First key fields
CLKEY2 CHAR(*) Second key field
CLKEYN CHAR(*) nth key field
PAGENO INT2(5) Number of the next page
TIMESTMP CHAR(14) Time stamp
PAGELG INT2(5) Length of the VARDATA record returned
VARDATA RAW(*) Maximum length of the data section; varies according to database system
Working with Tables
The dictionary includes many functions for working with tables. There are five basic operations you can perform on tables: display, create, delete, modify, copy. Please do not confuse displaying a table with displaying the table entries (table contents). In order to display a table, it must previously exist; otherwise the system will display an error message in the status bar. For the following example, the table TABNA is used. To display this table, from the main dictionary screen, enter the table name in the Object name
input field with the radio button selected next to Tables. Then, click on the Display button at the bottom of the screen, or press the F7 function key, or, alternatively,
select Dictionary object Display from the menu.
In this screen, you can see table information such as
¨ Table type, shown next to the name of the object. In the example, it is a transparent table.
¨ Short text description.
¨ Name of the user who made the last change, and the date of the change.
¨ Master language.
¨ Table status. On the screen, you can see this table is saved and active.
¨ Development class. For information on development classes, refer to Chap. 6.
Delivery class, which sets the maintenance group for the table. It controls how tables will behave during client copy procedures, upgrades, and so forth.¨
Tab. Maint. Allowed flag, which indicates whether you can generate a screen for maintaining table entries.
¨Then, on the lower part of the screen, you can see the table fields with all associated characteristics such as:
¨ Field name.
¨ Key indicator. When set, this field is the primary key, or part of it.
¨ Data element.
¨ Basic data type.
¨ Length.
¨ Check table.
¨ Short text, describing the field.
Additional information about the table can be displayed by selecting the corresponding functions from the menu or directly from the application toolbar, such as keys, indexes, or technical settings.
Regards,
Balaji
**Rewards for helpful answers

Reg : Cluster and pool tables

Hi All,
I think this has been asked previously.
Have a doubt, i think this area is kind of opaque.
This is the scenario, we have standard business suite systems now i am going to get the data into hana using SLT how do i handle cluster and pool tables. Do i bring in the declustered data?
I am aware that we can get the data from these tables into BW on hana, not sure if that is correct.
What are the best practice approach for these table classes.
How have you implemented these kind of scenarios.
Message was edited by: Tom Flanagan

Hello,
SLT Supports replication of non-Unicode to Unicode systems.
Includes cluster / pool tables, etc. (writes into transparent tables in SAP HANA system).
Regards,
Subbu

Cluster tables , pool tables ,hashed tables?

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