What is Short Dump Analysis and secendry index ?

Question

Dear Experts .
1.) What is purpose of T-codes SE30 and ST22 ?
What is Short Dump Analysis ?
2.) What is secendry index , How to use it ? How it effects the Performance of a report ?
Please it is urgent ...
Regards : Rajneesh

Answer 1

Hi
A dump analysis is a comprehensive list that should enable you to identify the causes and possible solutions of program errors. The ABAP Workbench generates a short dump whenever a report or transaction terminates due to a serious error. The system enters the error in the system log and writes a snapshot of the program at the moment when it terminated into a special database table called SNAP.
Dump analyses give the user or programmer information about the causes of the error that has caused the program to terminate. Experienced users can use them to identify very quickly where and why this occurred. He or she can them solve the problem.
The snapshot contains the following information:
Why the program has terminated
What caused the program termination
Where in the program code the termination occurred
What you can do to correct the error
The values of the relevant system fields when the program terminated
The calls or events that were active when the program terminated
Any other programs that are affected.
http://help.sap.com/saphelp_nw70/helpdata/en/c6/617d0ce68c11d2b2ab080009b43351/content.htm
Index: Technical key of a database table.
Primary index: The primary index contains the key fields of the table and a pointer to the non-key fields of the table. The primary index is created automatically when the table is created in the database.
Secondary index: Additional indexes could be created considering the most frequently accessed dimensions of the table.
Structure of an Index
An index can be used to speed up the selection of data records from a table.
An index can be considered to be a copy of a database table reduced to certain fields. The data is stored in sorted form in this copy. This sorting permits fast access to the records of the table (for example using a binary search). Not all of the fields of the table are contained in the index. The index also contains a pointer from the index entry to the corresponding table entry to permit all the field contents to be read.
When creating indexes, please note that:
An index can only be used up to the last specified field in the selection! The fields which are specified in the WHERE clause for a large number of selections should be in the first position.
Only those fields whose values significantly restrict the amount of data are meaningful in an index.
When you change a data record of a table, you must adjust the index sorting. Tables whose contents are frequently changed therefore should not have too many indexes.
Make sure that the indexes on a table are as disjunctive as possible.
(That is they should contain as few fields in common as possible. If two indexes on a table have a large number of common fields, this could make it more difficult for the optimizer to choose the most selective index.)
Accessing tables using Indexes
The database optimizer decides which index on the table should be used by the database to access data records.
You must distinguish between the primary index and secondary indexes of a table. The primary index contains the key fields of the table. The primary index is automatically created in the database when the table is activated. If a large table is frequently accessed such that it is not possible to apply primary index sorting, you should create secondary indexes for the table.
The indexes on a table have a three-character index ID. '0' is reserved for the primary index. Customers can create their own indexes on SAP tables; their IDs must begin with Y or Z.
If the index fields have key function, i.e. they already uniquely identify each record of the table, an index can be called a unique index. This ensures that there are no duplicate index fields in the database.
When you define a secondary index in the ABAP Dictionary, you can specify whether it should be created on the database when it is activated. Some indexes only result in a gain in performance for certain database systems. You can therefore specify a list of database systems when you define an index. The index is then only created on the specified database systems when activated