Kbase P3628: Performance problem loading .df file on AS400
| Autor |
Progress Software Corporation - Progress |
| Acesso |
Público |
| Publicação |
16/10/2008 |
|
Status: Unverified
FACT(s) (Environment):
Progress/400 DataServer
IBM AS/400 (RISC)
Progress 9.1C
SYMPTOM(s):
Performance problem loading .df file
Client/Server connection
Problem appears only after the 200th table, i.e. during a long transaction being committed.
AS/400 machine has 256 MB of Main Storage (RAM)
WRKSYSSTS statistics prove that INTERACTIVE Storage Pool is overloaded and paging takes place.
CAUSE:
During the load of the df file there are some mechanisms on AS/400 that slow down naturally the whole process. First of all when you modify schema the journaling of the schema files is in effect and the larger the transaction is the more data is to be saved for eventual roll back (crash recovery). Basically during this phase the empty physical files related to each table and and respective indexes are created in the Database Library (called "placeholders"). When you commit the huge transaction there are even more work to be done on the AS/400 box. All placeholders are being deleted and real Physical files (tables) are being compiled from the generated DDS descriptions (placed in the P__DDS schema source file) and then Logical files (that corresponds to secondary indexes) are generated. This process is quite memory consuming.
FIX:
1. Add more memory depending how much performance gain you want to achieve (the goal should be to minimize the paging process shown in the wrksysts statistics),or
2. Split the df into smaller transactions that should be committed faster because of less resource requirements.