Basic difference between DB2 and Oracle:
· Db2 require more memory
· Oracle is twice as expensive as DB2
Hardware requirements
DB2 v8.1 256 MB RAM Minimum, 100 MB Hard Drive space Min
Oracle 9i 128 MB RAM Minimum, 140 MB Hard Drive space Min
Price
Oracle $15,000 Standard Edition, $40,000 Enterprise Edition
DB2 $ 7,500 Standard Edition, $25,000 Enterprise Edition
DB2 $ 7,500 Standard Edition, $25,000 Enterprise Edition
SQL
Oracle Function-based indexes, Domain indexes
DB2 Block indexes, Dimension block indexes
DB2 Block indexes, Dimension block indexes
Limitation
Parameter | DB2 | Oracle |
Name Length | 128 | 30 |
Maximum Column in Index key | 16 | 32 |
Maximum No of column | 1012 | 255 |
Longest Index Key | 1024 | 3155 |
Max table row length | 32677 | 255000 |
Longest SQL statement | 65535 | 16777216 |
Recursive sub queries | 28 | 64 |
Constant string size in Select | 32672 | 4000 |
Compression rate
DB2 offers Hardware based compression, for compression DB2 uses one compression dictionary for the entire database table, but oracle database uses a separate compression dictionary for each block in the database. (A block is a unit of storage; its size varies from 4K to 32K). DB2 compress substrings that span multiple columns; but oracle database can not compress the substring. DB2 compression dictionary is at table partition level. So if I have large data and it is partitioned by department; then DB2 compress this data with separate compression dictionary to each department.
Assuming 62 percent compression with DB2, we required 3.8 TB capacity for a 10 TB Data Warehouse versus 7.3 TB with Oracle running at 27 percent compression.
