Compression Level
The
ttImportFromOracle utility supports three compression levels. Use the level field of the -compression command-line option to specify the compression level.
The level field accepts any one of the following values:
| Values | Description |
|---|---|
0
|
This is the default value. Oracle database tables are not analyzed for compression and no compression clauses are generated for TimesTen tables. |
1
|
ttImportFromOracle analyzes Oracle database tables for compression using the maximum dictionary pointer size of 4 bytes for each column. The generated script includes the appropriate compression clauses to the generated CreateTables.sql DDL file for tables and columns that meet the compression criteria.
|
2
|
Like level 1, this option generates compression clauses, but it adjusts the dictionary pointer size based on the actual number of distinct values in the data. This approach can provide additional memory savings. However, if subsequent inserts or updates to the Oracle database increase the number of distinct values in a compressed column, the existing pointer size in the corresponding compressed TimesTen table may no longer be sufficient to represent the new values. To help mitigate this risk, see Padding.
|