Advaced Compression Limitations -- Based on no of columns

Question

URGENT NEED - Would appreciate your help -
Till date we worked on 10g where in our database is holding a partitioned table with less than 255 columns with each partition size of 70GB , and is being compressed and moved to history database ,we achieved good compression ratios in this activity.
But once the table is modified with more than 305 columns because of Business Requirement , the compresstion ratio is drastically reduced from 30 or 40 percent to only 5%.
So ,now we are looking at advanced compression i.e using , where we want to confirm whether this limitation exists even in 11g or overcomed.
Regards,
Phani Kumar P
[phone]
[email protected]

Answer 1

To advise you would require the DDL for the table and the business rules being followed that show what each column is for and its relationship to the other columns in the table.
Generally speaking when I see more than 50 columns in a table, there is the very rare exception, it is because people are thinking horizontally not vertically. Consider the following two tables.
CREATE TABLE bad_design (
row_identifie r NUMBER,
attribute1      NUMBER,
attribute_val1  VARCHAR2(20),
attribute2      NUMBER,
attribute_val2  VARCHAR2(20));
CREATE TABLE good_design (
row_identifier   NUMBER,
attribute_number NUMBER,
attribute_value  VARCHAR2(20));Both can be extended to hold 500 attributes. The first one will add 1000 columns. The second none.
Likely what you are experiencing is something like this.
A Boeing 747 contains more than 1.2 million parts. No sane person would ever consider a plane-parts inventory to start with program_id and line_number followed by 1.199 million columns. But that is the thinking that often leads to 305 columns.
If not then you are going to need to either post a lot of information or go back and examine what it is that appears to justify any object having 304 non-relational attributes.