Content Manager OnDemand can compress report data by using several different data compression algorithms before storing the data in cache storage and archive storage. The compression ratio that Content Manager OnDemand can achieve has a significant impact on the amount of space required to store reports.
The compression ratios that Content Manager OnDemand can achieve vary widely depending on the type of data and the format of the data. You cannot always accurately estimate the compression ratio by simply examining the data. On average, you can expect to achieve between 2:1 and 15:1 compression for AFP documents and up to 30:1 compression for line data reports. Compression for AFP documents is based on the output data file produced by ACIF, and not the input file, which might be line data. When ACIF formats line data with a page definition, it might increase the size of the data by adding AFP controls for positioning text.
Where inputFile is the report that you want to measure and outputFile is the compressed output.
To determine the compression ratio, divide the size of outputFile value by the length (-l 200000). For example, if the size of outputFile value is 66 000 bytes, then the compression ratio is 66000/200000 or 0.33 (3:1 compression).
Where groupPages is a file that contains a representative group of pages from a larger report and outputFile is the compressed output.
To determine the compression ratio, divide the size of outputFile value by groupPages value. For example, if the size of outputFile value is 40 000 bytes and the size of the group of pages is 200 000 bytes, then the compression ratio is 40000/200000 or 0.20 (5:1 compression).
The OD77, OD77Lite, and zEDC compression types implement the same compression and decompression algorithm. That is, something compressed with one can be decompressed by the other. However, all three have been tuned differently, so that compressed sizes are different. The OD77 compression tends to compress better than the zEDC, which in turn tends to compresses better than OD77Lite. Remember that different compression methods result in different CPU consumption, with greater compression consuming greater CPU. Experimentation should be performed with specific examples of data to determine what is the optimal compression to use.