Hi all, We are from university of Moratuwa,Sri lanka.We are willing to apply data compression to Derby in query processing as requirement of our Advanced Database course project.
Currently Derby has facility to trim the free space in raw data container(using SYSCS_UTIL.SYSCS_COMPRESS_TABLE system procedure).Our goal is to apply data compression(Run-length encoding Compression) for each of values(not field name) of a query before executing and decompressing the data when the execution finishes. Initially we went through the code base and identified that the data compression can be applied within the executeStatement() method of org.apache.derby.impl.jdbc.EmbedStatement class before calling ps.execute(),and we thought Using getParameterValueSet() method of Activation class the the attribute values of the parsed query can be obtained.But when we try to print the contents of the ParameterValueSet for typical insert query ,it is printing null(it is just empty set). We are expecting help from community regarding following questions. 1)What is wrong with point we identified to apply compression? 2)By applying compression before executing query,will the query execution process be affected? 3)Are there any possible place to apply compression and decompression before executing query? Thank you. -Reka
