1. A method comprising automatically, prior to execution of protocol data unit (PDU) processing instructions, merging different independent tables including PDU-related data into one merged table, generating a replacement query for a query to one of said independent tables, and caching data retrieved from the merged table, the method comprising: determining which data in said independent tables, among a plurality of candidate tables, to merge into a single monolithic combination table by examining table query instructions in said processing instructions, wherein the monolithic combination table associates a same lookup key with data in the candidate tables, the lookup key implemented as a flow identifier for contents of the PDUs being processed, the lookup key invoked via a lookup method that looks up a key value from said candidate tables; merging the data from a selection of data within said candidate tables into the single monolithic combination table, wherein the selecting includes determining whether candidate table data are compatible for merging according to compatibility criteria; compiling a replacement instruction based on the data merged in the single monolithic table, the compiling comprising: determining if a first query for data related to PDU in a first table is a query to data from a table merged into the single monolithic combination table formed from the data from multiple tables; generating a second query for the first query for data stored by the single monolithic combination table, the second query comprising instructions generated by a compiler in a target language other than the source language of the first query; and caching data retrieved from the single monolithic combination table in response to the second query.