How I can access R/3 pool and cluster tables at Oracle level?
Unlike transparent tables, the pool and cluster tables defined in the R/3 system do not have a direct equivalent at Oracle level. Instead, their data is stored in relevant table pools or table clusters. Only these pools and clusters have an equivalent at database level. The logic, which is used to extract the data of the pool and cluster tables from the table pools or table clusters, is integrated in the R/3 kernel. You do not have the option to copy this logic at Oracle level. Therefore, you can only ever access R/3 pool and cluster tables with R/3 tools. Also refer to Note 581312, which explains that direct access to SAP data via non-SAP interfaces is only allowed on a restricted basis.