15.01.2017 19:00, Adriano dos Santos Fernandes wrote: > So what I call virtual metadata and how would it solve the problems:
Sounds not bad, but requires more programming and is less effective than versioned metadata cache. > When a DDL command is issued, it will not change metadata directly. It > will change metadata in a memory structure tied to the current transaction. I would prefer other approach: DDL command change metadata in database directly and immediately. Every other transaction use ordinary versioning mechanics to see database (including metadata) in consistent state according to TIL. Metadata cache is either reduced or expanded to follow metadata versions in database. DFW is reduced to simple check for object valid state which is performed on base of ordinary undo log. No problems with circular references, no problem with mixing of DDL and DML. -- WBR, SD. ------------------------------------------------------------------------------ Developer Access Program for Intel Xeon Phi Processors Access to Intel Xeon Phi processor-based developer platforms. With one year of Intel Parallel Studio XE. Training and support from Colfax. Order your platform today. http://sdm.link/xeonphi Firebird-Devel mailing list, web interface at https://lists.sourceforge.net/lists/listinfo/firebird-devel
