Ok... I read it somewhere in the archives of the list.
But I found it a little "inadeguate":
- what about multiple fields primary key?
- what about transactions?
- what data modifications (insert update delete)?
'till now I imagine it so:
opening a transaction could be creating a directory on a dbfs/transactions/
each of such directories (like the complete connection) has
- a "ctrl" file which accept only COMMIT, ROLLBACK and ABORT
- an "error" file
- a "notice" file (postgresql has RAISE NOTICE... may be others have it too)
- a "data" file (append only in the transaction, but not outside) where the INSERT, UPDATES, DELETE and all the DDL and DCL commands will be written
- each SELECT have to be written in a different file (named sequentially): after writing the query, the same file could be read to get the results (in xml...)
- on errors, sequents writes fails and error file will be readable