On Sat, 2006-28-10 at 12:55 -0400, Derek Atkins wrote: > Quoting Phil Longstaff <[EMAIL PROTECTED]>: > > > Re slot table: even if lists aren't used, there is still the hierarchy > > based on sub-frames. A row in the slot table may still need a link to > > its parent, and this can't be the guid which identifies the whole slot. > > We will need some sort of secondary key, then, to represent the links > > within the hierarchy of one complete slot. Each row in a complete slot > > would have the same guid, so that a complete slot could be deleted using > > "delete from slots where guid='...'", the top level slot would have > > parent = null and secondary_key = 0, and other rows in the slot would > > have parent = secondary_key_of_parent. > > > > Of course, if there are no lists, is there really any reason to bury a > > single slot value in a hierarchy? If lists are gone, sub-frames may be > > gone too. > > Nah... Think of a KVP slot like a filesystem directory tree. Each node > can either be a File or a Directory. The Slot Path walks down the > tree (through KVP_FRAMEs) until you get down to a "file" node, a KVP_VALUE > of some data-type other that KVP_FRAME. Just because you don't have > a KVP_VALUE of type "list" doesn't mean you can't (or shouldn't) have > KVP_VALUE of type KVP_FRAME.
Yes, but without lists, the analogy is each node being either a file or a directory which can contain at most 1 file or directory in it. I question the usefulness of all of the directory levels. > However... You CAN model it as a flat table! > Take a look at the existing PG Backend KVP implementation. You can > model it as: > > text(32) object_id NOT NULL, > text slot_path NOT NULL, > enum(kvp_value_types) value_type, > ... values > > You can construct (and deconstruct) a full kvp tree this way. No > need to reference parents or anything like that. The slot_path would > be a string like "/A/B/C/D". Each "/" implies a KVP_FRAME with "/" > denoting the "root node". Fine, but without lists, isn't this equivalent to adding '/' to the list of chars which can be put into a KVP node name? Without lists, "/A/B/C" and "/A/B/D" are separate independent nodes. With lists, C and D are children in the list "/A/B". > The only question with this approach is how you model an empty KVP_FRAME > as a leaf-node in the tree. Yes, this works. By adding 'empty' to the KVP type enum (at least in the DB), you can model empty KVP frames. Phil _______________________________________________ gnucash-devel mailing list gnucash-devel@gnucash.org https://lists.gnucash.org/mailman/listinfo/gnucash-devel
