Mailing List Archive: 49091 messages
  • Home
  • Script library
  • AltME Archive
  • Mailing list
  • Articles Index
  • Site search

[REBOL] Re: possible data format ... Re: Re: dbms3.r 01

From: greggirwin:mindspring at: 16-Jan-2002 11:50

Hi Pekr, << Maybe I don't think so anymore :-) I talked the problem with my colleagues here, and Michael suggested, that any kind of locking, is done in memory. We found one interesting document though, which describes several scenarios, even one with lock field and time stamp ....>> But for this to work, you need some kind of file locking mechanism (e.g. SHARE under DOS), or shared memory, correct? I.e. if you have two separate dbms scripts running against the same file, how do they communicate lock information if REBOL doesn't give us the ability to "flag" locks against specific file offsets? << - very cool description .... >> Great information! <<RE: rec-num: XBase, it has its meaning. You can open dbase file without opening any index, so browser sorts records according to their rec-no. >> Right, if we have access to a block of records, whether as a complete file on disk or as the result of a query, there would be an implied order to them, but I see that as separate from a record identifier (its GUID). << I think that it depends upon what your intention is - do you want to have variable column records? I would not suggest it, as it is a little bit more difficult for any kind of anylysing software, which simply counts something in a loop .... >> Agreed, do we consider a database to contain only homogeneous records, does it maintain separate internal tables for different record types, or does it do what some OODBMS' do and store a collection of heterogeneous records which share a small common core allowing it to navigate and identify records of various types. In that scenario, reading all the records in a "table" is actually more like a query to find records by type (and a record may exist in multiple "extents" when you consider an inheritance model). --Gregg