In message of 3 Feb, Dennis Lee Bieber <wlfraed@ix.netcom.com> wrote: <snip> > But do you have the same meaning I associate with "flat file", or > could you be meaning a "heap file". To me, a "flat file" is one in which > all records share the same structural layout, whereas a "heap file", > while record oriented, does not mandate each record looks similar to the > previous or next. GEDCOM files can be considered a form of flat file if > you look at it from the view of > > data-level data-key associated data values > > where data-key identifies what type of data follows on the line. This is completely in contrast to the meaning of 'flat file' when I was working with mainframe data managers some fifteen years ago. Then a flat file was one with no structure like GEDCOM and which could be read easily by a text editor. A relational database was constructed from flat files, each of which was ported into a suitably defined table; though this required that each column in the flat file was used for a defined data type only. Thus comma separated variable (CSV) and tab separated variable (TSV) files are both flat files. GEDCOM on the other hand needs an extensive program to disentangle it and to communicate the data to a casual reader. The fact that you can read GEDCOM in a text editor, though, does not make it into a flat file. On a related topic, several genealogy programs use the GEDCOM structure as their input and output media. I wonder if the keep the data unaltered for processing or if they convert it to a different internal structure for processing. If the latter, I wonder what those structures are? -- Tim Powys-Lybbe                                          tim@powys.org              For a miscellany of bygones: http://powys.org/

Tim Powys-Lybbe wrote: > In message of 3 Feb, Dennis Lee Bieber <wlfraed@ix.netcom.com> wrote: > > <snip> > >> But do you have the same meaning I associate with "flat file", or >> could you be meaning a "heap file". To me, a "flat file" is one in which >> all records share the same structural layout, whereas a "heap file", >> while record oriented, does not mandate each record looks similar to the >> previous or next. GEDCOM files can be considered a form of flat file if >> you look at it from the view of >> >> data-level data-key associated data values >> >> where data-key identifies what type of data follows on the line. > > This is completely in contrast to the meaning of 'flat file' when I was > working with mainframe data managers some fifteen years ago. Then a > flat file was one with no structure like GEDCOM and which could be read > easily by a text editor. A relational database was constructed from flat > files, each of which was ported into a suitably defined table; though > this required that each column in the flat file was used for a defined > data type only. Thus comma separated variable (CSV) and tab separated > variable (TSV) files are both flat files. > > GEDCOM on the other hand needs an extensive program to disentangle it > and to communicate the data to a casual reader. The fact that you can > read GEDCOM in a text editor, though, does not make it into a flat file. > > On a related topic, several genealogy programs use the GEDCOM structure > as their input and output media. I wonder if the keep the data > unaltered for processing or if they convert it to a different internal > structure for processing. If the latter, I wonder what those structures > are? > try reading an FTM file with a text editor Hugh W

Tim Powys-Lybbe wrote: > On a related topic, several genealogy programs use the GEDCOM structure > as their input and output media. I wonder if the keep the data > unaltered for processing or if they convert it to a different internal > structure for processing. If the latter, I wonder what those structures > are? Each is different, and none that I know of use GEDCOM internally. Even LifeLines adds binary tree indexing bytes to the GEDCOM. My own (which is not published and can do almost nothing) stores the GEDCOM level zero records unmodified, but it does split them from each other and create several indexes to make them accessible. -- Wes Groleau There are more Baroque musicians than any other kind.