> From: Alex Rufon <[EMAIL PROTECTED]> > > Hi Chris/Oleg, > > I have the following questions for JDB: > 1. Would it be possible to use JDB without creating the physical file > structure? I.e. Folders and files.
This is an interesting and question which was discussed. There are a few approaches, but we need to work out a good and clear design. There a few aspects: A. Completely in-memory database, which is different from regular JDB database only in that the column-nouns are not mapped into physical files. B. Ability to have in-memory (temporary) tables along with regular mapped tables in regular JDB, like session temporary tables in RDBMS. But so that they are able to have foreign keys to regular mapped tables. C. Should temorary in-memory tables be represented exactly as regular mapped or as a simpler alternative, such as a boxed array with column names and column values? D. Concept of Views: they are treated as tables, but have featherweight implementation: contain a query, which has column aliases. It is realized into a Snapshot with list of autoids from the base table, but columns values are retrieved on demand from the underlying actual tables. E. The Views can be permanently defined in the database along with other tables; also transient Views can be used in a nested query. used to represent the transient inner result in a nested query. So we need to elaborate on these points. > 2. How do I find out the existing tables in a database without reading > the "dir" file? Documentation is updated. > 3. Isn't it logical to get a "Read" verb at the table level? It was there originally, but then decided to have uniform access through database interface. Insert should also be done through database. This improves level of granularity. > To explain > further, consider the following example: > NB. test table definition > testfields=: 0 : 0 > field1 int > field2 varchar > field3 char > field4 boolean > ) > > NB. Load the library and open may data directory > load 'data/jdb' > hf=: Open_jdb_ '/home/arufon/Temp/data' > NB. Create a new database named test > hd=: Create__hf 'test' > NB. Create a new table named test > ht=: Create__hd 'test';testfields > NB. Insert a sample data > Insert__ht 1;'first row';'a';0 > NB. Retrieve the data from the table > Reads__hd 'from test' > +------+---------+------+------+ > |field1|field2 |field3|field4| > +------+---------+------+------+ > |1 |first row|a |0 | > +------+---------+------+------+ > > What I am saying is that to read the data from the table, I need to > access the database locale 'hd' while I already have a reference for the > actual table locale in 'ht'. > > I can already do Insert on the table level as show in this code: > NB. Insert a sample data > Insert__ht 1;'first row';'a';0 > > I would be logical to be able to do the other DML commands on both the > table and database level right? > > Let me know what you think. :) > > r/alex > > > -- > "The right questions are more important than the right answers to the > wrong questions." > -Dr. John Romagna > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
