[Dbappbuilder-relannounce] ANNOUNCE: Rel version 1.0.11 Released!

[Rel a. list. <dba...@li...>]

This version of /Rel/--- an implementation of Date & Darwen's *Tutorial 
D* database language--- is a maintenance release featuring various 
enhancements and bug fixes.

Prior to installing this version of /Rel/, you must make a backup of 
your database(s). Then, install this update and load and attempt to 
execute your backup script(s). If your script successfully loads, you're 
done. If /Rel/ complains of syntax errors, you'll need to edit the 
backup script --- based on the "/Rel/ Version 1.0.11+ Syntax" article at 
http://dbappbuilder.sourceforge.net --- until the script successfully loads.

Changes in this update:

* Enhancement: DBrowser: Now displays human-friendly messages when 
attempting to open an already-open database, or when a connection 
attempt to a remote /Rel/ server fails.

* Enhancement: DBrowser: Now provides options to hide headings and 
declared types in headings in displayed output of relations.

* Enhancement: DBrowser: Now provides a "Get File Path" button to 
simplify putting file paths in source code.  This facilitates use of 
external data sources, described below.

* Enhancement: Rel: Some minor syntax improvements have been made, in 
accordance with changes to *Tutorial D*. Formerly-required parentheses 
around WRAP, UNWRAP, GROUP, UNGROUP clauses have been removed. UNGROUP 
(a) and UNWRAP (a) are now UNGROUP a and UNWRAP a, respectively.

* Enhancement: Rel: All error messages are now uniquely identified to 
disambiguate references to them.

* Enhancement: Rel: Updated to version 6.0.11 of the Berkeley Java DB, 
which is used as a storage engine.

* Enhancement: Rel: A student project has produced simple support for 
external CSV/XLS/XLSX/JDBC sources as relvars:

  e.g., VAR myvar EXTERNAL CSV "/home/dave/test.csv";
  e.g., VAR myvar EXTERNAL XLS "/home/dave/test.xls" DUP_REMOVE;
  e.g., VAR myvar EXTERNAL XLS "/home/dave/test.xlsx" DUP_COUNT;
  e.g., VAR myvar EXTERNAL XLS "/home/dave/test.xlsx" AUTOKEY;
  e.g., VAR myvar EXTERNAL JDBC 
"<host>,<user>,<password>,<database>.<table>,<driverpath>,<drivername>";

This feature also makes it possible to define new relvar types as /Rel/ 
plug-ins.  Documentation for this feature will be provided in the future.

* Enhancement: Rel: 'x RENAME {}' is now valid syntax.

* Enhancement: Rel: Errors occurring in a database constraint are now 
treated as if the constraint evaluates to false, and the failing 
constraint is named in the error message.

* Fix: DBrowser: Fixed minor errors parsing certain error messages.

* Fix: Rel: Given...

    VAR S BASE RELATION {
         SNO CHAR, SNAME CHAR, STATUS INTEGER, CITY CHAR
    } KEY {SNO};
    VAR SP BASE RELATION { SNO CHAR, PNO CHAR, QTY INTEGER } KEY {SNO, PNO};
    VAR SPQ BASE INIT(
       EXTEND S: {PQ := RELATION {TUPLE {SNO SNO}} COMPOSE SP}
    ) KEY{SNO};

...these failed:

   UPDATE SPQ WHERE SNO = "S2":
       {INSERT PQ RELATION {TUPLE {PNO "P5", QTY 500}}};
   UPDATE SPQ WHERE SNO = "S2": {UPDATE PQ WHERE PNO="P5": {QTY := 250}};
   UPDATE SPQ WHERE SNO = "S2": {DELETE PQ WHERE PNO="P5"};

This has been corrected.

* Fix: Rel: The following should have returned true but returned false:

      RELATION  {
             TUPLE { SUPPLIES RELATION {
               TUPLE {PID "P5"}
             }},
             TUPLE { SUPPLIES RELATION {
               TUPLE {PID "P2"}
             }},
             TUPLE { SUPPLIES RELATION {
               TUPLE {PID "P4"}
             }}
      }
      =
      RELATION  {
             TUPLE { SUPPLIES RELATION {
               TUPLE {PID "P5"}
             }},
             TUPLE { SUPPLIES RELATION {
               TUPLE {PID "P2"}
             }},
             TUPLE { SUPPLIES RELATION {
               TUPLE {PID "P4"}
             }}
      }

This has been corrected.  Internal changes to address this and similar 
errors in comparing relations with relation-valued attributes may have 
performance impact -- some queries may run faster, others slower.

* Fix: Rel: JOIN {}, TIMES {}, and COMPOSE {} now return DEE.

* Fix: Rel: XUNION {}, D_UNION {}, UNION {} now return TUPLE {}.

* Fix: Rel: XUNION {} {}, D_UNION {} {}, UNION {} {} return DUM.

* Fix: Rel: INTERSECT {} and INTERSECT {} {} throw an error.

* Fix: Rel: Type checking was too weak on comparison operators, allowing 
incorrect expressions like 'tuple{x 1} = tuple{y 2, x 1}' to return a 
result instead of throwing an error.  Fixed.

* Fix: Rel: RELATION {TUPLE {x 10, y DEE}} WHERE x = 100 UNGROUP y threw 
a fatal error.  It should have thrown a type error due to an attempt to 
ungroup integer 100. This has been fixed.

* Fix: Rel: Built-in operator name OP_GREATHERTHANOREQUALS corrected to 
OP_GREATERTHANOREQUALS.

* Fix: Rel: Assignment to a real relvar altered its CreationSequence. Fixed.

* Fix: Rel: CAST_AS_INTEGER("blah") and CAST_AS_RATIONAL("blah") should 
have thrown semantic errors, not fatal errors.  Fixed.

Note: This release includes experimental support for a work-in-progress 
visual query language called Rev. Using an icons-on-strings data-flow 
style, it permits constructing queries visually and iteratively, and 
allows testing sub-expressions whilst constructing a query. To 
experiment with it, install the Rev package and it will appear as an 
additional tab in a DBrowser session. To remove it, delete the rev.jar 
file. Further documentation and video demonstrations will be provided in 
the future.

For more information, or to download /Rel/, see 
http://dbappbuilder.sourceforge.net/Rel.html