The Rel Forum

This will be fixed in the next update.

I'll fix this in the next update.

In digging into this one, I've noticed the following also causes a similar exception: I should have this fixed in the next release.

The Tutorial D grammar specifies that a <real relation var def> ::= VAR <relation var name> <real or base> <relation type or init value> <candidate key def>. Therefore, the above should be: VAR S BASE RELATION { S# CHAR, Sname CHAR, Status INTEGER, City CHAR} INIT ( RELATION { TUPLE { S# 'S1', Sname...

There are no undue expectations. As little or as much as you're willing to contribute will be very much appreciated. Once you get started, let me know and I'll set you up write access to the Rel SVN repository.

I'd be interested in implementing the needed driver. I love the fact that Rel relies on the Java 6 platform. We could use all the new Java language additions (since 1.5), Concurrency utilities and NIO. Do you have a rough estimate of the effort needed? Excellent! I have no idea of the effort needed...

Hugh,

I just tried your is_num() operator on a Linux machine and a Windows XP machine, and it wasn't noticeably slow. How long would you estimate it takes to evaluate is_num('123') on your system?

I'm not surprised your is_num operator is slow. The changes I made to improve the performance of JOINs on relatively high cardinality relations have caused a loss of performance on low cardinality relations. It's something I'll have to address in the future. In the mean time, I have added the follow...

The Rel parser is generated by the JavaCC parser generator (https://javacc.dev.java.net/). I'm using the beta 4.1 version, because it fixes some bugs in the previous versions. Unfortunately, it also changes the parse error messages. Previously, upon encountering a parse error, it would just print th...

In versions of Rel prior to 0.3.x, LENGTH was a built-in operator. I forgot to include it in OperatorsChar.d when I released the 0.3.x series. It will be available in the next update (0.3.13), but for now, here's what it should have been: OPERATOR LENGTH(s CHAR) RETURNS INTEGER Java FOREIGN return n...

Yes, output of strings is certainly inconsistent with other types. This harks back to the time when OUTPUT was the sole output mechanism, so strings needed to be stripped of their delimiters so the old backup script would work. It's easy to change (I have to change a '0' to a '1' in one place!), so ...

This version of Rel includes some significant changes to ORDER and FOR. Previously, ORDER was a relational operator that returned tuples in a specified order, and FOR iterated over the tuples of a relation. Now, ORDER is an array operator that accepts a relation and returns a dynamically-created ARR...

As a result of discussions on the TTM list and considerable thought about ORDER() and FOR, version 0.3.12 will incorporate some changes: ORDER() now returns an ARRAY instead of a "sorted" relation. FOR now iterates the tuples of an ARRAY instead of a relation. This involves no significant ...

This version of Rel includes bug fixes and enhancements, primarily focusing on the Rel DBMS. The following bugs have been fixed in Rel: 1. Assigning a relvar to itself (e.g., myrelvar := myrelvar) could result in the Rel session becoming non-responsive. This has been corrected. 2. Under certain cond...

I have fixed this in version 0.3.10. I've also added more error-detection mechanisms to the backup process, so hopefully it won't appear to generate a backup without generating a backup -- at least, not without throwing an error message.