VistaDB .net database blog: All Comments

RE: LINQ test for custom IEnumerator

Jason Short — Tue, 01 Jul 2008 15:15:00 GMT

Currently there is nothing internal to do with LINQ. That is what we are discussing. The Entity Framework is part of the solution, but we are discussing adding it internal to the engine for DDA.

You are pretty much limited to your OS/RAM, size of tables, etc.

RE: LINQ test for custom IEnumerator

Christer Jensen — Sun, 29 Jun 2008 12:32:00 GMT

Do you expect to implement LINQ, in your base product. As far as i can see from the samples on the site, you query the data and then manipulate them using linq2objects. Am i missing something here ?. One of the powers in linq is to reduce the dataset required from the db. On a sidenote, how big can a vistadb table be, is there a limit ? regarding size / os.

RE: LINQ test for custom IEnumerator

Jason Short — Sun, 29 Jun 2008 01:54:00 GMT

I was not being LITERAL in the comment to the code. :)

The comment was about complexity of your query in a single line compared to what it would take in DDA today.

You can do a lot in that single line, LIKE reducing the queryset to only those with more than xx number of characters and then skipping to only the odd numbers. That is easy in LINQ. Maybe it is a contrived scenario (it is), but I am sure there are places for it.

RE: LINQ test for custom IEnumerator

Mark — Sat, 28 Jun 2008 14:53:00 GMT

Jason,

I am confused.

var foundrows = firsttable.Where(c => c.StringData.Length > 0).Skip(1);

This will the all items in firsttable, evaluate the condition selecting only those that have a length > 0 and then skip the first item of that filtered set.

"In DDA you would have to set .First(), then .MoveNext() and then move through each row checking for the length > 0."

What you describe here I believe is this -

var foundrows = firsttable.Skip(1).Where(c => c.StringData.Length > 0);

These two queries will return different results. Using LinqPAD

var data = new string[] {"", "x", "", "xx" };

var qOne = data.Where(s => s.Length > 0).Skip(1);

var qTwo = data.Skip(1).Where(s => s.Length > 0);

qOne.Dump();

IEnumerable<String>

qTwo.Dump();

IEnumerable<String>

Am I missing something?

RE: LINQ test for custom IEnumerator

Jason Short — Fri, 27 Jun 2008 22:10:00 GMT

The code didn't post so well, I will put it in the LINQ forum as well.

RE: VistaDB 3.4 Build 62 - New installer

Jason Short — Fri, 27 Jun 2008 13:11:00 GMT

We fixed some exceptions related to column mapping in relationships from 61 to 62. It was a strongly typed issue not allowing the cast. So give Build 62 a try.

RE: VistaDB 3.4 Build 62 - New installer

Uwe — Fri, 27 Jun 2008 12:07:00 GMT

Had some exceptions when doing ALTER TABLE stuff in Build 61. Went back to V3.3, worked there.

If final V3.4 has this exceptions, too, I will file a detailed issue report in the forum.

Keep your good work going!!! :-)

RE: VistaDB 3.4 Build 62 - New installer

Jason Short — Fri, 27 Jun 2008 01:10:00 GMT

Thanks! 3.4 is shaping up quite nicely. Performance is improving, memory footprint going down. And we feel we are just getting started with improvements to the engine!

RE: VistaDB 3.4 Build 62 - New installer

Ben — Thu, 26 Jun 2008 22:53:00 GMT

I am really looking forward to the release of 3.4. The testing I have done so far has shown very good speed increases.

RE: VistaDB Coolest Feature?

Jason Short — Fri, 20 Jun 2008 13:59:00 GMT

Sure you can. If you want a custom extention, go into the registry and build a mapping for the extention. Look at the one for vdb3 and copy it. It passes a %1 on the command line for the load option.

OR - We include the complete code to the Data Builder with all full licenses. Modify it to load / save your extention by default.