oqgraph-dev team mailing list archive

[Arjen Lentz <arjen@xxxxxxxxxxxxx>]

Hi Andrew

> The current behaviour always returns an empty set if the latch is NULL
> should this be changed then?

v2 allowed latch to be NULL, so we should probably keep that.
I don't see any reason to handle NULL and 0 differently though.


> No latch specified seems to work correctly as you specify:
> - or should it not have the latch, seq, linkid columns?

The below looks ok. Please ensure there are tests for each permutation in the basic test.
Perhaps we should create a no-search test as the basic test already checks schema foo which is really basic.

You can't leave columns out as they're part of the schema. You can't half a row in an RDBMS.
Resultsets should always be relationally consistent - the server core will actually enforce this because as you know it always applies its own filters even if the engine doesn't.

They are NULL because there is no WHERE clause on them specifying a different value, and no data to return - thus it should be the default of the column, which in case of a NULL column (e.g. a col that can be NULL) with no other DEFAULT value specified in the schema, is NULL.


> SELECT * FROM graph;
> latch origid destid weight seq linkid
> NULL 1 2 1 NULL NULL
> NULL 2 1 1 NULL NULL
> NULL 1 3 1 NULL NULL
> NULL 3 1 1 NULL NULL
> NULL 3 4 1 NULL NULL
> NULL 4 3 1 NULL NULL
> NULL 5 6 1 NULL NULL
> NULL 6 5 1 NULL NULL
> 
> Same for no latch with a filter:
> 
> SELECT * FROM graph WHERE destid=2 and origid=1;
> latch origid destid weight seq linkid
> NULL 1 2 1 NULL NULL
> 
> 
> 
> 
> On 29/05/13 08:08, Arjen Lentz wrote:
> > Hi Andrew
> >
> >> what should a no_search latch return?
> >
> > For latch=0/no_search, the table should look as inserted (i.e. like
> > a regular table).
> >
> > I was just wondering if you'd also set "no_search" as the default,
> > but I reckon it might be better to use an empty string or NULL
> > rather than no_search. Can you change that without causing hassles
> > elsewhere?
> >
> >
> <snipped>
> 
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Arjen Lentz, Exec.Director @ Open Query (http://openquery.com)
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