Asked 5 years, 6 months ago. Active 5 years, 4 months ago. Viewed times. Chris Webster Chris Webster 8 8 silver badges 20 20 bronze badges. Add a comment. Active Oldest Votes. Update If you would like to delete column values, e. Thanks, Flavian. My code is in flux right now, and it's a bit more complicated than the sample app I linked to above, so I can't easily drop it into this post. If this doesn't work, I'll try your update method instead.
Thanks for your help. I think the problem is that I'm using an insert to do my update. In Cassandra this works fine because Cassandra treats it as an upsert anyway, and it's good for my use case where I don't need to care if the record already exists or not because I'm only writing the key and one or two specific fields: the default Cassandra behaviour is what I want. This is fairly trivial and standard in Cassandra, but it introduces a subtle problem, namely that the new table needs to store a Record and at least one more column representing an index.
We refer to the columns that exist in the Table but not in the Record as unmatched columns, both in the documentation as well as the schema. The macro will pick up on the fact that our table now has more columns than our Record type needs, which means they need to somehow be mapped. This is better visible below, where both the body of the new store method as well as the Cassandra table DSL schema we might use for it are clearly visible.
The macro will always create a Tuple as described initially, of all the types of unmatched columns, succeeded by the Record type. UUID import com. InsertQuery case class MyRecord id : java. Default [ RecordsByCountry , Record ].
InsertQuery case class CountryRecord id : java. In some binder types, only the individual wire pairs are twisted, and pairs are not twisted around each other. Other binder types show twisting of wire pairs around each other e. Also, the crosstalk between phantom modes will most likely be larger than the crosstalk between differential modes. For all these reasons, crosstalk cancellation or vectoring needs to be applied when using the phantom mode. Otherwise, the extra bit rate gained over the phantom link is limited, and partially reduced by bit rate reduction over the differential modes.
Leveraging DSL Phantom Mode, Alcatel-Lucent has shown downstream speeds of Mbps over distances up to meters using 2 copper pairs, and obtained Mbps using 4 pairs — which means more than 1 Gbps upstream and downstream combined.
With further research currently ongoing to develop optimal deployment models and a specific set of customer premises equipment CPE -models, the technology is fully standards-based and has a bright future. Your browser does not support the video tag. Magic for Copper? Phantom Mode: Seeing Is Believing Phantom mode transmission over 2 pairs exploits the difference between the common mode voltages of the 2 pairs.
Phantom Technology Simplified In general, when N wire pairs are available, N normal differential channels and N-1 phantom channels can be used.
About ISE Staff. And this is why we offer another native construct, namely the DatabaseProvider trait. This is pretty simple in its design, it simply aims to provide a simple way of injecting a reference to a particular database inside a consumer. If I as your colleague and developer would now want to consume the UserService , I would basically create an instance or use a pre-existing one to basically consume methods that only require passing in known domain objects as parameters.
Notice how session , keySpace and everything else Cassandra specific has gone away? All I can see is a def storeUser user: User which is all very sensible, so the entire usage of Cassandra is now transparent to end consumers. Pretty much the only thing left is the ResultSet , and we can get rid of that too should we choose to map it to a domain specific class. It could be useful if we want to hide the fact that we are using Cassandra completely from any database service consumer.
Ok, so now we have all the elements in place to create the cake pattern, the next step is to basically flesh out the environments we want. We will go through that in more detail in a second, to show how we can specify more complex options using ContactPoint.
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