yes, that's what I thought. but, when I use these forms, INSERT ... ['A'] INSERT ... ['B']
The data is actually appended. not overwritten. so I guess this is something unexpected? Thanks, Aoi 2016-10-12 20:55 GMT-07:00 Vladimir Yudovin <vla...@winguzone.com>: > If you use form > INSERT ... ['A'] > INSERT ... ['B'] > > latest INSERT will overwrite first, because this insert the whole list. It's > better to use UPDATE like: > UPDATE ... SET events = events + ['A'] > UPDATE ... SET events = events + ['B'] > These operations add new elements to the end of existing list. > > > From here https://docs.datastax.com/en/cql/3.0/cql/cql_using/use_list_t.html > : > > These update operations are implemented internally without any > read-before-write. Appending and prepending a new element to the list writes > only the new element. > > > Best regards, Vladimir Yudovin, > Winguzone - Hosted Cloud Cassandra on Azure and SoftLayer. > Launch your cluster in minutes. > > > ---- On Wed, 12 Oct 2016 17:39:46 -0400Aoi Kadoya <cadyan....@gmail.com> > wrote ---- > > Hi, > > When inserting different data into a list type column from different > clients at the same time, is data supposed to be combined into one > list? > > For example, if these 2 queries were requested from clients at the > same timing, how events list should look like after? > > INSERT INTO cycling.upcoming_calendar (year, month, events) VALUES > (2015, 06, ['A']); > INSERT INTO cycling.upcoming_calendar (year, month, events) VALUES > (2015, 06, ['B']); > > In my understanding, each operation should be treated as atomic, which > makes me think that even if client throw the queries at the same time, > cassandra would take them separately and the last insert would update > the events list. (= data should be either ['A'] or ['B']) > > In my environment, I found that some data was saved as like ['A',B'] > in the case like above. > Is this expected behavior of list data type? > > I am still new to cassandra and trying to make myself understood how > this happened. > Appreciate if you could help me with figuring this out! > > Thanks, > Aoi > >
