Yes, that is correct.— Sent from Mailbox On Sat, Jun 21, 2014 at 8:18 PM, Kevin Burton <bur...@spinn3r.com> wrote:
> AH! that makes sense then… so second time around, when you write null, > you're actually writing a tombstone, then during the next compaction, less > data will be stored and the value will be removed. > Makes sense! Not sure why I didn't realize that immediately :-P > On Sat, Jun 21, 2014 at 6:20 AM, DuyHai Doan <doanduy...@gmail.com> wrote: >> With CQL3 semantics, setting a column to "null" means deleting it (e.g. >> creating a tombstone column). It is different from having a "non-null >> column name and a null cell". >> >> >> On Sat, Jun 21, 2014 at 12:17 PM, Jens Rantil <jens.ran...@tink.se> wrote: >> >>> Hi Kevin, >>> >>> I can explain as I've understood things. Experts, let me know if I got >>> this wrong! Here you go: >>> >>> Simplified, when using a CQL-created table the underlying clustering key >>> for your columns is actually (YOUR_CLUSTERING_KEY, columnname). Because of >>> this, setting YOURCOLUMN to null, simply deletes the key/value with key >>> (YOUR_CLUSTERING_KEY, YOURCOLUMN). >>> >>> To be able to still set meta data on a row-to-row-basis (TTL, for >>> example), as well as supporting empty rows (ie. all-nulls), every row also >>> has a row marker with key (YOUR_CLUSTERING_KEY, ROW_MARKER). Conceptually, >>> you could almost see ROW_MARKER as a hidden non-nullable column in your >>> table. >>> >>> Cheers, >>> Jens >>> >>> >>> On Sat, Jun 21, 2014 at 5:13 AM, Kevin Burton <bur...@spinn3r.com> wrote: >>> >>>> Let's say we have a table like with just an integer primary key named ID >>>> and a text column named VALUE… >>>> >>>> >>>> if we set value to 0, "hello world" >>>> >>>> … obviously , that's a normal value. >>>> >>>> However, what happens if we update it with >>>> >>>> 0, null >>>> >>>> … how is the 'null' stored? >>>> >>>> I couldn't find any documentation for this anywhere. >>>> >>>> The new null supersedes the older value of "hello world" so I assume it >>>> has to write it into an SSTable before both SSTables are compacted. >>>> >>>> -- >>>> >>>> Founder/CEO Spinn3r.com >>>> Location: *San Francisco, CA* >>>> Skype: *burtonator* >>>> blog: http://burtonator.wordpress.com >>>> … or check out my Google+ profile >>>> <https://plus.google.com/102718274791889610666/posts> >>>> <http://spinn3r.com> >>>> War is peace. Freedom is slavery. Ignorance is strength. Corporations >>>> are people. >>>> >>>> >>> >> > -- > Founder/CEO Spinn3r.com > Location: *San Francisco, CA* > Skype: *burtonator* > blog: http://burtonator.wordpress.com > … or check out my Google+ profile > <https://plus.google.com/102718274791889610666/posts> > <http://spinn3r.com> > War is peace. Freedom is slavery. Ignorance is strength. Corporations are > people.
