I did read those articles, but I didn't know know that deleting all the columns on a row was equivalent to deleting the row. Like I mentioned, I did delete all the columns from all my rows and then forced compaction before and after gc_grace had passed, but all the rows still exist. If they never disappear, then won't I run out of resources eventually?
-Kal On Tue, Feb 8, 2011 at 3:09 PM, Jeremiah Jordan <jeremiah.jor...@morningstar.com> wrote: > You will have the same problem. You just have to learn to ignore empty rows > when you query data. See articles on delete mentioned earlier. > >>>> >> >>> > http://wiki.apache.org/cassandra/FAQ#i_deleted_what_gives >>>> >> >>> > http://wiki.apache.org/cassandra/FAQ#range_ghosts > > -----Original Message----- > From: Kallin Nagelberg [mailto:kallin.nagelb...@gmail.com] > Sent: Tuesday, February 08, 2011 1:36 PM > To: user@cassandra.apache.org > Subject: Re: time to live rows > > I'm thinking if this row expiry notion doesn't pan out then I might > create a 'lastAccessed' column with a secondary index (i think that's > right) on it. Then I can periodically run a query to find all > lastAccessed columns less than a certain value and manually delete > them. Sound reasonable? > > -Kal > > On Tue, Feb 8, 2011 at 12:09 PM, Kallin Nagelberg > <kallin.nagelb...@gmail.com> wrote: >> Yes I did, on the org.apache.cassandra.db.ColumnFamilies.Main.Session object. >> >> -Kal >> >> On Tue, Feb 8, 2011 at 12:00 PM, Sylvain Lebresne <sylv...@datastax.com> >> wrote: >>> Did you force a major compaction (with jconsole or nodetool) after gc_grace >>> has elapsed ? >>> On Tue, Feb 8, 2011 at 5:46 PM, Kallin Nagelberg >>> <kallin.nagelb...@gmail.com> wrote: >>>> >>>> Thanks, gc_grace works in the CLI. >>>> >>>> However, I'm not observing the desired effect. I am setting TTL on a >>>> single column in my column family, and I see the columns disappear >>>> when using 'list Session' (my columnfamily) in the CLI. I created the >>>> column family with gc_grace = 60, and after observing for a few >>>> minutes I am still seeing all the rows come back, none of them with >>>> columns. I was hoping the GC would delete the empty rows. >>>> >>>> -Kal >>>> >>>> On Tue, Feb 8, 2011 at 11:39 AM, Sylvain Lebresne <sylv...@datastax.com> >>>> wrote: >>>> > Not very logically, It's actually gc_grace, not gc_grace_seconds in the >>>> > CLI. >>>> > >>>> > On Tue, Feb 8, 2011 at 5:34 PM, Kallin Nagelberg >>>> > <kallin.nagelb...@gmail.com> wrote: >>>> >> >>>> >> I'm trying to set the gc_grace_seconds column family parameter but no >>>> >> luck.. I got the name of it from the comment in cassandra.yaml: >>>> >> >>>> >> # - gc_grace_seconds: specifies the time to wait before garbage >>>> >> # collecting tombstones (deletion markers). defaults to 864000 >>>> >> (10 >>>> >> # days). See http://wiki.apache.org/cassandra/DistributedDeletes >>>> >> >>>> >> create column family Session >>>> >> with comparator = UTF8Type >>>> >> and keys_cached = 10000 >>>> >> and memtable_flush_after = 1440 >>>> >> and memtable_throughput = 32 >>>> >> and gc_grace_seconds = 60; >>>> >> >>>> >> error is 'No enum const class >>>> >> >>>> >> >>>> >> org.apache.cassandra.cli.CliUserHelp$ColumnFamilyArgument.GC_GRACE_SECONDS'. >>>> >> >>>> >> Thanks, >>>> >> -Kal >>>> >> >>>> >> On Tue, Feb 8, 2011 at 11:02 AM, Sylvain Lebresne >>>> >> <sylv...@datastax.com> >>>> >> wrote: >>>> >> >> I hope you don't consider this a hijack of the thread... >>>> >> >> >>>> >> >> What I'd like to know is the following: >>>> >> >> >>>> >> >> The GC removes TTL rows some time after they expire, at its >>>> >> >> convenience. >>>> >> >> But will they stop being returned as soon as they expire? (This is >>>> >> >> the >>>> >> >> expected behavior...) >>>> >> > >>>> >> > It is the individual column that have TTL. When a column expires, it >>>> >> > becomes >>>> >> > a delete tombstone. Now, a row with tombstones (even only them) will >>>> >> > show >>>> >> > during range request. But the explanation is >>>> >> > here: http://wiki.apache.org/cassandra/FAQ#range_ghosts >>>> >> > >>>> >> >> >>>> >> >> On Tue, Feb 8, 2011 at 5:11 PM, Kallin Nagelberg >>>> >> >> <kallin.nagelb...@gmail.com> wrote: >>>> >> >>> >>>> >> >>> So the empty row will be ultimately removed then? Is there a way to >>>> >> >>> for the GC to verify this? >>>> >> >>> >>>> >> >>> Thanks, >>>> >> >>> -Kal >>>> >> >>> >>>> >> >>> On Tue, Feb 8, 2011 at 2:21 AM, Stu Hood <stuh...@gmail.com> wrote: >>>> >> >>> > The expired columns were converted into tombstones, which will >>>> >> >>> > live >>>> >> >>> > for >>>> >> >>> > the >>>> >> >>> > GC timeout. The "empty" row will be cleaned up when those >>>> >> >>> > tombstones >>>> >> >>> > are >>>> >> >>> > removed. >>>> >> >>> > Returning the empty row is unfortunate... we'd love to find a >>>> >> >>> > more >>>> >> >>> > appropriate solution that might not involve endless scanning. >>>> >> >>> > See >>>> >> >>> > http://wiki.apache.org/cassandra/FAQ#i_deleted_what_gives >>>> >> >>> > http://wiki.apache.org/cassandra/FAQ#range_ghosts >>>> >> >>> > >>>> >> >>> > On Mon, Feb 7, 2011 at 1:49 PM, Kallin Nagelberg >>>> >> >>> > <kallin.nagelb...@gmail.com> wrote: >>>> >> >>> >> >>>> >> >>> >> I also tried forcing a major compaction on the column family >>>> >> >>> >> using >>>> >> >>> >> JMX >>>> >> >>> >> but the row remains. >>>> >> >>> >> >>>> >> >>> >> On Mon, Feb 7, 2011 at 4:43 PM, Kallin Nagelberg >>>> >> >>> >> <kallin.nagelb...@gmail.com> wrote: >>>> >> >>> >> > I tried that but I still see the row coming back on a list >>>> >> >>> >> > <columnfamily> in the CLI. My concern is that there will be a >>>> >> >>> >> > pointer >>>> >> >>> >> > to an empty row for all eternity. >>>> >> >>> >> > >>>> >> >>> >> > -Kal >>>> >> >>> >> > >>>> >> >>> >> > On Mon, Feb 7, 2011 at 4:38 PM, Aaron Morton >>>> >> >>> >> > <aa...@thelastpickle.com> >>>> >> >>> >> > wrote: >>>> >> >>> >> >> Deleting all the columns in a row via TTL has the same affect >>>> >> >>> >> >> as >>>> >> >>> >> >> deleting th >>>> >> >>> >> >> row, the data will physically by removed during compaction. >>>> >> >>> >> >> >>>> >> >>> >> >> Aaron >>>> >> >>> >> >> >>>> >> >>> >> >> >>>> >> >>> >> >> On 08 Feb, 2011,at 10:24 AM, Bill Speirs >>>> >> >>> >> >> <bill.spe...@gmail.com> >>>> >> >>> >> >> wrote: >>>> >> >>> >> >> >>>> >> >>> >> >> I don't think this is supported (but I could be completely >>>> >> >>> >> >> wrong). >>>> >> >>> >> >> However, I'd love to see this functionality as well. >>>> >> >>> >> >> >>>> >> >>> >> >> How would one go about requesting such a feature? >>>> >> >>> >> >> >>>> >> >>> >> >> Bill- >>>> >> >>> >> >> >>>> >> >>> >> >> On Mon, Feb 7, 2011 at 4:15 PM, Kallin Nagelberg >>>> >> >>> >> >> <kallin.nagelb...@gmail.com> wrote: >>>> >> >>> >> >>> Hey, >>>> >> >>> >> >>> >>>> >> >>> >> >>> I have read about the new TTL columns in Cassandra 0.7. In >>>> >> >>> >> >>> my >>>> >> >>> >> >>> case >>>> >> >>> >> >>> I'd >>>> >> >>> >> >>> like to expire an entire row automatically after a certain >>>> >> >>> >> >>> amount >>>> >> >>> >> >>> of >>>> >> >>> >> >>> time. Is this possible as well? >>>> >> >>> >> >>> >>>> >> >>> >> >>> Thanks, >>>> >> >>> >> >>> -Kal >>>> >> >>> >> >>> >>>> >> >>> >> >> >>>> >> >>> >> > >>>> >> >>> > >>>> >> >>> > >>>> >> >> >>>> >> > >>>> >> > >>>> > >>>> > >>> >>> >> >
