My cli knowledge sucks so far, so I'll leave that to others....I'm doing most of my reading/writing through a thrift client (hector/java based)
As for the implications, as of the latest version of Cassandra there is not theoretical limit to the number of columns that a particular row can hold. Over time you've got a couple of different options, if you're concerned that you end up with too many columns to manage then you'd probably want to start thinking about a warehousing strategy long-term for your older records that involves expiring columns that are older than X in your Cassandra cluster. But for the most part you shouldn't *need* to do that. On Wed, Jan 26, 2011 at 3:23 PM, Bill Speirs <bill.spe...@gmail.com> wrote: > I like this approach, but I have 2 questions: > > 1) what is the implications of continually adding columns to a single > row? I'm unsure how Cassandra is able to grow. I realize you can have > a virtually infinite number of columns, but what are the implications > of growing the number of columns over time? > > 2) maybe it's just a restriction of the CLI, but how do I do issue a > slice request? Also, what if start (or end) columns don't exist? I'm > guessing it's smart enough to get the columns in that range. > > Thanks! > > Bill- > > On Wed, Jan 26, 2011 at 4:12 PM, David McNelis > <dmcne...@agentisenergy.com> wrote: > > I would say in that case you might want to try a single column family > > where the key to the column is the system name. > > Then, you could name your columns as the timestamp. Then when retrieving > > information from the data store you can can, in your slice request, > specify > > your start column as X and end column as Y. > > Then you can use the stored column name to know when an event occurred. > > > > On Wed, Jan 26, 2011 at 2:56 PM, Bill Speirs <bill.spe...@gmail.com> > wrote: > >> > >> I'm looking to use Cassandra to store log messages from various > >> systems. A log message only has a message (UTF8Type) and a data/time. > >> My thought is to create a column family for each system. The row key > >> will be a TimeUUIDType. Each row will have 7 columns: year, month, > >> day, hour, minute, second, and message. I then have indexes setup for > >> each of the date/time columns. > >> > >> I was hoping this would allow me to answer queries like: "What are all > >> the log messages that were generated between X & Y?" The problem is > >> that I can ONLY use the equals operator on these column values. For > >> example, I cannot issuing: get system_x where month > 1; gives me this > >> error: "No indexed columns present in index clause with operator EQ." > >> The equals operator works as expected though: get system_x where month > >> = 1; > >> > >> What schema would allow me to get date ranges? > >> > >> Thanks in advance... > >> > >> Bill- > >> > >> * ColumnFamily description * > >> ColumnFamily: system_x_msg > >> Columns sorted by: org.apache.cassandra.db.marshal.UTF8Type > >> Row cache size / save period: 0.0/0 > >> Key cache size / save period: 200000.0/3600 > >> Memtable thresholds: 1.1671875/249/60 > >> GC grace seconds: 864000 > >> Compaction min/max thresholds: 4/32 > >> Read repair chance: 1.0 > >> Built indexes: [proj_1_msg.646179, proj_1_msg.686f7572, > >> proj_1_msg.6d696e757465, proj_1_msg.6d6f6e7468, > >> proj_1_msg.7365636f6e64, proj_1_msg.79656172] > >> Column Metadata: > >> Column Name: year (year) > >> Validation Class: org.apache.cassandra.db.marshal.IntegerType > >> Index Type: KEYS > >> Column Name: month (month) > >> Validation Class: org.apache.cassandra.db.marshal.IntegerType > >> Index Type: KEYS > >> Column Name: second (second) > >> Validation Class: org.apache.cassandra.db.marshal.IntegerType > >> Index Type: KEYS > >> Column Name: minute (minute) > >> Validation Class: org.apache.cassandra.db.marshal.IntegerType > >> Index Type: KEYS > >> Column Name: hour (hour) > >> Validation Class: org.apache.cassandra.db.marshal.IntegerType > >> Index Type: KEYS > >> Column Name: day (day) > >> Validation Class: org.apache.cassandra.db.marshal.IntegerType > >> Index Type: KEYS > > > > > > > > -- > > David McNelis > > Lead Software Engineer > > Agentis Energy > > www.agentisenergy.com > > o: 630.359.6395 > > c: 219.384.5143 > > A Smart Grid technology company focused on helping consumers of energy > > control an often under-managed resource. > > > > > -- *David McNelis* Lead Software Engineer Agentis Energy www.agentisenergy.com o: 630.359.6395 c: 219.384.5143 *A Smart Grid technology company focused on helping consumers of energy control an often under-managed resource.*
