Re: Counters and Top 10
With Composite Column Name, you can even have column composed of sore (int) and userid (uuid or whatever). Empty column value to avoid repeating user UUID. 2011/12/22 R. Verlangen : > I would suggest you to create a CF with a single row (or multiple for > historical data) with a date as key (utf8, e.g. 2011-12-22) and multiple > columns for every user's score. The column (utf8) would then be the score + > something unique of the user (e.g. hex representation of the TimeUUID). The > value would be the TimeUUID of the user. > > By default columns will be sorted and you can perform a slice to get the top > 10. > > 2011/12/14 cbert...@libero.it > >> Hi all, >> I'm using Cassandra in production for a small social network (~10.000 >> people). >> Now I have to assign some "credits" to each user operation (login, write >> post >> and so on) and then beeing capable of providing in each moment the top 10 >> of >> the most active users. I'm on Cassandra 0.7.6 I'd like to migrate to a new >> version in order to use Counters for the user points but ... what about >> the top >> 10? >> I was thinking about a specific ROW that always keeps the 10 most active >> users >> ... but I think it would be heavy (to write and to handle in thread-safe >> mode) >> ... can counters provide something like a "value ordered list"? >> >> Thanks for any help. >> Best regards, >> >> Carlo >> >> > -- sent from my Nokia 3210
Nodetool move failure, no data partitions determined
I was moving around some nodes in my cluster but when I get one node there appears an error: "Error during move: The data partitions for node [IP] have not been determined" How to solve this problem? -- View this message in context: http://cassandra-user-incubator-apache-org.3065146.n2.nabble.com/Nodetool-move-failure-no-data-partitions-determined-tp7126083p7126083.html Sent from the cassandra-u...@incubator.apache.org mailing list archive at Nabble.com.
R: Re: Counters and Top 10
Hi all, I've red all your messages concerning the top 10 ... any solution is possibile but I still did not find the best one. Using a composite Column Name as suggested would be smart cause it brings to a sorted row where I can have my top-10 in any moment but it can slow down all the platform since, for every operation, I have to read data from cassandra, calculate and store data back. Using counters I could just say "hey, +1 on this" and forget. But using counters I don't have any kind of value-sorting ... I know redis but I think it's too much to use a new key-value db just for this sorting ... I think I'll use a thread that run every X to generate the top10 row ... it won't be realtime but at least it will keep platform performance to a good level. Thank you all and merry christmas >Messaggio originale >Da: ben...@noisette.ch >Data: 25/12/2011 10.19 >A: >Ogg: Re: Counters and Top 10 > >With Composite Column Name, you can even have column composed of sore >(int) and userid (uuid or whatever). Empty column value to avoid >repeating user UUID. > > >2011/12/22 R. Verlangen : >> I would suggest you to create a CF with a single row (or multiple for >> historical data) with a date as key (utf8, e.g. 2011-12-22) and multiple >> columns for every user's score. The column (utf8) would then be the score + >> something unique of the user (e.g. hex representation of the TimeUUID). The >> value would be the TimeUUID of the user. >> >> By default columns will be sorted and you can perform a slice to get the top >> 10. >> >> 2011/12/14 cbert...@libero.it >> >>> Hi all, >>> I'm using Cassandra in production for a small social network (~10.000 >>> people). >>> Now I have to assign some "credits" to each user operation (login, write >>> post >>> and so on) and then beeing capable of providing in each moment the top 10 >>> of >>> the most active users. I'm on Cassandra 0.7.6 I'd like to migrate to a new >>> version in order to use Counters for the user points but ... what about >>> the top >>> 10? >>> I was thinking about a specific ROW that always keeps the 10 most active >>> users >>> ... but I think it would be heavy (to write and to handle in thread-safe >>> mode) >>> ... can counters provide something like a "value ordered list"? >>> >>> Thanks for any help. >>> Best regards, >>> >>> Carlo >>> >>> >> > > > >-- >sent from my Nokia 3210 >
reported bloom filter FP ratio
I have following CF Read Count: 68844 Read Latency: 9.942 ms. Write Count: 209712 Write Latency: 0.297 ms. Pending Tasks: 0 Bloom Filter False Postives: 10 Bloom Filter False Ratio: 0.00495 Bloom Filter Space Used: 2196632 why reported bloom filter FP ratio is not counted like this >>> 10/68844.0 0.00014525594096798558
Re: reported bloom filter FP ratio
> Read Count: 68844 [snip] > why reported bloom filter FP ratio is not counted like this 10/68844.0 > 0.00014525594096798558 Because the read count is total amount of reads to the CF, while the bloom filter is per sstable. The number of individual reads to sstables will be higher than the number of reads to the CF (unless you happen to have exactly one sstable or no rows ever span sstables). -- / Peter Schuller (@scode, http://worldmodscode.wordpress.com)
