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 ro...@us2.nl: 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 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
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: user@cassandra.apache.org 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 ro...@us2.nl: 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 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
Re: Counters and Top 10
In our case we didn't need an exact daily top-10 list of pages, just a good guess of it. So the way we did it was to insert a column with a short TTL (e.g. 12 hours) with the page id as the column name. Then, when constructing the top-10 list, we'd just slice through the entire list of unexpired page id's, get the actual activity data for each from another CF and then sort. The theory is that if a page is popular, they'd be referenced at least once in the past 12 hours anyway. Depending on the size of your hot pages and the frequency at which you'd need the top-10 list, you can then tune the TTL accordingly. We started at 24 hrs, then went down to 12 and then gradually downwards. So while it's not guaranteed to be the precise top-10 list for the day, it is a fairly accurate sampling of one. /Janne On 23 Dec 2011, at 11:52, aaron morton wrote: Counters only update the value of the column, they cannot be used as column names. So you cannot have a dynamically updating top ten list using counters. You have a couple of options. First use something like redis if that fits your use case. Redis could either be the database of record for the counts. Or just an aggregation layer, write the data to cassandra and sorted sets in redis then read the top ten from redis and use cassandra to rebuild redis if needed. The other is to periodically pivot the counts into a top ten row where you use regular integers for the column name. With only 10K users you could do this with an process that periodically reads all the users rows or where ever the counters are and updates the aggregate row. Depending on data size you cold use hive/pig or whatever regular programming language your are happy with. I guess you could also use redis to keep the top ten sorted and then periodically dump that back to cassandra and serve the read traffic from there. Hope that helps - Aaron Morton Freelance Developer @aaronmorton http://www.thelastpickle.com On 23/12/2011, at 3:46 AM, R. Verlangen wrote: 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 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
Re: Counters and Top 10
Counters only update the value of the column, they cannot be used as column names. So you cannot have a dynamically updating top ten list using counters. You have a couple of options. First use something like redis if that fits your use case. Redis could either be the database of record for the counts. Or just an aggregation layer, write the data to cassandra and sorted sets in redis then read the top ten from redis and use cassandra to rebuild redis if needed. The other is to periodically pivot the counts into a top ten row where you use regular integers for the column name. With only 10K users you could do this with an process that periodically reads all the users rows or where ever the counters are and updates the aggregate row. Depending on data size you cold use hive/pig or whatever regular programming language your are happy with. I guess you could also use redis to keep the top ten sorted and then periodically dump that back to cassandra and serve the read traffic from there. Hope that helps - Aaron Morton Freelance Developer @aaronmorton http://www.thelastpickle.com On 23/12/2011, at 3:46 AM, R. Verlangen wrote: 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 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
Re: Counters and Top 10
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 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
Counters and Top 10
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
