Hi Aaron, I did mean 1000 columns. But I see your point. The current CF schema has user_id as the row key and unnamed column order_num = order info as the col-val pair. The plan is to add named columns order_attr1, order_attr2... order_attr18. When I query for user_id = "user1" and order_attr1 = 1991 I want to get the order_num. Is this possible without super columns? Can I make Cassandra link the order_num to order_attr1 in any way?
An Example: RowKey: user1 => (column=Order100, value=Order100Info, timestamp=1363789981864000) => (column=Order101, value=Order101Info, timestamp=1363789985382000) => (column=Order102, value=Order102Info, timestamp=1363789990118000) => (column=OrderAttr1, value=1991, timestamp=1363790016318000) => (column=OrderAttr2, value=2015, timestamp=1363789936073000) => (column=OrderAttr3, value=4090, timestamp=1363789946805000) Thanks. On Tue, Mar 19, 2013 at 11:34 PM, aaron morton <aa...@thelastpickle.com>wrote: > > Assuming we have 1000 columns in 1 row of the column family and about > 900 of them have > > > > NamedColumn1=1 and of those 900 only 10 of them also have NamedColumn2=1. > Am assuming you mean 1,000 rows not columns. > > > does Cassandra > > optimized this in any way by fetching only the 10 versus the 900 and then > > > > filtering out the 10 I really need? > The most selective term is used first. All the rows that match that term > are read (in batches) and then filtered. > > > How does this affect the internal index column > > family and how often will it get compacted? > It is compacted when it needs it, not when the parent CF is compacted. > > > About expirations: if the column in the user defined column family > expires can I > > safely assume that its related indexes will also expire? > Yes > > > > > http://www.datastax.com/docs/1.1/ddl/indexes > > Maintaining Secondary Indexes > Emailed to ask for clarification. > > Cheers > > > ----------------- > Aaron Morton > Freelance Cassandra Consultant > New Zealand > > @aaronmorton > http://www.thelastpickle.com > > On 20/03/2013, at 5:08 AM, Mayank <4may...@gmail.com> wrote: > > > Thanks guys. I am working with Andy on this project. > > > > Further questions on the secondary indexes: > > Assuming we have 1000 columns in 1 row of the column family and about > 900 of them have > > > > NamedColumn1=1 and of those 900 only 10 of them also have > NamedColumn2=1. If I > > > > query for columns which have NamedColumn1=1 && NamedColumn2=1 does > Cassandra > > optimized this in any way by fetching only the 10 versus the 900 and then > > > > filtering out the 10 I really need? > > > > > > We ran some tests that show if only 10 of the 18 NamedColumns were > inserted only > > those 10 internal index column families are updated. In this case the > size of the > > > > user defined column families and the internal index column families will > differ. It > > > > is then expected that the user defined column family will get compacted > more often > > and tombstones removed more often. How does this affect the internal > index column > > > > family and how often will it get compacted? > > > > > > About expirations: if the column in the user defined column family > expires can I > > safely assume that its related indexes will also expire? > > > > > > Here is the link that talks about the rebuild: > > > > http://www.datastax.com/docs/1.1/ddl/indexes > > Maintaining Secondary Indexes > > > > When a node starts up, Cassandra rebuilds the secondary index of the > stored rows. To perform a hot rebuild of a secondary index, use the > nodetool utility rebuild_index command. > > > > > > We'll look further into Solr but at the moment it may not fit our > need/schedule. > > > > > - Will that result in Cassandra creating 18 new column families, > > > one for each index? > > Inserts will be slower, as each insert will potentially result in 18 > additional > > inserts. This is just the same as a RDBMS, more indexes == more insert > work. > > > > > - If a given column is not specified in any rows, will Cassandra > > > still create an index column family? > > Yes > > > > > - The documentation says that indexes are rebuilt with every > > > Cassandra restart. Why is that needed? What does the rebuild do? Does > it > > > read the whole column family into memory at once? > > That is not correct, do you have a link for the docs ? > > > > As Moshe said, standard cassandra i not a great fit for faceting. > Consider Solr > > or Data Stax > > http://3.datastax.com/datastax-enterprise.php > > > > > > Cheers > > > > ----------------- > > Aaron Morton > > Freelance Cassandra Consultant > > New Zealand > > > > @aaronmorton > > > > http://www.thelastpickle.com > > > > > > On 17/03/2013, at 10:17 PM, > > moshe.kr...@barclays.com > > wrote: > > > > > I do not think this is a good use case for Cassandra alone, assuming > the > > > queries can be any combination of the 18 columns. > > > I would consider using some combination of Cassandra and Solr, where > Solr > > > provides the indexing/search, and Cassandra provides the bulk store. > > > > > > From: Andy Stec [ > > mailto:andys...@gmail.com > > ] > > > Sent: Saturday, March 16, 2013 12:10 AM > > > To: > > user@cassandra.apache.org > > > > > Subject: Secondary Indexes > > > > > > We need to provide search capability based on a field that is a bitmap > > > combination of 18 possible values. We want to use secondary indexes to > > > improve performance. One possible solution is to create a named column > for > > > each value and have a secondary index for each of the 18 columns. > > > Questions we have are: > > > > > > > > > - Will that result in Cassandra creating 18 new column families, > > > one for each index? > > > > > > - If a given column is not specified in any rows, will Cassandra > > > still create an index column family? > > > > > > - The documentation says that indexes are rebuilt with every > > > Cassandra restart. Why is that needed? What does the rebuild do? Does > it > > > read the whole column family into memory at once? > > > > > > > > > > > > _______________________________________________ > > > > > > This message may contain information that is confidential or > privileged. 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