cassandra-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Jon Haddad <jonathan.had...@gmail.com>
Subject Re: Cassandra 3.10 has partial partition key search but does it result in a table scan?
Date Tue, 09 May 2017 14:28:55 GMT
Output from both queries, demonstrating full cluster scans:

https://gist.github.com/rustyrazorblade/c4947fc37da85bca50e08aa1ef3c7a06 <https://gist.github.com/rustyrazorblade/c4947fc37da85bca50e08aa1ef3c7a06>

Jon

> On May 9, 2017, at 9:24 AM, Jon Haddad <jonathan.haddad@gmail.com> wrote:
> 
> Nope, I didn’t comment on that query.   I specifically answered your question about
"select * from hello where a='foo' allow filtering;”
> 
> The query you’ve listed here looks like it would also do a full table scan (again,
I don’t see how it would be avoided).
> 
> I recommend firing up a 3 node cluster using CCM, creating a key space with RF=1, and
seeing what it does.  
> 
>> On May 9, 2017, at 9:12 AM, Kant Kodali <kant@peernova.com <mailto:kant@peernova.com>>
wrote:
>> 
>> Hi,
>> 
>> Are you saying The following query select max(b) from hello where a='a1' allow filtering;
doesn't result in a table scan? I got the result for this query and yes I just tried tracing
it and looks like it is indeed doing a table scan on ReadStage-2 although I am not sure if
I am interpreting it right? Finally is there anyway to prevent table scan while providing
the partial partition key and get the max b ?
>> 
>> <Screen Shot 2017-05-09 at 7.07.46 AM.png>
>> ​
>> 
>> 
>> On Tue, May 9, 2017 at 6:33 AM, Jon Haddad <jonathan.haddad@gmail.com <mailto:jonathan.haddad@gmail.com>>
wrote:
>> I don’t see any way it wouldn’t.  Have you tried tracing it?
>> 
>> > On May 9, 2017, at 8:32 AM, Kant Kodali <kant@peernova.com <mailto:kant@peernova.com>>
wrote:
>> >
>> > Hi All,
>> >
>> > It looks like Cassandra 3.10 has partial partition key search but does it result
in a table scan? for example I can have the following
>> >
>> > create table hello(
>> > a text,
>> > b int,
>> > c text,
>> > d text,
>> > primary key((a,b), c)
>> > );
>> >
>> > Now I can do select * from hello where a='foo' allow filtering;// This works
in 3.10 but I wonder if this query results in table scan and if so is there any way to limit
such that I get max b?
>> >
>> > Thanks!
>> 
>> 
> 


Mime
View raw message