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From "techpyaasa ." <techpya...@gmail.com>
Subject Re: Secondary Index
Date Sun, 25 Jun 2017 15:18:22 GMT
Thanks for the reply.

I just have one more doubt, please do clarify this.

Will be there any performance difference between these 2 queries for the
above table.

1. select * from ks1.cf1 where status=1;
2. select * from ks1.cf1 where id1=123456 and status=1;

where id1 is partition key and status is indexed column as I said above.

Could you please tell me the performance difference btwn above 2 queries.

Thanks in advance,

Techpyaasaa

On Tue, Jun 20, 2017 at 9:03 PM, ZAIDI, ASAD A <az192g@att.com> wrote:

> Hey there –
>
>
>
> Like other suggested before adding more index , look for opportunity to
> de-normalize your data model OR create composite keys for your primary
> index – if that works for you.
>
> Secondary index are there so you can leverage them they come with cost.
> They’re difficult to manage , as you repair data  your secondary index will
> NOT be automatically repaired so you’ll need to maintain them
>
> On each cluster node. Depending on size of your cluster that could be a
> significant effort. Be prepared to rebuild your new index (nodetool
> rebuild_index) as often as you change the data . performance will
> eventually get a hit cause index rebuilding is expensive operation on CPU
> ..
>
>
>
> See please http://docs.datastax.com/en/cql/3.1/cql/ddl/ddl_when_use_
> index_c.html
>
>
>
>
>
>
>
> *From:* techpyaasa . [mailto:techpyaasa@gmail.com]
> *Sent:* Tuesday, June 20, 2017 2:30 AM
> *To:* ZAIDI, ASAD A <az192g@att.com>
> *Cc:* user@cassandra.apache.org
> *Subject:* Re: Secondary Index
>
>
>
> Hi ZAIDI,
>
> Thanks for reply.
> Sorry I didn't get your line
> "You can get away the potential situation by leveraging composite key, if
> that is possible for you?"
>
> How can I get through it??
>
> Like I have a table as below
>
> CREATE TABLE ks1.cf1 (id1 bigint, id2 bigint, resp text, status int,
> PRIMARY KEY (id1, id2)
>
> ) WITH CLUSTERING ORDER BY (id2 ASC)
>
>
> 'status' will have values of 0/1/2/3/4 (4 possible values) , insertions to
> table(partition) will happen based on id2 i.e values(id1,id2,resp,status)
>
> I want to have a filtering/criteria applied on 'status' column too like
> select * from ks1.cf1 where id1=123 and status=0;
>
> How can I achieve this w/o secondary index (on 'status' column )??
>
>
>
> On Tue, Jun 20, 2017 at 12:09 AM, ZAIDI, ASAD A <az192g@att.com> wrote:
>
> If you’re only creating index so that your query work, think again!
> You’ll be storing secondary index on each node , queries involving index
> could create issues (slowness!!) down the road the when index on multiple
> node Is involved and  not maintained!  Tables involving a lot of
> inserts/delete could easily ruin index performance.
>
>
>
> You can get away the potential situation by leveraging composite key, if
> that is possible for you?
>
>
>
>
>
> *From:* techpyaasa . [mailto:techpyaasa@gmail.com]
> *Sent:* Monday, June 19, 2017 1:01 PM
> *To:* user@cassandra.apache.org
> *Subject:* Secondary Index
>
>
>
> Hi,
>
> I want to create Index on already existing table which has more than 3
> GB/node.
> We are using c*-2.1.17 with 2 DCs , each DC with 3 groups and each group
> has 7 nodes.(Total 42 nodes in cluster)
>
> So is it ok to create Index on this table now or will it have any problem?
> If its ok , how much time it would take for this process?
>
>
> Thanks in advance,
> TechPyaasa
>
>
>

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