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From daemeon reiydelle <daeme...@gmail.com>
Subject Re: Is Table created in all the nodes if the default consistency level used
Date Tue, 17 Mar 2015 05:37:40 GMT
If I am following your thread correctly, I think you might be confusing the
"creeation" of a table with the "recording of the definition" + "storage
for the table allocated".

When you define the table, based on your config, the existence of the table
is recorded in the master node(s). But tables are not "created" on data
nodes. Data nodes store the data (or their pieces of it) when actual data
is written to the table ... so creating a table does not cause memtables
(or empty sst's) to be created. When you insert into the table, and data
has to go "someplace", the memtables and sst's start tracking that data.
Does this clarify?

As an aside, you will only get stale data if the read consistency level
together with the number of nodes that went offline (which hold copies of
the table), allow it: e.g. imagine read consistency 1 and one node with
stale data, etc.



*.......*






*“Life should not be a journey to the grave with the intention of arriving
safely in apretty and well preserved body, but rather to skid in broadside
in a cloud of smoke,thoroughly used up, totally worn out, and loudly
proclaiming “Wow! What a Ride!” - Hunter ThompsonDaemeon C.M. ReiydelleUSA
(+1) 415.501.0198London (+44) (0) 20 8144 9872*

On Mon, Mar 16, 2015 at 8:41 PM, Saladi Naidu <naidusp2002@yahoo.com> wrote:

> There are 3 different things we are talking here
>
> 1. SimpleStrategy vs. NetworkTopology matter when you have single DC vs.
> Multiple DC's
> 2. In both cases you can specific replication factor, obviously in
> SimpleStratgey case you dont mention DC whereas in NetworkTopology, you can
> mentione mutiple options by each DC's replication requirements.
> 3. Now if your question is referred to single DC then even if your System
> keyspace is SimpleStartegy and your user table is NetworkToplogy, it should
> not matter and Table_Test will be created in all nodes
> 4. If your System_auth KS is set less than number of nodes, you will face
> AUTH issues.
>
> Naidu Saladi
>
>   ------------------------------
>  *From:* 鄢来琼 <laiqiong.yan@gtafe.com>
> *To:* "user@cassandra.apache.org" <user@cassandra.apache.org>
> *Sent:* Monday, March 16, 2015 2:13 AM
> *Subject:* Re: Is Table created in all the nodes if the default
> consistency level used
>
>  Hi Daemeon,
>
> Yes, I use “NetworkTopologyStrategy” strategy for “Table_test”,
> but “System keyspace” is Cassandra internal keyspace, its strategy is
> localStrategy.
> So my question is how to guarantee “Table_test” is created in all the
> nodes before any R/W opertions?
>
> Thanks.
>
> Peter
>
>
>
>
> *发件人:* daemeon reiydelle [mailto:daemeonr@gmail.com]
> *发送时间:* 2015年3月16日 14:35
> *收件人:* user@cassandra.apache.org
> *主题:* Re: Is Table created in all the nodes if the default consistency
> level used
>
>  If you want to guarantee that the data is written to all nodes before
> the code returns, then yes you have to use "consistency all". Otherwise
> there is a small risk of outdated data being served if a node goes offline
> longer than hints timeouts.
>  Somewhat looser options that can assure multiple copies are written, as
> you probably know, are quorum or a hard coded value. This applies to a
> typical installation with a substantial number of nodes of course, not a
> small 2-3 node cluster.
>  I am curious why localStrategy when you have such concerns about data
> consistency that you want to assure all nodes get data written. Can you
> elaborate on your use case?
>
>
>
>
>
>
>
>
>
>
> * ....... “Life should not be a journey to the grave with the intention of
> arriving safely in a pretty and well preserved body, but rather to skid in
> broadside in a cloud of smoke, thoroughly used up, totally worn out, and
> loudly proclaiming “Wow! What a Ride!” - Hunter Thompson Daemeon C.M.
> Reiydelle USA (+1) 415.501.0198 <%28%2B1%29%20415.501.0198> London (+44)
> (0) 20 8144 9872 <%28%2B44%29%20%280%29%2020%208144%209872>*
>
>  On Sun, Mar 15, 2015 at 8:11 PM, 鄢来琼 <laiqiong.yan@gtafe.com> wrote:
>  Could you tell me whether the meta data of the new table are build in
> all the nodes after execute the following statement.
>
> *cassandra_session.execute_async(*
>
> *“““**CREATE TABLE Table_test(*
>
> *      ID uuid,*
>
> *      Time timestamp,*
>
> *      Value double,*
>
> *      Date timestamp,*
>
> *      PRIMARY KEY ((ID,Date), Time)*
>
> *) WITH COMPACT STORAGE;*
>
> *”””*
> *)*
>
> As I know, the system keyspace is used to store the meta data, but the
> strategy is localStrategy, which only store meta data of local node.
> So I want to know whether table is created in all the nodes, should I add
> consistency_level setting to the above statement to make sure
> “create table” will be executed in all the nodes?
> Thanks.
>
>  Peter
>
>
>
>
>

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