Multi DC setup question

Hi All, We are setting up another Data Center and have the following question: 6 nodes in each DC Cassandra cluster. All key spaces have an RF of 3 Our scenario is Apps node connect to Cassandra cluster using LOCAL_QUORUM consistency. We want to ensure that If 5 nodes out of the 6 are

Cassandra Data Audit

To all Cassandra experts out there, Can you please let me know if there is any inbuilt Cassandra feature that allows audits on Column family data ? When I change any data in a CF, I want to record that change. Probably store the old value as well as the changed one. One way of

RE: Cassandra Data Audit

rance The Last Pickle http://www.thelastpickle.com 2016-02-24 6:36 GMT+01:00 Charulata Sharma (charshar) <chars...@cisco.com<mailto:chars...@cisco.com>>: To all Cassandra experts out there, Can you please let me know if there is any inbuilt Cassandra feature that allows

Read after Write inconsistent at times

Hi All, In my application sometimes I cannot read data that just got inserted. This happens very intermittently. Both write and read use LOCAL QUOROM. We have a cluster of 12 nodes which spans across 2 Data Centers and a RF of 3. Has anyone encountered this problem and if yes what steps have

Re: Read after Write inconsistent at times

lead to minimal dirfts in time across your cluster. Another thing that could help you out is using client side timestamps: https://docs.datastax.com/en/developer/java-driver/3.1/manual/query_timestamps/ (of course only when you are using a single client or all clients are in sync via ntp).

Re: Cannot achieve consistency level LOCAL_ONE

Hi, I am facing similar issues with SYSTEM_AUTH keyspace and wanted to know the implication of disabling the "cassandra" superuser. Thanks, Charu From: "wxn...@zjqunshuo.com" > Date: Wednesday, June 14, 2017 at

Simulating Read and WriteTimeouts programatically

Hi All, Recently I learnt that in C* driver versions 3.1.x and up, there is a change in retry. If the query statement is not idempotent, there won't be any retry and by default the queries are considered to be non idempotent. Hence, even though Retry policy is mentioned while setting up the C*

Commit Log question

Hi , Can anyone please tell me the implication of increasing the commitlog_segment_size_in_mb from the default value of 32 MB to a higher value? Some of our mutations are > 16MB, so the writes are failing. This is because of the way we store data in our Column families. 95% of the data is <

Async queries

Hi , We are observing some performance issues when executing a large number of read/write queries. We use executeAsync query for most of our read and write requests and then future.getUninterruptibly() methods before returning to the client application. Code snippet is: (In the bind portion

Re: Async queries

and releases a permit. The upcoming version (4.0) of the java driver uses CompletionStage/CompletableFuture (java 8 futures), although we'll probably provide a guava extension as well for those who still want to use ListenableFuture. Thanks, Andy On Mon, Oct 2, 2017 at 6:44 PM Charulata S

Lightweight transaction in Multi DC

Hi, We are facing a serious issue with CAS in a multi DC setup and I wanted to get some input on it from the forum. We have a Column family which stores counts for the number of events our application receives. When the counts reach a certain threshold, there is another process which

Re: Lightweight transaction in Multi DC

r@cassandra.apache.org> Subject: Re: Lightweight transaction in Multi DC Are you using CAS with SERIAL consistency level for your multi-DC setup ? On Fri, Sep 8, 2017 at 9:27 PM, Charulata Sharma (charshar) <chars...@cisco.com<mailto:chars...@cisco.com>> wrote: Hi, We are f

Re: Lightweight transaction in Multi DC

in Multi DC LOCAL_SERIAL is dc level, SERIAL checks for complete cluster level. On Fri, Sep 8, 2017 at 2:33 PM, Charulata Sharma (charshar) <chars...@cisco.com<mailto:chars...@cisco.com>> wrote: Yes …it is with LOCAL_SERIAL. Should I be using SERIAL ? Thanks, Charu From: DuyHai Doan

Strange metadata being appended in some rows

Hi, I am observing a very strange behavior in our cluster. Metadata is being prefixed in some rows. This metadata cannot be sent by application primarily because application writing to C* will not have this data, and also applications use custom Java objects and this metadata doesn’t fall

Right sizing Cassandra data nodes

Hi All, Looking for some insight into how application data archive and purge is carried out for C* database. Are there standard guidelines on calculating the amount of space that can be used for storing data in a specific node. Some pointers that I got while researching are; -

Re: Right sizing Cassandra data nodes

hysical machine / disks on a live node. -- Rahul Singh rahul.si...@anant.us Anant Corporation On Feb 19, 2018, 3:08 PM -0500, Charulata Sharma (charshar) <chars...@cisco.com>, wrote: Hi All, Looking for some insight into how application data archive and purge is carried out for C* database.

Tombstone experience

Hi All, I have shared my experience of tombstone clearing in this blog post. Sharing it in this forum for wider distribution. https://medium.com/cassandra-tombstones-clearing-use-case/the-curios-case-of-tombstones-d897f681a378 Thanks, Charu

Re: Too many tombstones using TTL

Hi, I have struggled a lot with tombstones and finally learnt the following: - Deletes are not the only operation that cause tombstones. Check if you are inserting any nulls in any of the table columns. If yes then if you use Prepared statements, then you can unset the null value.

Re: Drop TTLd rows: upgradesstables -a or scrub?

Scrub takes a very long time and does not remove the tombstones. You should do garbage cleaning. It immediately removes the tombstones. Thaks, Charu From: Oleksandr Shulgin Reply-To: "user@cassandra.apache.org" Date: Monday, September 10, 2018 at 6:53 AM To: "user@cassandra.apache.org"

Re: One time major deletion/purge vs periodic deletion

be to rely on TTL for removal of data and use the TWCS compaction strategy to handle removal and you just focus on insertion. On Tue, Mar 6, 2018, 07:39 Charulata Sharma (charshar) <chars...@cisco.com<mailto:chars...@cisco.com>> wrote: Hi, Wanted the community’s feedback

Using Spark to delete from Transactional Cluster

Hi, Wanted to know the community’s experiences and feedback on using Apache Spark to delete data from C* transactional cluster. We have spark installed in our analytical C* cluster and so far we have been using Spark only for analytics purposes. However, now with advanced features of Spark

Re: Using Spark to delete from Transactional Cluster

.us Anant Corporation On Mar 22, 2018, 2:19 PM -0500, Charulata Sharma (charshar) <chars...@cisco.com>, wrote: Hi, Wanted to know the community’s experiences and feedback on using Apache Spark to delete data from C* transactional cluster. We have spark installed in our analytical C* clu

Re: Using Spark to delete from Transactional Cluster

statements and deleting through spark is? To the best of my knowledge either way it's the same thing - normal deletion with tombstones replicated. Is it that you're doing deletes in the analytics DC instead of your real time one? On Fri, Mar 23, 2018 at 11:38 AM Charulata Sharma (charshar) <cha

Re: Using Spark to delete from Transactional Cluster

instead of deleting setting a TTL which will eventually get cleansed. -- Rahul Singh rahul.si...@anant.us Anant Corporation On Mar 22, 2018, 2:19 PM -0500, Charulata Sharma (charshar) <chars...@cisco.com>, wrote: Hi, Wanted to know the community’s experiences and feedback on using Apache

One time major deletion/purge vs periodic deletion

Hi, Wanted the community’s feedback on deciding the schedule of Archive and Purge job. Is it better to Purge a large volume of data at regular intervals (like run A jobs once in 3 months ) or purge smaller amounts more frequently (run the job weekly??) Some estimates on the number of