Transaction Timeout on get_count

[Yulian Oifa <oi...@gmail.com>]

Hello
I am having raw in which approximately 100 values is written per minute.
Those columns are then deleted ( it contains active records list ).
When i am trying to execute get_count on that raw i get transaction timeout
, even while the raw is empty.
I dont see anything in cassandra log on neither node , pending tasks are
zero.
What could be a reason for that , and how can it be resolved?
Best regards
Yulian Oifa

Re: Transaction Timeout on get_count

[Tupshin Harper <tu...@tupshin.com>]

Constant deletes and rewrites are a very poor pattern to use with
Cassandra. It would be better to write to a new row and partition every
minute and use a TTL to auto expire the old data.

-Tupshin
On Apr 6, 2014 2:55 PM, "Yulian Oifa" <oi...@gmail.com> wrote:

> Hello
> I am having raw in which approximately 100 values is written per minute.
> Those columns are then deleted ( it contains active records list ).
> When i am trying to execute get_count on that raw i get transaction
> timeout , even while the raw is empty.
> I dont see anything in cassandra log on neither node , pending tasks are
> zero.
> What could be a reason for that , and how can it be resolved?
> Best regards
> Yulian Oifa
>

Re: Transaction Timeout on get_count

[Yulian Oifa <oi...@gmail.com>]

Thank for you replies.
1) I can not create raw each X time , since it will not allow me to get a
complete list of currently active records ( this is the only reason i keep
this raw initially ).
2) As for compaction i thought that only raw ids are cached and not columns
itself. I have completed compaction and it indeed cleared most of data (
75% of complete table ,and there are some other raws ).
It looks like it did not cleared all the data from disk ( compaction should
set table into single file , while other files still left ) , but showed in
log that data cleared , also after compaction this raw became responsive.

Most of our data is wrotten once and kept in history , however we have also
counter columns which are not working good ( had troubles with that ) and
several places where we use create / delete approach.Now i understand why
our data grows so much , it just does not clears old data at all , but
marks it as tombstone...
What NOSQL database would you recommend for such usages ( write onces read
many mixed with counter columns mixed with read/write oftenly data)?

Thanks and best regards
Yulian Oifa




On Mon, Apr 7, 2014 at 5:57 PM, Lukas Steiblys <lu...@doubledutch.me> wrote:

>   Deleting a column simply produces a tombstone for that column, as far
> as I know. It's probably going through all the columns with tombstones and
> timing out. Compacting more often should help, but maybe Cassandra isn't
> the best choice overall for what you're trying to do.
>
> Lukas
>
>  *From:* Yulian Oifa <oi...@gmail.com>
> *Sent:* Sunday, April 6, 2014 11:54 AM
> *To:* user@cassandra.apache.org
> *Subject:* Transaction Timeout on get_count
>
>    Hello
> I am having raw in which approximately 100 values is written per minute.
> Those columns are then deleted ( it contains active records list ).
> When i am trying to execute get_count on that raw i get transaction
> timeout , even while the raw is empty.
> I dont see anything in cassandra log on neither node , pending tasks are
> zero.
> What could be a reason for that , and how can it be resolved?
> Best regards
> Yulian Oifa
>

Re: Transaction Timeout on get_count

[Lukas Steiblys <lu...@doubledutch.me>]

Deleting a column simply produces a tombstone for that column, as far as I know. It’s probably going through all the columns with tombstones and timing out. Compacting more often should help, but maybe Cassandra isn’t the best choice overall for what you’re trying to do.

Lukas

From: Yulian Oifa 
Sent: Sunday, April 6, 2014 11:54 AM
To: user@cassandra.apache.org 
Subject: Transaction Timeout on get_count

Hello

I am having raw in which approximately 100 values is written per minute.

Those columns are then deleted ( it contains active records list ).
When i am trying to execute get_count on that raw i get transaction timeout , even while the raw is empty.

I dont see anything in cassandra log on neither node , pending tasks are zero.

What could be a reason for that , and how can it be resolved?

Best regards
Yulian Oifa