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From Alain RODRIGUEZ <arodr...@gmail.com>
Subject Re: Deleting old items
Date Sat, 16 Feb 2013 18:05:52 GMT
"Can you point to the docs."

http://www.datastax.com/docs/1.1/configuration/storage_configuration#max-compaction-threshold

And thanks about the rest of your answers, once again ;-).

Alain


2013/2/16 aaron morton <aaron@thelastpickle.com>

>  Is that a feature that could possibly be developed one day ?
>
> No.
> Timestamps are essentially internal implementation used to resolve
> different values for the same column.
>
> With "min_compaction_level_threshold" did you mean "
> min_compaction_threshold"  ? If so, why should I do that, what are the
> advantage/inconvenient of reducing this value ?
>
> Yes, min_compaction_threshold, my bad.
> If you have a wide row and delete a lot of values you will end up with a
> lot of tombstones. These may dramatically reduce the read performance until
> they are purged. Reducing the compaction threshold makes compaction happen
> more frequently.
>
> Looking at the doc I saw that: "max_compaction_threshold: Ignored in
> Cassandra 1.1 and later.". How to ensure that I'll always keep a small
> amount of SSTables then ?
>
> AFAIK it's not.
> There may be some confusion about the location of the settings in CLI vs
> CQL.
> Can you point to the docs.
>
> Cheers
>
>    -----------------
> Aaron Morton
> Freelance Cassandra Developer
> New Zealand
>
> @aaronmorton
> http://www.thelastpickle.com
>
> On 13/02/2013, at 10:14 PM, Alain RODRIGUEZ <arodrime@gmail.com> wrote:
>
> Hi Aaron, once again thanks for this answer.
>
> "So is it possible to delete all the data inserted in some CF between 2
> dates or data older than 1 month ?"
>
> "No. "
>
> Why is there no way of deleting or getting data using the internal
> timestamp stored alongside of any inserted column (as described here:
> http://www.datastax.com/docs/1.1/ddl/column_family#standard-columns) ? Is
> that a feature that could possibly be developed one day ? It could
> be useful to perform delete of old data or to bring to a dev cluster just
> the last week of data for example.
>
> With "min_compaction_level_threshold" did you mean "
> min_compaction_threshold"  ? If so, why should I do that, what are the
> advantage/inconvenient of reducing this value ?
>
> Looking at the doc I saw that: "max_compaction_threshold: Ignored in
> Cassandra 1.1 and later.". How to ensure that I'll always keep a small
> amount of SSTables then ? Why is this deprecated ?
>
> Alain
>
>
> 2013/2/12 aaron morton <aaron@thelastpickle.com>
>
>> So is it possible to delete all the data inserted in some CF between 2
>> dates or data older than 1 month ?
>>
>> No.
>>
>> You need to issue row level deletes. If you don't know the row key you'll
>> need to do range scans to locate them.
>>
>> If you are deleting parts of wide rows consider reducing the
>> min_compaction_level_threshold on the CF to 2
>>
>> Cheers
>>
>>
>>    -----------------
>> Aaron Morton
>> Freelance Cassandra Developer
>> New Zealand
>>
>> @aaronmorton
>> http://www.thelastpickle.com
>>
>> On 12/02/2013, at 4:21 AM, Alain RODRIGUEZ <arodrime@gmail.com> wrote:
>>
>> Hi,
>>
>> I would like to know if there is a way to delete old/unused data easily ?
>>
>> I know about TTL but there are 2 limitations of TTL:
>>
>> - AFAIK, there is no TTL on counter columns
>> - TTL need to be defined at write time, so it's too late for data already
>> inserted.
>>
>> I also could use a standard "delete" but it seems inappropriate for such
>> a massive.
>>
>> In some cases, I don't know the row key and would like to delete all the
>> rows starting by, let's say, "1050#..."
>>
>> Even better, I understood that columns are always inserted in C* with
>> (name, value, timestamp). So is it possible to delete all the data inserted
>> in some CF between 2 dates or data older than 1 month ?
>>
>> Alain
>>
>>
>>
>
>

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