I'll email the docs people. I believe they are saying "use compaction throttling rather than this" not "this does nothing"
Although I used this in the last month on a machine with very little ram to limit compaction memory use. Cheers ----------------- Aaron Morton Freelance Cassandra Developer New Zealand @aaronmorton http://www.thelastpickle.com On 17/02/2013, at 7:05 AM, Alain RODRIGUEZ <arodr...@gmail.com> wrote: > "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 <aa...@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 <arodr...@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 <aa...@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 <arodr...@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 >> >> > >
