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From Alain RODRIGUEZ <arodr...@gmail.com>
Subject Re: Deletes, null values
Date Mon, 29 Apr 2013 15:52:25 GMT
I created it almost a year ago with cassandra-cli. Now show_schema returns:

create column family myCF
  with column_type = 'Standard'
  and comparator = 'UTF8Type'
  and default_validation_class = 'UTF8Type'
  and key_validation_class = 'UTF8Type'
  and read_repair_chance = 0.1
  and dclocal_read_repair_chance = 0.0
  and populate_io_cache_on_flush = false
  and gc_grace = 864000
  and min_compaction_threshold = 4
  and max_compaction_threshold = 12
  and replicate_on_write = true
  and compaction_strategy =
'org.apache.cassandra.db.compaction.SizeTieredCompactionStrategy'
  and caching = 'KEYS_ONLY'
  and bloom_filter_fp_chance = 0.01
  and compression_options = {'sstable_compression' :
'org.apache.cassandra.io.compress.SnappyCompressor'};

"The output looks correct to me. CQL table return values, including null,
for all of the selected columns."

I thought that C* had no null values... I use a lot of CF in which only the
columns name are filled up and I request a range of column to see which
references (like 1228#**16866) exists. So I would like those column to
simply disappear from the table.

Alain



2013/4/28 aaron morton <aaron@thelastpickle.com>

> What's your table definition ?
>
> select '1228#16857','1228#16866','1228#16875','1237#16544','1237#16553'
> from myCF where key = 'all';
>
>
> The output looks correct to me. CQL table return values, including null,
> for all of the selected columns.
>
> Cheers
>
>    -----------------
> Aaron Morton
> Freelance Cassandra Consultant
> New Zealand
>
> @aaronmorton
> http://www.thelastpickle.com
>
> On 27/04/2013, at 12:48 AM, Sorin Manolache <sorinm@gmail.com> wrote:
>
> On 2013-04-26 11:55, Alain RODRIGUEZ wrote:
>
> Of course:
>
> From CQL 2 (cqlsh -2):
>
> delete '183#16684','183#16714','183#16717' from myCF where key = 'all';
>
> And selecting this data as follow gives me the result above:
>
> select '1228#16857','1228#16866','1228#16875','1237#16544','1237#16553'
> from myCF where key = 'all';
>
> From thrift (phpCassa client):
>
> $pool = new
> ConnectionPool('myKeyspace',array('192.168.100.201'),6,0,30000,30000);
> $my_cf= new ColumnFamily($pool, 'myCF', true, true,
> ConsistencyLevel::QUORUM, ConsistencyLevel::QUORUM);
> $my_cf->remove('all', array('1228#16857','1228#16866','1228#16875'));
>
>
> I see. I'm sorry, I know nothing about phpCassa. I use batch_mutation with
> deletions and it works. But I guess phpCassa must use the same thrift
> primitives.
>
> Sorin
>
>
>
>
> 2013/4/25 Sorin Manolache <sorinm@gmail.com <mailto:sorinm@gmail.com<sorinm@gmail.com>
> >>
>
>    On 2013-04-25 11:48, Alain RODRIGUEZ wrote:
>
>        Hi, I tried to delete some columns using cql2 as well as thrift on
>        C*1.2.2 and instead of being unreachable, deleted columns have a
>        null value.
>
>        I am using no value in this CF, the only information I use is the
>        existence of the column. So when I select all the column for a
>        given key
>        I have the following returned:
>
>           1228#16857 | 1228#16866 | 1228#16875 | 1237#16544 | 1237#16553
>
>        -------------------+----------__--------+------------------+--__-----------------+------------__------
>                       null |              null |             null |
>                  |
>
>
>        This is quite annoying since my app thinks that I have 5 columns
>        there
>        when I should have 2 only.
>
>        I first thought that this was a visible marker of tombstones but
>        they
>        didn't vanish after a major compaction.
>
>        How can I get rid of these null/ghost columns and why does it
>        happen ?
>
>
>    I do something similar but I don't see null values. Could you please
>    post the code where you delete the columns?
>
>    Sorin
>
>
>
>
>

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