What happens if you use "update where....." rather than insert?
On Wed, Mar 11, 2015 at 7:58 PM, Guðmundur Örn Jóhannsson <
gudmundur....@gmail.com> wrote:
> I have a 3 node cluster of Cassandra version 2.0.9. My keyspace
> replication factor is 3 and I'm querying with consistency level ALL.
>
> Problem: When I do an insert to overwrite an old row, the old data still
> appears in all select queries! This does not apply to all cases, just a
> subset of the rows in this table. Some are a day old, some are 3 hours old.
> It happens both using commandline cqlsh and via the datastax java cql
> driver (in that case with CL=2)
>
> Of course this is a huge concern since the insert is accepted but has no
> effect, meaning that the write is effectively lost!
>
> Here is how it happens:
>
> First I do a select to see the original data:
>
> cqlsh> use mykeyspace
> cqlsh:mykeyspace> consistency all;
> Consistency level set to ALL.
> cqlsh:mykeyspace> select created_timestamp, stored_value from mytable
> where key_a = 'the_value' and key_b = '43052960';
>
> It returns the original row, as expected.
>
>
> Then I do the insert to overwrite it:
>
> cqlsh:mykeyspace> insert into mytable (key_a, key_b, created_timestamp,
> created_yyyymmdd, stored_value)
> values('the_value','43052960',dateof(now()),'20150312','test6');
>
> And re-run the previous select query, expecting to see the overwritten
> values, but it returns the old values for all columns.
>
>
> If I use a totally different value for the value of key_b, then the
> problem does not appear instantly, but it seems that in at least some
> cases, the issue appears over time. Not sure.
>
>
>
> My table looks like this:
>
> CREATE TABLE mytable (
> key_a text,
> key_b text,
> value_a text,
> created_timestamp timestamp,
> created_yyyymmdd text,
> stored_value text,
> PRIMARY KEY ((key_a), key_b)
> ) WITH
> bloom_filter_fp_chance=0.010000 AND
> caching='KEYS_ONLY' AND
> comment='' AND
> dclocal_read_repair_chance=0.000000 AND
> gc_grace_seconds=864000 AND
> index_interval=128 AND
> read_repair_chance=0.100000 AND
> replicate_on_write='true' AND
> populate_io_cache_on_flush='false' AND
> default_time_to_live=0 AND
> speculative_retry='99.0PERCENTILE' AND
> memtable_flush_period_in_ms=0 AND
> compaction={'class': 'SizeTieredCompactionStrategy'} AND
> compression={'sstable_compression': 'LZ4Compressor'};
> CREATE INDEX mytable_idx_yyyymmdd ON mytable (created_yyyymmdd);
>
> --
> regards,
> Gudmundur Johannsson
>
