Hi Guys, I have two cassandra 2.0.5 nodes, RF=2. When I do a:
select * from table1 where clustercolumn=‘something'
The trace indicates that it only needs to talk to one node, which I would have
expected. However when I do a:
select * from table2
Which is a small table with only has 20 rows in it, should be fully replicated,
and should be a much quicker query, trace indicates that cassandra is talking
to both nodes. This adds a 200ms to the query results, and is not necessary for
my application (this table might have an amendment once per year if that),
theres no real need to check both nodes for consistency.
At this point I’ve not altered anything to do with consistency level. Does this
mean that cassandra attempts to guess/infer what consistency level you need
depending on if your query includes a filter on a particular key or clustering
key?
Thanks,
Jacob
CREATE KEYSPACE mykeyspace WITH replication = { 'class': 'SimpleStrategy',
'replication_factor': ‘2' };
CREATE TABLE organisation (uuid uuid, name text, url text, PRIMARY KEY (uuid))
CREATE TABLE lookup_code (type text, code text, name text, PRIMARY KEY ((type),
code))
select * from lookup_code where type=‘mylist':
activity |
timestamp | source | source_elapsed
---------------------------------------------------------------------------+--------------+--------------+----------------
execute_cql3_query |
04:20:15,319 | 74.50.54.123 | 0
Parsing select * from lookup_code where type='research_area' LIMIT 10000; |
04:20:15,319 | 74.50.54.123 | 64
Preparing statement |
04:20:15,320 | 74.50.54.123 | 204
Executing single-partition query on lookup_code |
04:20:15,320 | 74.50.54.123 | 849
Acquiring sstable references |
04:20:15,320 | 74.50.54.123 | 870
Merging memtable tombstones |
04:20:15,320 | 74.50.54.123 | 894
Skipped 0/0 non-slice-intersecting sstables, included 0 due to tombstones |
04:20:15,320 | 74.50.54.123 | 958
Merging data from memtables and 0 sstables |
04:20:15,320 | 74.50.54.123 | 976
Read 168 live and 0 tombstoned cells |
04:20:15,321 | 74.50.54.123 | 1412
Request complete |
04:20:15,321 | 74.50.54.123 | 2043
select * from organisation:
activity
| timestamp | source | source_elapsed
-------------------------------------------------------------------------------------------------+--------------+--------------+----------------
execute_cql3_query | 04:21:03,641 | 74.50.54.123 | 0
Parsing select * from
organisation LIMIT 10000; | 04:21:03,641 | 74.50.54.123 | 68
Preparing statement | 04:21:03,641 | 74.50.54.123 | 174
Determining
replicas to query | 04:21:03,642 | 74.50.54.123 | 307
Enqueuing request
to /72.249.82.85 | 04:21:03,642 | 74.50.54.123 | 1034
Sending message
to /72.249.82.85 | 04:21:03,643 | 74.50.54.123 | 1402
Message received
from /74.50.54.123 | 04:21:03,644 | 72.249.82.85 | 47
Executing seq scan across 0 sstables for [min(-9223372036854775808),
min(-9223372036854775808)] | 04:21:03,644 | 72.249.82.85 | 461
Read 1 live and 0
tombstoned cells | 04:21:03,644 | 72.249.82.85 | 560
Read 1 live and 0
tombstoned cells | 04:21:03,644 | 72.249.82.85 | 611
………..etc….....
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