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From Jonathan Ellis <jbel...@gmail.com>
Subject Re: Are 6..8 seconds to read 23.000 small rows - as it should be?
Date Fri, 04 Jun 2010 14:46:17 GMT
get_slice reads a single row.  do you mean there are 23,000 columns,
or are you running get_slice in a loop 23000 times?

On Fri, Jun 4, 2010 at 4:59 AM, Per Olesen <pol@trifork.com> wrote:
> Are 6..8 seconds to read 23.000 small rows - as it should be?
>
> I have a quick question on what I think is bad read performance for this simple setup:
>
>  <ColumnFamily Name="Dashboard"
>    ColumnType="Super"
>    CompareWith="UTF8Type"
>    CompareSubcolumnsWith="UTF8Type" />
>
> SCF:Dashboard
>  key:username1 -> {
>        SC:uniqStr1 -> { col1:val1, col2: val2, ... col8:val8 },
>        SC:uniqStr2 -> { col1:val1, col2: val2, ... col8:val8 },
>        SC:uniqStr3 -> { col1:val1, col2: val2, ... col8:val8 },
>        SC:uniqStr4 -> { col1:val1, col2: val2, ... col8:val8 },
>        ... up to 23.000 "rows"
>  key:username2 -> {
>        SC:uniqStr5 -> { col1:val1, col2: val2, ... col8:val8 },
>        SC:uniqStr6 -> { col1:val1, col2: val2, ... col8:val8 },
>        SC:uniqStr7 -> { col1:val1, col2: val2, ... col8:val8 },
>        SC:uniqStr8 -> { col1:val1, col2: val2, ... col8:val8 },
>        ...
>
> A given key "username1" has e.g. 23.000 super column unique (rows). When I try and simply
raw-read all these rows, it takes what I think isn't pretty fast - approximately 6-8 seconds.
I know, there are a millions things that affect this, but I would just like to have a yes
or no if this really can be as it should be?
>
> My cassandra is a pretty unchanged v0.6.1.
>
> I read using this code:
>
>  ColumnParent parent = new ColumnParent("Dashboard");
>
>  SlicePredicate predicate = new SlicePredicate();
>  SliceRange sliceRange = new SliceRange();
>  sliceRange.setCount(Integer.MAX_VALUE);
>  sliceRange.setStart(toRawValue(""));
>  sliceRange.setFinish(toRawValue(""));
>  predicate.setSlice_range(sliceRange);
>
>  // timing this takes 6-8 secs.
>  return client.get_slice(
>   "keyspace",
>   "theusername",
>   columnParent,
>   slicePredicate,
>   ConsistencyLevel.QUORUM
>  );
>
> My replication factor is 1 and I had two nodes setup in cluster when doing the reads.
>
> Shouldn't this be what cassandra can do dead-fast?
>
>



-- 
Jonathan Ellis
Project Chair, Apache Cassandra
co-founder of Riptano, the source for professional Cassandra support
http://riptano.com

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