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From "Ivan Ganza (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-4340) Cassandra upgrade to 1.1.1 resulted in slow query issue
Date Fri, 29 Jun 2012 14:11:44 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-4340?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13403930#comment-13403930
] 

Ivan Ganza commented on CASSANDRA-4340:
---------------------------------------

I dropped and tried to rebuild the CF.  At that point we noticed some schema options has changed
from earlier (we had originally defined this schema a year ago).

After doing this speed is (so far) very good -- and some sstables have been saved -- so this
is looking pretty good.  However we have to wait and see for the entire day of trading as
the trades build up.

New CF def looks like this:

create column family Quotes
    with column_type = Super
    and comparator = BytesType
    and subcomparator = BytesType
    and caching = all
    AND compression_options={sstable_compression:SnappyCompressor, chunk_length_kb:64};
                
> Cassandra upgrade to 1.1.1 resulted in slow query issue
> -------------------------------------------------------
>
>                 Key: CASSANDRA-4340
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-4340
>             Project: Cassandra
>          Issue Type: Bug
>          Components: Core
>    Affects Versions: 1.1.1
>         Environment: Ubuntu Linux, Java 7, Hector 1.0-1
>            Reporter: Ivan Ganza
>            Assignee: Pavel Yaskevich
>             Fix For: 1.1.2
>
>         Attachments: CassandraIssue.java
>
>
> We have recently introduced Cassandra at the Globe and Mail here in Toronto, Canada.
 We are processing and storing the North American stock-market feed.  We have found it to
work very quickly and things have been looking very good.
> Recently we upgraded to version 1.1.1 and then we have noticed some issues occurring.
> I will try to describe it for you here.  Basically one operation that we very often perform
and is very critical is the ability to 'get the latest quote'.  This would return to you the
latest Quote adjusted against exchange delay rules.  With Cassandra version 1.0.3 we could
get a Quote in around 2ms.  After update we are looking at time of at least 2-3 seconds.
> The way we query the quote is using a REVERSED SuperSliceQuery  with start=now, end=00:00:00.000
(beginning of day) LIMITED to 1.
> Our investigation leads us to suspect that, since upgrade, Cassandra seems to be reading
the sstable from disk even when we request a small range of day only 5 seconds back.  If you
look at the output below you can see that the query does NOT get slower as the lookback increases
from 5  sec, 60 sec, 15 min, 60 min, and 24 hours.
> We also noticed that the query was very fast for the first five minutes of trading, apparently
until the first sstable was flushed to disk.  After that we go into query times of 1-2 seconds
or so.
> Query time[lookback=5]:[1711ms]
> Query time[lookback=60]:[1592ms]
> Query time[lookback=900]:[1520ms]
> Query time[lookback=3600]:[1294ms]
> Query time[lookback=86400]:[1391ms]
> We would really appreciate input or help on this.
> Cassandra version: 1.1.1
> Hector version: 1.0-1
> ---
> public void testCassandraIssue() {
>             try {
>                   int[] seconds = new int[]{ 5, 60, 60 * 15, 60 * 60, 60 * 60 * 24};
>                   for(int sec : seconds) {
>                         DateTime start = new DateTime();
>                         SuperSliceQuery<String, String, String, String> superSliceQuery
= HFactory.createSuperSliceQuery(keyspaceOperator, StringSerializer.get(), StringSerializer.get(),
StringSerializer.get(), StringSerializer.get());
>                         superSliceQuery.setKey("101390" + "." + testFormatter.print(start));
>                         superSliceQuery.setColumnFamily("Quotes");
>                         superSliceQuery.setRange(superKeyFormatter.print(start),
>                                     superKeyFormatter.print(start.minusSeconds(sec)),
>                                     true,
>                                     1);
>                         long theStart = System.currentTimeMillis();
>                         QueryResult<SuperSlice<String, String, String>> result
= superSliceQuery.execute();
>                         long end = System.currentTimeMillis();
>                         System.out.println("Query time[lookback=" + sec + "]:[" + (end
- theStart) + "ms]");
>                   }
>             } catch(Exception e) {
>                   e.printStackTrace();
>                   fail(e.getMessage());
>             }
>       }
> ---
> create column family Quotes
>     with column_type = Super
>     and  comparator = BytesType
>     and subcomparator = BytesType
>     and keys_cached = 7000
>     and rows_cached = 0
>     and row_cache_save_period = 0
>     and key_cache_save_period = 3600
>     and memtable_throughput = 255
>     and memtable_operations = 0.29
>     AND compression_options={sstable_compression:SnappyCompressor, chunk_length_kb:64};

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