Home | About | Sematext search-lucene.com search-hadoop.com
NEW: Monitor These Apps!
elasticsearch, apache solr, apache hbase, hadoop, redis, casssandra, amazon cloudwatch, mysql, memcached, apache kafka, apache zookeeper, apache storm, ubuntu, centOS, red hat, debian, puppet labs, java, senseiDB
 Search Hadoop and all its subprojects:

Switch to Threaded View
HBase >> mail # user >> Fastest way to find is a row exist?


Copy link to this message
-
Re: Fastest way to find is a row exist?
Is KeyOnlyFilter using the BloomFilters too?

Here is, with more details, what I'm doing.

Few questions.
- Can I create one single KeyOnlyFilter and give the same filter to
all the gets?
- Will bloom filters benefit in such scenario? My key is small. Let's
say average 128 bytes.

The goal here is to check about 500 entries at a time to validate if
they already exist or not.

In my MR, I'm starting when I have more than 100K lines to handle, and
each line car have up to 1K entries. So it can result up to 100M
gets... Job took initially 500 minutes to complete. I have added few
pretty good nodes and it's not taking less than 300 minutes. But I
would like to get under 100 minutes if I can...

Thanks,

JM

Vector<Get> gets_entry_exist = new Vector<Get>();
for (Entry entry : entries.getEntries())
{
Get entry_exist = new Get(entry.toKey());
entry_exist.setFilter(new KeyOnlyFilter());
gets_entry_exist.add(entry_exist);
}

Result[] result_entry_exist = table_entry.get(gets_entry_exist);

int index = 0;
for (Entry entry : entries.getEntries())
{
boolean isEmpty =  result_entry_exist[index++].isEmpty();
if (isEmpty)
{
// Process here
}
}
{
2013/1/4, Damien Hardy <[EMAIL PROTECTED]>:
> Hello Jean-Marc,
>
> BloomFilters are just designed for that.
>
> But they say if a row doesn't exist with a ash of the key (not the oposit,
> 2 rowkeys could have the same ash result).
>
> If you want to be sure the rowkey exists you have to search for it in the
> HFile ( the whole mechanism is transparent with the get() ).
>
> Their is also an KeOnlyFilter
> http://hbase.apache.org/apidocs/org/apache/hadoop/hbase/filter/KeyOnlyFilter.html
> preventing from getting the whole columns of the existing key as return
> (which could be heavy).
>
> Cheers,
>
> --
> Damien
>
>
> 2013/1/4 Jean-Marc Spaggiari <[EMAIL PROTECTED]>
>
>> Hi,
>>
>> What's the fastest way to know if a row exist?
>>
>> Today I'm doing that:
>>
>> Get get_entry_exist = new Get(key).addColumn(CF_DATA, C_DATA);
>> Result entry_exist = table_entry.get(get_entry_exist);
>>
>> But should this be faster?
>> Get get_entry_exist = new Get(key);
>> Result entry_exist = table_entry.get(get_entry_exist);
>>
>> There is only one CF and one C on my table.
>>
>> Or is there an even faster way?
>>
>> Also, is there a way to make that even faster? I think BloomFilters
>> can help, right?
>>
>> Thanks,
>>
>> JM
>>
>
NEW: Monitor These Apps!
elasticsearch, apache solr, apache hbase, hadoop, redis, casssandra, amazon cloudwatch, mysql, memcached, apache kafka, apache zookeeper, apache storm, ubuntu, centOS, red hat, debian, puppet labs, java, senseiDB