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From David Medinets <david.medin...@gmail.com>
Subject Re: total table rows
Date Mon, 09 Nov 2015 16:03:09 GMT
It's not recommended to read the Metadata table? When I needed the 'real'
number, I ran a compaction. When I needed an estimate I just read the
table. I also upgraded our ingest process to track numbers as a second
phase to avoid the need for compaction to get 'real' numbers.

On Mon, Nov 9, 2015 at 10:52 AM, Josh Elser <josh.elser@gmail.com> wrote:

> Note that CountingIterator is in the system iterator package
> (FirstEntryInRowIterator also isn't in the user package for iterators, so
> its stability is a little questionable too). I think David ran into this a
> long time ago as well.
>
> Stable versions of both of these would be good, IMO. It isn't like Z is
> the first one to ask how to count the unique rows :)
>
>
> William Slacum wrote:
>
>> Pranked... you can't use a CountingIterator, because it can't be init'd.
>> Can we get rid of that limitation?
>>
>> On Mon, Nov 9, 2015 at 10:43 AM, William Slacum<wslacum@gmail.com>
>> wrote:
>>
>> An interator stack of FirstEntryInRowIterator + CountingIterator will
>>> return the count of rows in each tablet, which can then be combined on
>>> the
>>> client side.
>>>
>>> On Mon, Nov 9, 2015 at 10:25 AM, Josh Elser<josh.elser@gmail.com>
>>> wrote:
>>>
>>> Yeah, there's no explicit tracking of all rows in Accumulo, you're stuck
>>>> with enumerating them (or explicitly tracking them yourself at ingest
>>>> time).
>>>>
>>>> The easiest approach you can take is probably using the
>>>> FirstEntryInRowIterator and counting each row on the client-side.
>>>>
>>>> You could do another summation in a second iterator but this is a little
>>>> tricky to get correct. I tried to touch on this a little in a blog
>>>> post[1].
>>>> If this is a one-off question you want to answer, doing the summation on
>>>> the client side is likely not to take excessively longer than a
>>>> server-side
>>>> summation.
>>>>
>>>> [1]
>>>>
>>>> https://blogs.apache.org/accumulo/entry/thinking_about_reads_over_accumulo
>>>>
>>>>
>>>> z11373 wrote:
>>>>
>>>> I want to get total rows of a table (likely has more than 100M rows), I
>>>>> think
>>>>> to get that information, Accumulo would have to iterate all rows :-(
>>>>> This
>>>>> may not be typical Accumulo scenario.
>>>>>
>>>>> Is there a more efficient way to get total number of rows in a table?
>>>>> When Accumulo iterating those items, does it mean it will pull the data
>>>>> to
>>>>> the client? If yes, is there a way to ask it to return just the number,
>>>>> since that's the only data I care.
>>>>>
>>>>> Thanks,
>>>>> Z
>>>>>
>>>>>
>>>>>
>>>>> --
>>>>> View this message in context:
>>>>>
>>>>> http://apache-accumulo.1065345.n5.nabble.com/total-table-rows-tp15484.html
>>>>> Sent from the Developers mailing list archive at Nabble.com.
>>>>>
>>>>>
>>

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