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From S L <slouie.at.w...@gmail.com>
Subject Re: How does hbase find regionservers for scans
Date Tue, 18 Jul 2017 18:36:17 GMT
Thanks for the tip with RowPrefixFilter.  THAT works compared to
PrefixFilter.  However, regarding the timerange, when i type in the
epoch time, that returns 0 rows.  However, if I use epoch time in
milliseconds, that returns tons of rows.

I have more questions now:
1) Why does my hbase work wtih epoch in milliseconds but your example
says to use epoch seconds.
2) Also, how do you use PrefixFilter because I thought PrefixFilter
was what I needed via common sense but apparently my common sense
didn't work.

Thanks for answering all my questions the last couple weeks.

 scan 'dbi_based_data', {ROWPREFIXFILTER=> '26', COLUMNS =>
'raw_data:processlist', TIMERANGE => [1499205600, 1499206200]}

ROW                                COLUMN+CELL

0 row(s) in 0.2350 seconds


scan 'dbi_based_data', {ROWPREFIXFILTER=> '26', COLUMNS =>
'raw_data:processlist', TIMERANGE => [1499205600000, 1499206200000]}

<snip snip>
<snpi snip>

26_p3419.db160151.ycg1.dbi_149920 column=raw_data:processlist,
timestamp=1499206083343, value= <snip snip>

351 row(s) in 184.6360 seconds




On Fri, Jul 14, 2017 at 8:14 PM, Ted Yu <yuzhihong@gmail.com> wrote:
>
> I wonder what time unit you were using.
>
> From the example in hbase-shell/src/main/ruby/shell/commands/scan.rb :
>
>   hbase> scan 't1', {COLUMNS => 'c1', TIMERANGE => [1303668804, 1303668904]}
>
> You can see the time range having much smaller values.
>
> Please look at ROWPREFIXFILTER example in the same scan.rb
>
> If you check the table UI for dbi_based_data, you would see the start key
> of each region.
> From there it is easy to pinpoint which server hosts the relevant region.
>
> Cheers
>
> On Fri, Jul 14, 2017 at 7:51 PM, S L <slouie.at.work@gmail.com> wrote:
>
> > Sorry if this is a basic question.  How does hbase determine which
> > regionserver the rows are supposed to be stored on?  My rowkey looks like
> > hash_servername_timestamp, e.g.
> >
> > 33_myserver.mydomain.com_1234567890
> >
> > If I run the following command:
> >
> > scan 'dbi_based_data', {FILTER => "PrefixFilter('0')", COLUMNS =>
> > 'raw_data:processlist', TIMERANGE => [1499205600000, 1499206200000]}
> >
> > I get all the rows that start with "0".  Since hbase stores things in
> > lexical order, it seems like all rows that were stored lexically first gets
> > returned.
> >
> > However, if I run the following command, hbase times out.  Even if I extend
> > the timeout period to 3 minutes, it still times out.
> >
> > scan 'dbi_based_data', {FILTER => "PrefixFilter('28')", COLUMNS =>
> > 'raw_data:processlist', TIMERANGE => [1499205600000, 1499206200000]}
> >
> > It seems like if it was any other prefix other than "0", it times out (like
> > above prefix = 28).  I don't understand why it would timeout since it
> > should be able to calculate which region/regionserver it should go to since
> > I gave it the prefix to use.
> >
> >
> > I performed "hbase hbck" and it says that
> >
> > 9 region servers are alive, 2 are dead
> >
> > # of total regions is 15850 for the db but there's only 350 for the table
> > I'm querying.  There are 0 inconsistencies so the status is "OK".
> >
> > Thanks in advance for any help you can give me.
> >

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