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From Maryann Xue <maryann....@gmail.com>
Subject Re: Inner Join not returning any results in Phoenix
Date Tue, 24 Feb 2015 16:41:15 GMT
Hi Matt,

I just noticed these lines in your very first message:

*PS* Something that may or may not be of note: In the environments I am
using:

WORKING: *hbase-0.98.8-hadoop2 / phoenix-4.2.2-server.jar*

FAILING:     *hbase-0.98.9-hadoop2* / *phoenix-4.2.2-server.jar*


What do you mean by WORKING and FAILING?


I still cannot reproduce the bug here. Could you please post DDLs you used
for related tables?



Thanks,

Maryann




On Tue, Feb 24, 2015 at 11:27 AM, James Taylor <jamestaylor@apache.org>
wrote:

> FYI, SQuirrel sets the max rows to return as 100. You can change this in
> the tool, though.
>
>
> On Tuesday, February 24, 2015, Maryann Xue <maryann.xue@gmail.com> wrote:
>
>> Thanks a lot, Matt, for the reply! Very helpful. "*SERVER FILTER BY
>> PageFilter 100*" does look like a but here. I will try again to
>> reproduce it.
>>
>>
>> Thanks,
>> Maryann
>>
>> On Tue, Feb 24, 2015 at 6:07 AM, Matthew Johnson <matt.johnson@algomi.com
>> > wrote:
>>
>>> Hi Maryann,
>>>
>>>
>>>
>>> Thanks for that - I will schedule an update to the latest version of
>>> Phoenix then for later this week (and try out the merge-join hints).
>>>
>>>
>>>
>>> In the meantime, here are my explain plans:
>>>
>>>
>>>
>>> *JOIN WITH NO SQUIRREL LIMIT*
>>>
>>>
>>>
>>> *PLAN*
>>>
>>> *CLIENT 2-CHUNK PARALLEL 1-WAY FULL SCAN OVER mytable1*
>>>
>>> *    PARALLEL INNER-JOIN TABLE 0*
>>>
>>> *        CLIENT 3-CHUNK PARALLEL 1-WAY FULL SCAN OVER mytable2*
>>>
>>>
>>>
>>> *JOIN WITH SQUIRREL LIMIT 100*
>>>
>>>
>>>
>>> *PLAN*
>>>
>>> *CLIENT 2-CHUNK PARALLEL 1-WAY FULL SCAN OVER mytable1*
>>>
>>> *CLIENT 100 ROW LIMIT*
>>>
>>> *    PARALLEL INNER-JOIN TABLE 0*
>>>
>>> *        CLIENT 3-CHUNK SERIAL 1-WAY FULL SCAN OVER mytable2*
>>>
>>> *            SERVER FILTER BY PageFilter 100*
>>>
>>> *            SERVER 100 ROW LIMIT*
>>>
>>> *        CLIENT 100 ROW LIMIT*
>>>
>>>
>>>
>>>
>>>
>>> I’m not really sure how to read that, but it does seem to suggest that
>>> ‘mytable2’ is being limited to 100 – thoughts?
>>>
>>>
>>>
>>> Cheers,
>>>
>>> Matt
>>>
>>>
>>>
>>> *From:* Maryann Xue [mailto:maryann.xue@gmail.com]
>>> *Sent:* 23 February 2015 18:10
>>>
>>> *To:* user@phoenix.apache.org
>>> *Subject:* Re: Inner Join not returning any results in Phoenix
>>>
>>>
>>>
>>> Hi Matt,
>>>
>>>
>>>
>>> Yes, the upgrade is as easy as that. I believe things will work fine
>>> with existing tables.
>>>
>>> I tried with a similar query but didn't see that it was a Phoenix bug.
>>> So could you please try the following explain statement and see the
>>> execution plan:
>>>
>>>
>>>
>>> EXPLAIN *SELECT * FROM "mytable1" hc*
>>>
>>> *INNER JOIN “mytable2” bs*
>>>
>>> *On hc."myId" = bs.”myId”*
>>>
>>>
>>>
>>>
>>>
>>> Thanks,
>>>
>>> Maryann
>>>
>>>
>>>
>>>
>>>
>>> On Fri, Feb 20, 2015 at 1:09 PM, Matthew Johnson <
>>> matt.johnson@algomi.com> wrote:
>>>
>>> Hi Maryann,
>>>
>>>
>>>
>>> That’s a good point – I am using 4.2.2, so if that feature is 4.3+ then
>>> that would explain why it’s not working. Is upgrading versions of Phoenix
>>> as simple as removing the previous jar from HBase lib folder and dropping
>>> the new Phoenix jar in (and restarting HBase)? Will all the existing
>>> Phoenix tables and views be backwards-compatible and work with the new
>>> version?
>>>
>>>
>>>
>>> Cheers,
>>>
>>> Matt
>>>
>>>
>>>
>>>
>>>
>>> *From:* Maryann Xue [mailto:maryann.xue@gmail.com]
>>> *Sent:* 20 February 2015 17:46
>>>
>>>
>>> *To:* user@phoenix.apache.org
>>> *Subject:* Re: Inner Join not returning any results in Phoenix
>>>
>>>
>>>
>>> Which version of Phoenix are you using, Matt? This feature is only
>>> available in the latest releases of 4.3/3.3.
>>>
>>>
>>>
>>> On Fri, Feb 20, 2015 at 12:11 PM, Matthew Johnson <
>>> matt.johnson@algomi.com> wrote:
>>>
>>> Hi Maryann,
>>>
>>>
>>>
>>> Unfortunately my two tables are roughly the same size (~500k), but I
>>> have tested a different join where one table is ~500k and the other is ~20k
>>> and putting the larger one first is definitely far more performant. I
>>> believe you are right about running out of memory, I can see this repeated
>>> a few times in the region server logs followed by what appears to be a
>>> restart or disconnect:
>>>
>>>
>>>
>>> *[JvmPauseMonitor] util.JvmPauseMonitor: Detected pause in JVM or host
>>> machine (eg GC): pause of approximately 1083ms*
>>>
>>>
>>>
>>> I have been looking at the Phoenix page on joins (
>>> http://phoenix.apache.org/joins.html) and it mentions using Sort-Merge
>>> joins for large tables by using a hint. I have tried this though with no
>>> success:
>>>
>>>
>>>
>>> *SELECT /*+ USE_SORT_MERGE_JOIN*/ count(*) FROM “mytable1” hc*
>>>
>>> *INNER JOIN “mytable2” bs*
>>>
>>> *On hc.”myId” = bs.”myId”*
>>>
>>>
>>>
>>> Am I putting the hint in the wrong place? Does it need to go next to the
>>> JOIN rather than the SELECT?
>>>
>>>
>>>
>>> I will try increasing the memory available to the Region Servers as well
>>> to see if that helps.
>>>
>>>
>>>
>>> Thanks!
>>>
>>> Matt
>>>
>>>
>>>
>>>
>>>
>>> *From:* Maryann Xue [mailto:maryann.xue@gmail.com]
>>> *Sent:* 20 February 2015 16:28
>>> *To:* user@phoenix.apache.org
>>>
>>>
>>> *Subject:* Re: Inner Join not returning any results in Phoenix
>>>
>>>
>>>
>>> Hi Matt,
>>>
>>>
>>>
>>> The error you got with "Limit Rows" off might be related to insufficient
>>> memory on region servers for one of your tables. Which is the larger table
>>> between table1 and table2? You might want to try putting the larger table
>>> as the first table in your join query and see if it works.
>>>
>>>
>>>
>>> And I will quickly check if the LIMIT problem is a Phoenix bug and will
>>> keep you posted.
>>>
>>>
>>>
>>>
>>>
>>> Thanks,
>>>
>>> Maryann
>>>
>>>
>>>
>>>
>>>
>>> On Fri, Feb 20, 2015 at 11:14 AM, Matthew Johnson <
>>> matt.johnson@algomi.com> wrote:
>>>
>>> Hi Abe,
>>>
>>>
>>>
>>> Glad to hear I’m not alone! Will try and figure out exactly what’s
>>> happening and maybe raise a Jira :-)
>>>
>>>
>>>
>>>
>>>
>>> @Constantin – I have tried with and without the “Limit Rows” – but
>>> without it, and without any indexes, the query runs for a while (about 10
>>> minutes?) and then throws an error:
>>>
>>>
>>>
>>> *Error: Encountered exception in sub plan [0] execution.*
>>>
>>>
>>>
>>> Which I’m guessing is either HBase or Zookeeper timeout. The weird thing
>>> is that in standard SQL databases (eg Oracle, MySQL etc) then the “Limit
>>> Rows” does not affect any aggregate functions like ‘count’, because the
>>> actual number of result rows for a count is just 1 row (the count itself).
>>> But in HBase it seems that the Row Limit, as Abe mentioned, is applied to
>>> one of the table BEFORE it does the join, so it affects the results of the
>>> ‘count’ function.
>>>
>>>
>>>
>>> When I try to create my indexes so I am able to do the join without Row
>>> Limit, I get the following error:
>>>
>>>
>>>
>>> ERROR 1029 (42Y88): Mutable secondary indexes must have the
>>> hbase.regionserver.wal.codec property set to
>>> org.apache.hadoop.hbase.regionserver.wal.IndexedWALEditCodec in the
>>> hbase-sites.xml of every region server
>>>
>>>
>>>
>>> Which I am happy to do (will have to wait until outside of business
>>> hours though), but I am curious, will this have any impact on the rest of
>>> my cluster and could it have any unforeseen consequences?
>>>
>>>
>>>
>>> Thanks again for the input!
>>>
>>>
>>>
>>> Cheers,
>>>
>>> Matt
>>>
>>>
>>>
>>>
>>>
>>> *From:* Ciureanu, Constantin (GfK) [mailto:Constantin.Ciureanu@gfk.com]
>>> *Sent:* 20 February 2015 15:48
>>>
>>>
>>> *To:* user@phoenix.apache.org
>>> *Subject:* RE: Inner Join not returning any results in Phoenix
>>>
>>>
>>>
>>> Hello Matt,
>>>
>>>
>>>
>>> http://codingclues.eu/2008/the-squirrel-100-rows-problem/
>>>
>>>
>>>
>>> Can you please test again after unchecking “Contents- Limit rows” and
>>> “SQL – Limit rows”?
>>>
>>>
>>>
>>> [image: SQL tab]
>>>
>>>
>>>
>>> P.S. Off-topic – it’s as funny as this “problem” (not possible to send
>>> an email for more than 500 miles away J
>>> http://www.ibiblio.org/harris/500milemail.html )
>>>
>>>
>>>
>>> Regards,
>>>
>>>   Constantin
>>>
>>>
>>>
>>> *From:* Abe Weinograd [mailto:abe@flonet.com]
>>> *Sent:* Friday, February 20, 2015 4:18 PM
>>> *To:* user
>>> *Subject:* Re: Inner Join not returning any results in Phoenix
>>>
>>>
>>>
>>> Matt,
>>>
>>>
>>>
>>> I have seen this same issue.  When passing a LIMIT to a query with joins
>>> (most query tools do it implicitly), Phoenix seems to apply that to the
>>> table on the right of the join I believe.  I hadn't had a chance to play
>>> with it more and file a JIRA, but what you are describing is consistent
>>> with what I have seen.
>>>
>>>
>>>
>>> Abe
>>>
>>>
>>>
>>> On Fri, Feb 20, 2015 at 10:04 AM, Matthew Johnson <
>>> matt.johnson@algomi.com> wrote:
>>>
>>> Hi Constantin,
>>>
>>>
>>>
>>> Many thanks for your reply – the quotes were both of the same type
>>> (double quotes for table and column names, single quotes for string
>>> literals), it is just my email client that formatted them weirdly, sorry!
>>>
>>>
>>>
>>> I have discovered what I believe is an important piece of the puzzle to
>>> my problem. I am using Squirrel SQL as my JDBC client for Phoenix, and it
>>> has a “Limit Rows” feature. When I try and count the number of rows in a
>>> single table:
>>>
>>>
>>>
>>> *select count(*) from “mytable1”*
>>>
>>>
>>>
>>> I get the expected number of results (eg 20,000). But when I join two
>>> tables together, it seems that the “Limit Rows” from Squirrel is somehow
>>> being applied before the join is performed, and if “Limit Rows” is set to
>>> 100 I get 100 results or less. If the inner join is quite sparse (eg 20,000
>>> rows in a table but only 100 of these will join with a second table) then I
>>> believe it tries to join the first 100 it finds and returns no results. In
>>> my experience of Oracle or MySQL, joins are done entirely on server side
>>> and then you just get back the number of rows you limited, rather than what
>>> appears to be happening which is the row limit is applied to the first
>>> table before the join is attempted with the second table. Is that how
>>> Phoenix works?
>>>
>>>
>>>
>>> I have also discovered that I get different results (with “Limit Rows”
>>> turned on) depending on which order I join the tables:
>>>
>>>
>>>
>>> *SELECT count(*) FROM “mytable1” hc*
>>>
>>> *INNER JOIN “mytable2” bs*
>>>
>>> *On hc.”myId” = bs.”myId”*
>>>
>>>
>>>
>>> Gives me a very different number of results than:
>>>
>>>
>>>
>>> *SELECT count(*) FROM “mytable2” bs*
>>>
>>> *INNER JOIN “mytable1” hc*
>>>
>>> *On hc.”myId” = bs.”myId”*
>>>
>>>
>>>
>>>
>>>
>>> Unfortunately I cannot test whether I get the same number of results
>>> with “Limit Rows” turned off because my query times out! So I am now
>>> looking at creating secondary indexes on the “myId” column in both tables
>>> to see if I am able to do this join quicker. Does a join like this use a
>>> lot of memory on server side? Is something likely to be running out of
>>> resources?
>>>
>>>
>>>
>>> Many thanks again for your time.
>>>
>>>
>>>
>>> Cheers,
>>>
>>> Matt
>>>
>>>
>>>
>>>
>>>
>>> *From:* Ciureanu, Constantin (GfK) [mailto:Constantin.Ciureanu@gfk.com]
>>> *Sent:* 20 February 2015 14:40
>>> *To:* user@phoenix.apache.org
>>> *Subject:* RE: Inner Join not returning any results in Phoenix
>>>
>>>
>>>
>>> Hi Matthew,
>>>
>>>
>>>
>>> Is it working without the quotes “ / *"*  ?   (I see you are using 2
>>> types of quotes, weird)
>>>
>>> I guess that’s not needed, and probably causing troubles.   I don’t have
>>> to use quotes anyway.
>>>
>>>
>>>
>>> Alternatively check the types of data in those 2 tables (if the field
>>> types are not the same in both tables, the join will not work).
>>>
>>>
>>>
>>> Good luck,
>>>
>>>   Constantin
>>>
>>>
>>>
>>> *From:* Matthew Johnson [mailto:matt.johnson@algomi.com]
>>> *Sent:* Friday, February 20, 2015 12:54 PM
>>> *To:* user@phoenix.apache.org
>>> *Subject:* Inner Join not returning any results in Phoenix
>>>
>>>
>>>
>>> Hi guys,
>>>
>>>
>>>
>>> I’m a little bit stuck with doing an Inner Join with Phoenix. I set up
>>> one environment, created tables in HBase, and then created views (rather
>>> than tables) in Phoenix, and am able to query as expected (when I join my
>>> two tables I see results). I’ve just promoted to another environment, with
>>> the exact same setup, but my Inner Join returns no results!
>>>
>>>
>>>
>>> I run the following two individual queries:
>>>
>>>
>>>
>>> *SELECT * FROM "mytable1" hc*
>>>
>>> *where hc."myId" = 'XS0'*
>>>
>>>
>>>
>>> *SELECT * FROM "mytable2" bs*
>>>
>>> *where bs."myId" = 'XS0'*
>>>
>>>
>>>
>>> And both of these queries give results. But when I run:
>>>
>>>
>>>
>>> *SELECT * FROM "mytable1" hc*
>>>
>>> *INNER JOIN “mytable2” bs*
>>>
>>> *On hc."myId" = bs.”myId”*
>>>
>>>
>>>
>>> I get no results. I also get no results if I try:
>>>
>>>
>>>
>>> *SELECT * FROM "mytable1" hc*
>>>
>>> *where hc."myId" in (select distinct “myId” from “mytable2”)*
>>>
>>>
>>>
>>> I have checked in HBase shell and can see the “myId” value is as
>>> expected (XS0 in both tables). I am not sure if there are any logs that I
>>> can look at to get some insight?
>>>
>>>
>>>
>>> Many thanks in advance for any suggestions!
>>>
>>>
>>>
>>> Cheers,
>>>
>>> Matt
>>>
>>>
>>>
>>> *PS* Something that may or may not be of note: In the environments I am
>>> using:
>>>
>>> WORKING: *hbase-0.98.8-hadoop2 / phoenix-4.2.2-server.jar*
>>>
>>> FAILING:     *hbase-0.98.9-hadoop2* / *phoenix-4.2.2-server.jar*
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>
>>

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