Just wondering if anyone has any suggestions:
This executes successfully:
hive select * from twitter limit 5;
This does not work:
hive select tweet_id from twitter limit 5; // I have given the exception info
below:
Here is the output of this:
hive select * from twitter limit 5;
OK
Please use if not exists clause and let us know if it works.
I am wondering if a table exists already in your database with the same
name.
-Ramki.
On Sat, Mar 9, 2013 at 11:23 PM, Abhishek Gayakwad a.gayak...@gmail.comwrote:
it is an old installation, we recently upgraded hive 0.7.0 to 0.9.0
Hi,
It clearly is a classpath issue! When you do a select * from tab , it
works because HIve just fetches the data from HDFS using a FetchTask and
doesn't start any MR job (It probably uses json jar in your local hive lib
directory to deserialize and limit the rows to 5 and hence not raising
When you execute the following query,
hive select * from twitter limit 5;
Hive runs it in local mode and not use MapReduce.
For the query,
hive select tweet_id from twitter limit 5;
I think you need to add JSON jars to overcome this error. You might have
added these in a previous session. If
Ramki/John
Many Thanks, that really helped. I have run the add jars in the new session and
it appears to be running. However i was wondering about by passing MR, why
would we do it and what is the use of it. Will appreciate any input.
Thanks
Sai
From: Ramki
Well, you get the results faster.
Please check this:
https://cwiki.apache.org/Hive/gettingstarted.html#GettingStarted-Runtimeconfiguration
Under section Hive, Map-Reduce and Local-Mode, it says
This can be very useful to run queries over small data sets - in such cases
local mode execution
If you upgrade Hive, you have to do a upgrade/migration on the metastore
database. There are scripts that come with hive distributions for this. If
you're starting from scratch, you could just drop the old database.
On Sun, Mar 10, 2013 at 1:23 AM, Abhishek Gayakwad a.gayak...@gmail.comwrote:
Hi Sai
Local mode is just for trials, for any pre prod/production environment you need
MR jobs.
Hive under the hood stores data in HDFS (mostly) and definitely we use
hadoop/hive for larger data volumes. So MR should be in there to process them.
Regards
Bejoy KS
Sent from remote device,
Hello,
I have a table with userid, movieId and some more columns say c1, c2, c3
I want to group the records by userId and then do some processing on those
records (for each user) and
output less number of records (or same number of records) based on some
logic.
The processing involves
Hi All,
Could anyone describe what the required thread safety for a UDF is? I
understand that one is instantiated for each use of the function in an
expression, but can there be multiple threads executing the methods of a
single UDF object at once?
Thanks,
Shaun
Many Thanks Guys, you guys r really helpful. Really appreciate it.
Thanks
Sai
From: bejoy...@yahoo.com bejoy...@yahoo.com
To: user@hive.apache.org; Sai Sai saigr...@yahoo.in
Sent: Sunday, 10 March 2013 12:06 PM
Subject: Re: java.lang.NoClassDefFoundError:
Yes , in a map only query your udf will be executed at the mapper side.
I don't know how you can make your udf thread safe. But what I do set the
number of reducers to 1 and make sure that I write a query which has both map
and reduce.
Then the udf will be executed at the reduce phase and
Hadoop tasks use a single thread, so there won't be multiple threads
accessing the UDF.
However, there's a flip side of thread safety if your UDF maintains state;
is it receiving all the data it should or is the data being sharded over
multiple processes in a way that defeats the UDF? My favorite
I have files like this:
03/11/13 10:59:52 0ec0 1009 180538126 92041 2300 0 0 7 21|47|20|33|11
0:2775
03/11/13 10:59:52 0744 1010 178343610 92042 350 1 0 -1 NULL NULL 22 45
the format is separated by blank space:
date time threadid gid userid [variable formated data grouped by fields
Hi Mark,
I am using external table in HIVE.
This is how I am adding the partition
alter table mytable add partition (pt=1) location '/test/a/';
I am able to run HIVE queries only if '/test/a/b' folder is deleted.
How can I retain this folder structure and still issue queries?
Thanks
Suresh
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