Not seeing your hive data after importing from the marketplace?

In my previous post I wrote about 4 ways to load data onto Hadoop on Azure.

After publishing the post I started to look into a fifth way – importing data from the Windows Azure Datamarket

Hadoop on Azure includes the ability to provide it with credentials to the market place, a query to run and the name of a hive table to create and will do the rest – query the data through the marketplace, store it on HDFS and create a hive table on top.

To configure that – click the ‘Manage Cluster’ tile on the Hadoop on Azure homepage

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and then click on the ‘DataMarket’ button

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To get to this screen, in which you can provide all the details

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You can get (and test) the query from the marketplace’s query builder tool –

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After entering all the details and clicking the ‘import data’ button a job will get started, and when completed you will have a hive table with the dataset (you can leave this screen and check back on the job history later, naturally it is all done asynchronously).

The best way to validate that (after of course making sure the job had completed successfully through the job history screen) is to use the hive interactive console – in the Hadoop on Azure homepage click the ‘Interactive Console’ tile and be sure to click the ‘Hive’ button on the top left.

It will take a few seconds for the tables dropdown to get populated, so bare with it, but once it has you should be able to see the table name you’ve entered in the list, and if you do, you should be able to run QL queries on it through the interactive console, I (eventually, see note below) loaded data from the ThreeHourlyForecast table for Heathrow from the met office’s data feed and so I could execute a query such as ‘select * from lhrmetdata’ and see the results displayed in the console. result.

However – with this particular data set I did bump into a bit of a glitch and what is probably a bug in this preview release – when I ran the import data job, the job info page reported the ‘Completed Successfully’ status –

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…but the dropdown in the hive interactive console never showed my table, nor did running the ‘show tables’ command.

I poked around the file system on the server (by RDP-ing into it and using the web interface as well as the command line, and I could see the data feed had been downloaded successfully, so I could not figure out what had gone wrong, until ‘jpposthuma’ on HadoopOnAzureCTP Yahoo group provided a spot on advice – to check the downloader.exe log file and so – I’ve opened the MapReduce web console on the server (after RDP-ing into it) and I clicked the log link at the bottom left –

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The downloader.exe log file was the first listed in the directory listing

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I downloaded the file and opened it in notepad (it is not viewed well in the browser), and the problem became clear immediately (I’ve highlighted the key area) –

 

2012-04-22 17:28:00,645 INFO  Microsoft.Hadoop.DataLoader.DataLoaderProgram: Start DataLoader …
2012-04-22 17:28:00,708 INFO  Microsoft.Hadoop.DataLoader.DataLoaderProgram: Overwriting flag [-o] is not set
2012-04-22 17:28:00,739 INFO  Microsoft.Hadoop.DataLoader.DataLoaderMediator: Begin transfer
2012-04-22 17:28:00,739 INFO  Microsoft.Hadoop.DataLoader.DataLoaderMediator: Transferring schema
2012-04-22 17:28:00,770 INFO  Microsoft.Hadoop.DataLoader.ODataSource: Begin exporting schema
2012-04-22 17:28:00,801 INFO  Microsoft.Hadoop.DataLoader.ODataSource:     build http request to data market: https://api.datamarket.azure.com/Data.ashx/DataGovUK/MetOfficeWeatherOpenData/ThreeHourlyForecast?$top=100
2012-04-22 17:28:04,130 INFO  Microsoft.Hadoop.DataLoader.ODataSource: End exporting schema
2012-04-22 17:28:04,130 INFO  Microsoft.Hadoop.DataLoader.FtpChannel: Begin pushing schema
2012-04-22 17:28:05,708 INFO  Microsoft.Hadoop.DataLoader.FtpChannel: Ftp response code: ClosingData
2012-04-22 17:28:05,708 INFO  Microsoft.Hadoop.DataLoader.FtpChannel: End pushing schema
2012-04-22 17:28:05,708 INFO  Microsoft.Hadoop.DataLoader.DataLoaderMediator: Transferring data
2012-04-22 17:28:05,723 INFO  Microsoft.Hadoop.DataLoader.FtpChannel: Begin pushing data
2012-04-22 17:28:05,786 INFO  Microsoft.Hadoop.DataLoader.ODataSource: Begin exporting data
2012-04-22 17:28:05,786 INFO  Microsoft.Hadoop.DataLoader.ODataSource:     exporting page #0
2012-04-22 17:28:05,786 INFO  Microsoft.Hadoop.DataLoader.ODataSource:     build http request to data market: https://api.datamarket.azure.com/Data.ashx/DataGovUK/MetOfficeWeatherOpenData/ThreeHourlyForecast?$top=100
2012-04-22 17:28:06,286 INFO  Microsoft.Hadoop.DataLoader.ODataSource: End exporting data. Total 100 rows exported
2012-04-22 17:28:06,395 INFO  Microsoft.Hadoop.DataLoader.FtpChannel: Ftp response code: ClosingData
2012-04-22 17:28:06,395 INFO  Microsoft.Hadoop.DataLoader.FtpChannel: End pushing data. Total 100 rows pushed
2012-04-22 17:28:06,395 INFO  Microsoft.Hadoop.DataLoader.DataLoaderMediator: End transfer
2012-04-22 17:28:06,411 INFO  Microsoft.Hadoop.DataLoader.DataLoaderMediator: Begin creating Hive table
2012-04-22 17:28:06,442 INFO  Microsoft.Hadoop.DataLoader.DataLoaderMediator: Begin HiveCli execution
2012-04-22 17:28:06,442 INFO  Microsoft.Hadoop.DataLoader.DataLoaderMediator:     cmd = c:\apps\dist\bin\hive.cmd
2012-04-22 17:28:06,442 INFO  Microsoft.Hadoop.DataLoader.DataLoaderMediator:     params = -v -f c:\apps\dist\logs\userlogs\hiveql\93e6a3e5-4914-4f78-8731-6bd9f2dcb94d.hql
2012-04-22 17:28:07,911 INFO  Microsoft.Hadoop.DataLoader.DataLoaderMediator:     [HiveCli stderr] Hive history file=C:\Apps\dist\logs\history/hive_job_log_yossidahan_201204221728_335367629.txt
2012-04-22 17:28:08,333 INFO  Microsoft.Hadoop.DataLoader.DataLoaderMediator:     [HiveCli stdout] CREATE EXTERNAL TABLE lhrmetdata ( ID BIGINT,ForecastSiteCode INT,PredictionId STRING,SiteName STRING,Country STRING,Continent STRING,StartTime TINYINT,Day STRING,Date STRING,TimeStep SMALLINT,SignificantWeatherId SMALLINT,ScreenTemperature SMALLINT,WindSpeed SMALLINT,WindDirection TINYINT,WindGust SMALLINT,VisibilityCode STRING,RelativeHumidity SMALLINT,ProbabilityPrecipitation SMALLINT,FeelsLikeTemperature SMALLINT,UVIndex SMALLINT,PredictionTime TINYINT ) COMMENT ‘external table to /uploads/lhrmetdata/lhrmetdata/content.dat created on 2012-04-22T17:28:06.411+00:00’ROW FORMAT DELIMITED FIELDS TERMINATED BY ’01’ LOCATION ‘/uploads/lhrmetdata/lhrmetdata’
2012-04-22 17:28:08,551 ERROR Microsoft.Hadoop.DataLoader.DataLoaderMediator:     [HiveCli stderr] FAILED: Parse Error: line 1:163 mismatched input ‘Date’ expecting Identifier near ‘,’ in column specification
2012-04-22 17:28:09,067 INFO  Microsoft.Hadoop.DataLoader.DataLoaderMediator: End HiveCli execution. Return code = 0
2012-04-22 17:28:09,067 INFO  Microsoft.Hadoop.DataLoader.DataLoaderMediator: End creating Hive table
2012-04-22 17:28:09,083 INFO  Microsoft.Hadoop.DataLoader.DataLoaderProgram: Shutdown DataLoader …

 

The data feed contained a field named ‘Date’ which is a reserved word and so the parsing of the hive command filed.

However – I now knew I had the feed data stored in HDFS already, and I knew what was wrong, so I could simply execute a slightly modified hive create command changing the column name from Date to TheDate; with the original command provided in the log above this was very easy to figure out –

CREATE EXTERNAL TABLE lhrmetdata ( ID BIGINT,ForecastSiteCode INT,PredictionId STRING,SiteName STRING,Country STRING,Continent STRING,StartTime TINYINT,Day STRING,TheDate STRING,TimeStep SMALLINT,SignificantWeatherId SMALLINT,ScreenTemperature SMALLINT,WindSpeed SMALLINT,WindDirection TINYINT,WindGust SMALLINT,VisibilityCode STRING,RelativeHumidity SMALLINT,ProbabilityPrecipitation SMALLINT,FeelsLikeTemperature SMALLINT,UVIndex SMALLINT,PredictionTime TINYINT ) COMMENT ‘external table to /uploads/lhrmetdata/lhrmetdata/content.dat created on 2012-04-22T17:28:06.411+00:00’ROW FORMAT DELIMITED FIELDS TERMINATED BY ’01’ LOCATION ‘/uploads/lhrmetdata/lhrmetdata’

As expected this command completed successfully and my table now showed in the dropdown list

So – valid reason for failing, was just confusing that the job was reported as successful initially, but I’d expect this to be ironed out before Hadoop on Azure gets released and ultimately – a great way to work with marketplace data!

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Loading data onto Hadoop on Azure

I’m fortunate enough to have some time and opportunity to look into Hadoop on Azure and I think is really really cool!

A side effect to something like this is almost always a bunch of random posts of notes I’m taking in the process, and I suspect this won’t be an exception; these are written mainly for my own sake if I’m honest, but hopefully beneficial for others too.

This one is about loading data.

Before Hadoop can analyse data, it needs data, so – how can one load data set onto HDFS on Azure in order to run jobs on it?

The samples provided through the portal include a handy button which allows one click deployment of the files needed to run the sample onto the cluster –

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This is very useful as it takes care of all the preparation needed to run the job, which is pretty good when one just wants to see a sample running, but moving on from this – what does one do?

There are several ways to get data onto HDFS, and I bet my list is not complete, but here’s what I’ve experimented with –

To start with – looking at the description of the word count sample, for example – you can find a couple of options –

Using fs.put() command in the interactive console

This will open up a dialog allowing you to chose a local file and specify a destination on HDFS and upload the data for you.

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The result is the specified file loaded into HDFS at the specified location (and name)

Use FTPS to upload data

This requires using a tool like curl as secure FTP is needed, and the password needs to be MD5 hashed so I’ve used the powershell script provided with the word count sample to upload the file securely –

$serverName = "XXSERVERNAMEXX.cloudapp.net"; $userName = "XXUSERNAMEXX"; 
$password = "XXPASSWORDXX"; 
$fileToUpload = "test.txt"; 
$destination = "/user/yossi/test_ftps.txt"; 
$passwordHash ="";
Clear-Variable passwordHash; 
$Md5Hasher = [System.Security.Cryptography.MD5]::Create();
$hashBytes = $Md5Hasher.ComputeHash($([Char[]]$password)) 
foreach ($byte in $hashBytes)
           { $passwordHash += “{0:x2}” -f $byte } 
$curlCmd = "c:\users\yossidah\documents\curl.exe -k --ftp-create-dirs -T $fileToUpload -u $userName" 
$curlCmd += ":$passwordHash ftps://$serverName" + ":2226$destination" 
invoke-expression $curlCmd 
#----- end curl ftps to hadoop on azure powershell example ----

It is worth nothing that by default all ports on the Hadoop cluster are closed, so for this to work you have to open the FTPS port by by clicking on the ‘Open Ports’ tile and opening the FTPS port –

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Other two options for uploading files I’ve played with are

Using the Hadoop command line

If you can get the file ontop the head node (I’ve downloaded it from my skydrive account, for example), you can use the command line hadoop fs –copyFromLocal to load the file onto HDFS, but frankly this seems more trouble then its worth given the previous two options

Load data directly from Azure Storage

This is much more interesting – under the ‘Manage Cluster’ tile you can find an option to ‘Set up ASV’ or ‘Set up S3’

This lets you configure Hadoop with credentials to the storage account in the relevant cloud platform and this lights up two options –

  1. You can now use hadoop fs -cp to copy a file from Azure Storage to HDFS using the ASV:// or s3/s3n monikers for the source file.
  2. You can actually run a job directly with the data on the cloud blob and even write the result back to a blob, again – using the relevant moniker, for example – hadoop.cmd jar hadoop-examples-0.20.203.1-SNAPSHOT.jar wordcount asv://foo/input asv://foo/output

So – 4 nice and easy ways to get data to Hadoop on Azure to get started

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