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From Jörn Franke <jornfra...@gmail.com>
Subject Re: Accessing Hbase tables through Spark, this seems to work
Date Tue, 18 Oct 2016 07:18:15 GMT
Careful Hbase with Phoenix is only in certain scenarios faster. When it is about processing
small amounts out of a bigger amount of data (depends on node memory, the operation etc).
 Hive+tez+orc can  be rather competitive, llap makes sense for interactive ad-hoc queries
that are rather similar. Both Phoenix and hive follow different purposes with a different
architecture and underlying data structure.

> On 18 Oct 2016, at 07:44, Mich Talebzadeh <mich.talebzadeh@gmail.com> wrote:
> 
> yes Hive external table is partitioned on a daily basis (datestamp below)
> 
> CREATE EXTERNAL TABLE IF NOT EXISTS ${DATABASE}.externalMarketData (
>      KEY string
>    , SECURITY string
>    , TIMECREATED string
>    , PRICE float
> )
> COMMENT 'From prices Kakfa delivered by Flume location by day'
> ROW FORMAT serde 'org.apache.hadoop.hive.serde2.OpenCSVSerde'
> STORED AS TEXTFILE
> LOCATION 'hdfs://rhes564:9000/data/prices/'
> --TBLPROPERTIES ("skip.header.line.count"="1")
> ;
> ALTER TABLE ${DATABASE}.externalMarketData set location 'hdfs://rhes564:9000/data/prices/${TODAY}';
> 
> and there is insert/overwrite into managed table every 15 minutes.
> 
> INSERT OVERWRITE TABLE ${DATABASE}.marketData PARTITION (DateStamp = "${TODAY}")
> SELECT
>       KEY
>     , SECURITY
>     , TIMECREATED
>     , PRICE
>     , 1
>     , CAST(from_unixtime(unix_timestamp()) AS timestamp)
> FROM ${DATABASE}.externalMarketData
> 
> That works fine. However, Hbase is much faster for data retrieval with phoenix
> 
> When we get Hive with LLAP, I gather Hive will replace Hbase.
> 
> So in summary we have
> 
> raw data delivered to HDFS
> data ingested into Hbase via cron
> HDFS directory is mapped to Hive external table
> There is Hive managed table with added optimisation/indexing (ORC)
> 
> There are a number of ways of doing it as usual.
> 
> Thanks
> 
> 
> 
> Dr Mich Talebzadeh
>  
> LinkedIn  https://www.linkedin.com/profile/view?id=AAEAAAAWh2gBxianrbJd6zP6AcPCCdOABUrV8Pw
>  
> http://talebzadehmich.wordpress.com
> 
> Disclaimer: Use it at your own risk. Any and all responsibility for any loss, damage
or destruction of data or any other property which may arise from relying on this email's
technical content is explicitly disclaimed. The author will in no case be liable for any monetary
damages arising from such loss, damage or destruction.
>  
> 
>> On 18 October 2016 at 00:48, ayan guha <guha.ayan@gmail.com> wrote:
>> I do not see a rationale to have hbase in this scheme of things....may be I am missing
something? 
>> 
>> If data is delivered in HDFS, why not just add partition to an existing Hive table?

>> 
>>> On Tue, Oct 18, 2016 at 8:23 AM, Mich Talebzadeh <mich.talebzadeh@gmail.com>
wrote:
>>> Thanks Mike,
>>>  
>>> My test csv data comes as
>>>  
>>> UUID,                                 ticker,  timecreated,          price
>>> a2c844ed-137f-4820-aa6e-c49739e46fa6, S01,     2016-10-17T22:02:09,  53.36665625650533484995
>>> a912b65e-b6bc-41d4-9e10-d6a44ea1a2b0, S02,     2016-10-17T22:02:09,  86.31917515824627016510
>>> 5f4e3a9d-05cc-41a2-98b3-40810685641e, S03,     2016-10-17T22:02:09,  95.48298277703729129559
>>>  
>>>  
>>> And this is my Hbase table with one column family
>>>  
>>> create 'marketDataHbase', 'price_info'
>>>  
>>> It is populated every 15 minutes from test.csv files delivered via Kafka and
Flume to HDFS
>>>  
>>> Create a fat csv file based on all small csv files for today --> prices/2016-10-17
>>> Populate data into Hbase table using org.apache.hadoop.hbase.mapreduce.ImportTsv
>>> This is pretty quick using MapReduce
>>>  
>>> That importTsv only appends new rows to Hbase table as the choice of UUID as
rowKey avoids any issues.
>>>  
>>> So I only have 15 minutes lag in my batch Hbase table.
>>>  
>>> I have both Hive ORC tables and Phoenix views on top of this Hbase tables.
>>>  
>>> Phoenix offers the fastest response if used on top of Hbase. unfortunately, Spark
2 with Phoenix is broken
>>> Spark on Hive on Hbase looks OK. This works fine with Spark 2
>>> Spark on Hbase tables directly using key, value DFs for each column. Not as fast
as 2 but works. I don't think a DF is a good choice for a key, value pair?
>>> Now if I use Zeppelin to read from Hbase
>>>  
>>> I can use Phoenix JDBC. That looks very fast
>>> I can use Spark csv directly on HDFS csv files.
>>> I can use Spark on Hive tables
>>>  
>>> If I use Tableau on Hbase data then, only sql like code is useful. Phoenix or
Hive
>>>  
>>> I don't want to change the design now. But admittedly Hive is the best SQL on
top of Hbase. Next release of Hive is going to have in-memory database (LLAP) so we can cache
Hive tables in memory. That will be faster. Many people underestimate Hive but I still believe
it has a lot to offer besides serious ANSI compliant SQL.
>>>  
>>> Regards
>>>  
>>>  Mich
>>>  
>>>  
>>>  
>>>  
>>>  
>>>  
>>>  
>>>  
>>>  
>>>  
>>>  
>>>  
>>> 
>>> Dr Mich Talebzadeh
>>>  
>>> LinkedIn  https://www.linkedin.com/profile/view?id=AAEAAAAWh2gBxianrbJd6zP6AcPCCdOABUrV8Pw
>>>  
>>> http://talebzadehmich.wordpress.com
>>> 
>>> Disclaimer: Use it at your own risk. Any and all responsibility for any loss,
damage or destruction of data or any other property which may arise from relying on this email's
technical content is explicitly disclaimed. The author will in no case be liable for any monetary
damages arising from such loss, damage or destruction.
>>>  
>>> 
>>>> On 17 October 2016 at 21:54, Michael Segel <msegel_hadoop@hotmail.com>
wrote:
>>>> Mitch, 
>>>> 
>>>> Short answer… no, it doesn’t scale. 
>>>> 
>>>> Longer answer… 
>>>> 
>>>> You are using an UUID as the row key?  Why?  (My guess is that you want to
avoid hot spotting)
>>>> 
>>>> So you’re going to have to pull in all of the data… meaning a full table
scan… and then perform a sort order transformation, dropping the UUID in the process. 
>>>> 
>>>> You would be better off not using HBase and storing the data in Parquet files
in a directory partitioned on date.  Or rather the rowkey would be the max_ts - TS so that
your data is in LIFO. 
>>>> Note: I’ve used the term epoch to describe the max value of a long (8 bytes
of ‘FF’ ) for the max_ts. This isn’t a good use of the term epoch, but if anyone has
a better term, please let me know.
>>>> 
>>>> 
>>>> 
>>>> Having said that… if you want to use HBase, you could do the same thing.
 If you want to avoid hot spotting, you could load the day’s transactions using a bulk loader
so that you don’t have to worry about splits. 
>>>> 
>>>> But that’s just my $0.02 cents worth. 
>>>> 
>>>> HTH
>>>> 
>>>> -Mike
>>>> 
>>>> PS. If you wanted to capture the transactions… you could do the following
schemea:
>>>> 
>>>> 1) Rowkey = max_ts - TS  
>>>> 2) Rows contain the following:
>>>> CUSIP (Transaction ID)
>>>> Party 1 (Seller)
>>>> Party 2 (Buyer)
>>>> Symbol
>>>> Qty
>>>> Price
>>>> 
>>>> This is a trade ticket. 
>>>> 
>>>> 
>>>> 
>>>>> On Oct 16, 2016, at 1:37 PM, Mich Talebzadeh <mich.talebzadeh@gmail.com>
wrote:
>>>>> 
>>>>> Hi,
>>>>> 
>>>>> I have trade data stored in Hbase table. Data arrives in csv format to
HDFS and then loaded into Hbase via periodic load with org.apache.hadoop.hbase.mapreduce.ImportTsv.
>>>>> 
>>>>> The Hbase table has one Column family "trade_info" and three columns:
ticker, timecreated, price.
>>>>> 
>>>>> The RowKey is UUID. So each row has UUID, ticker, timecreated and price
in the csv file
>>>>> 
>>>>> Each row in Hbase is a key, value map. In my case, I have one Column
Family and three columns. Without going into semantics I see Hbase as a column oriented database
where column data stay together.
>>>>> 
>>>>> So I thought of this way of accessing the data.
>>>>> 
>>>>> I define an RDD for each column in the column family as below. In this
case column trade_info:ticker
>>>>> 
>>>>> //create rdd
>>>>> val hBaseRDD = sc.newAPIHadoopRDD(conf, classOf[TableInputFormat],classOf[org.apache.hadoop.hbase.io.ImmutableBytesWritable],classOf[org.apache.hadoop.hbase.client.Result])
>>>>> val rdd1 = hBaseRDD.map(tuple => tuple._2).map(result => (result.getRow,
result.getColumn("price_info".getBytes(), "ticker".getBytes()))).map(row => {
>>>>> (
>>>>>   row._1.map(_.toChar).mkString,
>>>>>   row._2.asScala.reduceLeft {
>>>>>     (a, b) => if (a.getTimestamp > b.getTimestamp) a else b
>>>>>   }.getValue.map(_.toChar).mkString
>>>>> )
>>>>> })
>>>>> case class columns (key: String, ticker: String)
>>>>> val dfticker = rdd1.toDF.map(p => columns(p(0).toString,p(1).toString))
>>>>> 
>>>>> Note that the end result is a DataFrame with the RowKey -> key and
column -> ticker
>>>>> 
>>>>> I use the same approach to create two other DataFrames, namely dftimecreated
and dfprice for the two other columns.
>>>>> 
>>>>> Note that if I don't need a column, then I do not create a DF for it.
So a DF with each column I use. I am not sure how this compares if I read the full row through
other methods if any.
>>>>> 
>>>>> Anyway all I need to do after creating a DataFrame for each column is
to join themthrough RowKey to slice and dice data. Like below.
>>>>> 
>>>>> Get me the latest prices ordered by timecreated and ticker (ticker is
stock)
>>>>> 
>>>>> val rs = dfticker.join(dftimecreated,"key").join(dfprice,"key").orderBy('timecreated
desc, 'price desc).select('timecreated, 'ticker, 'price.cast("Float").as("Latest price"))
>>>>> rs.show(10)
>>>>> 
>>>>> +-------------------+------+------------+
>>>>> |        timecreated|ticker|Latest price|
>>>>> +-------------------+------+------------+
>>>>> |2016-10-16T18:44:57|   S16|   97.631966|
>>>>> |2016-10-16T18:44:57|   S13|    92.11406|
>>>>> |2016-10-16T18:44:57|   S19|    85.93021|
>>>>> |2016-10-16T18:44:57|   S09|   85.714645|
>>>>> |2016-10-16T18:44:57|   S15|    82.38932|
>>>>> |2016-10-16T18:44:57|   S17|    80.77747|
>>>>> |2016-10-16T18:44:57|   S06|    79.81854|
>>>>> |2016-10-16T18:44:57|   S18|    74.10128|
>>>>> |2016-10-16T18:44:57|   S07|    66.13622|
>>>>> |2016-10-16T18:44:57|   S20|    60.35727|
>>>>> +-------------------+------+------------+
>>>>> only showing top 10 rows
>>>>> 
>>>>> Is this a workable solution?
>>>>> 
>>>>> Thanks
>>>>> 
>>>>> 
>>>>> Dr Mich Talebzadeh
>>>>>  
>>>>> LinkedIn  https://www.linkedin.com/profile/view?id=AAEAAAAWh2gBxianrbJd6zP6AcPCCdOABUrV8Pw
>>>>>  
>>>>> http://talebzadehmich.wordpress.com
>>>>> 
>>>>> Disclaimer: Use it at your own risk. Any and all responsibility for any
loss, damage or destruction of data or any other property which may arise from relying on
this email's technical content is explicitly disclaimed. The author will in no case be liable
for any monetary damages arising from such loss, damage or destruction.
>>>>>  
>>>> 
>>> 
>> 
>> 
>> 
>> -- 
>> Best Regards,
>> Ayan Guha
> 

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