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Subject: Number of Mapper when reading from Cassandra
From: Amjad ALSHABANI <ashshabani@gmail.com>
To: user@hive.apache.org
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Hello All,
I have tow tables created in Hive, one  read the data immidiately from
Cassandra DB and the other takes the data from stored files (data already
exported in somewhow from the same Cassandra DB)

Both tables are identical (in data)
but when running the same request it gives me very different number of
mapper for each of them (P.S I m using the same hive config for both
requests)

*hive -e " select count(1) from keyring.cred"*

will take 2338 mapper and 1 reducer

while:

*hive -e "select count(1) from keyring.cred_seq"*

will take just 151 mapper and 1 reducer

Any idea how to minimize this number, and where does this explosion in
mapper number come from??

any response will be appreciated :)

Cheers!!

Amjad

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<div dir=3D"ltr">Hello All,<div>I have tow tables created in Hive, one =A0r=
ead the data immidiately from Cassandra DB and the other takes the data fro=
m stored files (data already exported in somewhow from the same Cassandra D=
B)=A0</div>
<div><br></div><div>Both tables are identical (in data)</div><div>but when =
running the same request it gives me very different number of mapper for ea=
ch of them (P.S I m using the same hive config for both requests)</div>
<div><br></div><div><font face=3D"times new roman, serif"><b>hive -e &quot;=
 select count(1) from keyring.cred&quot;</b></font></div><div><br></div><di=
v>will take 2338 mapper and 1 reducer</div><div><br></div><div>while:</div>
<div><br></div><div><font face=3D"times new roman, serif"><b>hive -e &quot;=
select count(1) from keyring.cred_seq&quot;</b></font></div><div><br></div>=
<div>will take just 151 mapper and 1 reducer</div><div><br><div>Any idea ho=
w to minimize this number, and where does this explosion in mapper number c=
ome from??</div>
</div><div><br></div><div>any response will be appreciated :)</div><div><br=
></div><div>Cheers!!</div><div><br></div><div>Amjad</div><div><br></div></d=
iv>

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