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From: Ashish Thusoo <athusoo@facebook.com>
To: "hive-user@hadoop.apache.org" <hive-user@hadoop.apache.org>
Date: Mon, 26 Jan 2009 15:31:01 -0800
Subject: RE: Migration Strategy
Thread-Topic: Migration Strategy
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If you are adding a column at the end of the table, you should be ok with t=
he old data staying in the state that it was provided it is created with Me=
tadataTypedColumnSetSerDe (I am not sure what happens with DynamicSerDe). M=
etadataTypedColumnSetSerdDe interprets missing columns at the end as nulls =
in the old data. Note this only works when adding columns at the end withou=
t changing names...

Ashish

________________________________
From: Josh Ferguson [mailto:josh@besquared.net]
Sent: Monday, January 26, 2009 3:06 PM
To: hive-user@hadoop.apache.org
Subject: Migration Strategy

What's the current strategy for when you have a production system and you r=
ealize you need to add another column to the table or do some other thing? =
Seems like you'd have to make a new table, run a script to transform and lo=
ad all your old data to the new table, and then remove the old table. Is th=
is what is currently being done?

Josh F.

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<DIV dir=3Dltr align=3Dleft><SPAN class=3D584282723-26012009><FONT face=3DA=
rial=20
color=3D#0000ff size=3D2>If you are adding a column at the end of the table=
, you=20
should be ok with the old data staying in the state that it was provided it=
 is=20
created with MetadataTypedColumnSetSerDe (I am not sure what happens with=20
DynamicSerDe). MetadataTypedColumnSetSerdDe interprets missing columns at t=
he=20
end as nulls in the old data. Note this only works when adding columns at t=
he=20
end without changing names...</FONT></SPAN></DIV>
<DIV dir=3Dltr align=3Dleft><SPAN class=3D584282723-26012009><FONT face=3DA=
rial=20
color=3D#0000ff size=3D2></FONT></SPAN>&nbsp;</DIV>
<DIV dir=3Dltr align=3Dleft><SPAN class=3D584282723-26012009><FONT face=3DA=
rial=20
color=3D#0000ff size=3D2>Ashish</FONT></SPAN></DIV>
<DIV dir=3Dltr align=3Dleft><SPAN class=3D584282723-26012009></SPAN>&nbsp;<=
/DIV>
<DIV class=3DOutlookMessageHeader lang=3Den-us dir=3Dltr align=3Dleft>
<HR tabIndex=3D-1>
<FONT face=3DTahoma size=3D2><B>From:</B> Josh Ferguson [mailto:josh@besqua=
red.net]=20
<BR><B>Sent:</B> Monday, January 26, 2009 3:06 PM<BR><B>To:</B>=20
hive-user@hadoop.apache.org<BR><B>Subject:</B> Migration=20
Strategy<BR></FONT><BR></DIV>
<DIV></DIV>What's the current strategy for when you have a production syste=
m and=20
you realize you need to add another column to the table or do some other th=
ing?=20
Seems like you'd have to make a new table, run a script to transform and lo=
ad=20
all your old data to the new table, and then remove the old table. Is this =
what=20
is currently being done?
<DIV><BR></DIV>
<DIV>Josh F.</DIV></BODY></HTML>

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