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Date: Sun, 5 Apr 2015 21:29:29 -0400
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 <CACEcauUT364yM_PHPKUe5C1W=1L+MHtDFi6UBpmoo3g70jJOBQ@mail.gmail.com>
Subject: Re: INSERT OVERWRITE partition while SELECT is going on
From: Lefty Leverenz <leftyleverenz@gmail.com>
To: user@hive.apache.org
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Actually, hive.support.concurrency
<https://cwiki.apache.org/confluence/display/Hive/Configuration+Properties#ConfigurationProperties-hive.support.concurrency>
is
false by default so you should set it to true for locking.

-- Lefty

On Fri, Apr 3, 2015 at 4:52 PM, Lefty Leverenz <leftyleverenz@gmail.com>
wrote:

> I'm no expert, but I don't think SELECTs are broken by an INSERT.  See
> Locking <https://cwiki.apache.org/confluence/display/Hive/Locking> for
> details.
>
> As I understand it, the INSERT needs an exclusive lock on the partition
> which it cannot get while the partition has a shared lock on it.
>
> Can someone confirm or correct this?
>
> -- Lefty
>
> On Fri, Apr 3, 2015 at 4:33 PM, Thomas Kwan <thomas.kwan@manage.com>
> wrote:
>
>> Hi there,
>>
>> If we have multiple SELECTs going on for a table, will doing a "INSERT
>> OVERWRITE" to replace a partition break those SELECTs?
>>
>> thanks in advance
>>
>>
>

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<div dir=3D"ltr">Actually,=C2=A0<a href=3D"https://cwiki.apache.org/conflue=
nce/display/Hive/Configuration+Properties#ConfigurationProperties-hive.supp=
ort.concurrency">hive.support.concurrency</a>=C2=A0is false by default so y=
ou should set it to true for locking.</div><div class=3D"gmail_extra"><br c=
lear=3D"all"><div><div class=3D"gmail_signature"><div dir=3D"ltr">-- Lefty<=
/div></div></div>
<br><div class=3D"gmail_quote">On Fri, Apr 3, 2015 at 4:52 PM, Lefty Levere=
nz <span dir=3D"ltr">&lt;<a href=3D"mailto:leftyleverenz@gmail.com" target=
=3D"_blank">leftyleverenz@gmail.com</a>&gt;</span> wrote:<br><blockquote cl=
ass=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1px #ccc solid;p=
adding-left:1ex"><div dir=3D"ltr">I&#39;m no expert, but I don&#39;t think =
SELECTs are broken by an INSERT.=C2=A0 See=C2=A0<a href=3D"https://cwiki.ap=
ache.org/confluence/display/Hive/Locking" target=3D"_blank">Locking</a>=C2=
=A0for details.<div><br></div><div>As I understand it, the INSERT needs an =
exclusive lock on the partition which it cannot get while the partition has=
 a shared lock on it.<div><br></div><div>Can someone confirm or correct thi=
s?</div></div></div><div class=3D"gmail_extra"><span class=3D"HOEnZb"><font=
 color=3D"#888888"><br clear=3D"all"><div><div><div dir=3D"ltr">-- Lefty</d=
iv></div></div></font></span><div><div class=3D"h5">
<br><div class=3D"gmail_quote">On Fri, Apr 3, 2015 at 4:33 PM, Thomas Kwan =
<span dir=3D"ltr">&lt;<a href=3D"mailto:thomas.kwan@manage.com" target=3D"_=
blank">thomas.kwan@manage.com</a>&gt;</span> wrote:<br><blockquote class=3D=
"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1px #ccc solid;padding=
-left:1ex"><div dir=3D"ltr">Hi there,<div><br></div><div>If we have multipl=
e SELECTs going on for a table, will doing a &quot;INSERT OVERWRITE&quot; t=
o replace a partition break those SELECTs?</div><div><br></div><div>thanks =
in advance</div><div><br></div></div>
</blockquote></div><br></div></div></div>
</blockquote></div><br></div>

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