NOLOCK option in Vertica

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debfawn
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NOLOCK option in Vertica

Post by debfawn » Wed Jul 10, 2013 2:25 pm

Hey guys,

I have a bunch of queries I need to convert from SQL Server. The queries have a NOLOCK option on each table which is supposed to improve concurrency on a busy system...

Can I do this in Vertica? Is it necessary?

Thank you,
Deb

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nnani
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Re: NOLOCK option in Vertica

Post by nnani » Thu Jul 11, 2013 7:54 am

Hello,

Vertica support read commited isolation level on its table by defauls.
This means only the latest commited data will be read in your select statements(queries).
This allows new data to be loaded while concurrent queries are running.
Also, Vertica has no option matching NOLOCK and Vertica uses shared lock for select operations by default.
So this should not affect the perfomance if you don't mention it in your queries.
nnani........
Long way to go

You can check out my blogs at vertica-howto

debfawn
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Re: NOLOCK option in Vertica

Post by debfawn » Thu Jul 11, 2013 12:50 pm

Thank you, nnani!

So I'll just remove all the NOLOCK commands from my scripts.

Cool.

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