What Happens when using Direct Option in Copy , Insert, Update Command

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vigneshn
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What Happens when using Direct Option in Copy , Insert, Update Command

Post by vigneshn » Sat Mar 07, 2015 3:02 pm

In Document it says Direct options allows data to be moved directly to WOS [ Secondary storage]. But How does it happen during processing. Sorry if I am wrong, According to the computer knowledge I have gained, the data cannot directly move to harddisk without passing main memory. If that is the case then what really happens when using Direct options. Please help me understand

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JimKnicely
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Re: What Happens when using Direct Option in Copy , Insert, Update Command

Post by JimKnicely » Sun Mar 08, 2015 5:08 pm

Hi,

There is a resource pool named WOSDATA that is set up in main memory specifically to hold projection data prior to being written to disk. The default size is 2 GB.

Code: Select all

dbadmin=> select name, memorysize, maxmemorysize from resource_pools where name = 'wosdata';
  name   | memorysize | maxmemorysize
---------+------------+---------------
 wosdata | 2G         | 2G
(1 row)
I'd imagine that data would have to pass through the host's main memory modules via the Vertica process in some manner, but it won't be placed the the special WOS area.
Jim Knicely

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Note: I work for HPE. My views, opinions, and thoughts expressed here do not represent those of my employer.

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