GitHub user DaveBirdsall opened a pull request:
https://github.com/apache/incubator-trafodion/pull/1043
[TRAFODION-25] Temporary code for UPDATE costing
This adds some temporary code for UPDATE costing.
The existing code returns a constant value for cost on all UPDATE
operations; it is a stub that was put in when the predecessor product was
ported to Hadoop and HBase. The temporary code is a copy of the costing code
for DELETE. It is being put in because we have an immediate need for parallel
UPDATE plans in a particular application, which you don't get with the current
stub.
This temporary code, of course, uses the DELETE theory of operation, which
understates the costs for UPDATE in general. So it is a stop-gap until better
code can be written.
To turn on this code, one must issue CQD HBASE_UPDATE_COSTING 'ON'. Without
this CQD, the old stub, a constant cost of 1, will be used.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/DaveBirdsall/incubator-trafodion Trafodion25u
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/incubator-trafodion/pull/1043.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #1043
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commit 55e65d2b2a65153c6d5ef58d994980795560f72f
Author: Dave Birdsall <[email protected]>
Date: 2017-04-03T20:15:46Z
[TRAFODION-25] Temporary code for UPDATE costing
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