GitHub user davies opened a pull request:
https://github.com/apache/spark/pull/11437
[SPARK-13582] [SQL] defer dictionary decoding in parquet reader
## What changes were proposed in this pull request?
This PR defer the resolution from a id of dictionary to value until the
column is actually accessed (inside getInt/getLong), this is very useful for
those columns and rows that are filtered out. It's also useful for binary type,
we will not need to copy all the byte arrays.
## How was this patch tested?
Manually test TPCDS Q7 with scale factor 10, saw about 30% improvements
(after PR #11274).
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/davies/spark decode_dict
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/spark/pull/11437.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 #11437
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commit 6676e746b887730eadf9cca297ede4cff7a0de2f
Author: Davies Liu <[email protected]>
Date: 2016-02-29T23:08:52Z
defer dictionary decoding
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