GitHub user parthchandra opened a pull request:
https://github.com/apache/drill/pull/254
DRILL-4053: Reduce metadata cache file size. Save a merged schema insâ¦
â¦tead of
repeating for every row group. Save maxValue in a row group iff minVal
equals maxVal and null otherwise.
This patch has the following changes to reduce the size of a metadata cache
file. -
1) Do not write the schema for every row group. Instead merge the schemas
and keep only one copy. This change currently does not handle the case where
the type of a field mutates.
2) Instead of min and max values for every field, we keep only the max
value and that too only if the min and max values are equal. This allows
partition pruning to occur correctly.
3) Use the Jackson afterburner module to deserialize faster
4) Use a string array instead of SchemaPath for simpler deserialization.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/parthchandra/incubator-drill DRILL-4053
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/drill/pull/254.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 #254
----
commit 3ff4a9f3e5b106066563481bf6af7a6b573bafe5
Author: Parth Chandra <[email protected]>
Date: 2015-10-29T01:24:16Z
DRILL-4053: Reduce metadata cache file size. Save a merged schema instead of
repeating for every row group. Save maxValue in a row group iff minVal
equals maxVal and null otherwise.
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