GitHub user xuanyuanking opened a pull request:
https://github.com/apache/spark/pull/14957
[SPARK-4502][SQL]Support parquet nested struct pruning and add relevaâ¦
## What changes were proposed in this pull request?
Like the description in
[SPARK-4502](https://issues.apache.org/jira/browse/SPARK-4502), we have the
same problem in Baidu and our user's parquet file has complex nested parquet
struct(400+ fields and 4 layer nested) so this problem brings unnecessary data
read and time spend. This pr fixed the problem and main fix ideas list as
follows:
1. Add booleanConf `spark.sql.parquet.nestColumnPruning`, when itâs
closed, same logical with before
2. In `FileSourceStrategy`, traverse `projects[NamedExpression]` and
generate a map which key is attributeName, value is a Seq[String] of
corresponding nested fields.
For example: [âpeopleâ -> (âpeople.ageâ, âpeople.addr.cityâ)]
3. Replace the attributeName in origin requiredColumns.
For example: origin requiredColumns is [âpeopleâ, âconsumeâ],
replace it to [âpeople.ageâ, âpeople.addr.cityâ, âconsumeâ]
4. Merge structType of fields in same structType and merge filter attributes
For example: the json format of struct type [âpeople.addr.cityâ,
âpeople.addr.zip_codeâ] will merge to [âpeople.addr.[city,zip_code]â]
5. `StructType.apply` read the columns contains â.â Recursively
## How was this patch tested?
add new test in `ParquetQuerySuite`
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/xuanyuanking/spark SPARK-4502
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/spark/pull/14957.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 #14957
----
commit 7eaa4287a5c112a192cca388863324ffd855203e
Author: liyuanjian <[email protected]>
Date: 2016-09-05T08:27:02Z
[SPARK-4502][SQL]Support parquet nested struct pruning and add relevant
tests
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