[GitHub] spark pull request #14957: [SPARK-4502][SQL]Support parquet nested struct pr...

[xuanyuanking]

GitHub user xuanyuanking opened a pull request:

    https://github.com/apache/spark/pull/14957

    [SPARK-4502][SQL]Support parquet nested struct pruning and add releva…

    ## 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 it’s 
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:  [“people” -> (“people.age”, “people.addr.city”)] 
    
    3. Replace the attributeName in origin requiredColumns.
    For example:  origin requiredColumns is [“people”, “consume”], 
replace it to [“people.age”, “people.addr.city”, “consume”]
    
    4. Merge structType of fields in same structType and merge filter attributes
    For example:  the json format of struct type [“people.addr.city”, 
“people.addr.zip_code”] will merge to [“people.addr.[city,zip_code]”]
    
    5.  `StructType.apply` read the columns contains “.” 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 <liyuanj...@baidu.com>
Date:   2016-09-05T08:27:02Z

    [SPARK-4502][SQL]Support parquet nested struct pruning and add relevant 
tests

----


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