spark-instrumented-optimizer/data
WeichenXu 925449283d [SPARK-22666][ML][SQL] Spark datasource for image format
## What changes were proposed in this pull request?

Implement an image schema datasource.

This image datasource support:
  - partition discovery (loading partitioned images)
  - dropImageFailures (the same behavior with `ImageSchema.readImage`)
  - path wildcard matching (the same behavior with `ImageSchema.readImage`)
  - loading recursively from directory (different from `ImageSchema.readImage`, but use such path: `/path/to/dir/**`)

This datasource **NOT** support:
  - specify `numPartitions` (it will be determined by datasource automatically)
  - sampling (you can use `df.sample` later but the sampling operator won't be pushdown to datasource)

## How was this patch tested?
Unit tests.

## Benchmark
I benchmark and compare the cost time between old `ImageSchema.read` API and my image datasource.

**cluster**: 4 nodes, each with 64GB memory, 8 cores CPU
**test dataset**: Flickr8k_Dataset (about 8091 images)

**time cost**:
- My image datasource time (automatically generate 258 partitions):  38.04s
- `ImageSchema.read` time (set 16 partitions): 68.4s
- `ImageSchema.read` time (set 258 partitions):  90.6s

**time cost when increase image number by double (clone Flickr8k_Dataset and loads double number images)**:
- My image datasource time (automatically generate 515 partitions):  95.4s
- `ImageSchema.read` (set 32 partitions): 109s
- `ImageSchema.read` (set 515 partitions):  105s

So we can see that my image datasource implementation (this PR) bring some performance improvement compared against old`ImageSchema.read` API.

Closes #22328 from WeichenXu123/image_datasource.

Authored-by: WeichenXu <weichen.xu@databricks.com>
Signed-off-by: Xiangrui Meng <meng@databricks.com>
2018-09-05 11:59:00 -07:00
..
graphx [GRAPHX][EXAMPLES] move graphx test data directory and update graphx document 2016-07-02 08:40:23 +01:00
mllib [SPARK-22666][ML][SQL] Spark datasource for image format 2018-09-05 11:59:00 -07:00
streaming [SPARK-9057][STREAMING] Twitter example joining to static RDD of word sentiment values 2015-12-18 15:06:54 +00:00