## What changes were proposed in this pull request?
Due to implementation limitation, currently Spark can't compare or do equality check between map types. As a result, map values can't appear in EQUAL or comparison expressions, can't be grouping key, etc.
The more important thing is, map loop up needs to do equality check of the map key, and thus can't support map as map key when looking up values from a map. Thus it's not useful to have map as map key.
This PR proposes to stop users from creating maps using map type as key. The list of expressions that are updated: `CreateMap`, `MapFromArrays`, `MapFromEntries`, `MapConcat`, `TransformKeys`. I manually checked all the places that create `MapType`, and came up with this list.
Note that, maps with map type key still exist, via reading from parquet files, converting from scala/java map, etc. This PR is not to completely forbid map as map key, but to avoid creating it by Spark itself.
Motivation: when I was trying to fix the duplicate key problem, I found it's impossible to do it with map type map key. I think it's reasonable to avoid map type map key for builtin functions.
## How was this patch tested?
updated test
Closes#23045 from cloud-fan/map-key.
Authored-by: Wenchen Fan <wenchen@databricks.com>
Signed-off-by: Wenchen Fan <wenchen@databricks.com>
## What changes were proposed in this pull request?
Fix typos and misspellings, per https://github.com/apache/spark-website/pull/158#issuecomment-435790366
## How was this patch tested?
Existing tests.
Closes#22950 from srowen/Typos.
Authored-by: Sean Owen <sean.owen@databricks.com>
Signed-off-by: Sean Owen <sean.owen@databricks.com>
## What changes were proposed in this pull request?
Add note about AddJar return value change in migration guide
## How was this patch tested?
n/a
Closes#22826 from srowen/SPARK-25760.2.
Authored-by: Sean Owen <sean.owen@databricks.com>
Signed-off-by: Sean Owen <sean.owen@databricks.com>
## What changes were proposed in this pull request?
Since Spark 2.2, view definitions are stored in a different way from prior versions. This may cause Spark unable to read views created by prior versions. See [SPARK-25797](https://issues.apache.org/jira/browse/SPARK-25797) for more details.
Basically, we have 2 options.
1) Make Spark 2.2+ able to get older view definitions back. Since the expanded text is buggy and unusable, we have to use original text (this is possible with [SPARK-25459](https://issues.apache.org/jira/browse/SPARK-25459)). However, because older Spark versions don't save the context for the database, we cannot always get correct view definitions without view default database.
2) Recreate the views by `ALTER VIEW AS` or `CREATE OR REPLACE VIEW AS`.
This PR aims to add migration doc to help users troubleshoot this issue by above option 2.
## How was this patch tested?
N/A.
Docs are generated and checked locally
```
cd docs
SKIP_API=1 jekyll serve --watch
```
Closes#22846 from seancxmao/SPARK-25797.
Authored-by: seancxmao <seancxmao@gmail.com>
Signed-off-by: Wenchen Fan <wenchen@databricks.com>
## What changes were proposed in this pull request?
In the PR, I propose to switch `from_json` on `FailureSafeParser`, and to make the function compatible to `PERMISSIVE` mode by default, and to support the `FAILFAST` mode as well. The `DROPMALFORMED` mode is not supported by `from_json`.
## How was this patch tested?
It was tested by existing `JsonSuite`/`CSVSuite`, `JsonFunctionsSuite` and `JsonExpressionsSuite` as well as new tests for `from_json` which checks different modes.
Closes#22237 from MaxGekk/from_json-failuresafe.
Lead-authored-by: Maxim Gekk <maxim.gekk@databricks.com>
Co-authored-by: hyukjinkwon <gurwls223@apache.org>
Signed-off-by: Wenchen Fan <wenchen@databricks.com>
## What changes were proposed in this pull request?
This takes over original PR at #22019. The original proposal is to have null for float and double types. Later a more reasonable proposal is to disallow empty strings. This patch adds logic to throw exception when finding empty strings for non string types.
## How was this patch tested?
Added test.
Closes#22787 from viirya/SPARK-25040.
Authored-by: Liang-Chi Hsieh <viirya@gmail.com>
Signed-off-by: hyukjinkwon <gurwls223@apache.org>
## What changes were proposed in this pull request?
1. Split the main page of sql-programming-guide into 7 parts:
- Getting Started
- Data Sources
- Performance Turing
- Distributed SQL Engine
- PySpark Usage Guide for Pandas with Apache Arrow
- Migration Guide
- Reference
2. Add left menu for sql-programming-guide, keep first level index for each part in the menu.
## How was this patch tested?
Local test with jekyll build/serve.
Closes#22746 from xuanyuanking/SPARK-24499.
Authored-by: Yuanjian Li <xyliyuanjian@gmail.com>
Signed-off-by: gatorsmile <gatorsmile@gmail.com>
