776f299fc8
## What changes were proposed in this pull request?
In the PR, I propose to add new function - *schema_of_json()* which infers schema of JSON string literal. The result of the function is a string containing a schema in DDL format.
One of the use cases is using of *schema_of_json()* in the combination with *from_json()*. Currently, _from_json()_ requires a schema as a mandatory argument. The *schema_of_json()* function will allow to point out an JSON string as an example which has the same schema as the first argument of _from_json()_. For instance:
```sql
select from_json(json_column, schema_of_json('{"c1": [0], "c2": [{"c3":0}]}'))
from json_table;
```
## How was this patch tested?
Added new test to `JsonFunctionsSuite`, `JsonExpressionsSuite` and SQL tests to `json-functions.sql`
Author: Maxim Gekk <maxim.gekk@databricks.com>
Closes #21686 from MaxGekk/infer_schema_json.
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| .. | ||
| catalyst | ||
| core | ||
| hive | ||
| hive-thriftserver | ||
| create-docs.sh | ||
| gen-sql-markdown.py | ||
| mkdocs.yml | ||
| README.md | ||
Spark SQL
This module provides support for executing relational queries expressed in either SQL or the DataFrame/Dataset API.
Spark SQL is broken up into four subprojects:
- Catalyst (sql/catalyst) - An implementation-agnostic framework for manipulating trees of relational operators and expressions.
- Execution (sql/core) - A query planner / execution engine for translating Catalyst's logical query plans into Spark RDDs. This component also includes a new public interface, SQLContext, that allows users to execute SQL or LINQ statements against existing RDDs and Parquet files.
- Hive Support (sql/hive) - Includes an extension of SQLContext called HiveContext that allows users to write queries using a subset of HiveQL and access data from a Hive Metastore using Hive SerDes. There are also wrappers that allow users to run queries that include Hive UDFs, UDAFs, and UDTFs.
- HiveServer and CLI support (sql/hive-thriftserver) - Includes support for the SQL CLI (bin/spark-sql) and a HiveServer2 (for JDBC/ODBC) compatible server.
Running sql/create-docs.sh generates SQL documentation for built-in functions under sql/site.