39a0493387
## What changes were proposed in this pull request?
**1. Document `from_csv(..., schema_of_csv(...))` support:**
```R
csv <- "Amsterdam,2018"
df <- sql(paste0("SELECT '", csv, "' as csv"))
head(select(df, from_csv(df$csv, schema_of_csv(csv))))
```
```
from_csv(csv)
1 Amsterdam, 2018
```
**2. Allow `from_json(..., schema_of_json(...))`**
Before:
```R
df2 <- sql("SELECT named_struct('name', 'Bob') as people")
df2 <- mutate(df2, people_json = to_json(df2$people))
head(select(df2, from_json(df2$people_json, schema_of_json(head(df2)$people_json))))
```
```
Error in (function (classes, fdef, mtable) :
unable to find an inherited method for function ‘from_json’ for signature ‘"Column", "Column"’
```
After:
```R
df2 <- sql("SELECT named_struct('name', 'Bob') as people")
df2 <- mutate(df2, people_json = to_json(df2$people))
head(select(df2, from_json(df2$people_json, schema_of_json(head(df2)$people_json))))
```
```
from_json(people_json)
1 Bob
```
**3. (While I'm here) Allow `structType` as schema for `from_csv` support to match with `from_json`.**
Before:
```R
csv <- "Amsterdam,2018"
df <- sql(paste0("SELECT '", csv, "' as csv"))
head(select(df, from_csv(df$csv, structType("city STRING, year INT"))))
```
```
Error in (function (classes, fdef, mtable) :
unable to find an inherited method for function ‘from_csv’ for signature ‘"Column", "structType"’
```
After:
```R
csv <- "Amsterdam,2018"
df <- sql(paste0("SELECT '", csv, "' as csv"))
head(select(df, from_csv(df$csv, structType("city STRING, year INT"))))
```
```
from_csv(csv)
1 Amsterdam, 2018
```
## How was this patch tested?
Manually tested and unittests were added.
Closes #23184 from HyukjinKwon/SPARK-26227-1.
Authored-by: Hyukjin Kwon <gurwls223@apache.org>
Signed-off-by: Hyukjin Kwon <gurwls223@apache.org>
|
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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.