## What changes were proposed in this pull request?
[HIVE-12063](https://issues.apache.org/jira/browse/HIVE-12063) improved pad decimal numbers with trailing zeros to the scale of the column. The following description is copied from the description of HIVE-12063.
> HIVE-7373 was to address the problems of trimming tailing zeros by Hive, which caused many problems including treating 0.0, 0.00 and so on as 0, which has different precision/scale. Please refer to HIVE-7373 description. However, HIVE-7373 was reverted by HIVE-8745 while the underlying problems remained. HIVE-11835 was resolved recently to address one of the problems, where 0.0, 0.00, and so on cannot be read into decimal(1,1).
However, HIVE-11835 didn't address the problem of showing as 0 in query result for any decimal values such as 0.0, 0.00, etc. This causes confusion as 0 and 0.0 have different precision/scale than 0.
The proposal here is to pad zeros for query result to the type's scale. This not only removes the confusion described above, but also aligns with many other DBs. Internal decimal number representation doesn't change, however.
**Spark SQL**:
```sql
// bin/spark-sql
spark-sql> select cast(1 as decimal(38, 18));
1
spark-sql>
// bin/beeline
0: jdbc:hive2://localhost:10000/default> select cast(1 as decimal(38, 18));
+----------------------------+--+
| CAST(1 AS DECIMAL(38,18)) |
+----------------------------+--+
| 1.000000000000000000 |
+----------------------------+--+
// bin/spark-shell
scala> spark.sql("select cast(1 as decimal(38, 18))").show(false)
+-------------------------+
|CAST(1 AS DECIMAL(38,18))|
+-------------------------+
|1.000000000000000000 |
+-------------------------+
// bin/pyspark
>>> spark.sql("select cast(1 as decimal(38, 18))").show()
+-------------------------+
|CAST(1 AS DECIMAL(38,18))|
+-------------------------+
| 1.000000000000000000|
+-------------------------+
// bin/sparkR
> showDF(sql("SELECT cast(1 as decimal(38, 18))"))
+-------------------------+
|CAST(1 AS DECIMAL(38,18))|
+-------------------------+
| 1.000000000000000000|
+-------------------------+
```
**PostgreSQL**:
```sql
postgres=# select cast(1 as decimal(38, 18));
numeric
----------------------
1.000000000000000000
(1 row)
```
**Presto**:
```sql
presto> select cast(1 as decimal(38, 18));
_col0
----------------------
1.000000000000000000
(1 row)
```
## How was this patch tested?
unit tests and manual test:
```sql
spark-sql> select cast(1 as decimal(38, 18));
1.000000000000000000
```
Spark SQL Upgrading Guide:
Closes#26697 from wangyum/SPARK-28461.
Authored-by: Yuming Wang <yumwang@ebay.com>
Signed-off-by: HyukjinKwon <gurwls223@apache.org>
## What changes were proposed in this pull request?
[HIVE-12063](https://issues.apache.org/jira/browse/HIVE-12063) improved pad decimal numbers with trailing zeros to the scale of the column. The following description is copied from the description of HIVE-12063.
> HIVE-7373 was to address the problems of trimming tailing zeros by Hive, which caused many problems including treating 0.0, 0.00 and so on as 0, which has different precision/scale. Please refer to HIVE-7373 description. However, HIVE-7373 was reverted by HIVE-8745 while the underlying problems remained. HIVE-11835 was resolved recently to address one of the problems, where 0.0, 0.00, and so on cannot be read into decimal(1,1).
However, HIVE-11835 didn't address the problem of showing as 0 in query result for any decimal values such as 0.0, 0.00, etc. This causes confusion as 0 and 0.0 have different precision/scale than 0.
The proposal here is to pad zeros for query result to the type's scale. This not only removes the confusion described above, but also aligns with many other DBs. Internal decimal number representation doesn't change, however.
**Spark SQL**:
```sql
// bin/spark-sql
spark-sql> select cast(1 as decimal(38, 18));
1
spark-sql>
// bin/beeline
0: jdbc:hive2://localhost:10000/default> select cast(1 as decimal(38, 18));
+----------------------------+--+
| CAST(1 AS DECIMAL(38,18)) |
+----------------------------+--+
| 1.000000000000000000 |
+----------------------------+--+
// bin/spark-shell
scala> spark.sql("select cast(1 as decimal(38, 18))").show(false)
+-------------------------+
|CAST(1 AS DECIMAL(38,18))|
+-------------------------+
|1.000000000000000000 |
+-------------------------+
// bin/pyspark
>>> spark.sql("select cast(1 as decimal(38, 18))").show()
+-------------------------+
|CAST(1 AS DECIMAL(38,18))|
+-------------------------+
| 1.000000000000000000|
+-------------------------+
// bin/sparkR
> showDF(sql("SELECT cast(1 as decimal(38, 18))"))
+-------------------------+
|CAST(1 AS DECIMAL(38,18))|
+-------------------------+
| 1.000000000000000000|
+-------------------------+
```
**PostgreSQL**:
```sql
postgres=# select cast(1 as decimal(38, 18));
numeric
----------------------
1.000000000000000000
(1 row)
```
**Presto**:
```sql
presto> select cast(1 as decimal(38, 18));
_col0
----------------------
1.000000000000000000
(1 row)
```
## How was this patch tested?
unit tests and manual test:
```sql
spark-sql> select cast(1 as decimal(38, 18));
1.000000000000000000
```
Spark SQL Upgrading Guide:
Closes#25214 from wangyum/SPARK-28461.
Authored-by: Yuming Wang <yumwang@ebay.com>
Signed-off-by: HyukjinKwon <gurwls223@apache.org>
### What changes were proposed in this pull request?
A java like string trim method trims all whitespaces that less or equal than 0x20. currently, our UTF8String handle the space =0x20 ONLY. This is not suitable for many cases in Spark, like trim for interval strings, date, timestamps, PostgreSQL like cast string to boolean.
### Why are the changes needed?
improve the white spaces handling in UTF8String, also with some bugs fixed
### Does this PR introduce any user-facing change?
yes,
string with `control character` at either end can be convert to date/timestamp and interval now
### How was this patch tested?
add ut
Closes#26626 from yaooqinn/SPARK-29986.
Authored-by: Kent Yao <yaooqinn@hotmail.com>
Signed-off-by: Wenchen Fan <wenchen@databricks.com>
### What changes were proposed in this pull request?
Modify `UTF8String.toInt/toLong` to support trim spaces for both sides before converting it to byte/short/int/long.
With this kind of "cheap" trim can help improve performance for casting string to integrals. The idea is from https://github.com/apache/spark/pull/24872#issuecomment-556917834
### Why are the changes needed?
make the behavior consistent.
### Does this PR introduce any user-facing change?
yes, cast string to an integral type, and binary comparison between string and integrals will trim spaces first. their behavior will be consistent with float and double.
### How was this patch tested?
1. add ut.
2. benchmark tests
the benchmark is modified based on https://github.com/apache/spark/pull/24872#issuecomment-503827016
```scala
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.spark.sql.execution.benchmark
import org.apache.spark.benchmark.Benchmark
/**
* Benchmark trim the string when casting string type to Boolean/Numeric types.
* To run this benchmark:
* {{{
* 1. without sbt:
* bin/spark-submit --class <this class> --jars <spark core test jar> <spark sql test jar>
* 2. build/sbt "sql/test:runMain <this class>"
* 3. generate result: SPARK_GENERATE_BENCHMARK_FILES=1 build/sbt "sql/test:runMain <this class>"
* Results will be written to "benchmarks/CastBenchmark-results.txt".
* }}}
*/
object CastBenchmark extends SqlBasedBenchmark {
This conversation was marked as resolved by yaooqinn
override def runBenchmarkSuite(mainArgs: Array[String]): Unit = {
val title = "Cast String to Integral"
runBenchmark(title) {
withTempPath { dir =>
val N = 500L << 14
val df = spark.range(N)
val types = Seq("int", "long")
(1 to 5).by(2).foreach { i =>
df.selectExpr(s"concat(id, '${" " * i}') as str")
.write.mode("overwrite").parquet(dir + i.toString)
}
val benchmark = new Benchmark(title, N, minNumIters = 5, output = output)
Seq(true, false).foreach { trim =>
types.foreach { t =>
val str = if (trim) "trim(str)" else "str"
val expr = s"cast($str as $t) as c_$t"
(1 to 5).by(2).foreach { i =>
benchmark.addCase(expr + s" - with $i spaces") { _ =>
spark.read.parquet(dir + i.toString).selectExpr(expr).collect()
}
}
}
}
benchmark.run()
}
}
}
}
```
#### benchmark result.
normal trim v.s. trim in toInt/toLong
```java
================================================================================================
Cast String to Integral
================================================================================================
Java HotSpot(TM) 64-Bit Server VM 1.8.0_231-b11 on Mac OS X 10.15.1
Intel(R) Core(TM) i5-5287U CPU 2.90GHz
Cast String to Integral: Best Time(ms) Avg Time(ms) Stdev(ms) Rate(M/s) Per Row(ns) Relative
------------------------------------------------------------------------------------------------------------------------
cast(trim(str) as int) as c_int - with 1 spaces 10220 12994 1337 0.8 1247.5 1.0X
cast(trim(str) as int) as c_int - with 3 spaces 4763 8356 357 1.7 581.4 2.1X
cast(trim(str) as int) as c_int - with 5 spaces 4791 8042 NaN 1.7 584.9 2.1X
cast(trim(str) as long) as c_long - with 1 spaces 4014 6755 NaN 2.0 490.0 2.5X
cast(trim(str) as long) as c_long - with 3 spaces 4737 6938 NaN 1.7 578.2 2.2X
cast(trim(str) as long) as c_long - with 5 spaces 4478 6919 1404 1.8 546.6 2.3X
cast(str as int) as c_int - with 1 spaces 4443 6222 NaN 1.8 542.3 2.3X
cast(str as int) as c_int - with 3 spaces 3659 3842 170 2.2 446.7 2.8X
cast(str as int) as c_int - with 5 spaces 4372 7996 NaN 1.9 533.7 2.3X
cast(str as long) as c_long - with 1 spaces 3866 5838 NaN 2.1 471.9 2.6X
cast(str as long) as c_long - with 3 spaces 3793 5449 NaN 2.2 463.0 2.7X
cast(str as long) as c_long - with 5 spaces 4947 5961 1198 1.7 603.9 2.1X
```
Closes#26622 from yaooqinn/cheapstringtrim.
Authored-by: Kent Yao <yaooqinn@hotmail.com>
Signed-off-by: Wenchen Fan <wenchen@databricks.com>
### What changes were proposed in this pull request?
remove the leading "interval" in `CalendarInterval.toString`.
### Why are the changes needed?
Although it's allowed to have "interval" prefix when casting string to int, it's not recommended.
This is also consistent with pgsql:
```
cloud0fan=# select interval '1' day;
interval
----------
1 day
(1 row)
```
### Does this PR introduce any user-facing change?
yes, when display a dataframe with interval type column, the result is different.
### How was this patch tested?
updated tests.
Closes#26401 from cloud-fan/interval.
Authored-by: Wenchen Fan <wenchen@databricks.com>
Signed-off-by: Wenchen Fan <wenchen@databricks.com>
### What changes were proposed in this pull request?
During creation of array, if CreateArray does not gets any children to set data type for array, it will create an array of null type .
### Why are the changes needed?
When empty array is created, it should be declared as array<null>.
### Does this PR introduce any user-facing change?
No
### How was this patch tested?
Tested manually
Closes#26324 from amanomer/29462.
Authored-by: Aman Omer <amanomer1996@gmail.com>
Signed-off-by: HyukjinKwon <gurwls223@apache.org>
### What changes were proposed in this pull request?
re-arrange the parser rules to make it clear that multiple unit TO unit statement like `SELECT INTERVAL '1-1' YEAR TO MONTH '2-2' YEAR TO MONTH` is not allowed.
### Why are the changes needed?
This is definitely an accident that we support such a weird syntax in the past. It's not supported by any other DBs and I can't think of any use case of it. Also no test covers this syntax in the current codebase.
### Does this PR introduce any user-facing change?
Yes, and a migration guide item is added.
### How was this patch tested?
new tests.
Closes#26285 from cloud-fan/syntax.
Authored-by: Wenchen Fan <wenchen@databricks.com>
Signed-off-by: Wenchen Fan <wenchen@databricks.com>
### What changes were proposed in this pull request?
This PR fixes the incorrect `EqualNullSafe` symbol in `sql-migration-guide.md`.
### Why are the changes needed?
Fix documentation error.
### Does this PR introduce any user-facing change?
No.
### How was this patch tested?
N/A
Closes#26163 from wangyum/EqualNullSafe-symbol.
Authored-by: Yuming Wang <yumwang@ebay.com>
Signed-off-by: Sean Owen <sean.owen@databricks.com>
### What changes were proposed in this pull request?
When inserting a value into a column with the different data type, Spark performs type coercion. Currently, we support 3 policies for the store assignment rules: ANSI, legacy and strict, which can be set via the option "spark.sql.storeAssignmentPolicy":
1. ANSI: Spark performs the type coercion as per ANSI SQL. In practice, the behavior is mostly the same as PostgreSQL. It disallows certain unreasonable type conversions such as converting `string` to `int` and `double` to `boolean`. It will throw a runtime exception if the value is out-of-range(overflow).
2. Legacy: Spark allows the type coercion as long as it is a valid `Cast`, which is very loose. E.g., converting either `string` to `int` or `double` to `boolean` is allowed. It is the current behavior in Spark 2.x for compatibility with Hive. When inserting an out-of-range value to a integral field, the low-order bits of the value is inserted(the same as Java/Scala numeric type casting). For example, if 257 is inserted to a field of Byte type, the result is 1.
3. Strict: Spark doesn't allow any possible precision loss or data truncation in store assignment, e.g., converting either `double` to `int` or `decimal` to `double` is allowed. The rules are originally for Dataset encoder. As far as I know, no mainstream DBMS is using this policy by default.
Currently, the V1 data source uses "Legacy" policy by default, while V2 uses "Strict". This proposal is to use "ANSI" policy by default for both V1 and V2 in Spark 3.0.
### Why are the changes needed?
Following the ANSI SQL standard is most reasonable among the 3 policies.
### Does this PR introduce any user-facing change?
Yes.
The default store assignment policy is ANSI for both V1 and V2 data sources.
### How was this patch tested?
Unit test
Closes#26107 from gengliangwang/ansiPolicyAsDefault.
Authored-by: Gengliang Wang <gengliang.wang@databricks.com>
Signed-off-by: Dongjoon Hyun <dhyun@apple.com>
### What changes were proposed in this pull request?
The commit 4e6d31f570 changed default behavior of `size()` for the `NULL` input. In this PR, I propose to update the SQL migration guide.
### Why are the changes needed?
To inform users about new behavior of the `size()` function for the `NULL` input.
### Does this PR introduce any user-facing change?
No
### How was this patch tested?
N/A
Closes#26066 from MaxGekk/size-null-migration-guide.
Authored-by: Maxim Gekk <max.gekk@gmail.com>
Signed-off-by: Wenchen Fan <wenchen@databricks.com>
### What changes were proposed in this pull request?
Updated the SQL migration guide regarding to recently supported special date and timestamp values, see https://github.com/apache/spark/pull/25716 and https://github.com/apache/spark/pull/25708.
Closes#25834
### Why are the changes needed?
To let users know about new feature in Spark 3.0.
### Does this PR introduce any user-facing change?
No
Closes#25948 from MaxGekk/special-values-migration-guide.
Authored-by: Maxim Gekk <max.gekk@gmail.com>
Signed-off-by: Dongjoon Hyun <dhyun@apple.com>
### What changes were proposed in this pull request?
Currently, there is no migration section for PySpark, SparkCore and Structured Streaming.
It is difficult for users to know what to do when they upgrade.
This PR proposes to create create a "Migration Guide" tap at Spark documentation.
This page will contain migration guides for Spark SQL, PySpark, SparkR, MLlib, Structured Streaming and Core. Basically it is a refactoring.
There are some new information added, which I will leave a comment inlined for easier review.
1. **MLlib**
Merge [ml-guide.html#migration-guide](https://spark.apache.org/docs/latest/ml-guide.html#migration-guide) and [ml-migration-guides.html](https://spark.apache.org/docs/latest/ml-migration-guides.html)
```
'docs/ml-guide.md'
↓ Merge new/old migration guides
'docs/ml-migration-guide.md'
```
2. **PySpark**
Extract PySpark specific items from https://spark.apache.org/docs/latest/sql-migration-guide-upgrade.html
```
'docs/sql-migration-guide-upgrade.md'
↓ Extract PySpark specific items
'docs/pyspark-migration-guide.md'
```
3. **SparkR**
Move [sparkr.html#migration-guide](https://spark.apache.org/docs/latest/sparkr.html#migration-guide) into a separate file, and extract from [sql-migration-guide-upgrade.html](https://spark.apache.org/docs/latest/sql-migration-guide-upgrade.html)
```
'docs/sparkr.md' 'docs/sql-migration-guide-upgrade.md'
Move migration guide section ↘ ↙ Extract SparkR specific items
docs/sparkr-migration-guide.md
```
4. **Core**
Newly created at `'docs/core-migration-guide.md'`. I skimmed resolved JIRAs at 3.0.0 and found some items to note.
5. **Structured Streaming**
Newly created at `'docs/ss-migration-guide.md'`. I skimmed resolved JIRAs at 3.0.0 and found some items to note.
6. **SQL**
Merged [sql-migration-guide-upgrade.html](https://spark.apache.org/docs/latest/sql-migration-guide-upgrade.html) and [sql-migration-guide-hive-compatibility.html](https://spark.apache.org/docs/latest/sql-migration-guide-hive-compatibility.html)
```
'docs/sql-migration-guide-hive-compatibility.md' 'docs/sql-migration-guide-upgrade.md'
Move Hive compatibility section ↘ ↙ Left over after filtering PySpark and SparkR items
'docs/sql-migration-guide.md'
```
### Why are the changes needed?
In order for users in production to effectively migrate to higher versions, and detect behaviour or breaking changes before upgrading and/or migrating.
### Does this PR introduce any user-facing change?
Yes, this changes Spark's documentation at https://spark.apache.org/docs/latest/index.html.
### How was this patch tested?
Manually build the doc. This can be verified as below:
```bash
cd docs
SKIP_API=1 jekyll build
open _site/index.html
```
Closes#25757 from HyukjinKwon/migration-doc.
Authored-by: HyukjinKwon <gurwls223@apache.org>
Signed-off-by: Dongjoon Hyun <dhyun@apple.com>
## What changes were proposed in this pull request?
Add AL2 license to metadata of all .md files.
This seemed to be the tidiest way as it will get ignored by .md renderers and other tools. Attempts to write them as markdown comments revealed that there is no such standard thing.
## How was this patch tested?
Doc build
Closes#24243 from srowen/SPARK-26918.
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?
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>
