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new b0548c6 [SPARK-37165][SQL] Add REPEATABLE in TABLESAMPLE to specify
seed
b0548c6 is described below
commit b0548c66672b54dfa82914c09caa581e0ff33947
Author: Huaxin Gao <huaxin_...@apple.com>
AuthorDate: Sat Oct 30 09:27:11 2021 -0700
[SPARK-37165][SQL] Add REPEATABLE in TABLESAMPLE to specify seed
### What changes were proposed in this pull request?
Add REPEATABLE in SQL syntax TABLESAMPLE so user can specify seed.
### Why are the changes needed?
Current syntax for TABLESAMPLE:
- TABLESAMPLE(x PERCENT)
- TABLESAMPLE(BUCKET x OUT OF y)
`Dataset.sample` has a param to specify seed, so we should allow SQL has a
way to specify seed too.
```
def sample(fraction: Double, seed: Long): Dataset[T] = {
sample(withReplacement = false, fraction = fraction, seed = seed)
}
```
Most of the DBMS uses REPEATABLE to let user specify seed, e.g. DB2, we
will follow the same way.
<img width="1032" alt="Screen Shot 2021-10-29 at 8 46 04 AM"
src="https://user-images.githubusercontent.com/13592258/139465718-285ab5fb-a9cf-4bef-bc32-88301745b12b.png";>
### Does this PR introduce _any_ user-facing change?
Yes
new SQL syntax
- TABLESAMPLE(x PERCENT) [REPEATABLE (seed)]
- TABLESAMPLE(BUCKET x OUT OF y) [REPEATABLE (seed)]
### How was this patch tested?
new UT
Closes #34442 from huaxingao/sample_syntax.
Authored-by: Huaxin Gao <huaxin_...@apple.com>
Signed-off-by: Huaxin Gao <huaxin_...@apple.com>
---
docs/sql-ref-ansi-compliance.md | 1 +
.../org/apache/spark/sql/catalyst/parser/SqlBase.g4 | 5 ++++-
.../spark/sql/catalyst/parser/AstBuilder.scala | 21 ++++++++++++++-------
.../scala/org/apache/spark/sql/SQLQuerySuite.scala | 16 ++++++++++++++++
4 files changed, 35 insertions(+), 8 deletions(-)
diff --git a/docs/sql-ref-ansi-compliance.md b/docs/sql-ref-ansi-compliance.md
index 4527faa..2de8ba7 100644
--- a/docs/sql-ref-ansi-compliance.md
+++ b/docs/sql-ref-ansi-compliance.md
@@ -493,6 +493,7 @@ Below is a list of all the keywords in Spark SQL.
|REGEXP|non-reserved|non-reserved|not a keyword|
|RENAME|non-reserved|non-reserved|non-reserved|
|REPAIR|non-reserved|non-reserved|non-reserved|
+|REPEATABLE|non-reserved|non-reserved|non-reserved|
|REPLACE|non-reserved|non-reserved|non-reserved|
|RESET|non-reserved|non-reserved|non-reserved|
|RESPECT|non-reserved|non-reserved|non-reserved|
diff --git
a/sql/catalyst/src/main/antlr4/org/apache/spark/sql/catalyst/parser/SqlBase.g4
b/sql/catalyst/src/main/antlr4/org/apache/spark/sql/catalyst/parser/SqlBase.g4
index 32b080c..e1bccf6 100644
---
a/sql/catalyst/src/main/antlr4/org/apache/spark/sql/catalyst/parser/SqlBase.g4
+++
b/sql/catalyst/src/main/antlr4/org/apache/spark/sql/catalyst/parser/SqlBase.g4
@@ -674,7 +674,7 @@ joinCriteria
;
sample
- : TABLESAMPLE '(' sampleMethod? ')'
+ : TABLESAMPLE '(' sampleMethod? ')' (REPEATABLE '('seed=INTEGER_VALUE')')?
;
sampleMethod
@@ -1194,6 +1194,7 @@ ansiNonReserved
| REFRESH
| RENAME
| REPAIR
+ | REPEATABLE
| REPLACE
| RESET
| RESPECT
@@ -1460,6 +1461,7 @@ nonReserved
| REFRESH
| RENAME
| REPAIR
+ | REPEATABLE
| REPLACE
| RESET
| RESPECT
@@ -1726,6 +1728,7 @@ REFERENCES: 'REFERENCES';
REFRESH: 'REFRESH';
RENAME: 'RENAME';
REPAIR: 'REPAIR';
+REPEATABLE: 'REPEATABLE';
REPLACE: 'REPLACE';
RESET: 'RESET';
RESPECT: 'RESPECT';
diff --git
a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/parser/AstBuilder.scala
b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/parser/AstBuilder.scala
index 768d406..722a055 100644
---
a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/parser/AstBuilder.scala
+++
b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/parser/AstBuilder.scala
@@ -1174,13 +1174,14 @@ class AstBuilder extends SqlBaseBaseVisitor[AnyRef]
with SQLConfHelper with Logg
*
* This currently supports the following sampling methods:
* - TABLESAMPLE(x ROWS): Sample the table down to the given number of rows.
- * - TABLESAMPLE(x PERCENT): Sample the table down to the given percentage.
Note that percentages
- * are defined as a number between 0 and 100.
- * - TABLESAMPLE(BUCKET x OUT OF y): Sample the table down to a 'x' divided
by 'y' fraction.
+ * - TABLESAMPLE(x PERCENT) [REPEATABLE (y)]: Sample the table down to the
given percentage with
+ * seed 'y'. Note that percentages are defined as a number between 0 and 100.
+ * - TABLESAMPLE(BUCKET x OUT OF y) [REPEATABLE (z)]: Sample the table down
to a 'x' divided by
+ * 'y' fraction with seed 'z'.
*/
private def withSample(ctx: SampleContext, query: LogicalPlan): LogicalPlan
= withOrigin(ctx) {
// Create a sampled plan if we need one.
- def sample(fraction: Double): Sample = {
+ def sample(fraction: Double, seed: Long): Sample = {
// The range of fraction accepted by Sample is [0, 1]. Because Hive's
block sampling
// function takes X PERCENT as the input and the range of X is [0, 100],
we need to
// adjust the fraction.
@@ -1188,13 +1189,19 @@ class AstBuilder extends SqlBaseBaseVisitor[AnyRef]
with SQLConfHelper with Logg
validate(fraction >= 0.0 - eps && fraction <= 1.0 + eps,
s"Sampling fraction ($fraction) must be on interval [0, 1]",
ctx)
- Sample(0.0, fraction, withReplacement = false, (math.random *
1000).toInt, query)
+ Sample(0.0, fraction, withReplacement = false, seed, query)
}
if (ctx.sampleMethod() == null) {
throw QueryParsingErrors.emptyInputForTableSampleError(ctx)
}
+ val seed = if (ctx.seed != null) {
+ ctx.seed.getText.toLong
+ } else {
+ (math.random * 1000).toLong
+ }
+
ctx.sampleMethod() match {
case ctx: SampleByRowsContext =>
Limit(expression(ctx.expression), query)
@@ -1202,7 +1209,7 @@ class AstBuilder extends SqlBaseBaseVisitor[AnyRef] with
SQLConfHelper with Logg
case ctx: SampleByPercentileContext =>
val fraction = ctx.percentage.getText.toDouble
val sign = if (ctx.negativeSign == null) 1 else -1
- sample(sign * fraction / 100.0d)
+ sample(sign * fraction / 100.0d, seed)
case ctx: SampleByBytesContext =>
val bytesStr = ctx.bytes.getText
@@ -1222,7 +1229,7 @@ class AstBuilder extends SqlBaseBaseVisitor[AnyRef] with
SQLConfHelper with Logg
}
case ctx: SampleByBucketContext =>
- sample(ctx.numerator.getText.toDouble /
ctx.denominator.getText.toDouble)
+ sample(ctx.numerator.getText.toDouble /
ctx.denominator.getText.toDouble, seed)
}
}
diff --git a/sql/core/src/test/scala/org/apache/spark/sql/SQLQuerySuite.scala
b/sql/core/src/test/scala/org/apache/spark/sql/SQLQuerySuite.scala
index 11b7ee6..0b8e10c 100644
--- a/sql/core/src/test/scala/org/apache/spark/sql/SQLQuerySuite.scala
+++ b/sql/core/src/test/scala/org/apache/spark/sql/SQLQuerySuite.scala
@@ -4211,6 +4211,22 @@ class SQLQuerySuite extends QueryTest with
SharedSparkSession with AdaptiveSpark
sql("SELECT * FROM testData, LATERAL (SELECT * FROM testData)").collect()
}
}
+
+ test("TABLE SAMPLE") {
+ withTable("test") {
+ sql("CREATE TABLE test(c int) USING PARQUET")
+ for (i <- 0 to 20) {
+ sql(s"INSERT INTO test VALUES ($i)")
+ }
+ val df1 = sql("SELECT * FROM test TABLESAMPLE (20 PERCENT) REPEATABLE
(12345)")
+ val df2 = sql("SELECT * FROM test TABLESAMPLE (20 PERCENT) REPEATABLE
(12345)")
+ checkAnswer(df1, df2)
+
+ val df3 = sql("SELECT * FROM test TABLESAMPLE (BUCKET 4 OUT OF 10)
REPEATABLE (6789)")
+ val df4 = sql("SELECT * FROM test TABLESAMPLE (BUCKET 4 OUT OF 10)
REPEATABLE (6789)")
+ checkAnswer(df3, df4)
+ }
+ }
}
case class Foo(bar: Option[String])
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