Correct fetchsize property name in docs

## What changes were proposed in this pull request?

Replace `fetchSize` with `fetchsize` in the docs.

## How was this patch tested?

I manually tested `fetchSize` and `fetchsize`. The latter has an effect. See also [`JdbcUtils.scala#L38`](https://github.com/apache/spark/blob/v2.0.0/sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/jdbc/JdbcUtils.scala#L38) for the definition of the property.

Author: Daniel Darabos <darabos.daniel@gmail.com>

Closes #14975 from darabos/patch-3.

1 files changed, 3 insertions, 3 deletions

diff --git a/sql/core/src/test/scala/org/apache/spark/sql/jdbc/JDBCSuite.scala b/sql/core/src/test/scala/org/apache/spark/sql/jdbc/JDBCSuite.scala
index 2d8ee338a9..10f15ca280 100644
--- a/sql/core/src/test/scala/org/apache/spark/sql/jdbc/JDBCSuite.scala
+++ b/sql/core/src/test/scala/org/apache/spark/sql/jdbc/JDBCSuite.scala
@@ -289,7 +289,7 @@ class JDBCSuite extends SparkFunSuite
     assert(names(2).equals("mary"))
   }
 
-  test("SELECT first field when fetchSize is two") {
+  test("SELECT first field when fetchsize is two") {
     val names = sql("SELECT NAME FROM fetchtwo").collect().map(x => x.getString(0)).sortWith(_ < _)
     assert(names.size === 3)
     assert(names(0).equals("fred"))
@@ -305,7 +305,7 @@ class JDBCSuite extends SparkFunSuite
     assert(ids(2) === 3)
   }
 
-  test("SELECT second field when fetchSize is two") {
+  test("SELECT second field when fetchsize is two") {
     val ids = sql("SELECT THEID FROM fetchtwo").collect().map(x => x.getInt(0)).sortWith(_ < _)
     assert(ids.size === 3)
     assert(ids(0) === 1)
@@ -352,7 +352,7 @@ class JDBCSuite extends SparkFunSuite
       urlWithUserAndPass, "TEST.PEOPLE", new Properties()).collect().length === 3)
   }
 
-  test("Basic API with illegal FetchSize") {
+  test("Basic API with illegal fetchsize") {
     val properties = new Properties()
     properties.setProperty(JdbcUtils.JDBC_BATCH_FETCH_SIZE, "-1")
     val e = intercept[SparkException] {