[SPARK-49843][SQL] Fix change comment on char/varchar columns
### What changes were proposed in this pull request?
Fix the issue in `AlterTableChangeColumnCommand` where changing the comment of a char/varchar column also tries to change the column type to string.
### Why are the changes needed?
Because the newColumn will always be a `StringType` even when the metadata says that it was originally char/varchar.
### Does this PR introduce _any_ user-facing change?
Yes, the query will no longer fail when using this code path.
### How was this patch tested?
New query in golden files.
### Was this patch authored or co-authored using generative AI tooling?
No.
Closes #48315 from stefankandic/fixAlterVarcharCol.
Authored-by: Stefan Kandic <stefan.kandic@databricks.com>
Signed-off-by: Max Gekk <max.gekk@gmail.com>
diff --git a/sql/core/src/main/scala/org/apache/spark/sql/catalyst/analysis/ResolveSessionCatalog.scala b/sql/core/src/main/scala/org/apache/spark/sql/catalyst/analysis/ResolveSessionCatalog.scala
index a9ad752..884c870 100644
--- a/sql/core/src/main/scala/org/apache/spark/sql/catalyst/analysis/ResolveSessionCatalog.scala
+++ b/sql/core/src/main/scala/org/apache/spark/sql/catalyst/analysis/ResolveSessionCatalog.scala
@@ -26,7 +26,7 @@
import org.apache.spark.sql.catalyst.expressions.{Alias, Attribute}
import org.apache.spark.sql.catalyst.plans.logical._
import org.apache.spark.sql.catalyst.rules.Rule
-import org.apache.spark.sql.catalyst.util.{quoteIfNeeded, toPrettySQL, ResolveDefaultColumns => DefaultCols}
+import org.apache.spark.sql.catalyst.util.{quoteIfNeeded, toPrettySQL, CharVarcharUtils, ResolveDefaultColumns => DefaultCols}
import org.apache.spark.sql.catalyst.util.ResolveDefaultColumns._
import org.apache.spark.sql.connector.catalog.{CatalogExtension, CatalogManager, CatalogPlugin, CatalogV2Util, LookupCatalog, SupportsNamespaces, V1Table}
import org.apache.spark.sql.connector.expressions.Transform
@@ -36,7 +36,7 @@
import org.apache.spark.sql.execution.datasources.v2.DataSourceV2Utils
import org.apache.spark.sql.internal.{HiveSerDe, SQLConf}
import org.apache.spark.sql.internal.connector.V1Function
-import org.apache.spark.sql.types.{MetadataBuilder, StructField, StructType}
+import org.apache.spark.sql.types.{MetadataBuilder, StringType, StructField, StructType}
import org.apache.spark.util.ArrayImplicits._
/**
@@ -87,7 +87,11 @@
val colName = a.column.name(0)
val dataType = a.dataType.getOrElse {
table.schema.findNestedField(Seq(colName), resolver = conf.resolver)
- .map(_._2.dataType)
+ .map {
+ case (_, StructField(_, st: StringType, _, metadata)) =>
+ CharVarcharUtils.getRawType(metadata).getOrElse(st)
+ case (_, field) => field.dataType
+ }
.getOrElse {
throw QueryCompilationErrors.unresolvedColumnError(
toSQLId(a.column.name), table.schema.fieldNames)
diff --git a/sql/core/src/test/resources/sql-tests/analyzer-results/charvarchar.sql.out b/sql/core/src/test/resources/sql-tests/analyzer-results/charvarchar.sql.out
index 5c1417f..5247970 100644
--- a/sql/core/src/test/resources/sql-tests/analyzer-results/charvarchar.sql.out
+++ b/sql/core/src/test/resources/sql-tests/analyzer-results/charvarchar.sql.out
@@ -264,6 +264,18 @@
-- !query
+alter table char_part change column c1 comment 'char comment'
+-- !query analysis
+AlterTableChangeColumnCommand `spark_catalog`.`default`.`char_part`, c1, StructField(c1,CharType(5),true)
+
+
+-- !query
+alter table char_part change column v1 comment 'varchar comment'
+-- !query analysis
+AlterTableChangeColumnCommand `spark_catalog`.`default`.`char_part`, v1, StructField(v1,VarcharType(6),true)
+
+
+-- !query
alter table char_part add partition (v2='ke', c2='nt') location 'loc1'
-- !query analysis
org.apache.spark.sql.catalyst.analysis.PartitionsAlreadyExistException
diff --git a/sql/core/src/test/resources/sql-tests/inputs/charvarchar.sql b/sql/core/src/test/resources/sql-tests/inputs/charvarchar.sql
index 8117dec..be038e1 100644
--- a/sql/core/src/test/resources/sql-tests/inputs/charvarchar.sql
+++ b/sql/core/src/test/resources/sql-tests/inputs/charvarchar.sql
@@ -49,6 +49,8 @@
create table char_part(c1 char(5), c2 char(2), v1 varchar(6), v2 varchar(2)) using parquet partitioned by (v2, c2);
desc formatted char_part;
+alter table char_part change column c1 comment 'char comment';
+alter table char_part change column v1 comment 'varchar comment';
alter table char_part add partition (v2='ke', c2='nt') location 'loc1';
desc formatted char_part;
diff --git a/sql/core/src/test/resources/sql-tests/results/charvarchar.sql.out b/sql/core/src/test/resources/sql-tests/results/charvarchar.sql.out
index 568c9f3..8aafa25 100644
--- a/sql/core/src/test/resources/sql-tests/results/charvarchar.sql.out
+++ b/sql/core/src/test/resources/sql-tests/results/charvarchar.sql.out
@@ -557,6 +557,22 @@
-- !query
+alter table char_part change column c1 comment 'char comment'
+-- !query schema
+struct<>
+-- !query output
+
+
+
+-- !query
+alter table char_part change column v1 comment 'varchar comment'
+-- !query schema
+struct<>
+-- !query output
+
+
+
+-- !query
alter table char_part add partition (v2='ke', c2='nt') location 'loc1'
-- !query schema
struct<>
@@ -569,8 +585,8 @@
-- !query schema
struct<col_name:string,data_type:string,comment:string>
-- !query output
-c1 char(5)
-v1 varchar(6)
+c1 char(5) char comment
+v1 varchar(6) varchar comment
v2 varchar(2)
c2 char(2)
# Partition Information
@@ -612,8 +628,8 @@
-- !query schema
struct<col_name:string,data_type:string,comment:string>
-- !query output
-c1 char(5)
-v1 varchar(6)
+c1 char(5) char comment
+v1 varchar(6) varchar comment
v2 varchar(2)
c2 char(2)
# Partition Information
@@ -647,8 +663,8 @@
-- !query schema
struct<col_name:string,data_type:string,comment:string>
-- !query output
-c1 char(5)
-v1 varchar(6)
+c1 char(5) char comment
+v1 varchar(6) varchar comment
v2 varchar(2)
c2 char(2)
# Partition Information
@@ -682,8 +698,8 @@
-- !query schema
struct<col_name:string,data_type:string,comment:string>
-- !query output
-c1 char(5)
-v1 varchar(6)
+c1 char(5) char comment
+v1 varchar(6) varchar comment
v2 varchar(2)
c2 char(2)
# Partition Information
