[SPARK-49543][SQL] Add SHOW COLLATIONS command

docs/sql-ref-ansi-compliance.md

@@ -460,6 +460,7 @@ Below is a list of all the keywords in Spark SQL.
 |CODEGEN|non-reserved|non-reserved|non-reserved|
 |COLLATE|reserved|non-reserved|reserved|
 |COLLATION|reserved|non-reserved|reserved|
+|COLLATIONS|reserved|non-reserved|non-reserved|
 |COLLECTION|non-reserved|non-reserved|non-reserved|
 |COLUMN|reserved|non-reserved|reserved|
 |COLUMNS|non-reserved|non-reserved|non-reserved|

docs/sql-ref-syntax-aux-show-collations.md

@@ -0,0 +1,111 @@
+---
+layout: global
+title: SHOW COLLATIONS
+displayTitle: SHOW COLLATIONS
+license: |
+  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.
+---
+
+### Description
+
+Returns the list of collations supported by Spark. An optional pattern may be used to filter
+the results. The `LIKE` clause is optional.
+
+### Syntax
+
+```sql
+SHOW COLLATIONS [ LIKE regex_pattern ]
+```
+
+### Parameters
+
+* **regex_pattern**
+
+    Specifies the regular expression pattern that is used to filter the results of the statement.
+
+    * Except for `*` and `|` character, the pattern works like a regular expression.
+    * `*` alone matches 0 or more characters and `|` is used to separate multiple different regular expressions,
+      any of which can match.
+    * The leading and trailing blanks are trimmed in the input pattern before processing. The pattern match is case-insensitive.
+
+### Output
+
+The output has the following columns:
+
+| Column | Type | Nullable | Description |
+|--------|------|----------|-------------|
+| NAME | STRING | No | The name of the collation. |
+| LANGUAGE | STRING | Yes | The display language of the locale, or `null` for locale-independent collations. |
+| COUNTRY | STRING | Yes | The display country of the locale, or `null` for locale-independent collations. |
+| ACCENT_SENSITIVITY | STRING | No | Whether the collation is accent-sensitive (`ACCENT_SENSITIVE`) or accent-insensitive (`ACCENT_INSENSITIVE`). |
+| CASE_SENSITIVITY | STRING | No | Whether the collation is case-sensitive (`CASE_SENSITIVE`) or case-insensitive (`CASE_INSENSITIVE`). |
+| PAD_ATTRIBUTE | STRING | No | The pad attribute of the collation: `NO_PAD` or `RTRIM`. |
+| ICU_VERSION | STRING | Yes | The ICU library version used for the collation, or `null` for non-ICU collations such as `UTF8_BINARY` and `UTF8_LCASE`. |
+
+### Examples
+
+```sql
+-- List all supported collations (results truncated)
+SHOW COLLATIONS;
++-----------------+--------+-------+------------------+----------------+-------------+-----------+
+|             NAME|LANGUAGE|COUNTRY|ACCENT_SENSITIVITY|CASE_SENSITIVITY|PAD_ATTRIBUTE|ICU_VERSION|
++-----------------+--------+-------+------------------+----------------+-------------+-----------+
+|      UTF8_BINARY|    null|   null|  ACCENT_SENSITIVE|  CASE_SENSITIVE|       NO_PAD|       null|
+|       UTF8_LCASE|    null|   null|  ACCENT_SENSITIVE|CASE_INSENSITIVE|       NO_PAD|       null|
+|          UNICODE|    null|   null|  ACCENT_SENSITIVE|  CASE_SENSITIVE|       NO_PAD|       78.2|
+|       UNICODE_CI|    null|   null|  ACCENT_SENSITIVE|CASE_INSENSITIVE|       NO_PAD|       78.2|
+|           en_USA|  English| United States|ACCENT_SENSITIVE|CASE_SENSITIVE|  NO_PAD|       78.2|
+|        en_USA_CI|  English| United States|ACCENT_SENSITIVE|CASE_INSENSITIVE| NO_PAD|       78.2|
+|              ...|     ...|    ...|               ...|             ...|         ...|        ...|
++-----------------+--------+-------+------------------+----------------+-------------+-----------+
+
+-- List all collations matching `UTF8_BINARY*`
+SHOW COLLATIONS LIKE 'UTF8_BINARY*';
++-----------------+--------+-------+------------------+----------------+-------------+-----------+
+|             NAME|LANGUAGE|COUNTRY|ACCENT_SENSITIVITY|CASE_SENSITIVITY|PAD_ATTRIBUTE|ICU_VERSION|
++-----------------+--------+-------+------------------+----------------+-------------+-----------+
+|      UTF8_BINARY|    null|   null|  ACCENT_SENSITIVE|  CASE_SENSITIVE|       NO_PAD|       null|
+| UTF8_BINARY_RTRIM|    null|   null|  ACCENT_SENSITIVE|  CASE_SENSITIVE|        RTRIM|       null|
++-----------------+--------+-------+------------------+----------------+-------------+-----------+
+
+-- List all collations matching `UNICODE*`
+SHOW COLLATIONS LIKE 'UNICODE*';
++--------------+--------+-------+-------------------+----------------+-------------+-----------+
+|          NAME|LANGUAGE|COUNTRY| ACCENT_SENSITIVITY|CASE_SENSITIVITY|PAD_ATTRIBUTE|ICU_VERSION|
++--------------+--------+-------+-------------------+----------------+-------------+-----------+
+|       UNICODE|    null|   null|   ACCENT_SENSITIVE|  CASE_SENSITIVE|       NO_PAD|       78.2|
+|    UNICODE_AI|    null|   null| ACCENT_INSENSITIVE|  CASE_SENSITIVE|       NO_PAD|       78.2|
+| UNICODE_AI_RTRIM|    null|   null|ACCENT_INSENSITIVE|CASE_SENSITIVE|        RTRIM|       78.2|
+|    UNICODE_CI|    null|   null|   ACCENT_SENSITIVE|CASE_INSENSITIVE|       NO_PAD|       78.2|
+| UNICODE_CI_AI|    null|   null| ACCENT_INSENSITIVE|CASE_INSENSITIVE|       NO_PAD|       78.2|
+|UNICODE_CI_AI_RTRIM|    null|   null|ACCENT_INSENSITIVE|CASE_INSENSITIVE|      RTRIM|       78.2|
+| UNICODE_CI_RTRIM|    null|   null|  ACCENT_SENSITIVE|CASE_INSENSITIVE|       RTRIM|       78.2|
+|  UNICODE_RTRIM|    null|   null|   ACCENT_SENSITIVE|  CASE_SENSITIVE|        RTRIM|       78.2|
++--------------+--------+-------+-------------------+----------------+-------------+-----------+
+
+-- List all collations matching `UNICODE` or `UTF8_BINARY`
+SHOW COLLATIONS LIKE 'UNICODE|UTF8_BINARY';
++-----------+--------+-------+------------------+----------------+-------------+-----------+
+|       NAME|LANGUAGE|COUNTRY|ACCENT_SENSITIVITY|CASE_SENSITIVITY|PAD_ATTRIBUTE|ICU_VERSION|
++-----------+--------+-------+------------------+----------------+-------------+-----------+
+|UTF8_BINARY|    null|   null|  ACCENT_SENSITIVE|  CASE_SENSITIVE|       NO_PAD|       null|
+|    UNICODE|    null|   null|  ACCENT_SENSITIVE|  CASE_SENSITIVE|       NO_PAD|       78.2|
++-----------+--------+-------+------------------+----------------+-------------+-----------+
+```
+
+### Related Statements
+
+* [STRING TYPE](sql-ref-datatypes.html)

docs/sql-ref-syntax.md

@@ -125,6 +125,7 @@ You use SQL scripting to execute procedural logic in SQL.
  * [SET](sql-ref-syntax-aux-conf-mgmt-set.html)
  * [SET VAR](sql-ref-syntax-aux-set-var.html)
  * [SHOW CACHED TABLES](sql-ref-syntax-aux-show-cached-tables.html)
+ * [SHOW COLLATIONS](sql-ref-syntax-aux-show-collations.html)
  * [SHOW COLUMNS](sql-ref-syntax-aux-show-columns.html)
  * [SHOW CREATE TABLE](sql-ref-syntax-aux-show-create-table.html)
  * [SHOW DATABASES](sql-ref-syntax-aux-show-databases.html)

sql/api/src/main/antlr4/org/apache/spark/sql/catalyst/parser/SqlBaseLexer.g4

@@ -179,6 +179,7 @@ CLUSTERED: 'CLUSTERED';
 CODEGEN: 'CODEGEN';
 COLLATE: 'COLLATE';
 COLLATION: 'COLLATION';
+COLLATIONS: 'COLLATIONS';
 COLLECTION: 'COLLECTION';
 COLUMN: 'COLUMN';
 COLUMNS: 'COLUMNS';

sql/api/src/main/antlr4/org/apache/spark/sql/catalyst/parser/SqlBaseParser.g4

@@ -377,6 +377,7 @@ statement
     | SHOW CREATE TABLE identifierReference (AS SERDE)?                #showCreateTable
     | SHOW CURRENT namespace                                           #showCurrentNamespace
     | SHOW CATALOGS (LIKE? pattern=stringLit)?                            #showCatalogs
+    | SHOW COLLATIONS (LIKE? pattern=stringLit)?                          #showCollations
     | (DESC | DESCRIBE) FUNCTION EXTENDED? describeFuncName            #describeFunction
     | (DESC | DESCRIBE) PROCEDURE identifierReference                  #describeProcedure
     | (DESC | DESCRIBE) namespace EXTENDED?
@@ -2321,6 +2322,7 @@ nonReserved
     | CODEGEN
     | COLLATE
     | COLLATION
+    | COLLATIONS
     | COLLECTION
     | COLUMN
     | COLUMNS

sql/connect/client/jdbc/src/test/scala/org/apache/spark/sql/connect/client/jdbc/SparkConnectDatabaseMetaDataSuite.scala

@@ -209,7 +209,7 @@ class SparkConnectDatabaseMetaDataSuite extends ConnectFunSuite with RemoteSpark
     withConnection { conn =>
       val metadata = conn.getMetaData
       // scalastyle:off line.size.limit
-      assert(metadata.getSQLKeywords === "ADD,AFTER,AGGREGATE,ALWAYS,ANALYZE,ANTI,ANY_VALUE,ARCHIVE,ASC,BINDING,BUCKET,BUCKETS,BYTE,CACHE,CACHED,CASCADE,CATALOG,CATALOGS,CHANGE,CHANGES,CLEAR,CLUSTER,CLUSTERED,CODEGEN,COLLATION,COLLECTION,COLUMNS,COMMENT,COMPACT,COMPACTIONS,COMPENSATION,COMPUTE,CONCATENATE,CONTAINS,CONTINUE,COST,DATA,DATABASE,DATABASES,DATEADD,DATEDIFF,DATE_ADD,DATE_DIFF,DAYOFYEAR,DAYS,DBPROPERTIES,DEFINED,DEFINER,DELAY,DELIMITED,DESC,DFS,DIRECTORIES,DIRECTORY,DISTRIBUTE,DIV,DO,ELSEIF,ENFORCED,ESCAPED,EVOLUTION,EXCHANGE,EXCLUDE,EXCLUSIVE,EXIT,EXPLAIN,EXPORT,EXTEND,EXTENDED,FIELDS,FILEFORMAT,FIRST,FLOW,FOLLOWING,FORMAT,FORMATTED,FOUND,FUNCTIONS,GENERATED,GEOGRAPHY,GEOMETRY,HANDLER,HOURS,IDENTIFIED,IDENTIFIER,IF,IGNORE,ILIKE,IMMEDIATE,INCLUDE,INCLUSIVE,INCREMENT,INDEX,INDEXES,INPATH,INPUT,INPUTFORMAT,INVOKER,ITEMS,ITERATE,JSON,KEY,KEYS,LAST,LAZY,LEAVE,LEVEL,LIMIT,LINES,LIST,LOAD,LOCATION,LOCK,LOCKS,LOGICAL,LONG,LOOP,MACRO,MAP,MATCHED,MATERIALIZED,MEASURE,METRICS,MICROSECOND,MICROSECONDS,MILLISECOND,MILLISECONDS,MINUS,MINUTES,MONTHS,MSCK,NAME,NAMESPACE,NAMESPACES,NANOSECOND,NANOSECONDS,NORELY,NULLS,OFFSET,OPTION,OPTIONS,OUTPUTFORMAT,OVERWRITE,PARTITIONED,PARTITIONS,PERCENT,PIVOT,PLACING,PRECEDING,PRINCIPALS,PROCEDURES,PROPERTIES,PURGE,QUARTER,QUERY,RECORDREADER,RECORDWRITER,RECOVER,RECURSION,REDUCE,REFRESH,RELY,RENAME,REPAIR,REPEAT,REPEATABLE,REPLACE,RESET,RESPECT,RESTRICT,ROLE,ROLES,SCHEMA,SCHEMAS,SECONDS,SECURITY,SEMI,SEPARATED,SERDE,SERDEPROPERTIES,SETS,SHORT,SHOW,SINGLE,SKEWED,SORT,SORTED,SOURCE,STATISTICS,STORED,STRATIFY,STREAM,STREAMING,STRING,STRUCT,SUBSTR,SYNC,SYSTEM_TIME,SYSTEM_VERSION,TABLES,TARGET,TBLPROPERTIES,TERMINATED,TIMEDIFF,TIMESTAMPADD,TIMESTAMPDIFF,TIMESTAMP_LTZ,TIMESTAMP_NTZ,TINYINT,TOUCH,TRANSACTION,TRANSACTIONS,TRANSFORM,TRUNCATE,TRY_CAST,TYPE,UNARCHIVE,UNBOUNDED,UNCACHE,UNLOCK,UNPIVOT,UNSET,UNTIL,USE,VAR,VARIABLE,VARIANT,VERSION,VIEW,VIEWS,VOID,WATERMARK,WEEK,WEEKS,WHILE,X,YEARS,ZONE")
+      assert(metadata.getSQLKeywords === "ADD,AFTER,AGGREGATE,ALWAYS,ANALYZE,ANTI,ANY_VALUE,ARCHIVE,ASC,BINDING,BUCKET,BUCKETS,BYTE,CACHE,CACHED,CASCADE,CATALOG,CATALOGS,CHANGE,CHANGES,CLEAR,CLUSTER,CLUSTERED,CODEGEN,COLLATION,COLLATIONS,COLLECTION,COLUMNS,COMMENT,COMPACT,COMPACTIONS,COMPENSATION,COMPUTE,CONCATENATE,CONTAINS,CONTINUE,COST,DATA,DATABASE,DATABASES,DATEADD,DATEDIFF,DATE_ADD,DATE_DIFF,DAYOFYEAR,DAYS,DBPROPERTIES,DEFINED,DEFINER,DELAY,DELIMITED,DESC,DFS,DIRECTORIES,DIRECTORY,DISTRIBUTE,DIV,DO,ELSEIF,ENFORCED,ESCAPED,EVOLUTION,EXCHANGE,EXCLUDE,EXCLUSIVE,EXIT,EXPLAIN,EXPORT,EXTEND,EXTENDED,FIELDS,FILEFORMAT,FIRST,FLOW,FOLLOWING,FORMAT,FORMATTED,FOUND,FUNCTIONS,GENERATED,GEOGRAPHY,GEOMETRY,HANDLER,HOURS,IDENTIFIED,IDENTIFIER,IF,IGNORE,ILIKE,IMMEDIATE,INCLUDE,INCLUSIVE,INCREMENT,INDEX,INDEXES,INPATH,INPUT,INPUTFORMAT,INVOKER,ITEMS,ITERATE,JSON,KEY,KEYS,LAST,LAZY,LEAVE,LEVEL,LIMIT,LINES,LIST,LOAD,LOCATION,LOCK,LOCKS,LOGICAL,LONG,LOOP,MACRO,MAP,MATCHED,MATERIALIZED,MEASURE,METRICS,MICROSECOND,MICROSECONDS,MILLISECOND,MILLISECONDS,MINUS,MINUTES,MONTHS,MSCK,NAME,NAMESPACE,NAMESPACES,NANOSECOND,NANOSECONDS,NORELY,NULLS,OFFSET,OPTION,OPTIONS,OUTPUTFORMAT,OVERWRITE,PARTITIONED,PARTITIONS,PERCENT,PIVOT,PLACING,PRECEDING,PRINCIPALS,PROCEDURES,PROPERTIES,PURGE,QUARTER,QUERY,RECORDREADER,RECORDWRITER,RECOVER,RECURSION,REDUCE,REFRESH,RELY,RENAME,REPAIR,REPEAT,REPEATABLE,REPLACE,RESET,RESPECT,RESTRICT,ROLE,ROLES,SCHEMA,SCHEMAS,SECONDS,SECURITY,SEMI,SEPARATED,SERDE,SERDEPROPERTIES,SETS,SHORT,SHOW,SINGLE,SKEWED,SORT,SORTED,SOURCE,STATISTICS,STORED,STRATIFY,STREAM,STREAMING,STRING,STRUCT,SUBSTR,SYNC,SYSTEM_TIME,SYSTEM_VERSION,TABLES,TARGET,TBLPROPERTIES,TERMINATED,TIMEDIFF,TIMESTAMPADD,TIMESTAMPDIFF,TIMESTAMP_LTZ,TIMESTAMP_NTZ,TINYINT,TOUCH,TRANSACTION,TRANSACTIONS,TRANSFORM,TRUNCATE,TRY_CAST,TYPE,UNARCHIVE,UNBOUNDED,UNCACHE,UNLOCK,UNPIVOT,UNSET,UNTIL,USE,VAR,VARIABLE,VARIANT,VERSION,VIEW,VIEWS,VOID,WATERMARK,WEEK,WEEKS,WHILE,X,YEARS,ZONE")
       // scalastyle:on line.size.limit
     }
   }

sql/core/src/main/scala/org/apache/spark/sql/execution/SparkSqlParser.scala

@@ -501,6 +501,13 @@ class SparkSqlAstBuilder extends AstBuilder {
     ShowCatalogsCommand(Option(ctx.pattern).map(x => string(visitStringLit(x))))
   }
 
+  /**
+   * Create a [[ShowCollationsCommand]] logical command.
+   */
+  override def visitShowCollations(ctx: ShowCollationsContext): LogicalPlan = withOrigin(ctx) {
+    ShowCollationsCommand(Option(ctx.pattern).map(x => string(visitStringLit(x))))
+  }
+
   /**
    * Converts a multi-part identifier to a TableIdentifier.
    *

sql/core/src/main/scala/org/apache/spark/sql/execution/command/ShowCollationsCommand.scala

@@ -0,0 +1,57 @@
+/*
+ * 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.command
+
+import scala.jdk.CollectionConverters._
+
+import org.apache.spark.sql.{Row, SparkSession}
+import org.apache.spark.sql.catalyst.expressions.{Attribute, AttributeReference}
+import org.apache.spark.sql.catalyst.util.{CollationFactory, StringUtils}
+import org.apache.spark.sql.types.StringType
+
+/**
+ * The command for `SHOW COLLATIONS`.
+ */
+case class ShowCollationsCommand(pattern: Option[String]) extends LeafRunnableCommand {
+  override val output: Seq[Attribute] = Seq(
+    AttributeReference("NAME", StringType, nullable = false)(),
+    AttributeReference("LANGUAGE", StringType, nullable = true)(),
+    AttributeReference("COUNTRY", StringType, nullable = true)(),
+    AttributeReference("ACCENT_SENSITIVITY", StringType, nullable = false)(),
+    AttributeReference("CASE_SENSITIVITY", StringType, nullable = false)(),
+    AttributeReference("PAD_ATTRIBUTE", StringType, nullable = false)(),
+    AttributeReference("ICU_VERSION", StringType, nullable = true)())
+
+  override def run(sparkSession: SparkSession): Seq[Row] = {
+    val collations = CollationFactory.listCollations().asScala
+      .map(CollationFactory.loadCollationMeta)
+    val filtered = pattern
+      .map(p => collations.filter(m => StringUtils.filterPattern(Seq(m.collationName), p).nonEmpty))
+      .getOrElse(collations)
+    filtered.map { m =>
+      Row(
+        m.collationName,
+        m.language,
+        m.country,
+        if (m.accentSensitivity) "ACCENT_SENSITIVE" else "ACCENT_INSENSITIVE",
+        if (m.caseSensitivity) "CASE_SENSITIVE" else "CASE_INSENSITIVE",
+        m.padAttribute,
+        m.icuVersion)
+    }.toSeq
+  }
+}

sql/core/src/test/resources/sql-tests/results/keywords-enforced.sql.out

@@ -55,6 +55,7 @@ CLUSTERED	false
 CODEGEN	false
 COLLATE	true
 COLLATION	true
+COLLATIONS	true
 COLLECTION	false
 COLUMN	true
 COLUMNS	false
@@ -432,6 +433,7 @@ CAST
 CHECK
 COLLATE
 COLLATION
+COLLATIONS
 COLUMN
 CONSTRAINT
 CREATE

sql/core/src/test/resources/sql-tests/results/keywords.sql.out

@@ -55,6 +55,7 @@ CLUSTERED	false
 CODEGEN	false
 COLLATE	false
 COLLATION	false
+COLLATIONS	false
 COLLECTION	false
 COLUMN	false
 COLUMNS	false

sql/core/src/test/resources/sql-tests/results/nonansi/keywords.sql.out

@@ -55,6 +55,7 @@ CLUSTERED	false
 CODEGEN	false
 COLLATE	false
 COLLATION	false
+COLLATIONS	false
 COLLECTION	false
 COLUMN	false
 COLUMNS	false

sql/core/src/test/scala/org/apache/spark/sql/connector/DataSourceV2SQLSuite.scala

@@ -3223,6 +3223,37 @@ class DataSourceV2SQLSuiteV1Filter
       Row("testcat"), Row("testcat2")))
   }
 
+  test("SPARK-49543: ShowCollations") {
+    val schema = new StructType()
+      .add("NAME", StringType, nullable = false)
+      .add("LANGUAGE", StringType, nullable = true)
+      .add("COUNTRY", StringType, nullable = true)
+      .add("ACCENT_SENSITIVITY", StringType, nullable = false)
+      .add("CASE_SENSITIVITY", StringType, nullable = false)
+      .add("PAD_ATTRIBUTE", StringType, nullable = false)
+      .add("ICU_VERSION", StringType, nullable = true)
+
+    val df = sql("SHOW COLLATIONS")
+    assert(df.schema === schema)
+
+    val allCollations = df.collect()
+    assert(allCollations.exists(_.getString(0) == "UTF8_BINARY"))
+    assert(allCollations.exists(_.getString(0) == "UNICODE"))
+    assert(allCollations.exists(_.getString(0) == "UNICODE_CI"))
+
+    val utf8Row = allCollations.find(_.getString(0) == "UTF8_BINARY").get
+    assert(utf8Row.getString(3) == "ACCENT_SENSITIVE")
+    assert(utf8Row.getString(4) == "CASE_SENSITIVE")
+
+    val likeResult = sql("SHOW COLLATIONS LIKE 'UNICODE*'").collect()
+    assert(likeResult.nonEmpty)
+    assert(likeResult.forall(_.getString(0).startsWith("UNICODE")))
+
+    val exactResult = sql("SHOW COLLATIONS LIKE 'UTF8_BINARY'").collect()
+    assert(exactResult.length == 1)
+    assert(exactResult.head.getString(0) == "UTF8_BINARY")
+  }
+
   test("CREATE INDEX should fail") {
     val t = "testcat.tbl"
     withTable(t) {

sql/core/src/test/scala/org/apache/spark/sql/execution/command/DDLParserSuite.scala

@@ -820,4 +820,16 @@ class DDLParserSuite extends AnalysisTest with SharedSparkSession {
       parser.parsePlan("SHOW CATALOGS LIKE 'defau*'"),
       ShowCatalogsCommand(Some("defau*")))
   }
+
+  test("SHOW COLLATIONS") {
+    comparePlans(
+      parser.parsePlan("SHOW COLLATIONS"),
+      ShowCollationsCommand(None))
+    comparePlans(
+      parser.parsePlan("SHOW COLLATIONS LIKE 'UNICODE*'"),
+      ShowCollationsCommand(Some("UNICODE*")))
+    comparePlans(
+      parser.parsePlan("SHOW COLLATIONS LIKE 'UTF8_BINARY'"),
+      ShowCollationsCommand(Some("UTF8_BINARY")))
+  }
 }