[SPARK-48906][SQL] Introduce SHOW COLLATIONS LIKE ... syntax to sho…

…w all collations

### What changes were proposed in this pull request?
The pr aims to introduce `SHOW COLLATIONS LIKE ...` syntax to `show all collations`.

### Why are the changes needed?
End-users will be able to obtain `collations` currently supported by the spark through SQL.
Other databases, such as `MySQL`, also have similar syntax,
ref: https://dev.mysql.com/doc/refman/9.0/en/show-collation.html
<img width="958" alt="image" src="https://github.com/user-attachments/assets/1d5106b3-f8b8-42c5-b3ad-0f35c61ad5e2">

postgresql: https://database.guide/how-to-return-a-list-of-available-collations-in-postgresql/

### Does this PR introduce _any_ user-facing change?
Yes, end-users will be able to obtain `collation` currently supported by the spark through commands similar to the following

|name|provider|version|binaryEquality|binaryOrdering|lowercaseEquality|
| --------- | ----------- | ----------- | ----------- | ----------- | ----------- |

```
spark-sql (default)> SHOW COLLATIONS;
UTF8_BINARY	spark	1.0	true	true	false
UTF8_LCASE	spark	1.0	false	false	true
ff_Adlm	icu	153.120.0.0	false	false	false
ff_Adlm_CI	icu	153.120.0.0	false	false	false
ff_Adlm_AI	icu	153.120.0.0	false	false	false
ff_Adlm_CI_AI	icu	153.120.0.0	false	false	false
...

spark-sql (default)> SHOW COLLATIONS LIKE '*UTF8_BINARY*';
UTF8_BINARY	spark	1.0	true	true	false
Time taken: 0.043 seconds, Fetched 1 row(s)
```

<img width="513" alt="image" src="https://github.com/user-attachments/assets/d5765e32-718d-4236-857d-d508f5473329">

### How was this patch tested?
Add new UT.

### Was this patch authored or co-authored using generative AI tooling?
No.

Closes apache#47364 from panbingkun/show_collation_syntax.

Authored-by: panbingkun <panbingkun@baidu.com>
Signed-off-by: Max Gekk <max.gekk@gmail.com>

common/unsafe/src/main/java/org/apache/spark/sql/catalyst/util/CollationFactory.java

@@ -23,12 +23,14 @@
 import java.util.function.Function;
 import java.util.function.BiFunction;
 import java.util.function.ToLongFunction;
+import java.util.stream.Stream;
 
+import com.ibm.icu.text.CollationKey;
+import com.ibm.icu.text.Collator;
 import com.ibm.icu.text.RuleBasedCollator;
 import com.ibm.icu.text.StringSearch;
 import com.ibm.icu.util.ULocale;
-import com.ibm.icu.text.CollationKey;
-import com.ibm.icu.text.Collator;
+import com.ibm.icu.util.VersionInfo;
 
 import org.apache.spark.SparkException;
 import org.apache.spark.unsafe.types.UTF8String;
@@ -88,6 +90,17 @@ public Optional<String> getVersion() {
     }
   }
 
+  public record CollationMeta(
+    String catalog,
+    String schema,
+    String collationName,
+    String language,
+    String country,
+    String icuVersion,
+    String padAttribute,
+    boolean accentSensitivity,
+    boolean caseSensitivity) { }
+
   /**
    * Entry encapsulating all information about a collation.
    */
@@ -342,6 +355,23 @@ private static int collationNameToId(String collationName) throws SparkException
       }
 
       protected abstract Collation buildCollation();
+
+      protected abstract CollationMeta buildCollationMeta();
+
+      static List<CollationIdentifier> listCollations() {
+        return Stream.concat(
+          CollationSpecUTF8.listCollations().stream(),
+          CollationSpecICU.listCollations().stream()).toList();
+      }
+
+      static CollationMeta loadCollationMeta(CollationIdentifier collationIdentifier) {
+        CollationMeta collationSpecUTF8 =
+          CollationSpecUTF8.loadCollationMeta(collationIdentifier);
+        if (collationSpecUTF8 == null) {
+          return CollationSpecICU.loadCollationMeta(collationIdentifier);
+        }
+        return collationSpecUTF8;
+      }
     }
 
     private static class CollationSpecUTF8 extends CollationSpec {
@@ -364,6 +394,9 @@ private enum CaseSensitivity {
        */
       private static final int CASE_SENSITIVITY_MASK = 0b1;
 
+      private static final String UTF8_BINARY_COLLATION_NAME = "UTF8_BINARY";
+      private static final String UTF8_LCASE_COLLATION_NAME = "UTF8_LCASE";
+
       private static final int UTF8_BINARY_COLLATION_ID =
         new CollationSpecUTF8(CaseSensitivity.UNSPECIFIED).collationId;
       private static final int UTF8_LCASE_COLLATION_ID =
@@ -406,7 +439,7 @@ private static CollationSpecUTF8 fromCollationId(int collationId) {
       protected Collation buildCollation() {
         if (collationId == UTF8_BINARY_COLLATION_ID) {
           return new Collation(
-            "UTF8_BINARY",
+            UTF8_BINARY_COLLATION_NAME,
             PROVIDER_SPARK,
             null,
             UTF8String::binaryCompare,
@@ -417,7 +450,7 @@ protected Collation buildCollation() {
             /* supportsLowercaseEquality = */ false);
         } else {
           return new Collation(
-            "UTF8_LCASE",
+            UTF8_LCASE_COLLATION_NAME,
             PROVIDER_SPARK,
             null,
             CollationAwareUTF8String::compareLowerCase,
@@ -428,6 +461,52 @@ protected Collation buildCollation() {
             /* supportsLowercaseEquality = */ true);
         }
       }
+
+      @Override
+      protected CollationMeta buildCollationMeta() {
+        if (collationId == UTF8_BINARY_COLLATION_ID) {
+          return new CollationMeta(
+            CATALOG,
+            SCHEMA,
+            UTF8_BINARY_COLLATION_NAME,
+            /* language = */ null,
+            /* country = */ null,
+            /* icuVersion = */ null,
+            COLLATION_PAD_ATTRIBUTE,
+            /* accentSensitivity = */ true,
+            /* caseSensitivity = */ true);
+        } else {
+          return new CollationMeta(
+            CATALOG,
+            SCHEMA,
+            UTF8_LCASE_COLLATION_NAME,
+            /* language = */ null,
+            /* country = */ null,
+            /* icuVersion = */ null,
+            COLLATION_PAD_ATTRIBUTE,
+            /* accentSensitivity = */ true,
+            /* caseSensitivity = */ false);
+        }
+      }
+
+      static List<CollationIdentifier> listCollations() {
+        CollationIdentifier UTF8_BINARY_COLLATION_IDENT =
+          new CollationIdentifier(PROVIDER_SPARK, UTF8_BINARY_COLLATION_NAME, "1.0");
+        CollationIdentifier UTF8_LCASE_COLLATION_IDENT =
+          new CollationIdentifier(PROVIDER_SPARK, UTF8_LCASE_COLLATION_NAME, "1.0");
+        return Arrays.asList(UTF8_BINARY_COLLATION_IDENT, UTF8_LCASE_COLLATION_IDENT);
+      }
+
+      static CollationMeta loadCollationMeta(CollationIdentifier collationIdentifier) {
+        try {
+          int collationId = CollationSpecUTF8.collationNameToId(
+            collationIdentifier.name, collationIdentifier.name.toUpperCase());
+          return CollationSpecUTF8.fromCollationId(collationId).buildCollationMeta();
+        } catch (SparkException ignored) {
+          // ignore
+          return null;
+        }
+      }
     }
 
     private static class CollationSpecICU extends CollationSpec {
@@ -684,6 +763,20 @@ protected Collation buildCollation() {
           /* supportsLowercaseEquality = */ false);
       }
 
+      @Override
+      protected CollationMeta buildCollationMeta() {
+        return new CollationMeta(
+          CATALOG,
+          SCHEMA,
+          collationName(),
+          ICULocaleMap.get(locale).getDisplayLanguage(),
+          ICULocaleMap.get(locale).getDisplayCountry(),
+          VersionInfo.ICU_VERSION.toString(),
+          COLLATION_PAD_ATTRIBUTE,
+          caseSensitivity == CaseSensitivity.CS,
+          accentSensitivity == AccentSensitivity.AS);
+      }
+
       /**
        * Compute normalized collation name. Components of collation name are given in order:
        * - Locale name
@@ -704,6 +797,37 @@ private String collationName() {
         }
         return builder.toString();
       }
+
+      private static List<String> allCollationNames() {
+        List<String> collationNames = new ArrayList<>();
+        for (String locale: ICULocaleToId.keySet()) {
+          // CaseSensitivity.CS + AccentSensitivity.AS
+          collationNames.add(locale);
+          // CaseSensitivity.CS + AccentSensitivity.AI
+          collationNames.add(locale + "_AI");
+          // CaseSensitivity.CI + AccentSensitivity.AS
+          collationNames.add(locale + "_CI");
+          // CaseSensitivity.CI + AccentSensitivity.AI
+          collationNames.add(locale + "_CI_AI");
+        }
+        return collationNames.stream().sorted().toList();
+      }
+
+      static List<CollationIdentifier> listCollations() {
+        return allCollationNames().stream().map(name ->
+          new CollationIdentifier(PROVIDER_ICU, name, VersionInfo.ICU_VERSION.toString())).toList();
+      }
+
+      static CollationMeta loadCollationMeta(CollationIdentifier collationIdentifier) {
+        try {
+          int collationId = CollationSpecICU.collationNameToId(
+            collationIdentifier.name, collationIdentifier.name.toUpperCase());
+          return CollationSpecICU.fromCollationId(collationId).buildCollationMeta();
+        } catch (SparkException ignored) {
+          // ignore
+          return null;
+        }
+      }
     }
 
     /**
@@ -730,9 +854,12 @@ public CollationIdentifier identifier() {
     }
   }
 
+  public static final String CATALOG = "SYSTEM";
+  public static final String SCHEMA = "BUILTIN";
   public static final String PROVIDER_SPARK = "spark";
   public static final String PROVIDER_ICU = "icu";
   public static final List<String> SUPPORTED_PROVIDERS = List.of(PROVIDER_SPARK, PROVIDER_ICU);
+  public static final String COLLATION_PAD_ATTRIBUTE = "NO_PAD";
 
   public static final int UTF8_BINARY_COLLATION_ID =
     Collation.CollationSpecUTF8.UTF8_BINARY_COLLATION_ID;
@@ -923,4 +1050,12 @@ public static String getClosestSuggestionsOnInvalidName(
 
     return String.join(", ", suggestions);
   }
+
+  public static List<CollationIdentifier> listCollations() {
+    return Collation.CollationSpec.listCollations();
+  }
+
+  public static CollationMeta loadCollationMeta(CollationIdentifier collationIdentifier) {
+    return Collation.CollationSpec.loadCollationMeta(collationIdentifier);
+  }
 }

docs/sql-ref-ansi-compliance.md

@@ -442,6 +442,7 @@ 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|reserved|
 |COLLECTION|non-reserved|non-reserved|non-reserved|
 |COLUMN|reserved|non-reserved|reserved|
 |COLUMNS|non-reserved|non-reserved|non-reserved|

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

@@ -162,6 +162,7 @@ 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

@@ -260,6 +260,7 @@ statement
     | SHOW PARTITIONS identifierReference partitionSpec?               #showPartitions
     | SHOW identifier? FUNCTIONS ((FROM | IN) ns=identifierReference)?
         (LIKE? (legacy=multipartIdentifier | pattern=stringLit))?      #showFunctions
+    | SHOW COLLATIONS (LIKE? pattern=stringLit)?                       #showCollations
     | SHOW CREATE TABLE identifierReference (AS SERDE)?                #showCreateTable
     | SHOW CURRENT namespace                                           #showCurrentNamespace
     | SHOW CATALOGS (LIKE? pattern=stringLit)?                            #showCatalogs
@@ -1837,6 +1838,7 @@ nonReserved
     | CODEGEN
     | COLLATE
     | COLLATION
+    | COLLATIONS
     | COLLECTION
     | COLUMN
     | COLUMNS

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/catalog/SessionCatalog.scala

@@ -24,6 +24,7 @@ import java.util.concurrent.TimeUnit
 import javax.annotation.concurrent.GuardedBy
 
 import scala.collection.mutable
+import scala.jdk.CollectionConverters.CollectionHasAsScala
 import scala.util.{Failure, Success, Try}
 
 import com.google.common.cache.{Cache, CacheBuilder}
@@ -39,7 +40,8 @@ import org.apache.spark.sql.catalyst.expressions.{Alias, Cast, Expression, Expre
 import org.apache.spark.sql.catalyst.parser.{CatalystSqlParser, ParserInterface}
 import org.apache.spark.sql.catalyst.plans.logical.{LogicalPlan, Project, SubqueryAlias, View}
 import org.apache.spark.sql.catalyst.trees.CurrentOrigin
-import org.apache.spark.sql.catalyst.util.{CharVarcharUtils, StringUtils}
+import org.apache.spark.sql.catalyst.util.{CharVarcharUtils, CollationFactory, StringUtils}
+import org.apache.spark.sql.catalyst.util.CollationFactory.CollationMeta
 import org.apache.spark.sql.connector.catalog.CatalogManager
 import org.apache.spark.sql.connector.catalog.CatalogManager.SESSION_CATALOG_NAME
 import org.apache.spark.sql.errors.{QueryCompilationErrors, QueryExecutionErrors}
@@ -1899,6 +1901,17 @@ class SessionCatalog(
       .filter(isTemporaryFunction)
   }
 
+  /**
+   * List all built-in collations with the given pattern.
+   */
+  def listCollations(pattern: Option[String]): Seq[CollationMeta] = {
+    val collationIdentifiers = CollationFactory.listCollations().asScala.toSeq
+    val filteredCollationNames = StringUtils.filterPattern(
+      collationIdentifiers.map(_.getName), pattern.getOrElse("*")).toSet
+    collationIdentifiers.filter(ident => filteredCollationNames.contains(ident.getName)).map(
+      CollationFactory.loadCollationMeta)
+  }
+
   // -----------------
   // | Other methods |
   // -----------------

sql/catalyst/src/test/resources/ansi-sql-2016-reserved-keywords.txt

@@ -48,6 +48,7 @@ CLOSE
 COALESCE
 COLLATE
 COLLATION
+COLLATIONS
 COLLECT
 COLUMN
 COMMIT

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

@@ -1096,4 +1096,16 @@ class SparkSqlAstBuilder extends AstBuilder {
       withIdentClause(ctx.identifierReference(), UnresolvedNamespace(_)),
       cleanedProperties)
   }
+
+  /**
+   * Create a [[ShowCollationsCommand]] command.
+   * Expected format:
+   * {{{
+   *   SHOW COLLATIONS (LIKE? pattern=stringLit)?;
+   * }}}
+   */
+  override def visitShowCollations(ctx: ShowCollationsContext): LogicalPlan = withOrigin(ctx) {
+    val pattern = Option(ctx.pattern).map(x => string(visitStringLit(x)))
+    ShowCollationsCommand(pattern)
+  }
 }

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

@@ -0,0 +1,62 @@
+/*
+ * 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 org.apache.spark.sql.{Row, SparkSession}
+import org.apache.spark.sql.catalyst.expressions.{Attribute, AttributeReference}
+import org.apache.spark.sql.catalyst.util.CollationFactory.CollationMeta
+import org.apache.spark.sql.types.StringType
+
+/**
+ * A command for `SHOW COLLATIONS`.
+ *
+ * The syntax of this command is:
+ * {{{
+ *    SHOW COLLATIONS (LIKE? pattern=stringLit)?;
+ * }}}
+ */
+case class ShowCollationsCommand(pattern: Option[String]) extends LeafRunnableCommand {
+
+  override val output: Seq[Attribute] = Seq(
+    AttributeReference("COLLATION_CATALOG", StringType, nullable = false)(),
+    AttributeReference("COLLATION_SCHEMA", StringType, nullable = false)(),
+    AttributeReference("COLLATION_NAME", StringType, nullable = false)(),
+    AttributeReference("LANGUAGE", StringType)(),
+    AttributeReference("COUNTRY", StringType)(),
+    AttributeReference("ACCENT_SENSITIVITY", StringType, nullable = false)(),
+    AttributeReference("CASE_SENSITIVITY", StringType, nullable = false)(),
+    AttributeReference("PAD_ATTRIBUTE", StringType, nullable = false)(),
+    AttributeReference("ICU_VERSION", StringType)())
+
+  override def run(sparkSession: SparkSession): Seq[Row] = {
+    val systemCollations: Seq[CollationMeta] =
+      sparkSession.sessionState.catalog.listCollations(pattern)
+
+    systemCollations.map(m => Row(
+      m.catalog,
+      m.schema,
+      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
+    ))
+  }
+}

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

@@ -48,6 +48,7 @@ CLUSTERED	false
 CODEGEN	false
 COLLATE	true
 COLLATION	true
+COLLATIONS	true
 COLLECTION	false
 COLUMN	true
 COLUMNS	false
@@ -381,6 +382,7 @@ CAST
 CHECK
 COLLATE
 COLLATION
+COLLATIONS
 COLUMN
 CONSTRAINT
 CREATE