Fix MATERIALIZE/CLEAR INDEX IN PARTITION support

Add IN PARTITION clause parsing for CLEAR INDEX statements.
Fix EXPLAIN output for MATERIALIZE INDEX IN PARTITION to show Partition
without requiring PARTITION ID syntax.
Normalize CLEAR_INDEX to DROP_INDEX in EXPLAIN output.

Fixes 4 additional tests.

Author: claude

internal/explain/statements.go

@@ -1320,6 +1320,10 @@ func explainAlterCommand(sb *strings.Builder, cmd *ast.AlterCommand, indent stri
 	if cmdType == ast.AlterClearColumn {
 		cmdType = ast.AlterDropColumn
 	}
+	// CLEAR_INDEX is shown as DROP_INDEX in EXPLAIN AST
+	if cmdType == ast.AlterClearIndex {
+		cmdType = ast.AlterDropIndex
+	}
 	// DELETE_WHERE is shown as DELETE in EXPLAIN AST
 	if cmdType == ast.AlterDeleteWhere {
 		cmdType = "DELETE"
@@ -1397,17 +1401,27 @@ func explainAlterCommand(sb *strings.Builder, cmd *ast.AlterCommand, indent stri
 		if cmd.Index != "" {
 			fmt.Fprintf(sb, "%s Identifier %s\n", indent, cmd.Index)
 		}
+		// CLEAR INDEX IN PARTITION clause
+		if cmd.Partition != nil {
+			fmt.Fprintf(sb, "%s Partition (children 1)\n", indent)
+			Node(sb, cmd.Partition, depth+2)
+		}
 	case ast.AlterMaterializeIndex:
 		if cmd.Index != "" {
 			fmt.Fprintf(sb, "%s Identifier %s\n", indent, cmd.Index)
 		}
-		// MATERIALIZE INDEX can have IN PARTITION ID clause
-		if cmd.Partition != nil && cmd.PartitionIsID {
-			if lit, ok := cmd.Partition.(*ast.Literal); ok {
-				fmt.Fprintf(sb, "%s Partition_ID Literal_\\'%s\\' (children 1)\n", indent, lit.Value)
-				Node(sb, cmd.Partition, depth+2)
+		// MATERIALIZE INDEX can have IN PARTITION or IN PARTITION ID clause
+		if cmd.Partition != nil {
+			if cmd.PartitionIsID {
+				if lit, ok := cmd.Partition.(*ast.Literal); ok {
+					fmt.Fprintf(sb, "%s Partition_ID Literal_\\'%s\\' (children 1)\n", indent, lit.Value)
+					Node(sb, cmd.Partition, depth+2)
+				} else {
+					fmt.Fprintf(sb, "%s Partition_ID (children 1)\n", indent)
+					Node(sb, cmd.Partition, depth+2)
+				}
 			} else {
-				fmt.Fprintf(sb, "%s Partition_ID (children 1)\n", indent)
+				fmt.Fprintf(sb, "%s Partition (children 1)\n", indent)
 				Node(sb, cmd.Partition, depth+2)
 			}
 		}
@@ -1660,12 +1674,15 @@ func countAlterCommandChildren(cmd *ast.AlterCommand) int {
 		if cmd.Index != "" {
 			children++
 		}
+		if cmd.Partition != nil {
+			children++
+		}
 	case ast.AlterMaterializeIndex:
 		if cmd.Index != "" {
 			children++
 		}
-		// MATERIALIZE INDEX can have IN PARTITION ID clause
-		if cmd.Partition != nil && cmd.PartitionIsID {
+		// MATERIALIZE INDEX can have IN PARTITION or IN PARTITION ID clause
+		if cmd.Partition != nil {
 			children++
 		}
 	case ast.AlterMaterializeColumn:

parser/parser.go

@@ -4771,6 +4771,14 @@ func (p *Parser) parseAlterCommand() *ast.AlterCommand {
 					cmd.Index = p.current.Value
 					p.nextToken()
 				}
+				// Parse IN PARTITION clause
+				if p.currentIs(token.IN) {
+					p.nextToken() // skip IN
+					if p.currentIs(token.PARTITION) {
+						p.nextToken() // skip PARTITION
+						cmd.Partition = p.parseExpression(LOWEST)
+					}
+				}
 			} else if p.currentIs(token.COLUMN) {
 				cmd.Type = ast.AlterClearColumn
 				p.nextToken()

parser/testdata/01114_materialize_clear_index_compact_parts/metadata.json

@@ -1,9 +1,5 @@
 {
   "explain_todo": {
-    "stmt12": true,
-    "stmt15": true,
-    "stmt16": true,
-    "stmt8": true,
-    "stmt9": true
+    "stmt8": true
   }
 }