1 files changed, 133 insertions, 0 deletions
diff --git a/weed/query/engine/describe.go b/weed/query/engine/describe.go
new file mode 100644
index 000000000..3a26bb2a6
--- /dev/null
+++ b/weed/query/engine/describe.go
@@ -0,0 +1,133 @@
+package engine
+
+import (
+	"context"
+	"fmt"
+	"strings"
+
+	"github.com/seaweedfs/seaweedfs/weed/query/sqltypes"
+)
+
+// executeDescribeStatement handles DESCRIBE table commands
+// Shows table schema in PostgreSQL-compatible format
+func (e *SQLEngine) executeDescribeStatement(ctx context.Context, tableName string, database string) (*QueryResult, error) {
+	if database == "" {
+		database = e.catalog.GetCurrentDatabase()
+		if database == "" {
+			database = "default"
+		}
+	}
+
+	// Auto-discover and register topic if not already in catalog (same logic as SELECT)
+	if _, err := e.catalog.GetTableInfo(database, tableName); err != nil {
+		// Topic not in catalog, try to discover and register it
+		if regErr := e.discoverAndRegisterTopic(ctx, database, tableName); regErr != nil {
+			fmt.Printf("Warning: Failed to discover topic %s.%s: %v\n", database, tableName, regErr)
+			return &QueryResult{Error: fmt.Errorf("topic %s.%s not found and auto-discovery failed: %v", database, tableName, regErr)}, regErr
+		}
+	}
+
+	// Get topic schema from broker
+	recordType, err := e.catalog.brokerClient.GetTopicSchema(ctx, database, tableName)
+	if err != nil {
+		return &QueryResult{Error: err}, err
+	}
+
+	// System columns to include in DESCRIBE output
+	systemColumns := []struct {
+		Name  string
+		Type  string
+		Extra string
+	}{
+		{"_ts", "TIMESTAMP", "System column: Message timestamp"},
+		{"_key", "VARBINARY", "System column: Message key"},
+		{"_source", "VARCHAR(255)", "System column: Data source (parquet/log)"},
+	}
+
+	// Format schema as DESCRIBE output (regular fields + system columns)
+	totalRows := len(recordType.Fields) + len(systemColumns)
+	result := &QueryResult{
+		Columns: []string{"Field", "Type", "Null", "Key", "Default", "Extra"},
+		Rows:    make([][]sqltypes.Value, totalRows),
+	}
+
+	// Add regular fields
+	for i, field := range recordType.Fields {
+		sqlType := e.convertMQTypeToSQL(field.Type)
+
+		result.Rows[i] = []sqltypes.Value{
+			sqltypes.NewVarChar(field.Name), // Field
+			sqltypes.NewVarChar(sqlType),    // Type
+			sqltypes.NewVarChar("YES"),      // Null (assume nullable)
+			sqltypes.NewVarChar(""),         // Key (no keys for now)
+			sqltypes.NewVarChar("NULL"),     // Default
+			sqltypes.NewVarChar(""),         // Extra
+		}
+	}
+
+	// Add system columns
+	for i, sysCol := range systemColumns {
+		rowIndex := len(recordType.Fields) + i
+		result.Rows[rowIndex] = []sqltypes.Value{
+			sqltypes.NewVarChar(sysCol.Name),  // Field
+			sqltypes.NewVarChar(sysCol.Type),  // Type
+			sqltypes.NewVarChar("YES"),        // Null
+			sqltypes.NewVarChar(""),           // Key
+			sqltypes.NewVarChar("NULL"),       // Default
+			sqltypes.NewVarChar(sysCol.Extra), // Extra - description
+		}
+	}
+
+	return result, nil
+}
+
+// Enhanced executeShowStatementWithDescribe handles SHOW statements including DESCRIBE
+func (e *SQLEngine) executeShowStatementWithDescribe(ctx context.Context, stmt *ShowStatement) (*QueryResult, error) {
+	switch strings.ToUpper(stmt.Type) {
+	case "DATABASES":
+		return e.showDatabases(ctx)
+	case "TABLES":
+		// Parse FROM clause for database specification, or use current database context
+		database := ""
+		// Check if there's a database specified in SHOW TABLES FROM database
+		if stmt.Schema != "" {
+			// Use schema field if set by parser
+			database = stmt.Schema
+		} else {
+			// Try to get from OnTable.Name with proper nil checks
+			if stmt.OnTable.Name != nil {
+				if nameStr := stmt.OnTable.Name.String(); nameStr != "" {
+					database = nameStr
+				} else {
+					database = e.catalog.GetCurrentDatabase()
+				}
+			} else {
+				database = e.catalog.GetCurrentDatabase()
+			}
+		}
+		if database == "" {
+			// Use current database context
+			database = e.catalog.GetCurrentDatabase()
+		}
+		return e.showTables(ctx, database)
+	case "COLUMNS":
+		// SHOW COLUMNS FROM table is equivalent to DESCRIBE
+		var tableName, database string
+
+		// Safely extract table name and database with proper nil checks
+		if stmt.OnTable.Name != nil {
+			tableName = stmt.OnTable.Name.String()
+			if stmt.OnTable.Qualifier != nil {
+				database = stmt.OnTable.Qualifier.String()
+			}
+		}
+
+		if tableName != "" {
+			return e.executeDescribeStatement(ctx, tableName, database)
+		}
+		fallthrough
+	default:
+		err := fmt.Errorf("unsupported SHOW statement: %s", stmt.Type)
+		return &QueryResult{Error: err}, err
+	}
+}