Method generateAddIndex

schema/generator.go:3207–3350

generateAddIndex generates DDL to add an index.

(table QualifiedName, index Index)

// generateAddIndex generates DDL to add an index.
func (g *Generator) generateAddIndex(table QualifiedName, index Index) string {
	var uniqueOption string
	var clusteredOption string
	if index.unique {
		uniqueOption = " UNIQUE"
	}
	if index.clustered {
		clusteredOption = " CLUSTERED"
	} else {
		clusteredOption = " NONCLUSTERED"
	}

	columns := []string{}
	for _, indexColumn := range index.columns {
		var column string
		// For simple column references (ColName), use escapeSQLIdent to preserve quoting
		if colName, ok := indexColumn.columnExpr.(*parser.ColName); ok {
			column = g.escapeSQLIdent(colName.Name)
		} else {
			// For expressions (functional indexes), format with quote awareness
			if !g.config.LegacyIgnoreQuotes {
				column = g.formatExprQuoteAware(indexColumn.columnExpr)
			} else {
				// Legacy mode: use parser.String for backward compatibility
				column = parser.String(indexColumn.columnExpr)
			}
			if g.indexKeyPartNeedsParens(indexColumn.columnExpr) {
				column = "(" + column + ")"
			}
		}
		if indexColumn.length != nil {
			column += fmt.Sprintf("(%d)", *indexColumn.length)
		}
		if indexColumn.direction == DescScr {
			column += fmt.Sprintf(" %s", indexColumn.direction)
		}
		if indexColumn.operatorClass != "" {
			column += " " + indexColumn.operatorClass
		}
		if indexColumn.withoutOverlaps {
			column += " WITHOUT OVERLAPS"
		}
		columns = append(columns, column)
	}

	optionDefinition := g.generateIndexOptionDefinition(index.options)

	switch g.mode {
	case GeneratorModeMssql:
		var ddl string
		var partition string
		if !index.primary {
			ddl = fmt.Sprintf(
				"CREATE%s%s INDEX %s ON %s",
				uniqueOption,
				clusteredOption,
				g.escapeSQLIdent(index.name),
				g.escapeQualifiedName(table),