Function BuildDuckDBCopyFromSQL

server/conn_copy.go:161–190

BuildDuckDBCopyFromSQL generates a DuckDB COPY FROM statement

(tableName, columnList, filePath string, opts *CopyFromOptions)

	opts.HasHeader = copyWithCSVRegex.MatchString(upperQuery) && copyWithHeaderRegex.MatchString(upperQuery)

	return opts, nil
}

// BuildDuckDBCopyFromSQL generates a DuckDB COPY FROM statement
func BuildDuckDBCopyFromSQL(tableName, columnList, filePath string, opts *CopyFromOptions) string {
	// DuckDB syntax: COPY table FROM 'file' (FORMAT CSV, HEADER, NULL 'value', DELIMITER ',', QUOTE '"')
	// AUTO_DETECT FALSE disables sniffer to prevent it from overriding our settings
	// STRICT_MODE FALSE allows reading rows that don't strictly comply with CSV standard
	// PARALLEL FALSE avoids "Parallel CSV Reader does not support full read" errors
	// on files streamed from COPY FROM STDIN (temp files with no seek support for sniffing)
	copyOptions := []string{
		"FORMAT CSV",
		"AUTO_DETECT FALSE",
		"STRICT_MODE FALSE",
		"PARALLEL FALSE",
		fmt.Sprintf("MAX_LINE_SIZE %d", copyMaxLineSizeBytes),
	}
	if opts.HasHeader {
		copyOptions = append(copyOptions, "HEADER")
	}
	// Always specify NULL string - DuckDB doesn't recognize \N by default
	copyOptions = append(copyOptions, fmt.Sprintf("NULL '%s'", opts.NullString))
	// Always specify DELIMITER explicitly (required when AUTO_DETECT is FALSE)
	copyOptions = append(copyOptions, fmt.Sprintf("DELIMITER '%s'", opts.Delimiter))
	// Always specify QUOTE for CSV to ensure proper quote handling
	if opts.Quote != "" {
		copyOptions = append(copyOptions, fmt.Sprintf("QUOTE '%s'", opts.Quote))
		// Set ESCAPE to match QUOTE for RFC 4180 compliance (doubled quotes = escaped quote)
		escape := opts.Escape
		if escape == "" {
			escape = opts.Quote
		}
		copyOptions = append(copyOptions, fmt.Sprintf("ESCAPE '%s'", escape))