Optimizing Memory Usage while Working with Big Files having Large Datasets

When building a workbook with large data sets, or reading a big Microsoft Excel file, the total amount of RAM the process will take is always a concern. There are measures which can be adapted to cope with the challenge. Aspose.Cells provides some relevant options and API calls to lower, reduce and optimize memory use. Also, it can help the process to work more efficiently and run faster.

Use MemorySetting.MemoryPreference option to optimize memory used for cells data to decrease the overall memory cost. When building large data set for cells, it can save a certain amount of memory compared to using the default setting MemorySetting.Normal.

Optimizing Memory

The following example shows how to optimize memory usage while working with large data in Aspose.Cells for JavaScript via C++.

<!DOCTYPE html>
<html>
    <head>
        <title>Aspose.Cells Example</title>
    </head>
    <body>
        <h1>Optimize Memory Usage Example</h1>
        <input type="file" id="fileInput" accept=".xls,.xlsx,.csv" />
        <button id="runExample">Run Example</button>
        <a id="downloadLink" style="display: none;">Download Result</a>
        <div id="result"></div>
    </body>

    <script src="aspose.cells.js.min.js"></script>
    <script type="text/javascript">
        const { Workbook, SaveFormat, MemorySetting } = AsposeCells;
        
        AsposeCells.onReady({
            license: "/lic/aspose.cells.enc",
            fontPath: "/fonts/",
            fontList: [
                "arial.ttf",
                "NotoSansSC-Regular.ttf"
            ]
        }).then(() => {
            console.log("Aspose.Cells initialized");
        });

        document.getElementById('runExample').addEventListener('click', async () => {
            const fileInput = document.getElementById('fileInput');
            if (!fileInput.files.length) {
                document.getElementById('result').innerHTML = '<p style="color: red;">Please select an Excel file or leave empty to create a new one.</p>';
                // Allow creating a new workbook even if no file selected; return only if user explicitly requires file.
            }

            // If a file is provided, open it; otherwise create a new workbook
            let workbook;
            if (fileInput.files.length) {
                const file = fileInput.files[0];
                const arrayBuffer = await file.arrayBuffer();
                workbook = new Workbook(new Uint8Array(arrayBuffer));
            } else {
                workbook = new Workbook();
            }

            // apply the setting to existing "Sheet1"
            workbook.worksheets.get(0).cells.memorySetting = MemorySetting.MemoryPreference;

            // apply the setting globally
            workbook.settings.memorySetting = MemorySetting.MemoryPreference;

            // Saving the modified Excel file
            const outputData = workbook.save(SaveFormat.Xlsx);
            const blob = new Blob([outputData]);
            const downloadLink = document.getElementById('downloadLink');
            downloadLink.href = URL.createObjectURL(blob);
            downloadLink.download = 'out.xlsx';
            downloadLink.style.display = 'block';
            downloadLink.textContent = 'Download Modified Excel File';

            document.getElementById('result').innerHTML = '<p style="color: green;">Memory settings applied successfully! Click the download link to get the modified file.</p>';
        });
    </script>
</html>

Caution

The default option, MemorySetting.Normal is applied for all versions. For some situations, such as building a workbook with a large data set for cells, the MemorySetting.MemoryPreference option may optimize the memory use and decrease the memory cost for the application. However, this option may degrade performance in some special cases such as follow.

Accessing Cells Randomly and Repeatedly: The most efficient sequence for accessing the cells collection is cell by cell in one row, and then row by row. Especially, if you access rows/cells by the Enumerator acquired from Cells, RowCollection and Row, the performance would be maximized with MemorySetting.MemoryPreference.
Inserting & Deleting Cells & Rows: Please note that if there are lots of insert/delete operations for Cells/Rows, the performance degradation will be notable for MemorySetting.MemoryPreference mode as compared to the MemorySetting.Normal mode.
Operating on Different Cell Types: If most of the cells contain string values or formulas, the memory cost will be the same as MemorySetting.Normal mode but if there are lots of empty cells, or cell values are numeric, bool and so on, the MemorySetting.MemoryPreference option will give better performance.