Cache Rendered Pages To Speed Up Render Times

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Introduction

When working with large Quarto documents, render times can become a significant bottleneck. One effective way to speed up render times is by caching rendered pages. In this article, we will explore how to cache rendered pages in Quarto and provide additional tips on how to optimize your Quarto workflow.

What is Caching?

Caching is a technique used to store the results of expensive function calls so that they can be reused instead of recalculated. In the context of Quarto, caching rendered pages means storing the rendered HTML output of a page in a cache directory, so that when the same page is rendered again, the cached version can be used instead of re-rendering the page from scratch.

Benefits of Caching Rendered Pages

Caching rendered pages offers several benefits, including:

  • Faster render times: By reusing cached versions of rendered pages, you can significantly reduce the time it takes to render your Quarto document.
  • Improved performance: Caching reduces the load on your system and network, making it ideal for large Quarto documents or those with complex rendering requirements.
  • Enhanced user experience: Faster render times and improved performance result in a better user experience, making it easier for readers to access and engage with your content.

How to Cache Rendered Pages in Quarto

To cache rendered pages in Quarto, you can use the freeze: auto option in the execute section of your main Quarto options. This option tells Quarto to only re-render pages when the content changes.

Example Quarto Configuration

quarto:
  execute:
    freeze: auto

By setting freeze: auto, Quarto will cache rendered pages and only re-render them when the content changes. This can significantly speed up render times, especially for large Quarto documents.

Pre-Render Script to Clear Cache

However, there may be cases where you need to clear the cache manually, such as when updating R packages used in your Quarto document. To achieve this, you can use a pre-render script to clear out the cache for files where the R packages have been updated.

Example Pre-Render Script

#!/bin/bash

# Get the list of updated R packages
updated_packages=$(Rscript -e "installed.packages()")

# Clear the cache for files where the R packages have been updated
for file in $(find . -name "*.qmd"); do
  if grep -q "$updated_packages" "$file"; then
    rm -rf "$file.cache"
  fi
done

This pre-render script uses Rscript to get the list of updated R packages and then clears the cache for files where the R packages have been updated.

Best Practices for Caching Rendered Pages

To get the most out of caching rendered pages in Quarto, follow these best practices:

  • Use freeze: auto: Set freeze: auto in the execute section of your main Quarto options to enable caching.
  • Clear cache manually: Use a pre-render script to clear the cache for files where the R packages have been updated.
  • Monitor cache size: Keep an eye on the size of your cache directory to ensure it doesn't grow too large and impact performance.
  • Test and optimize: Test your Quarto document with caching enabled and optimize your workflow as needed.

Conclusion

Introduction

In our previous article, we explored how to cache rendered pages in Quarto to speed up render times. In this article, we will answer some frequently asked questions about caching rendered pages in Quarto.

Q: What is the difference between freeze: auto and freeze: true?

A: freeze: auto and freeze: true are both used to enable caching in Quarto. However, freeze: auto only re-renders pages when the content changes, whereas freeze: true re-renders all pages every time the document is rendered.

Q: How do I clear the cache manually?

A: You can clear the cache manually by deleting the cache directory. The cache directory is usually located in the same directory as your Quarto document, and its name is the same as your Quarto document with a .cache extension.

Q: Can I cache only specific pages?

A: Yes, you can cache only specific pages by using the freeze option in the execute section of your Quarto document. For example, you can use freeze: auto to cache only pages that have changed since the last render.

Q: How do I monitor the size of my cache directory?

A: You can monitor the size of your cache directory by using the du command in the terminal. For example, you can use du -h .cache to get the size of the cache directory in human-readable format.

Q: Can I use caching with other Quarto features?

A: Yes, you can use caching with other Quarto features, such as incremental rendering and live preview. However, you may need to adjust your Quarto configuration to ensure that caching works correctly with these features.

Q: How do I troubleshoot caching issues?

A: You can troubleshoot caching issues by checking the Quarto logs for errors related to caching. You can also try disabling caching and re-rendering your Quarto document to see if the issue persists.

Q: Can I cache rendered pages in a different location?

A: Yes, you can cache rendered pages in a different location by specifying the cache option in the execute section of your Quarto document. For example, you can use cache: /path/to/cache to cache rendered pages in a different directory.

Q: How do I update my Quarto configuration to use caching?

A: To update your Quarto configuration to use caching, you need to add the quarto section to your Quarto document and set the execute option to freeze: auto. For example, you can add the following code to your Quarto document:

quarto:
  execute:
    freeze: auto

Conclusion

Caching rendered pages is a powerful technique for speeding up render times in Quarto. By answering these frequently asked questions, we hope to have provided you with a better understanding of how to use caching in Quarto. If you have any further questions, please don't hesitate to ask.