How to load and parse a large PDF from stream chunk by chunk without loading it completely in the memory?

[atharva-uptiq]

I’m working on a project where I need to load and parse a large PDF file (over 2GB) from a stream without loading the entire file into memory. I have a ReadStream created from Google Cloud Storage (GCS) / S3, and I want to process the PDF using JavaScript (node).

My goal is to efficiently read the PDF in chunks, extracting text and other relevant data for further processing.

Additionally, I would like to know how this approach can be extended to handle other document types, such as CSV, DOCX, or Excel files.

If anyone has experience with handling large PDFs in this way or can provide insights on best practices for stream processing, I would greatly appreciate your help!

[dosubot[bot]]

Hey @atharva-uptiq! I'm here to help you out with any bugs, questions, or contributions you might have. Let's solve this together!

LangChain provides support for handling large PDF files using streams, but primarily in Python. For JavaScript, you might need to look into libraries like pdf-lib or pdfjs-dist that can handle PDF parsing in a streaming manner. These libraries allow you to process PDFs page by page without loading the entire file into memory.

For handling streams from GCS or S3, you can use the respective SDKs to create a read stream and then pipe this stream into your PDF processing logic. Here's a general approach:

1. Create a Read Stream: Use the GCS or S3 SDK to create a read stream for your PDF file.
2. Process the Stream: Use a PDF library that supports streaming to process the PDF page by page. For example, pdf-lib allows you to work with PDF documents in a more memory-efficient way.
3. Extract Text: As you process each page, extract the text and any other relevant data.

For other document types like CSV, DOCX, or Excel, you can use libraries such as csv-parser for CSV files, mammoth for DOCX, and exceljs for Excel files. These libraries also support streaming and can help you process large files efficiently.

While LangChain doesn't provide JavaScript-specific tools for this task, these libraries and approaches should help you achieve your goal of processing large files in chunks.

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