I want to combine PDFs totaling 23 Gig. 7 will only address 2 directly (Max size). Will 9 or 11 address 23 Gig of memory?

[dickRDA]

Will Acrobat 9 or 11 directly address at least 23 Gig?  I want to combine documents totaling 23 Gig.  I have Acrobat 7, running Windows 7, which limits me to 2 Gig as that is all the memory it can address directly.

[try67]

It will probably work in Acrobat XI, but earlier versions are a gamble.

[dickRDA]

Who can tell me how much memory XI will address, or 9?   I "chatted" with Adobe Tech - they passed me off three times, supposedly to more technically oriented people each time - NOTHING!  Finally, the last guy told me he could not help me - to go to THIS Forum.

[Test Screen Name]

What makes you say it is limited to 2 GB? Have you tested it, or do you assume it has that limit because it is a 32-bit app (still is, by the way)?

[dickRDA]

I made no assumptions.  I have tried many times - only less than 2 Gig works - and won't give me an error message - that there is not enough memory.  They say that Acrobat is NO Limit but, in fact, it does depend on how much memory the program can address directly.  It it not my machine as it has 32 Gig of RAM and researching on the web said that Acrobat 7 was written such that it can only address 2 Gig (which was a lot at that time) and therefore that is the DeFacto Limit - only later versions are able to directly address more memory.  However, unfortunately, it did not say which & how much later versions will address.

So, I repeat the question:  How much memory will Acrobat 9 and 11 directly address?

[Dave Merchant]

You can't create a 23GB PDF document, period. As per the ISO standard, the overall file size must be under ~10GB because the tables defining whereabouts in the file each page object is stored only work with 10 bits.

All versions of Acrobat and Reader, past and present, are 32-bit applications.

[dickRDA]

How about an answer?  What is the earliest version of Acrobat that will combine documents to create a 10GB PDF file?  That would still be better than what I have.

[Test Screen Name]

dickRDA, I don't know why you are asking about discontinued products that can't be purchased, but Acrobat 9 and 11, like the current versions DC and 2017, are all 32-bit apps on Windows (not Mac). In case you don't know, that means 2 GB of memory can be used.  Acrobat does NOT read files entirely into memory to process them so it is capable of working with larger files. I have done so. You may have hit a bug, in the very old version you are using, especially as it was the first to support files over 2 GB. How exactly do you combine? Have you tried other methods?

Dave Merchant, NO. What you describe is a limitation of the "xref table", but later versions of the PDF reference make that optional, and can use "xref streams" instead. These limit file sizes, not to 2GB but to almost 10 GB. XRef streams start by defining how many bytes are used to represent an offset, and there is no specified limit on this. So long as an app supports PDF 1.5, the xref table can be left out. This does forbid its use for PDF/X-1a, PDF/X-3 and PDF/A-1 too.

There ARE implementation limits in Acrobat. It uses 64-bit file addressing, which limits it to about 18 billion gigabytes, a little more than the theoretical limit on NTFS file size, and more than 10,000 times the total data believed to be held by Google, Amazon, Microsoft and Facebook.. Before Acrobat 7, 32-bit file addressing was used, which did limit files to 2GB or 4GB (can't remember which), even though the xref table allowed bigger files.

[dickRDA]

Of course these discontinued products can be purchased - from individuals, on eBay or even on Amazon.

I don't claim to know all the tech details but, I'm sure that even my 7 will work with files bigger that 2 GB, I know because I did it - HOWEVER, you can't save the file!  You get an error message - too much, or not enough memory, I don't remember exactly what it said.

How did I do the combining?  Simply as they tell you:  File->Create PDF->form multiple files, then bring them all in, in the order you want them.  It works wonderfully - until you try to SAVE it.

I have no idea what the "xref table" or "xref streams" are but, I would like to know IF THEY CAN ALLOW ME TO SAVE A FILE LARGER THAN 2 GB.

Does anyone have an ANSWER to my question?

[try67]

I've just used Acrobat XI to save a file that's larger than 4 GB, so the ANSWER to your QUESTION is YES.