What's the maximum number of pages a PDF produced by pdfTeX can have?

Question

Are there some limitations regarding the pdflatex command with respect to the count of pages of the input files?

My highest page count, when compiling, was 90 without any troubles. (2008)

Currently another document will be prepared which will be approx. 170 pages in sum.

EDIT: Thanks to all answers. They were helpful.

Answer 1

TeX is designed to have very limited memory requirements (basically once a page is shipped out it is gone) I had people generating longtable documents with 10s of thousands of pages back in the 1990's so on modern machines I don't think 170 pages is going to stress the system too much.

What is more important than page count is page complexity: if you have a high resolution plot done in tikz or picture mode or some such then that ends up being an awful lot of boxes on the same page. That's why sometimes it helps to generate such things as external graphics to be included. Unless they are changing on each run that will typically speed things up even if calculating them inline doesn't exceed memory requirements.

Answer 2

The pages are stored in a page structure, a balanced tree. The top node contains an integer with the number of pages. The maximal integer number in PDF and TeX is 2³¹−1 (2,147,483,647). However indirect objects are needed to store pages in the PDF format (PDF specification):

• 1 Page node per page;
• 1 Resources object per page (pdfTeX generates the object for each page, even if the resource objects are the same and could be shared);
• 1 Contents object per page (in theory equal pages could share the same object, but it is not supported by pdfTeX and unlikely for real documents).
• Overhead of the page tree structure with additional kid nodes;
• And the document has a few additional objects (e.g. Catalog, Info).

Thus more than 3 indirect objects are needed per page. But the number of indirect objects (indirect objects are PDF objects that can be referenced by the object number and are recorded in the cross reference section) is limited: 2²³−1 (8,388,607).

The following test file explores the maximal number of pages with pdfTeX. It does only generates minimal pages without fonts, annotations. The pages are completely empty (\shipout\hbox{}).

% pdftex --ini test.tex
\catcode`\{=1
\catcode`\}=2
\pdfoutput=1
\iffalse
  \pdfobjcompresslevel=2
  \pdfcompresslevel=9
\else
  \pdfobjcompresslevel=0
  \pdfcompresslevel=0
\fi
\pdfminorversion=5
\countdef\pageno=0
\chardef\one=1
\countdef\max=255
\max=2621437
\def\x{%
  \advance\pageno\one
  \shipout\hbox{}%
  \ifnum\max=\pageno
    \let\x\relax
  \fi
  \x
}
\x
\end

Tested with pdfTeX 3.1415925-2.4-1.40.13 (TeX Live 2012). Result:

Pages: 2,621,437
File size: 862,082,448 bytes
PDF without object stream compression

If the page number is increased by one, then pdfTeX complains with an error message:

! TeX capacity exceeded, sorry [indirect objects table size=8388607].

PDF object stream compression of PDF-1.5 decreases the file size, but costs indirect objects for storing the object streams. That decreases the maximal number of pages. For testing, replace \iffalse by \iftrue in the example above and play with the setting for \max. Result:

Pages: 2,603,538
File size: 329,412,496
PDF with object stream compression

In practice especially annotations costs objects (and therefore pages), whereas fonts can be reused throughout the document.

Summary

The theoretical maximal number of pages for PDF files with pdfTeX is 2,621,437 (empty pages and without object stream compression of PDF-1.5).

Answer 3

Other than architectural limits of PDF (the number of indirect objects in a PDF is limited to 8Mi as per ISO-32000:2008, and numbers are limited to 2Gi), there are no known limits. If memory allows and your disc is large enough, pdfTeX should be able to generate PDF up to some TiBytes. It will fail eventually—the offset size in the compressed xref table is limited to 2⁴⁰(5 bytes)—but extending that limit is easy.

Answer 4

A few years ago I compiled a Beamer document with 10'000 pages and 30'000 formulas without any issues. A colleague's PhD thesis compiled nicely as well: 1'500 pages, 1'300 of them full-pages images with 5--10 lines of caption each, resulting in a 4.5 GB PDF file.

So within thinkable limits there is no limit.

However you may encounter limits in the number of concurrent auxiliary files. Creating hundreds of different indices or listoffloats may result in issues with those limits. IIRC there was a number of 17 concurrent file streams TeX may be able to write to.