19 simple tables giving “TeX capacity exceeded” / “Too many unprocessed floats”?

Question

When I added a couple of rather unremarkable tables to my document, it stopped compiling (using pdflatex):

"TeX capacity exceeded (main memory)"

I searched the web a bit (well, actually, mostly tex.SE), and found mention that using lualatex should avoid memory issues. So I tried running the code with lualatex, and got

"Too many unprocessed floats"

So, I tried to come up with a minimal working example, and was surprised to find that this little bit of code was sufficient to trigger the problem:

\documentclass{scrbook}

\usepackage[ngerman]{babel}
\usepackage[T1]{fontenc}

\begin{document}

\begin{table*}\begin{tabular}{|c|}Foo\\\end{tabular}\end{table*}
\begin{table*}\begin{tabular}{|c|}Foo\\\end{tabular}\end{table*}
\begin{table*}\begin{tabular}{|c|}Foo\\\end{tabular}\end{table*}
\begin{table*}\begin{tabular}{|c|}Foo\\\end{tabular}\end{table*}
\begin{table*}\begin{tabular}{|c|}Foo\\\end{tabular}\end{table*}
\begin{table*}\begin{tabular}{|c|}Foo\\\end{tabular}\end{table*}
\begin{table*}\begin{tabular}{|c|}Foo\\\end{tabular}\end{table*}
\begin{table*}\begin{tabular}{|c|}Foo\\\end{tabular}\end{table*}
\begin{table*}\begin{tabular}{|c|}Foo\\\end{tabular}\end{table*}
\begin{table*}\begin{tabular}{|c|}Foo\\\end{tabular}\end{table*}
\begin{table*}\begin{tabular}{|c|}Foo\\\end{tabular}\end{table*}
\begin{table*}\begin{tabular}{|c|}Foo\\\end{tabular}\end{table*}
\begin{table*}\begin{tabular}{|c|}Foo\\\end{tabular}\end{table*}
\begin{table*}\begin{tabular}{|c|}Foo\\\end{tabular}\end{table*}
\begin{table*}\begin{tabular}{|c|}Foo\\\end{tabular}\end{table*}
\begin{table*}\begin{tabular}{|c|}Foo\\\end{tabular}\end{table*}
\begin{table*}\begin{tabular}{|c|}Foo\\\end{tabular}\end{table*}
\begin{table*}\begin{tabular}{|c|}Foo\\\end{tabular}\end{table*}
\begin{table*}\begin{tabular}{|c|}Foo\\\end{tabular}\end{table*}

\end{document}

Apparently, I am missing something essential here, as 19 "simple" tables shouldn't be bringing LaTeX down...?!?

Answer 1

You can use the command \clearpage. This prints all floats that are not yet placed and starts a new page.

Answer 2

Each float is pushed in a queue, which is capable to contain only 18 objects (allocated as boxes \bx@A to \bx@R).

This may be extended: the package morefloats was written just for this. However the error "Too many unprocessed floats" is usually caused by too strict limits on float positioning: a table specified with

\begin{table}[!h]

and which can't be placed "there" will block all subsequent floats until coming to a \clearpage command (maybe issued by \chapter) or the end of the document. If 18 floats follow it, the error will be issued.