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<H2><A NAME="s9">9. Limits, a few minor ones</A> </H2>
<P>The following limits apply.
<P>There must not be any ASCII TAB characters in the data.
This is the primary limit as the ASCII TAB character is
the delimiter in tables.
The following names are reserved to the awk language, and should not
be used to indicate column names:
<P><EM>BEGIN, END, break, continue, else, exit, exp, for, getline, if, in,
index, int, length, log, next, print, printf, split, sprintf, sqrt,
substr, while</EM>, and possibly others, depending on the implementation
of your awk (i.e. mawk, gawk, etc.). Refer to the man page and the
documentation of you awk interpeter.
<P>Horizontal TABs and newlines, although forbidden as such in
table data, can be conveniently represented by means of the
ASCII strings '\t' and '\n' respectively.
This rule applies to tables only. Files in 'list' format can
contain any characters literally, including physical TABs and
newlines.
<P>The number of columns in a table may be limited to 32.768
by some AWK implementations (I think <CODE>mawk</CODE> is one of those).
It should not be a problem though, as it is a very high number anyway.
In spite of this, mawk is very fast and I recommend it
over other AWK implementations.
<P>A more serious drawback of the operator-stream paradigm is that it
is process-based. This means that an average pipeline will open
several processes at once, one or more for each operator. On
complex queries this can lead to exceed the max. No. of child processes
allowed by your operating system. This limit is O.S. specific and it
can usually be overcome by getting the system administrator to increase
this value as needed.
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