I am using the method proposed by Nikos Alexandris in "How to apply alternate row coloring in a longtable in LyX?"
works to a limited extent but the shaded rows does not fill the whole width of page. Shading per cell, but the shading breaks column lines and there are gaps in shading.
here is my example tex code that does the broken shading. The tex gets auto generated so I am just showing a short table. real data is longer and should typically span pages with repeated headers.
\date{\today}
\documentclass[9pt]{article}
\usepackage{graphicx}
\usepackage{longtable}
\usepackage[margin=0.5in]{geometry}
\usepackage{fancyhdr}
\LTchunksize=200
\setlength{\parindent}{0cm}
\title{test}
\author{R}
\setlength{\headheight}{0.4in}
\setlength{\headwidth}{\textwidth}
\usepackage[table]{xcolor}
% define lightgray
\definecolor{lightgray}{gray}{0.9}
% alternate rowcolors for all long-tables
\let\oldlongtable\longtable
\let\endoldlongtable\endlongtable
\renewenvironment{longtable}{\rowcolors{2}{white}{lightgray}\oldlongtable} {
\endoldlongtable}
\begin{document}
\section{Sector}
\begin{longtable}{ @{\extracolsep{\fill}} |l | r | r | r | r | r|}
\hline
{} & Beta & Phys & Phys & Phys & comp \\
Industry Code & {} & {} & {} & {} & {} \endhead
\hline
Materials & 16,365,792 & 13,419,455 & 13,419,455 & 0.00 & -201,593 \\
Goods & 471,925 & 1,110,412 & 1,110,412 & 0.00 & -11,947 \\
Services & 7,122,991 & 8,511,225 & 9,492,570 & -981,345 & -75,117 \\
Banks & 5,078,280 & 6,123,238 & 12,084,671 & -5,961,433 & -69,738 \\
Health & 2,141,346 & 5,059,382 & 5,059,382 & 0.00 & -26,319 \\
Industrials & -6,013,491 & -4,758,346 & 6,036,445 & -10,794,791 & 3,722 \\
row & -4,093,746 & -3,755,730 & 0.00 & -3,755,730 & 45,628 \\
row & -1,753,606 & -1,006,601 & 2,533,792 & -3,540,393 & -18,962 \\
Consumer & 2,227,195 & 2,317,581 & 2,317,581 & 0.00 & -30,632 \\
All & 20,808,544 & 25,160,345 & 54,728,908 & -29,568,563 & nan \\
\hline
\end{longtable}
\end{document}
