如何在Kafka Topic中找到消息的偏移量？偏移量包含多条消息还是一条消息？
答案 0 :(得分：1)
偏移仅链接到主题的单个分区内的单个消息。
您可以在许多分区和许多主题中使用相同的偏移量，但是除非您明确要求生产者这样做，否则这些值之间几乎没有关联。
没有简单的方法来查找单个消息的偏移量。您需要扫描整个主题（或至少一个分区）
答案 1 :(得分：0)
假设您已经使用\documentclass{article}
\usepackage[latin1]{inputenc}
\usepackage{tikz}
\usetikzlibrary{shapes,arrows}
%%%<
\usepackage{verbatim}
\usepackage[active,tightpage]{preview}
\PreviewEnvironment{tikzpicture}
\setlength\PreviewBorder{5pt}%
%%%>
\begin{document}
\pagestyle{empty}
\tikzset
{
arrow/.style={
->,>=stealth}
}
% Define block styles
\tikzstyle{decision} = [diamond, draw,
text width=4.5em, text badly centered, inner sep=0pt]
\tikzstyle{block} = [rectangle, draw,
text width=5em, text centered, rounded corners, minimum height=4em]
\tikzstyle{block1} = [rectangle, draw,
text width=6em, text centered, rounded corners, minimum height=4em]
\tikzstyle{block2} = [rectangle, draw,
text width=15em, text centered, rounded corners, minimum height=4em]
\tikzstyle{block3} = [rectangle, draw,
text width=20em, text centered, rounded corners, minimum height=4em]
\tikzstyle{line} = [draw, -latex']
\begin{tikzpicture}[node distance = 2.5cm, auto]
% Place nodes
\node [block3] (Watermarked Image) {Watermarked Image};
\node[decision, above of =Watermarked Image,node distance=4cm ] (Difference between selected coefficients) {Difference between selected coefficients };
\node [block, left of=Difference between selected coefficients, node distance=3.5cm] (Inverse DCT for each block)
{Inverse DCT for each block};
\node [block, right of=Difference between selected coefficients, node distance=3.5cm] (Modify AC coefficients)
{Modify AC coefficients and perform Inverse DCT for each block};
\node [block2, above of=Difference between selected coefficients] (Genetic Algorithm)
{Genetic Algorithm search DCT coefficients to find best option for insert watermark};
\node [block, above of=Genetic Algorithm] (DCT for each block)
{DCT for each block};
\node [block, left of=DCT for each block] (Watermark Message)
{Watermark Message};
\node [block, above of=DCT for each block] (8x8 Image Blocking)
{8x8 Image Blocking};
\node [block, above of=Watermark Message] (Host Image)
{Host Image};
% Draw edges
\path [line] (Host Image) -- (8x8 Image Blocking);
\path [line] (8x8 Image Blocking) -- (DCT for each block);
\path [line] (DCT for each block) -- (Genetic Algorithm);
%\path [line] (Watermark Message) -- (Genetic Algorithm);
%\path [line] (Modify AC coefficients) -- (Inverse DCT for each block);
%\path [line] (Inverse DCT for each block) -- (Watermarked Image);
\path [line] (Genetic Algorithm) -- (Difference between selected coefficients);
\path [line] (Difference between selected coefficients) -- node {yes} (Inverse DCT for each block);
\path [line] (Difference between selected coefficients) -- node {no}(Modify AC coefficients);
\coordinate (n2nl) at ([xshift=-2cm]Genetic Algorithm.north);
\coordinate (n2nr) at ([xshift=-3cm]Watermarked Image.north);
\coordinate (n2ns) at ([xshift=3cm]Watermarked Image.east);
\draw[arrow] (Watermark Message.south -| n2nl) -- (n2nl);
\draw[arrow] (Inverse DCT for each block.south -| n2nr) -- (n2nr);
% \draw[arrow] (Modify AC coefficients.south -| n2ns) -- (n2ns);
\draw[arrow] ([xshift=-0.5cm]Modify AC coefficients.south) -| ([xshift=3cm]Watermarked Image.north);
\end{tikzpicture}
\end{document}
或consume()阅读了该消息，并且对该消息的详细信息感兴趣，则可以使用以下代码找到相应的分区和偏移量： / p>
poll()Kafka主题分为多个分区。 Kafka以循环方式在分区之间分配传入消息（除非您已指定要分区的密钥）。因此，对于尚未阅读的随机消息，可能必须扫描所有分区以找到消息，然后扫描相应的偏移量。