小编Sun*_*mar的帖子

我对数据库很新,我还没有很多工作.现在我想了解术语数据库集群.我google了很多,发现了许多有用的链接,但我无法理解它们 - 也许是因为我对数据库的基础知识很少,而且它们都是非常技术性的语言.

我需要就这几点提出建议:

1. PostgreSQL中的数据库集群是什么？
2. 如何在PostgreSQL中创建集群？

我有一个卡桑德拉1.1.2安装我的系统为单节点集群上有三个keyspaces: hotel,student和employee.我希望尽可能转储键空间模式hotel及其列族数据,并在其他Cassandra集群上恢复转储.任何人都可以详细建议我该怎么做？

当提交日志目录的总大小超过 680 Mb 时，它会抛出此异常

ERROR [COMMIT-LOG-ALLOCATOR] 2012-07-04 15:04:57,070 AbstractCassandraDaemon.java (line 134) Exception in thread Thread[COMMIT-LOG-ALLOCATOR,5,main]
java.io.IOError: java.io.IOException: Map failed
    at org.apache.cassandra.db.commitlog.CommitLogSegment.<init>(CommitLogSegment.java:127)
    at org.apache.cassandra.db.commitlog.CommitLogAllocator$3.run(CommitLogAllocator.java:203)
    at org.apache.cassandra.db.commitlog.CommitLogAllocator$1.runMayThrow(CommitLogAllocator.java:95)
    at org.apache.cassandra.utils.WrappedRunnable.run(WrappedRunnable.java:30)
    at java.lang.Thread.run(Unknown Source)
Caused by: java.io.IOException: Map failed
    at sun.nio.ch.FileChannelImpl.map(Unknown Source)
    at org.apache.cassandra.db.commitlog.CommitLogSegment.<init>(CommitLogSegment.java:119)
    ... 4 more
Caused by: java.lang.OutOfMemoryError: Map failed
    at sun.nio.ch.FileChannelImpl.map0(Native Method)
    ... 6 more
ERROR [StorageServiceShutdownHook] 2012-07-04 15:04:57,075 AbstractCassandraDaemon.java (line 134) Exception in thread Thread[StorageServiceShutdownHook,5,main]
java.lang.NullPointerException
    at org.apache.cassandra.gms.Gossiper.stop(Gossiper.java:1132)
    at org.apache.cassandra.service.StorageService$2.runMayThrow(StorageService.java:489)
    at org.apache.cassandra.utils.WrappedRunnable.run(WrappedRunnable.java:30)
    at java.lang.Thread.run(Unknown Source)

我是cassandra的新手.我必须编写一个使用cassandra的应用程序.我想知道哪一个对我更好,这样我将来不会遇到太多问题.我应该在申请时使用哪种API.

嗨，我遇到了一个问题，我有一个 svg。当我尝试更改高度和宽度以及视图框的高度和宽度时，svg 内的绘图将无法放入框内

这是我的 mysvg 我给出的简短形式

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">
<svg width="500pt" height="500pt" viewBox="0 0 500 500" version="1.1" xmlns="http://www.w3.org/2000/svg">
    <g transform="translate(528,270)" > 
        <g id="states" fill="green" width="500pt" height="500pt" >
            <a id="s01">
                <path d="M158.95067408594068,46.88327098850149L185.03303599629845,44.0148159910488L189.74121811302572,59.50889743727097L196.59587401503094,82.27898337817625L199.0518321008348,87.17077847298319L201.13017099189912,89.85649424407167L200.707578706067,91.7588142001174L202.6261541288344,92.6205139503571L200.33524838576966,95.29216920133321L200.7363444144292,97.59217497211156L199.80999341478454,100.8918397716738L202.09021078470892,106.20782432993735L201.64399529140977,111.17790897235179L204.03767592952832,115.96122130827978L196.3574723373462,117.09985438789514L163.47293491613115,121.08122011183377L163.22294648718562,123.55296427740802L167.13791879442175,126.6835133291724L166.871741037497,129.76735843938286L168.2485001228969,131.1400084527912L166.21795234496457,134.1137855808483L164.12121282499038,134.9547500732084L159.81791064191435,132.36796011584426L158.90469329765804,127.88713803963412L157.64560372254968,127.51168600895127L156.5390262005875,131.08669596034315L156.36678872306632,134.46030822963786L152.20800610122825,133.97284127048096L148.16895577705603,105.98121856614907L148.12136132417422,70.56398790998259L148.15893441899317,50.102043132249676L146.40831263672231,48.33943105796875Z" stroke="#FFFFFF" stroke-dasharray="1, 0" stroke-width="1.5"></path>
                <text x="162.66165594858754" y="86.92631614090374" style="">AL</text>
                <title></title>
            </a>
        </g>
    </g>
</svg>

这就是我更改宽度和高度或视图框或两者时发生的情况 \

现在宽度高度减少但绘图保持不变