nutch和solr建立搜索引擎基础（单机版）
cd ${APACHE_SOLR_HOME} cp -r server/solr/configsets/basic_configs server/solr/configsets/nutchcp ${NUTCH_RUNTIME_HOME}/conf/schema.xml server/solr/configsets/nutch/conf
mv server/solr/configsets/nutch/conf/managed-schema server/solr/configsets/nutch/conf/managed-schema.backup
#启动solr服务
solr start
#创建nutch core
solr create -c nutch -d server/solr/configsets/nutch/conf/ -force #-force：强制以root身份执行，生产环境请勿使用该参数
创建过程并非一帆风顺，整个过程充满了各种bug，从这个角度考虑，生产环境中有必要更换到solr的稳定版，好在这些坑已经趟过：
问题1：Caused by: Unknown parameters: {enablePositionInc rements=true}
具体信息：
Copying configuration to new core instance directory:
/opt/solr-6.6.0/server/solr/nutch
Creating new core 'nutch' using command:
http://localhost:8983/solr/admin/cores?action=CREATE&name=nutch&instanceDir=nutch
ERROR: Error CREATEing SolrCore 'nutch': Unable to create core Caused by: Unknown parameters: {enablePositionIncrements=true}
解决办法：
vimserver/solr/configsets/nutch/conf/schema.xml 找到并去掉enablePositionIncrements=true
问题2：ERROR: Error CREATEing SolrCore 'nutch': Unable to create core Caused by: defaultSearchField has been deprecated and is incompatible with configs with luceneMatchVersion >= 6.6.0.Use 'df' on requests instead.
解决办法：
vim server/solr/configsets/nutch/conf/solrconfig.xml 将luceneMatchVersion版本修改为6.2.0
问题3：org.apache.solr.common.SolrException: fieldType 'booleans' not found in the schema
解决办法:
vim /opt/solr-6.6.0/server/solr/configsets/nutch/conf/solrconfig.xml
找到booleans，替换成boolean，如下：
<lst name="typeMapping">
<str name="valueClass">java.lang.Boolean</str>
<str name="fieldType">boolean</str>
</lst>
Then it will work..
问题3以后，会发生多起类似事件，如下：
ERROR: Error CREATEing SolrCore 'nutch': Unable to create core Caused by: fieldType 'tdates' not found in the schema
ERROR: Error CREATEing SolrCore 'nutch': Unable to create core Caused by: fieldType 'tlongs' not found in the schema
ERROR: Error CREATEing SolrCore 'nutch': Unable to create core Caused by: fieldType 'tdoubles' not f ound in the schema
参照问题3的方法，一次性去掉''中关键字的复数形式即可。
问题4：ERROR:
Core 'nutch' already exists!
Checked core existence using Core API command:
http://localhost:8983/solr/admin/cores?action=STATUS&core=nutch
解决办法：
solr delete -c nutch #删除core 'nutch'
如果删除完，还提示这个错误，这是由于每次修改完配置文件，需要重启下solr服务，更新下状态。
最终的执行结果：
solr create -c nutch -d server/solr/configsets/nutch/conf/ -force
Copying configuration to new core instance directory:
/opt/solr-6.6.0/server/solr/nutch
Creating new core 'nutch' using command:
http://localhost:8983/solr/admin/cores?action=CREATE&name=nutch&instanceDir=nutch
{
"responseHeader":{
"status":0,
"QTime":3408},
"core":"nutch"}
执行成功！
在浏览器中访问
http://localhost:8983/solr/#/
可以看到名称为nutch的core
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