我想用elasticsearch为博客的文章做站内搜索，后台用的php。
文章表articles的全部字段如下：
id title content user_id created_at updated_at现在我想为文章表的title字段、content字段、updated_at字段，共三个字段创建索引。
下面是我参照elasticsearch-php客户端的官方文档写的创建索引blog和创建类型article的demo，分词用到了ik分词。
其中有些选项不太清楚什么意思，具体问题在下面代码中（有4个），请大神帮解答一下，谢谢。
官方文档链接：https://www.elastic.co/guide/en/elasticsearch/client/php-api/current/_index_management_operations.html#_create_an_index_advanced_example
$params = [
'index' => 'blog',
'body' => [
'settings' => [
'number_of_shards' => 1,
'number_of_replicas' => 0,
'analysis' => [
'filter' => [
//1、这里的两个shingle应该改成article吗？
'shingle' => [
'type' => 'shingle'
]
],
//2、char_filter里面内容表示什么意思？包括pre_negs和post_negs。
'char_filter' => [
'pre_negs' => [
'type' => 'pattern_replace',
'pattern' => '(\\w+)\\s+((?i:never|no|nothing|nowhere|noone|none|not|havent|hasnt|hadnt|cant|couldnt|shouldnt|wont|wouldnt|dont|doesnt|didnt|isnt|arent|aint))\\b',
'replacement' => '~$1 $2'
],
'post_negs' => [
'type' => 'pattern_replace',
'pattern' => '\\b((?i:never|no|nothing|nowhere|noone|none|not|havent|hasnt|hadnt|cant|couldnt|shouldnt|wont|wouldnt|dont|doesnt|didnt|isnt|arent|aint))\\s+(\\w+)',
'replacement' => '$1 ~$2'
]
],
//3、analyzer的内容需要怎么修改吗？
'analyzer' => [
'blog' => [
'type' => 'custom',
'tokenizer' => 'standard',
'filter' => ['lowercase', 'stop', 'kstem']
]
]
]
],
'mappings' => [
'article' => [
"_all" => [
"analyzer" => "ik_max_word",
"search_analyzer" => "ik_max_word",
"term_vector" => "no",
"store" => "false"
],
'properties' => [
'title' => [
'type' => 'string',
'store' => 'no',
'term_vector' => 'with_positions_offsets',
'analyzer' => 'ik_max_word',
'search_analyzer' => 'ik_max_word',
'include_in_all' => 'true',
'boost' => 9
],
'content' => [
'type' => 'string',
'store' => 'no',
'term_vector' => 'with_positions_offsets',
'analyzer' => 'ik_max_word',
'search_analyzer' => 'ik_max_word',
'include_in_all' => 'true',
'boost' => 8
],
//4、时间只是用来在搜索的时候排序使用，下面的选项该怎么填写？
'updated_at' => [
'type' => '',
'store' => '',
'term_vector' => '',
'analyzer' => '',
'search_analyzer' => '',
'include_in_all' => '',
'boost' =>
]
]
]
]
]
];
$client->indices()->create($params);