I would guess the problem is that the field on which you're trying to do the regular expression is mapped as "not_analyzed". It appears that regular expressions in Lucene only work on analyzed fields.
My test setup below works if the "message" field is set to analyzed (which is the default), but does not work if I set it to "not_analyzed".
curl -XPOST 'http://localhost:9200/test2' -d '{
"mappings" : {
"test" : {
"properties" : {
"post_date" : { "type" : "date"},
"message" : { "type" : "string" }
}
}
}
}'
curl -XPUT 'http://localhost:9200/test2/test/1' -d '{
"post_date" : "2015-11-15T14:12:12",
"message" : "ABC"
}'
