Need help to decide between the type of spellchecker to use in solr? - solr

Question

I have a list of cities on mysql db which is hooked onto a UI for autocompletion purposes. I am currently using solr-5.3.0. Data import is happening through scheduled delta imports. I have the following questions:
I want to implement spell checker to this feature. I tried using:
DirectSolrSpellChecker
IndexBasedSpellChecker
FileBasedSpellChecker
Out of these 3 only FileBasedSpellChecker is able to give
suggestions that solely exists on db. For eg, while searching
cologne I've got results like
{
"responseHeader":{
"status":0,
"QTime":4,
"params":{
"q":"searchfield:kolakata",
"indent":"true",
"spellcheck":"true",
"wt":"json"}},
"response":{"numFound":0,"start":0,"docs":[]
},
"spellcheck":{
"suggestions":[
"cologne",{
"numFound":4,
"startOffset":12,
"endOffset":19,
"suggestion":["Cologne",
"Bologna",
"Cogne",
"Bastogne"]}],
"collations":[
"collation","searchfield:Cologne"]}}
These cities are pretty accurate and exists in db/file.
But when I use other 2 I got results like
{
"responseHeader":{
"status":0,
"QTime":4,
"params":{
"q":"searchfield:kolakata",
"indent":"true",
"spellcheck":"true",
"wt":"json"}},
"response":{"numFound":0,"start":0,"docs":[]
},
"spellcheck":{
"suggestions":[
"cologne",{
"numFound":4,
"startOffset":12,
"endOffset":19,
"suggestion":["Cologne",
"Cologn",
"Colognei"]}],
"collations":[
"collation","searchfield:Cologne"]}}
These cities who are not present in my db.
Though FileBasedSpellChecker is giving satisfactory results, but I
am a little apprehensive in using them because, I would need to keep
updating the file manually everytime a new city gets added/removed.
Also its generally not advisable to use FileBasedSpellChecker in
general.
I also need to make the suggestions searchable as well, that means
currently I am accessing the doc returned in
"responseHeader":{"response":{"docs":[<some-format>]}}
to search for results in that city, but now I want the suggestor to
return the results in the same <some-format> instead of just
string results, in order to get it integrated with UI properly.
One minor change requested is to sort the suggestions in ascending
order of edit/levenshtein distance. This is not a hard requirement
and can be negotiated with.
edit
My solrconfig looks like this:
<requestHandler name="/select" class="solr.SearchHandler">
<lst name="defaults">
<str name="echoParams">explicit</str>
<int name="rows">10</int>
<str name="df">searchfield</str>
<str name="spellcheck">true</str>
<str name="spellcheck.collate">true</str>
<str name="spellcheck.dictionary">file</str>
<str name="spellcheck.maxCollationTries">5</str>
<str name="spellcheck.count">5</str>
</lst>
<arr name="last-components">
<str>spellcheck</str>
</arr>
</requestHandler>
and
<searchComponent name="spellcheck" class="solr.SpellCheckComponent">
<str name="queryAnalyzerFieldType">text_ngram</str>
<lst name="spellchecker">
<str name="name">file</str>
<str name="classname">solr.FileBasedSpellChecker</str>
<str name="sourceLocation">spellings.txt</str>
<str name="spellcheckIndexDir">./spellchecker</str>
</lst>
</searchComponent>
schema looks like this:
<field name="name" type="string" indexed="true" stored="true" multiValued="false" />
<field name="latlng" type="location" indexed="true" stored="true" multiValued="false" />
<field name="citycode" type="string" indexed="true" stored="true" multiValued="false" />
<field name="country" type="string" indexed="true" stored="true" multiValued="false" />
<field name="searchscore" type="float" indexed="true" stored="true" multiValued="false" />
<field name="searchfield" type="text_ngram" indexed="true" stored="false" multiValued="true" omitNorms="true" omitTermFreqAndPositions="true" />
<defaultSearchFieldsearchfield</defaultSearchField>
<solrQueryParser defaultOperator="OR"/>
<copyField source="name" dest="searchfield"/>