Help with Empty Facets After Upgrading to Solr 9.8.1

[Vincenzo D'Amore]

Hi Solr Community,

I'm reaching out for help understanding an issue I've encountered after
upgrading from Solr 8 to Solr 9.8.1. Since the upgrade, my facet queries
are returning empty results, even though the indexed data appears to be
intact.

I've also upgraded the schema version to 1.7 as part of the migration. The
most significant change seems to be related to two custom solr.TextField-based
field types that previously supported faceting in Solr 8 but no longer do
in Solr 9.8.1.

Here are the field type definitions that are causing trouble:

<fieldType name="kwd" stored="true" indexed="true" class="solr.TextField">
  <analyzer type="index">
    <tokenizer class="solr.KeywordTokenizerFactory"/>
    <filter class="solr.LowerCaseFilterFactory" />
  </analyzer>
</fieldType>

<fieldType name="payloads" stored="true" indexed="true"
class="solr.TextField" positionIncrementGap="1000">
  <analyzer type="index">
    <tokenizer class="solr.WhitespaceTokenizerFactory"/>
    <filter class="solr.DelimitedPayloadTokenFilterFactory"
encoder="float" delimiter=":"/>
  </analyzer>
  <analyzer type="query">
    <tokenizer class="solr.WhitespaceTokenizerFactory"/>
  </analyzer>
</fieldType>

These fields used to work fine for faceting in Solr 8. Now, after this
issue or knows if there were changes in Solr 9.x that affect faceting on
TextField types? Are there recommended alternatives or adjustments I should
make to restore facet functionality?

Any guidance or suggestions would be greatly appreciated!

Thanks in advance,
Vincenzo
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Vincenzo D'Amore