Elasticsearch Migration / Upgrade

[haarg]

Discussed in #1182

Hosted Elasticsearch

• Move Elasticsearch server setup to config files #1202
• Upload data to hosted ES instance

Elasticsearch Compatibility Issues

This list of issues may not be comprehensive, but is all of the things I found in the change logs that seemed relevant to our codebase.

Elasticsearch 5

• search_type=scan removed in Elasticsearch 5 #1262
• fields parameter has been replaced by stored_fields #1263
• Deprecated queries removed: filtered, missing, query #1264
• Removed support for the deprecated filter fields in nested query, in favour of query. #1265
• Removed support for the top level filter element in function_score query, replaced by query. #1266
• Removed support for the deprecated top level filter in the search api #1267
• The _timestamp and _ttl fields were deprecated and are now removed. #1268
• string fields replaced by text/keyword fields #1269

Post upgrade

• Convert mappings to use text/keyword types
• Fix script syntax to use source rather than inline

Elasticsearch 6

• Indexes with multiple types can no longer be created #1297
• The Groovy scripting language has now been removed. Was deprecated in ES 5.
  • drop support for metacpan_script #1205
  • index module name length as separate field #1206
  • use inline expression script for preferring short module names #1207
• integer values no longer supported for boolean fields #1273

Elasticsearch 7

• Negative boosts are not allowed #1270
• ES7: hits.total is now an object in the search response #1301

Elasticsearch 8

• All type support has been removed
  • REST API endpoints containing mapping types have been removed
  • Searches on the _type field are no longer supported
  • The type query has been removed
• The nested_filter and nested_path properties have been removed from the search API’s sort request body parameter. Was deprecated in 6.