Legacy Search Engine is the default search= engine, it is SQL based and uses Doctrine's database connection. So its co= nnections are, and should be, defined in the same way as for storage engine= , and no further specific configuration is needed.
Its features and performance are limited, and if you have specific searc= h or performance needs you should rather look towards using Solr.
Search can be configured in= dependently from storage, and the following configuration example shows bot= h the default values, and how you configure legacy as the search engine:
ezpublish:
repositories:
main:
storage:
engine: legacy
connection: default
search:
engine: legacy
connection: default=20