Is the full-text search in TeamConnect the same as Elasticsearch?

No. Elasticsearch provides global searching based on an index stored on a dedicated server. Full text search can still be achieved directly from your database, though it may not be as robust as the new global search.

How many shards should I use?

The default value of 5 primary shards should be more than sufficient for almost all clients.

Can Elasticsearch work with clustered instances? What infrastructure is needed on premise?

Yes. On-premise clients will need one instance of TeamConnect Enterprise (clustered or not) and one instance of Elasticsearch.

What hardware requirements are suggested for Elasticsearch?

The suggested Elasticsearch hardware requirements are flexible depending on each use case. General requirements include:

8 GB RAM (most configurations can make do with 4 GB RAM)

Are there words which Elasticsearch will not search on?

Elasticsearch/Lucene has the following words filtered out of searches:

"a", "an", "and", "are", "as", "at", "be", "but", "by",

"for", "if", "in", "into", "is", "it",

"no", "not", "of", "on", "or", "such",

"that", "the", "their", "then", "there", "these",

"they", "this", "to", "was", "will", "with"