Search sessions and cursor pagination

SearchSessionManager retains a committed IndexSearcher view while a client pages through results. Later commits and refreshes do not change that session.

using var searchers = new SearcherManager(directory);
using var sessions = new SearchSessionManager(searchers);
using var session = sessions.OpenSession();

var page = session.Search(
    new TermQuery("body", "coffee"),
    pageSize: 20,
    sorts: [SortField.Numeric("price"), SortField.String("name")]);

while (page.NextCursor is not null)
{
    page = session.Search(
        new TermQuery("body", "coffee"),
        pageSize: 20,
        cursor: page.NextCursor,
        sorts: [SortField.Numeric("price"), SortField.String("name")]);
}

Dispose sessions promptly. Abandoned sessions expire automatically.

Limits

The defaults allow 256 sessions, eight retained generations, 4 GiB of uniquely retained snapshot files, and a 15-minute lifetime. New sessions are rejected when a limit is reached. Set LimitPolicy to EvictOldest when replacing the oldest session is preferable.

GetDiagnostics() reports active sessions, age, generations, retained bytes and files, files awaiting deletion, and lifecycle failures.

Cursors

Cursors are opaque, versioned and limited to 4 KiB by default. They contain only internal continuation state. They are bound to the session, index, commit generation, query, sort definition and optional ranking identity.

Set CursorIntegrityKey to at least 16 bytes to protect tokens with HMAC-SHA256. Keep the key outside logs and configuration files that may be exposed.

Every sort ends with document ID as its final tie-breaker. Numeric and integer fields missing a sort value use 0; missing strings use an empty value. Non-finite score and numeric boundaries are rejected.

Ranking compatibility

Pass rankingIdentity when application-owned ranking affects compatibility. Basic identity-only RankingProfile requests are supported directly. Pipelines, rules, rescorers, fusion, pinning and diversification are rejected until they supply complete continuation state; LeanCorpus does not silently rerank each page independently.

Sessions currently retain committed SearcherManager views. Near-real-time sessions are not supported.