What causes "Unknown query session: " + sessionId" in t8y2/dbx?

Re-execute the original query to obtain a fresh sessionId, then paginate with the new id.

t8y2/dbx · error · IllegalArgumentException

Unknown query session: " + sessionId

Error message

Unknown query session: " + sessionId

What it means

fetchQueryPage looks up a paged query result by sessionId in the QUERY_SESSIONS map. If the id is absent, the plugin throws this IllegalArgumentException: pagination was requested for a session that was never started or has been evicted/expired.

Source

Thrown at plugins/jdbc/src/main/java/app/dbx/jdbc/DbxJdbcPlugin.java:1265

    private static void restorePagedQueryTransaction(Connection connection, boolean restoreAutoCommit) {
        if (!restoreAutoCommit) {
            return;
        }
        try {
            connection.rollback();
        } catch (SQLException ignored) {
        }
        try {
            connection.setAutoCommit(true);
        } catch (SQLException ignored) {
        }
    }

    private static JsonNode fetchQueryPage(String sessionId, int pageSize) throws SQLException {
        QuerySession session = QUERY_SESSIONS.get(sessionId);
        if (session == null) {
            throw new IllegalArgumentException("Unknown query session: " + sessionId);
        }
        return readQuerySessionPage(session, pageSize);
    }

    private static JsonNode readQuerySessionPage(QuerySession session, int pageSize) throws SQLException {
        int effectivePageSize = Math.max(1, pageSize);
        ArrayNode rows = MAPPER.createArrayNode();
        boolean truncated = false;

        while (rows.size() < effectivePageSize && session.rowsReturned < session.maxRows) {
            ArrayNode row;
            if (session.pendingRow != null) {
                row = session.pendingRow;
                session.pendingRow = null;
            } else {
                if (!session.resultSet.next()) {
                    closeQuerySession(session.id);
                    return queryPageResult(session, rows, false, false);

View on GitHub (pinned to c0390bff16)

Solutions

Re-execute the original query to obtain a fresh sessionId, then paginate with the new id.
Paginate fully before the session expires/gets evicted — increase page size or speed up fetching.
Ensure all page requests go to the same plugin instance/process; pin requests to one worker or share session state.
Handle this error by restarting pagination from the first page instead of treating it as fatal data loss.

Example fix

// before
page2 = fetchQueryPage("sess-42", 500);   // session evicted -> error
// after
result = executeQuery(sql);                // fresh session
for (page : result.pages()) consume(page); // paginate before expiry

Defensive patterns

Strategy: retry

Validate before calling

// Java: validate sessionId shape before paginating
if (sessionId == null || sessionId.isBlank())
    throw new IllegalArgumentException("sessionId required; run the query first");

Try / catch

try {
    page = plugin.fetchQueryPage(sessionId, pageSize);
} catch (IllegalArgumentException e) {
    if (e.getMessage().startsWith("Unknown query session")) {
        result = plugin.executeQuery(sql);      // session expired/evicted: restart
        page = result.firstPage();
    } else {
        throw e;
    }
}

Prevention

Fetch all pages promptly after the query instead of holding session ids across long gaps
Never persist session ids across process restarts or redeployments
Route all pagination requests to the same plugin instance/worker
Use a larger pageSize if eviction is likely before you finish consuming pages

When it happens

Trigger: Calling the fetch-page operation with a sessionId returned by a previous run after a plugin restart (static map cleared), after session eviction (map size limit/TTL), a typo'd/stale id, or a session created on a different plugin instance (multi-process setup).

Common situations: Long-running jobs paginating slowly while the session cache evicts old entries, load-balanced workers where page 2 hits a different process, or client restarts resuming pagination from a persisted session id.

Related errors

AI-assisted analysis of t8y2/dbx@c0390bff16 (2026-09-05). Data as JSON: /api/errors/2f77d3c554e815e3. Report an issue: GitHub.