DuckDB: failed with OOM killer

```
SELECT REGEXP_REPLACE(Referer, '^https?://(?:www\.)?([^/]+)/.*$', '\1') AS k, AVG(STRLEN(Referer)) AS l, COUNT(*) AS c, MIN(Referer) FROM hits WHERE Referer <> '' GROUP BY k HAVING COUNT(*) > 100000 ORDER BY l DESC LIMIT 25;
-c .timer on -c SELECT REGEXP_REPLACE(Referer, '^https?://(?:www\.)?([^/]+)/.*$', '\1') AS k, AVG(STRLEN(Referer)) AS l, COUNT(*) AS c, MIN(Referer) FROM hits WHERE Referer <> '' GROUP BY k HAVING COUNT(*) > 100000 ORDER BY l DESC LIMIT 25; -c SELECT REGEXP_REPLACE(Referer, '^https?://(?:www\.)?([^/]+)/.*$', '\1') AS k, AVG(STRLEN(Referer)) AS l, COUNT(*) AS c, MIN(Referer) FROM hits WHERE Referer <> '' GROUP BY k HAVING COUNT(*) > 100000 ORDER BY l DESC LIMIT 25; -c SELECT REGEXP_REPLACE(Referer, '^https?://(?:www\.)?([^/]+)/.*$', '\1') AS k, AVG(STRLEN(Referer)) AS l, COUNT(*) AS c, MIN(Referer) FROM hits WHERE Referer <> '' GROUP BY k HAVING COUNT(*) > 100000 ORDER BY l DESC LIMIT 25;
./run.sh: line 19: 6545 Killed duckdb hits.db "${cli_params[@]}"
```

On `c6a.large`.

Reproduziere das SQL aus dem Issue über run.sh, insbesondere Zeile 19, in der angegebenen c6a.large-Umgebung, und untersuche den DuckDB-Aufruf sowie den beendeten Prozess. Als abgeschlossen gilt die Aufgabe, wenn das OOM-Verhalten erklärt ist und das Issue eine dokumentierte, reproduzierbare Lösung oder eine verifizierte Änderung enthält, die den Fehler verhindert.

Vom Indexierungsmodell aus dem Issue-Text verfasst.