public IndexMemCache getIndexMemCache() {
        if (indexMemCache != null) {
            return indexMemCache;
        }
        long[] values = getMemCacheConfig(MEMCHACHE_EXPIRE_INDEX, MEMCHACHE_MAX_INDEX, MEMCHACHE_MAX_RATE_INDEX, 30, 0.15f);
        indexMemCache = new IndexExpiredMemCache(values[0], values[1]);
        return indexMemCache;
    }
The path where realtime segments declare.
<pre>
    .../rt/table/tableA/host0/seg0_0 ... segN_0
    .../rt/table/tableA/host1/seg0_1 ... segN_1
</pre>
indexr-server/src/main/java/io/indexr/server/IndexRConfig.java