Apache Solr Reference Guide Covering Apache Solr 6.0

information:
Setting Name Type Default Description
numRecordsToKeep int 100 The number of update records to keep per log
maxNumLogsToKeep int 10 The maximum number of logs keep
numVersionBuckets int 65536 The number of buckets used to keep track of max version values
when checking for re-ordered updates; increase this value to reduce
the cost of synchronizing access to version buckets during
high-volume indexing, this requires (8 bytes (long) *
numVersionBuckets) of heap space per Solr core.
An example, to be included under in solrconfig.xml, employing the above
advanced settings:
${solr.ulog.dir:}
500
20
65536
Query Settings in SolrConfig
The settings in this section affect the way that Solr will process and respond to queries. These settings are all
configured in child elements of the element in solrconfig.xml.
...
Topics covered in this section:
Caches
Query Sizing and Warming
Query-Related Listeners
Caches
Solr caches are associated with a specific instance of an Index Searcher, a specific view of an index that doesn't
change during the lifetime of that searcher. As long as that Index Searcher is being used, any items in its cache
will be valid and available for reuse. Caching in Solr differs from caching in many other applications in that
cached Solr objects do not expire after a time interval; instead, they remain valid for the lifetime of the Index
Searcher.
When a new searcher is opened, the current searcher continues servicing requests while the new one
auto-warms its cache. The new searcher uses the current searcher's cache to pre-populate its own. When the
new searcher is ready, it is registered as the current searcher and begins handling all new search requests. The
old searcher will be closed once it has finished servicing all its requests.
In Solr, there are three cache implementations: solr.search.LRUCache, solr.search.FastLRUCache, a
nd solr.search.LFUCache .
The acronym LRU stands for Least Recently Used. When an LRU cache fills up, the entry with the oldest
last-accessed timestamp is evicted to make room for the new entry. The net effect is that entries that are
Apache Solr Reference Guide 6.0
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