= Codec Factory
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A `codecFactory` can be specified in `solrconfig.xml` to determine which Lucene {lucene-javadocs}/core/org/apache/lucene/codecs/Codec.html[`Codec`] is used when writing the index to disk.

If not specified, Lucene's default codec is implicitly used.

== Alternatives to the Default Codec
There are two alternatives to Lucene's default codec.

=== solr.SchemaCodecFactory

The {solr-javadocs}/solr-core/org/apache/solr/core/SchemaCodecFactory.html[`solr.SchemaCodecFactory`] supports 2 key features:

* Schema based per-fieldtype configuration for `docValuesFormat` and `postingsFormat` - see the <<field-type-definitions-and-properties.adoc#field-type-properties,Field Type Properties>> section for more details.
* A `compressionMode` option:
** `BEST_SPEED` (default) is optimized for search speed performance
** `BEST_COMPRESSION` is optimized for disk space usage

Example:

[source,xml]
----
<codecFactory class="solr.SchemaCodecFactory">
  <str name="compressionMode">BEST_COMPRESSION</str>
</codecFactory>
----

=== solr.SimpleTextCodecFactory

This factory for Lucene's {solr-javadocs}/solr-core/org/apache/solr/core/SimpleTextCodecFactory.html[`SimpleTextCodecFactory`] produces a plain text human-readable index format.

CAUTION: *FOR RECREATIONAL USE ONLY*. This codec should never be used in production. `SimpleTextCodec` is relatively slow and takes up a large amount of disk space. Its use should be limited to educational and debugging purposes.

Example:

[source,xml]
----
<codecFactory class="solr.SimpleTextCodecFactory"/>
----