# Understanding ES812Postings Codec Vs Lucene99 Codec

**URL:** <https://discuss.elastic.co/t/understanding-es812postings-codec-vs-lucene99-codec/379659>\
**Category:** Elasticsearch\
**Created:** [July 1, 2025, 9:09am UTC](https://discuss.elastic.co/t/understanding-es812postings-codec-vs-lucene99-codec/379659 "2025-07-01T09:09:19Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![Aditya\_Teltia](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/aditya_teltia/32/122447_2.png) [@Aditya\_Teltia](https://discuss.elastic.co/u/Aditya_Teltia)\
**Post date:** [July 1, 2025, 9:09am UTC](https://discuss.elastic.co/t/understanding-es812postings-codec-vs-lucene99-codec/379659/1 "2025-07-01T09:09:19Z")

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Hi Everyone,

I was going through the changes made in `elasticsearch` to tackle lucene's new posting format that uses FOR instead of PFOR and got to know that `elasticsearch` made its own PFOR codec `ES812Postings`.

My doubt is `LiveIndexWriterConfig` in lucene still loads default codec `Lucene99`, is Elasticsearch expecting postings to be written by multiple codecs or it will always be written by `ES812Postings` codec. Although it is clear elasticsearch prefers PFOR but It is not very clear what is the behaviour expected just by reading the code.