Simon Willnauer created LUCENE-9669: ---------------------------------------
Summary: N-2 compatibility for file formats Key: LUCENE-9669 URL: https://issues.apache.org/jira/browse/LUCENE-9669 Project: Lucene - Core Issue Type: Improvement Reporter: Simon Willnauer Currently Lucene supports reading and writing indices that have been created with the current or previous (N-1) version of Lucene. Lucene refuses to open an index created by N-2 or earlier versions. I would like to propose that Lucene adds support for opening indices created by version N-2 in read-only mode. Here's what I have in mind: - Read-only support. You can open a reader on an index created by version N-2, but you cannot open an IndexWriter on it, meaning that you can neither delete, update, add documents or force-merge N-2 indices. - File-format compatibility only. File-format compatibility enables reading the content of old indices, but not more. Everything that is done on top of file formats like analysis or the encoding of length normalization factors is not guaranteed and only supported on a best-effort basis. The reason I came up with these limitations is because I wanted to make the scope minimal in order to retain Lucene's ability to move forward. If there is consensus to move forward with this, I would like to target Lucene 9.0 with this change. This is a follow-up of the mailinglist thread [here|http://mail-archives.apache.org/mod_mbox/lucene-dev/202101.mbox/%3ccaahmpkg1bd9rtmvfr4jweygyaxwz5osy1hv9ubzks0fhsfn...@mail.gmail.com%3E] -- This message was sent by Atlassian Jira (v8.3.4#803005) --------------------------------------------------------------------- To unsubscribe, e-mail: issues-unsubscr...@lucene.apache.org For additional commands, e-mail: issues-h...@lucene.apache.org