Michael McCandless created LUCENE-8962: ------------------------------------------
Summary: Can we merge small segments during refresh, for faster searching? Key: LUCENE-8962 URL: https://issues.apache.org/jira/browse/LUCENE-8962 Project: Lucene - Core Issue Type: Improvement Components: core/index Reporter: Michael McCandless With near-real-time search we ask {{IndexWriter}} to write all in-memory segments to disk and open an {{IndexReader}} to search them, and this is typically a quick operation. However, when you use many threads for concurrent indexing, {{IndexWriter}} will accumulate write many small segments during {{refresh}} and this then adds search-time cost as searching must visit all of these tiny segments. The merge policy would normally quickly coalesce these small segments if given a little time ... so, could we somehow improve {{IndexWriter'}}s refresh to optionally kick off merge policy to merge segments below some threshold before opening the near-real-time reader? It'd be a bit tricky because while we are waiting for merges, indexing may continue, and new segments may be flushed, but those new segments shouldn't be included in the point-in-time segments returned by refresh ... One could almost do this on top of Lucene today, with a custom merge policy, and some hackity logic to have the merge policy target small segments just written by refresh, but it's tricky to then open a near-real-time reader, excluding newly flushed but including newly merged segments since the refresh originally finished ... I'm not yet sure how best to solve this, so I wanted to open an issue for discussion! -- This message was sent by Atlassian Jira (v8.3.2#803003) --------------------------------------------------------------------- To unsubscribe, e-mail: dev-unsubscr...@lucene.apache.org For additional commands, e-mail: dev-h...@lucene.apache.org