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This article mainly shows you "what is the use of Solr Transaction Log", the content is easy to understand, clear, hope to help you solve your doubts, the following let the editor lead you to study and learn "what is the use of Solr Transaction Log" this article?

The original document is recorded for the index recovery function. In SolrCloud, each node has its own tlog. When updated, the entire document is written to tlog. In the case of an atomic update (Atomic update), the entire document is still written in, including what is read from the old document, in other words, when the atom is updated, the data written to tlog is not incremental data. Tlog is the key to consistency, and even if the JVM crashes before the index segment (segment) is closed, the index will not be lost.

When solr hard commits (hard commit), Transaction Log,Transaction Log is written to redo log, which is a bit like mysql.

Hard commit is to persist the data to disk, and what it does internally is as follows:

1. Generate a new tlog file and delete the old tlog.

2. Fsync the index file in memory to disk, and create an index descriptor, even if the jvm crashes or goes down, it will not affect this part of the index.

3. Make the index visible in searcher.

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