java - Upgrading Solr index from 6 to 8

Question

I have a core which was created years ago, running correctly from a Solr 6.x.

I've upgraded Solr to 7.7.3. I've launched the IndexUpgrade script:

/opt/solr/server/solr-webapp/webapp/WEB-INF/lib$ sudo java -cp lucene-core-7.7.3.jar:lucene-backward-codecs-7.7.3.jar org.apache.lucene.index.IndexUpgrader /var/solr/data/hms/data/index/

It silently run, so my assumption is that it did what it had to do correctly.

Then I've upgraded to Solr 8.7.0, and launched the script:

/opt/solr/server/solr-webapp/webapp/WEB-INF/lib$ sudo java -cp lucene-core-8.7.0.jar:lucene-backward-codecs-8.7.0.jar org.apache.lucene.index.IndexUpgrader /var/solr/data/hms/data/index/

This last code exits with this error:

Exception in thread "main" org.apache.lucene.index.IndexFormatTooOldException: Format version is not supported (resource BufferedChecksumIndexInput(MMapIndexInput(path="/var/solr/data/hms/data/index/segments_asky"))): This index was initially created with Lucene 6.x while the current version is 8.7.0 and Lucene only supports reading the current and previous major versions.. This version of Lucene only supports indexes created with release 7.0 and later.
    at org.apache.lucene.index.SegmentInfos.readCommit(SegmentInfos.java:322)
    at org.apache.lucene.index.SegmentInfos.readCommit(SegmentInfos.java:291)
    at org.apache.lucene.index.SegmentInfos$1.doBody(SegmentInfos.java:461)
    at org.apache.lucene.index.SegmentInfos$1.doBody(SegmentInfos.java:458)
    at org.apache.lucene.index.SegmentInfos$FindSegmentsFile.run(SegmentInfos.java:720)
    at org.apache.lucene.index.SegmentInfos$FindSegmentsFile.run(SegmentInfos.java:672)
    at org.apache.lucene.index.SegmentInfos.readLatestCommit(SegmentInfos.java:463)
    at org.apache.lucene.index.DirectoryReader.listCommits(DirectoryReader.java:260)
    at org.apache.lucene.index.IndexUpgrader.upgrade(IndexUpgrader.java:158)
    at org.apache.lucene.index.IndexUpgrader.main(IndexUpgrader.java:78)
    Suppressed: org.apache.lucene.index.CorruptIndexException: checksum passed (58082b0a). possibly transient resource issue, or a Lucene or JVM bug (resource=BufferedChecksumIndexInput(MMapIndexInput(path="/var/solr/data/hms/data/index/segments_asky")))
        at org.apache.lucene.codecs.CodecUtil.checkFooter(CodecUtil.java:466)
        at org.apache.lucene.index.SegmentInfos.readCommit(SegmentInfos.java:434)
        ... 9 more

Why is that? Am I not doing things correctly, i.e. first upgrade the index from 6 to 7 and then from 7 to 8? How can I get my index working with Solr 8?

Answer 1

I've recreated the core and the index, as Solr doesn't seem to deal well with indexes created more than one major version in the past.