On Tue, Aug 21, 2012 at 8:47 AM, Yandong Yao <yydz...@gmail.com> wrote:
> Hi guys, > > From http://wiki.apache.org/solr/MergingSolrIndexes, it said 'Using > "srcCore", care is taken to ensure that the merged index is not corrupted > even if writes are happening in parallel on the source index'. > > What does it means? If there are deletion request during merging, will this > deletion be processed correctly after merging finished? > Solr keeps an instance of the IndexReader for each srcCore which is a static snapshot of the index at the time of the merge request. This static snapshot is merged to the target core. Therefore any insert/delete request made to the srcCores after the merge request will not affect the merged index. > > 1) > eg: I have an existing core 'core0', and I want to merge core 'core1' and > 'core2' to core 'core0', so I will use > > http://localhost:8983/solr/admin/cores?action=mergeindexes&core=core0&srcCore=core1&srcCore=core2 > , > > During the merging happens, core0, core1, core2 have received deletion > request to delete some old documents, will the final core 'core0' contains > all content from 'core1' and 'core2' and also all documents matches > deletion criteria has been deleted? > The final core0 will not have documents deleted by requests made on core0. However, documents deleted on core1 and core2 will still be in core0 if the merge started before those requests were made. > > 2) > And if core0, core1, and core2 are processing deletion request, at the same > time core merge request comes in, what will happen then? Will merge request > block until deletion finished on all cores? > I believe core0 will continue to process deletion requests concurrently with the merge. As for core1 and core2, since a merge reserves their IndexReader, the answer depends on when a commit happens on core1 and core2. If, for example, 2 deletions were made on core1 and then a commit was issued (or autoCommit happened) and then the merge was triggered then the final core0 will not have those documents but it may still have docs deleted after the commit. > > Thanks very much in advance! > > Regards, > Yandong > -- Regards, Shalin Shekhar Mangar.
