Hi Shalin, Thanks very much for your detailed explanation!
Regards, Yandong 2012/8/21 Shalin Shekhar Mangar <shalinman...@gmail.com> > 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. >
