Updating Solr Field Value - solr

is there any possibility to update a value of a Solr-Field without reindexing the whole document?

Nope.
You need to index the document again with all the fields.
Solr will delete and insert the document again.
There is nice talk about it you may want to hear.

This functionality is available in the Solr version 4.0. That version is still in Beta, but will most likely be released before the end of the year. Please see the post - Solr 4.0: Partial documents update for more details on how this works.

When you want to change a single field of a document you will have to reindex the whole document, as solr does not support updating of a field only.

Related

How to reindex solr after schema change?

We need to modify the schema fields dynamically, which requires reindexing.The solr ref guide recommands deleting all the documents and then re-run the original index process,but that does fit us.Does anyone have other ideas?
Thanks for any help.
Reindexing is required. Best option is using Data Import Handler. If you don't want to run the queries from database or don't want to pass documents, then also solr provides way to index the solr core through other solr core.
You can do something like this :
For more details, read solr DIH and SolrEntityProcessor : https://solr.apache.org/guide/6_6/uploading-structured-data-store-data-with-the-data-import-handler.html#solrentityprocessor

Versioning in Solr

Solr by default overwrites any re-indexed document. But I want to save the old versions of updated documents.
Is it possible keep the previous versions of any document in the index? if not,please provide me with suggestions to do that.

Migrate solr standalone index to solrcloud

There are indexes of some solr cores which I convert them from solr4 to solr6 but in solr standalone mode. so they don't have the "version" field that solrcolud require.
Here now I want to migrate to solrcloud 6 and I need to put them under cluster. Because the version field dose not exist there in these indexes when I put them Under a solrcloud leader core on the data directory the replicas in the shard didn't update as I saw. so I decided to read them by lucene, get each doc fields, add them to a solrdoc and then put them doc by doc in solrcloud. But cause there are fields that not stored in these indexes so all fields that exist here in these indexes don't move there.
At the end it seems there is no way for me than re-indexing.
I appreciate if there is any better idea or solutions that can help me migrate more easily.
If there is any chance to reindex, just do so, it's going to be the best in the end (you have to deal with two separate issues: a) migrate from 4.X to 6.0 and b)from standalone to SolrCloud...it's going to be messy).
If you cannot reindex:
are all your fields stored OR have docValues=true? If so, you can get the original contents of your docs. Read them and index them with solrj or with some script.
if not, and you have a version field: try to manually put the index in Solrcloud. Not straighforward, but possible.
if you don't have a version field, I think it is impossible to put the index as is in Solrcloud (although some post on the net make you think it is). You could try to write some lucene code to add version field to all docs (with values that make sense), but this should be the very last resort.

Solr Upgrade from 3.4 to 4

In order to make use of pivot feature present on Solr 4, I upgraded from 3.4.
Shall I proceed with a full reindex of the content due this upgrade or are they compatible somehow?
And regarding my client-applications that are currently accessing my solr server 3.4, will they present problem after upgrade? (The preliminary test I did they are running, seems the xml schema returned in a query response didn't changed when you don't use new features)
You need to do a full reindex if you want to use the Solr 4 index structure. Else you need to change the Lucene version in solrconfig to use the old index.
The schema will need a new field called _version_ if you want to use the Real Time Get functionality.
Other then that most things are pretty much the same for the client.

Setting up Solr and Querying it

I am new to Solr.
I am not able to find out a proper document which could help me understand what all do I need to add in the solrconfig.xml and what is to be removed.
My SolrDocument would contain id, field1, field2. Out of the 2 fields, I want to update 1 of them. How do I do? I tried a few things but it overwrites the entire document.
/update is not working.
I have to add documents and retrieve them from inside a Java class.
You can refer to Solr Wiki for Solr Config.xml it is a good starting point to understand the configuration options.
Solr does not really have an update concept, it always deletes the existing document and replaces it with new document. There is a feature request open years back JIRA-139 to address this problem, but as of today it shows the fix version to be 4.1. But Solr 4.0 has a new feature Atomic update that you could try, if this is something very critical for you. Note: Solr 4.0 is still a Beta.
'/update' not working -> do you mean not working since it is replacing the old document with new document or do you get error/exception ?
To add & retrieve documents from Java, you can use SolrJ. SolrJ is Java client to access Solr programmatically. SolrJ - Solr Wiki.

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