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Erick Erickson commented on SOLR-8220: -------------------------------------- Given that stored values are compressed in 16k blocks and to return a single field from the stored data requires decompressing 16K, how much effect do LazyDocuments really have any more? I don't know, just askin' Since docValues avoids decompressing 16k per doc, disk seeks and the like I strongly suspect that it is vastly more efficient than getting the stored values. That's how Streaming Aggregation can return on 200k-400k docs/second. All that said, I suspect that there are negligible savings (or perhaps even costs) in mixing the two, i.e. if _any_ field to be returned is not DV, you might as well return all the fields from the stored data. Testing would tell though. > Read field from docValues for non stored fields > ----------------------------------------------- > > Key: SOLR-8220 > URL: https://issues.apache.org/jira/browse/SOLR-8220 > Project: Solr > Issue Type: Improvement > Reporter: Keith Laban > Attachments: SOLR-8220-ishan.patch, SOLR-8220-ishan.patch, > SOLR-8220-ishan.patch, SOLR-8220-ishan.patch, SOLR-8220.patch, SOLR-8220.patch > > > Many times a value will be both stored="true" and docValues="true" which > requires redundant data to be stored on disk. Since reading from docValues is > both efficient and a common practice (facets, analytics, streaming, etc), > reading values from docValues when a stored version of the field does not > exist would be a valuable disk usage optimization. > The only caveat with this that I can see would be for multiValued fields as > they would always be returned sorted in the docValues approach. I believe > this is a fair compromise. > I've done a rough implementation for this as a field transform, but I think > it should live closer to where stored fields are loaded in the > SolrIndexSearcher. > Two open questions/observations: > 1) There doesn't seem to be a standard way to read values for docValues, > facets, analytics, streaming, etc, all seem to be doing their own ways, > perhaps some of this logic should be centralized. > 2) What will the API behavior be? (Below is my proposed implementation) > Parameters for fl: > - fl="docValueField" > -- return field from docValue if the field is not stored and in docValues, > if the field is stored return it from stored fields > - fl="*" > -- return only stored fields > - fl="+" > -- return stored fields and docValue fields > 2a - would be easiest implementation and might be sufficient for a first > pass. 2b - is current behavior -- This message was sent by Atlassian JIRA (v6.3.4#6332) --------------------------------------------------------------------- To unsubscribe, e-mail: dev-unsubscr...@lucene.apache.org For additional commands, e-mail: dev-h...@lucene.apache.org