The answer does not convince me. Are you saying that a full table scan is always required e.g. when you want to determine the distinct values of a particular field and count the related documents with this value independent of the existence of an index or not?
Am Mo., 20. Mai 2019 um 09:10 Uhr schrieb Jan <[email protected]>: > Hi, > > I can't tell if views will handle this query very differently, but I doubt > that when using a view the extra `COLLECT` step will be removed. > That's not to say that there will be no performance difference when using > views (I simply don't know). But when it comes to the `COLLECT`, I guess it > will still stay around in the query even if a view is used. > > I guess the query could be most improved by implementing the distinct > operation directly on the index, which would remove the extra `COLLECT` > step entirely. > But that functionality is still a future to-do and not available yet. > > Best regards > Jan > > Am Sonntag, 19. Mai 2019 15:29:45 UTC+2 schrieb Andreas Jung: >> >> Running ArangoDB 3.4.5 on a collection with 100.000 items. >> Each item has singe-valued field _type and there are about 20 different >> values for this field. >> The field is indexed by a hash index: https://nimb.ws/yh4rRb >> >> This query performs a full table scan instead of using the index. >> Am I missing something here? >> >> For doc in import >> return distinct doc._type >> >> Query String: >> For doc in import >> return distinct doc._type >> >> Execution plan: >> Id NodeType Est. Comment >> 1 SingletonNode 1 * ROOT >> 2 EnumerateCollectionNode 95238 - FOR doc IN import /* full >> collection scan, projections: `_type` */ >> 3 CalculationNode 95238 - LET #1 = doc.`_type` /* >> attribute expression */ /* collections used: doc : import */ >> 4 CollectNode 76190 - COLLECT #3 = #1 /* >> distinct */ >> 5 ReturnNode 76190 - RETURN #3 >> >> Indexes used: >> none >> >> Optimization rules applied: >> Id RuleName >> 1 reduce-extraction-to-projection >> >> >> -- > You received this message because you are subscribed to the Google Groups > "ArangoDB" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To view this discussion on the web visit > https://groups.google.com/d/msgid/arangodb/0c325e78-45fd-4224-8de3-38dc49ecec4f%40googlegroups.com > <https://groups.google.com/d/msgid/arangodb/0c325e78-45fd-4224-8de3-38dc49ecec4f%40googlegroups.com?utm_medium=email&utm_source=footer> > . > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "ArangoDB" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/arangodb/CAL3mDby2x3wH4_cZZK0ieAEELwK_No39zeOuOQCYV4Z0ukj%2B3w%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
