lucene-java-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Erick Erickson <>
Subject Re: Fetching 1000 documents taking around 30ms
Date Sat, 02 Mar 2019 17:54:02 GMT
“Is this expected”

Yes. For each document, if there is any field with stored=true that does _not_ have docValues=true
or is flagged as useDocValuesAsStored=false, there is
1> a disk seek to read the stored data from the fdt file
2> decompression of the data read in <1>, 16K block minimum.

So getting this all in 30 ms for 1,000 docs isn’t bad at all.

If (and only if) _all_ the values you ask for are docValues=true and useDocValuesAsStored=true
then all the values will be returned from the in-memory docValues data.


> On Mar 2, 2019, at 1:12 AM, Venkat Kranthi Chalasani <>
> Hi,
> I have an index of ~4M documents. My queries are running in 1-2ms but fetching the top
hits (~1000 documents) takes around 30ms. Is this expected? 
> If it is, I was wondering if maintaining an application cache with docId as a key is
ok. I understand docIds are ephemeral as documents are added/deleted but in our usage of lucene,
we don’t add/delete documents. 
> thanks
> ---------------------------------------------------------------------
> To unsubscribe, e-mail:
> For additional commands, e-mail:

To unsubscribe, e-mail:
For additional commands, e-mail:

View raw message