scriptoriumadmin/featurebase
1
0
Fork 0
mirror of https://github.com/featurebasedb/featurebase.git synced 2026-10-07 03:17:50 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions

frame cache caveats documentation

Browse source
This commit is contained in:
Michael Baird 2017-07-13 09:32:47 -05:00
parent 25dd11d482
commit 55310a5309
1 changed files with 8 additions and 0 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

8
docs/query-language.md
View file

@ -341,6 +341,14 @@ have the attribute specified by `field` with one of the values specified in
**Result Type:** array of key/count objects
**Caveats:**
* TopN will return the top bitmaps by count only on frames with a ranked cache.
* The frame's cache size determines the limit of sorted bitmaps.
* Non-ranked frames maintain a LRU (least recently used) cache, thus a TopN query on this frame will return bitmaps in most recently setbit order.
* The ranked cache maintains a sorted set of bitmaps by count up to the cache size.
* Once full, the cache will truncate the set of bitmaps at the frame options CacheSize limit. Bitmaps with a similar count that straddle the limit will be truncated in no particular order.
* The TopN filter operation only applies to data in the cache, and not all bitmaps in the frame.
**Examples:**
```