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clarify sort order in TopN doc

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Michael Baird 2017-07-13 14:24:20 -05:00
parent 55310a5309
commit b313902edd
1 changed files with 2 additions and 2 deletions
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docs/query-language.md
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@ -342,9 +342,9 @@ 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.
* TopN on a frame with ranked cache will return the top bitmaps sorted by count.
* Non-ranked frames maintain a LRU (least recently used) cache, thus a TopN query on this frame will return bitmaps sorted in most recently setbit order.
* 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.