Github user xuchuanyin commented on a diff in the pull request:
https://github.com/apache/carbondata/pull/2581#discussion_r206454747
--- Diff: docs/datamap/bloomfilter-datamap-guide.md ---
@@ -103,3 +104,24 @@ If the datamap does not prune blocklets well, you can
try to increase the value
## Data Management With BloomFilter DataMap
Data management with BloomFilter datamap has no difference with that on
Lucene datamap. You can refer to the corresponding section in `CarbonData
BloomFilter DataMap`.
+
+## Useful Tips
++ BloomFilter DataMap is suggested to create on the high cardinality
columns.
++ BloomFilter datamap requires that the query conditions on index columns
are always simple `equal` or `in`,
+ such as 'col1=XX', 'col1 in (XX, YY)'. Otherwise the queries cannot
benefit from BloomFilter datamap.
++ We can create multiple BloomFilter datamaps on one table,
+ also we can create one BloomFilter datamap that contains multiple index
columns.
+ We do recommend the later behavior since the data loading and query
performance will be better.
++ `BLOOM_FPP` is only the expected number from user, the actually FPP may
be worse.
+ If the BloomFilter datamap does not work well,
+ you can try to increase `BLOOM_SIZE` and decrease `BLOOM_FPP` at the same
time.
+ Notice that bigger `BLOOM_SIZE` will increase the size of index file
+ and smaller `BLOOM_FPP` will increase runtime calculation while
performing query.
++ '0' skipped blocklets of BloomFilter datamap in explain output indicates
that
+ BloomFilter datamap does not prune better than Main datamap.
--- End diff --
Added an example scenario
---
