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hll_merge()

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Merges hll results (scalar version of the aggregate version hll_merge()).

Read about the underlying algorithm (HyperLogLog) and estimation accuracy.

Syntax

hll_merge( Expr1, Expr2, ...)

Arguments

  • Columns that have hll values to be merged.

Returns

The result for merging the columns *Exrp1*, *Expr2*, ... *ExprN* to one hll value.

Examples

range x from 1 to 10 step 1 
| extend y = x + 10
| summarize hll_x = hll(x), hll_y = hll(y)
| project merged = hll_merge(hll_x, hll_y)
| project dcount_hll(merged)
dcount_hll_merged
20