merge_tdigest()

Learn how to use the merge_tdigest() function to merge columns.

Merges tdigest results (scalar version of the aggregate version tdigest_merge()).

Read more about the underlying algorithm (T-Digest) and the estimated error here.

Syntax

merge_tdigest(exprs)

Parameters

NameTypeRequiredDescription
exprsdynamic✔️One or more comma-separated column references that have the tdigest values to be merged.

Returns

The result for merging the columns *Expr1*, *Expr2*, … *ExprN* to one tdigest.

Example

range x from 1 to 10 step 1 
| extend y = x + 10
| summarize tdigestX = tdigest(x), tdigestY = tdigest(y)
| project merged = merge_tdigest(tdigestX, tdigestY)
| project percentile_tdigest(merged, 100, typeof(long))

Output

percentile_tdigest_merged
20