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Update other_functions.md

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Example of max_block_size impact on runningDifference.
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Denis Zhuravlev 2019-09-02 17:15:40 -03:00 committed by GitHub
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@ -394,6 +394,33 @@ FROM
└─────────┴─────────────────────┴───────┘
```
Please note - block size affects the result. With each new block, the `runningDifference` state is reset.
``` sql
SELECT
number,
runningDifference(number + 1) AS diff
FROM numbers(100000)
WHERE diff != 1
┌─number─┬─diff─┐
│ 0 │ 0 │
└────────┴──────┘
┌─number─┬─diff─┐
│ 65536 │ 0 │
└────────┴──────┘
set max_block_size=100000 // default value is 65536!
SELECT
number,
runningDifference(number + 1) AS diff
FROM numbers(100000)
WHERE diff != 1
┌─number─┬─diff─┐
│ 0 │ 0 │
└────────┴──────┘
```
## runningDifferenceStartingWithFirstValue
Same as for [runningDifference](./other_functions.md#other_functions-runningdifference), the difference is the value of the first row, returned the value of the first row, and each subsequent row returns the difference from the previous row.