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Fix summingmergetree docs

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alesapin 2018-08-02 15:16:54 +03:00
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commit 4eef0278a6
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docs/en/operations/table_engines/summingmergetree.md
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@ -14,7 +14,7 @@ SummingMergeTree(EventDate, (OrderID, EventDate, BannerID, ...), 8192, (Shows, C
The columns to total are set explicitly (the last parameter – Shows, Clicks, Cost, ...). When merging, all rows with the same primary key value have their values totaled in the specified columns. The specified columns also must be numeric and must not be part of the primary key.
If the values were null in all of these columns, the row is deleted. (The exception is cases when the data part would not have any rows left in it.)
If the values were zero in all of these columns, the row is deleted. (The exception is cases when the data part would not have any rows left in it.)
For the other columns that are not part of the primary key, the first value that occurs is selected when merging. But if a column is of AggregateFunction type, then it is merged according to that function, which effectively makes this engine behave like `AggregatingMergeTree`.