How mongo identifies the first row when using updateOne,deleteOne

Working with Data
1

Dear,
how mongo identifies the first row when using updateOne,deleteOne.
can you explan the mechnism.
thanks a lot.

2

Hi @Yi_deng ,

The first document that is scanned by the filter side of the operation.

So if you match and sort on a criteria the first document that will be fetched will be applied with the update part…

Thanks
Pavel

1 Like
3

hi pavel
thanks a lot.
if i do not include sort operation in update, then ,how mongo identifies the first row?

4

By the natural order of the documents.

Usually it will be the insert order. But when not doing sort it can potentially be any of the documents answering the criteria…

5

thanks for your kindly help

6

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