Overview: Relational Merge
Use this operation to merge two datasets. Datasets will be merged at the points where the values of selected fields in one dataset are the same as the values of selected fields in the second dataset.
It is possible to then filter how to view the resulting dataset in a number of ways:
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merge all: all the fields of both the datasets will be shown, including both rows of matching common values and non-matching values unique to each dataset.
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merge matched: fields from both datasets will be shown, with rows sharing common values in the selected fields.
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merge unmatched: fields from both datasets will be shown, where rows sharing common values in the selected fields are excluded from the resulting dataset. Further filtering can select to show unmatched rows from both datasets, only the first dataset or only the second dataset.
This enables you to create a combined dataset, listing only the required relevant data.
Properties
Category: |
Combine |
Performance risk: |
Low performance risk. |
Knowledge required: |
None |
Effect on datasets
How many datasets are required to perform this operation? |
Two |
Does it create a new dataset? |
Yes |
Can you reconfigure this operation? |
Yes |
Can you apply this operation to a locked dataset? |
Yes |
Does it modify the current dataset in any way? |
No |
Requirements
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This operation needs two datasets.
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All supported field types can be used (integer, double, string and timestamp).
Results
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A new dataset is created, with fields from both component datasets listed on a single row if common values exist for both datasets.
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This implies that the order of the rows of the second dataset will change in the merged dataset. Fields with common values will be merged into the same row, at the point of the common value in the first dataset.
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The results will be determined by the selected merge results and the fields selected to be viewed.
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Depending on the configuration chosen, the created merged dataset will show either:
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only rows with all fields listed where both datasets had common values in the selected fields (matched rows)
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all rows of both datasets which had no common values in the selected fields (unmatched rows - all)
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rows of only dataset 1 which had no common values in the selected fields of both datasets (unmatched rows - first table only)
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rows of only dataset 2 which had no common values in the selected fields of both datasets (unmatched rows - second table only)
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all rows of both datasets, with rows sharing common values merged (all rows).
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