transformations:merge
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transformations:merge [2017/01/01 15:32] – dmitry | transformations:merge [2018/04/30 09:44] – dmitry | ||
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This transformation appends one or more columns from another table where certain columns in both tables match. | This transformation appends one or more columns from another table where certain columns in both tables match. | ||
- | There are two possible merge modes: | + | There are three possible merge modes: |
* Lookup Mode -- get **first** matching combination from the other table. If there are other combinations they are ignored. | * Lookup Mode -- get **first** matching combination from the other table. If there are other combinations they are ignored. | ||
* Left Join Mode -- get **all** matching combinations from the other table. It can increase number or rows in the current table. | * Left Join Mode -- get **all** matching combinations from the other table. It can increase number or rows in the current table. | ||
- | + | * Full Join Mode -- include all combinations of keys from both tables. Equivalent to the full outer join in SQL. | |
- | To make full outer join, first, append rows that exist in the other table but are missing in the current table using [[transformations: | + | |
EXAMPLE | EXAMPLE | ||
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| Yangtze | | Yangtze | ||
| Mississippi | | Mississippi | ||
+ | |||
+ | === Limitations === | ||
+ | The resulting table after Merge can't have more than 134,217,728 rows. | ||
=== See also === | === See also === | ||
* [[transformations: | * [[transformations: | ||
transformations/merge.txt · Last modified: 2024/04/11 23:55 by craigt