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Posted to commits@doris.apache.org by GitBox <gi...@apache.org> on 2020/11/17 11:10:17 UTC
[GitHub] [incubator-doris] acelyc111 opened a new issue #4915: Merge delete conditions to reduce judgments
acelyc111 opened a new issue #4915:
URL: https://github.com/apache/incubator-doris/issues/4915
**Is your feature request related to a problem? Please describe.**
Suppose there are several DELETE operations on a table, and the table has only 1 tablet:
```
DELETE FROM tbl WHERE date < '2020-11-01';
DELETE FROM tbl WHERE date < '2020-11-02';
DELETE FROM tbl WHERE date < '2020-11-03';
DELETE FROM tbl WHERE date < '2020-11-04';
```
There will be 4 delete predicates on a tablet, then launch a query on the table, doris will judge at most 4 predicates for every block or row, which is inefficient.
**Describe the solution you'd like**
We can merge the 4 predicates to one, for the example above, it should be:
```
DELETE FROM tbl WHERE date < '2020-11-04';
```
We can implement it in class `DeleteHandler`.
At the first step, the merge operation can be performed when delete predicate has conditions on only 1 column, we can merge **similar** predicates on the same column, the result is the union set for sub predicates.
```
op1 op2 result
eq eq in
eq in in
ne ne not in
ne not in not in
...
```
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[GitHub] [incubator-doris] HappenLee commented on issue #4915: Merge delete conditions to reduce judgments
Posted by GitBox <gi...@apache.org>.
HappenLee commented on issue #4915:
URL: https://github.com/apache/incubator-doris/issues/4915#issuecomment-729342995
sounds great~
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