bobhan1 opened a new pull request, #22270:
URL: https://github.com/apache/doris/pull/22270
## Proposed changes
Currently, when executing `insert into select` statement converted from a
delete stmt, doris will try to read all the values of the non-key columns from
the previous rows with the same key in storage layer, which is highly costly
and meaningless.
For example, for a table with the following schema
```
CREATE TABLE test (
`k1` int NOT NULL,
`c1` int,
`c2` int,
`c3` int,
`c4` int)
UNIQUE KEY(`k1`) DISTRIBUTED BY HASH(`k1`) BUCKETS 1
PROPERTIES("enable_unique_key_merge_on_write" = "true")
```
and data
```
k1,c1,c2,c3,c4
1,1,1,1,1
2,2,2,2,2
3,3,3,3,3
4,4,4,4,4
5,5,5,5,5
```
after execute some delete statement(which is transformed to `insert into
select` statement) that delete rows with k1=1,2,3, the data with delete_sign
column will be like
```
k1,c1,c2,c3,c4,__DORIS_DELETE_SIGN__
1,1,1,1,1,0
2,2,2,2,2,0
3,3,3,3,3,0
4,4,4,4,4,0
5,5,5,5,5,0
1,1,1,1,1,1
2,2,2,2,2,1
3,3,3,3,3,1
```
It's evitable that it reads lots of useless data. So this PR eliminates the
above process and use default or null value to fill the non-key columns when
inserting rows with marked delete sign, since the values in these columns are
useeless and will not be read.
## Further comments
If this is a relatively large or complex change, kick off the discussion at
[d...@doris.apache.org](mailto:d...@doris.apache.org) by explaining why you
chose the solution you did and what alternatives you considered, etc...
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