Re: [I] Slow comparisions to dictionary columns with type coercion [datafusion]
alamb closed issue #10220: Slow comparisions to dictionary columns with type coercion URL: https://github.com/apache/datafusion/issues/10220 -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: github-unsubscr...@datafusion.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org - To unsubscribe, e-mail: github-unsubscr...@datafusion.apache.org For additional commands, e-mail: github-h...@datafusion.apache.org
Re: [I] Slow comparisions to dictionary columns with type coercion [datafusion]
alamb commented on issue #10220: URL: https://github.com/apache/datafusion/issues/10220#issuecomment-2087629144 Thanks @erratic-pattern -- I hope to look at this tomorrow morning -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: github-unsubscr...@datafusion.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org - To unsubscribe, e-mail: github-unsubscr...@datafusion.apache.org For additional commands, e-mail: github-h...@datafusion.apache.org
Re: [I] Slow comparisions to dictionary columns with type coercion [datafusion]
erratic-pattern commented on issue #10220: URL: https://github.com/apache/datafusion/issues/10220#issuecomment-2087570905 https://github.com/apache/datafusion/pull/10323 is ready for review and avoids the previously discussed issues with https://github.com/apache/datafusion/pull/10221 -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: github-unsubscr...@datafusion.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org - To unsubscribe, e-mail: github-unsubscr...@datafusion.apache.org For additional commands, e-mail: github-h...@datafusion.apache.org
Re: [I] Slow comparisions to dictionary columns with type coercion [datafusion]
erratic-pattern commented on issue #10220:
URL: https://github.com/apache/datafusion/issues/10220#issuecomment-2075811286
I have a PR that fixes this. Here is the explain after making the change:
```
> explain SELECT * from test where column1 = 1;
+---+-+
| plan_type | plan|
+---+-+
| logical_plan | Filter: test.column1 = Dictionary(Int32, Utf8("1")) |
| | TableScan: test projection=[column1] |
| physical_plan | CoalesceBatchesExec: target_batch_size=8192 |
| | FilterExec: column1@0 = 1 |
| | MemoryExec: partitions=1, partition_sizes=[1] |
| | |
+---+-+
2 row(s) fetched.
Elapsed 0.008 seconds.
```
However it looks like some tests are failing so I am still looking into it.
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[I] Slow comparisions to dictionary columns with type coercion [datafusion]
alamb opened a new issue, #10220:
URL: https://github.com/apache/datafusion/issues/10220
### Is your feature request related to a problem or challenge?
In InfluxDB we use `Dictionary(Int32, Utf8)` columns a lot.
Queries like this (with string constants) work great and are very fast
```sql
SELECT ... WHERE column = '1'
```
Queries like this (note `1` is an integer, not a `'1'`) the query goes very
slow
```sql
SELECT ... WHERE column = 1
```
@erratic-pattern and I tracked this down to an issue/ limitation in type
coercion:
## Reproducer
```
DataFusion CLI v37.1.0
> create table test as values (arrow_cast('1', 'Dictionary(Int32, Utf8)'));
0 row(s) fetched.
Elapsed 0.010 seconds.
> select arrow_typeof(column1) from test;
++
| arrow_typeof(test.column1) |
++
| Dictionary(Int32, Utf8)|
++
1 row(s) fetched.
Elapsed 0.002 seconds.
> explain SELECT * from test where column1 = 1;
+---+---+
| plan_type | plan |
+---+---+
| logical_plan | Filter: CAST(test.column1 AS Utf8) = Utf8("1")|
| | TableScan: test projection=[column1]|
| physical_plan | CoalesceBatchesExec: target_batch_size=8192 |
| | FilterExec: CAST(column1@0 AS Utf8) = 1 |
| | MemoryExec: partitions=1, partition_sizes=[1] |
| | |
+---+---+
2 row(s) fetched.
Elapsed 0.003 seconds.
```
I think this shows the core problem:
```
| logical_plan | Filter: CAST(test.column1 AS Utf8) = Utf8("1")|
```
It basically shows the column is being converted to a string, rather than
the constant being converted to th ecorrect type.
Not only does this mean the column is being un-encoded for the comparsion,
it also means that `PruningPredicate` doesn't work either
### Describe the solution you'd like
I would like the query to go fast lol
Specifically, I think the filter should look like this (no cast on the
column, and instead the constant type matches)
```
| logical_plan | Filter: test.column1 = Dictionary(Int32, Utf8("1")) |
```
Note this is what happens if you compare the dictionary column to a string
literal (
```sql
> explain SELECT * from test where column1 = '1';
+---+-+
| plan_type | plan|
+---+-+
| logical_plan | Filter: test.column1 = Dictionary(Int32, Utf8("1")) |
| | TableScan: test projection=[column1] |
| physical_plan | CoalesceBatchesExec: target_batch_size=8192 |
| | FilterExec: column1@0 = 1 |
| | MemoryExec: partitions=1, partition_sizes=[1] |
| | |
+---+-+
2 row(s) fetched.
Elapsed 0.002 seconds.
>
```
### Describe alternatives you've considered
_No response_
### Additional context
_No response_
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