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Posted to github@datafusion.apache.org by "simonvandel (via GitHub)" <gi...@apache.org> on 2025/08/22 20:19:24 UTC
[PR] Support from-first syntax [datafusion]
simonvandel opened a new pull request, #17295:
URL: https://github.com/apache/datafusion/pull/17295
## Which issue does this PR close?
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- Closes #.
## Rationale for this change
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Why are you proposing this change? If this is already explained clearly in the issue then this section is not needed.
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I noticed in https://github.com/apache/datafusion/pull/17278 that `from` without an explicit projection did not work.
This should fix it.
The from-first syntax is also available in duckdb. See https://duckdb.org/docs/stable/sql/query_syntax/from.html#examples
## What changes are included in this PR?
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## Are these changes tested?
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Yes, added SLT test
## Are there any user-facing changes?
FROM-first syntax without projection is now supported.
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Re: [PR] Support from-first SQL syntax [datafusion]
Posted by "simonvandel (via GitHub)" <gi...@apache.org>.
simonvandel commented on code in PR #17295:
URL: https://github.com/apache/datafusion/pull/17295#discussion_r2295857111
##########
datafusion/sqllogictest/test_files/from-first.slt:
##########
@@ -0,0 +1,41 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements. See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership. The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License. You may obtain a copy of the License at
+
+# http://www.apache.org/licenses/LICENSE-2.0
+
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied. See the License for the
+# specific language governing permissions and limitations
+# under the License.
+
+query I
+FROM range(2)
+----
+0
+1
+
+query I
+FROM range(2)
+SELECT *
Review Comment:
I added some tests in [fe284b6](https://github.com/apache/datafusion/pull/17295/commits/fe284b6f655deccf040cc4a65387032f83de6f6e). Does this cover your question?
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Re: [PR] Support from-first SQL syntax [datafusion]
Posted by "adriangb (via GitHub)" <gi...@apache.org>.
adriangb commented on PR #17295:
URL: https://github.com/apache/datafusion/pull/17295#issuecomment-3281551846
> SHould we also make from t (without anything else) an error like it is in duckdb?
DuckDB *does* support `FROM t;`, it does *not* support `SELECT FROM t;`
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Re: [PR] Support from-first SQL syntax [datafusion]
Posted by "alamb (via GitHub)" <gi...@apache.org>.
alamb commented on PR #17295:
URL: https://github.com/apache/datafusion/pull/17295#issuecomment-3281536219
> So maybe the answer is that we should make `select from t1;` equivalent to "select no columns from t1" while keeping `from t1;` equivalent to `select * from t1;`?
I think we should be consistent with other databases
This proposal seems reasonable to me
SHould we also make `from t` (without anything else) an error like it is in duckdb?
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Re: [PR] Support from-first SQL syntax [datafusion]
Posted by "Jefffrey (via GitHub)" <gi...@apache.org>.
Jefffrey commented on code in PR #17295:
URL: https://github.com/apache/datafusion/pull/17295#discussion_r2295868517
##########
datafusion/sqllogictest/test_files/from-first.slt:
##########
@@ -0,0 +1,41 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements. See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership. The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License. You may obtain a copy of the License at
+
+# http://www.apache.org/licenses/LICENSE-2.0
+
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied. See the License for the
+# specific language governing permissions and limitations
+# under the License.
+
+query I
+FROM range(2)
+----
+0
+1
+
+query I
+FROM range(2)
+SELECT *
Review Comment:
Yep! 👍
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Re: [PR] Support from-first SQL syntax [datafusion]
Posted by "adriangb (via GitHub)" <gi...@apache.org>.
adriangb commented on PR #17295:
URL: https://github.com/apache/datafusion/pull/17295#issuecomment-3281120327
@alamb we discussed a bit in https://github.com/apache/datafusion/pull/17520#issuecomment-3280334178, I'm not sure that this PR introduced a bug. If I understand correctly `select from t1` should be equivalent to `select * from t1` -> then there is no bug. Now if `select from t1` is meant to be `select every row but no columns` then there is a bug but it has nothing to do with the where clause or projection pushdown.
FWIW:
```
DataFusion CLI v50.0.0
> create table t1 (a int, b int);
0 row(s) fetched.
Elapsed 0.004 seconds.
> insert into t1 values (1, 2);
+-------+
| count |
+-------+
| 1 |
+-------+
1 row(s) fetched.
Elapsed 0.010 seconds.
> select * from t1;
+---+---+
| a | b |
+---+---+
| 1 | 2 |
+---+---+
1 row(s) fetched.
Elapsed 0.003 seconds.
> select from t1;
+---+---+
| a | b |
+---+---+
| 1 | 2 |
+---+---+
1 row(s) fetched.
Elapsed 0.004 seconds.
> from t1;
+---+---+
| a | b |
+---+---+
| 1 | 2 |
+---+---+
1 row(s) fetched.
Elapsed 0.001 seconds.
```
Postgres:
```
postgres=# create table t1 (a int, b int);
CREATE TABLE
postgres=# insert into t1 values (1), (2);
INSERT 0 2
postgres=# select * from t1;
a | b
---+---
1 |
2 |
(2 rows)
postgres=# select from t1;
--
(2 rows)
postgres=# from t1;
ERROR: syntax error at or near "from"
LINE 1: from t1;
```
DuckDB:
```sql
DuckDB v1.3.2 (Ossivalis) 0b83e5d2f6
Enter ".help" for usage hints.
Connected to a transient in-memory database.
Use ".open FILENAME" to reopen on a persistent database.
D create table t1 AS (select 1 as a, 2 as b);
D insert into t1 values (1, 2);
D select from t1;
Parser Error:
SELECT clause without selection list
D from t1;
┌───────┬───────┐
│ a │ b │
│ int32 │ int32 │
├───────┼───────┤
│ 1 │ 2 │
│ 1 │ 2 │
└───────┴───────┘
```
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Re: [PR] Support from-first SQL syntax [datafusion]
Posted by "Jefffrey (via GitHub)" <gi...@apache.org>.
Jefffrey merged PR #17295:
URL: https://github.com/apache/datafusion/pull/17295
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Re: [PR] Support from-first SQL syntax [datafusion]
Posted by "Jefffrey (via GitHub)" <gi...@apache.org>.
Jefffrey commented on code in PR #17295:
URL: https://github.com/apache/datafusion/pull/17295#discussion_r2295640501
##########
datafusion/sqllogictest/test_files/from-first.slt:
##########
@@ -0,0 +1,41 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements. See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership. The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License. You may obtain a copy of the License at
+
+# http://www.apache.org/licenses/LICENSE-2.0
+
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied. See the License for the
+# specific language governing permissions and limitations
+# under the License.
+
+query I
+FROM range(2)
+----
+0
+1
+
+query I
+FROM range(2)
+SELECT *
Review Comment:
Is it valid to put specific columns in this `SELECT` that comes after the `FROM`?
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Re: [PR] Support from-first SQL syntax [datafusion]
Posted by "simonvandel (via GitHub)" <gi...@apache.org>.
simonvandel commented on PR #17295:
URL: https://github.com/apache/datafusion/pull/17295#issuecomment-3216792813
> Maybe need to update the SQL reference docs with this new behaviour?
>
> * https://datafusion.apache.org/user-guide/sql/select.html
I added some documentation in [9f1b436](https://github.com/apache/datafusion/pull/17295/commits/9f1b436a543dc1c34ed016e54678218ac9e73228)
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Re: [PR] Support from-first SQL syntax [datafusion]
Posted by "alamb (via GitHub)" <gi...@apache.org>.
alamb commented on PR #17295:
URL: https://github.com/apache/datafusion/pull/17295#issuecomment-3281069200
@xudong963 found this PR seems to have introduced a regression
- https://github.com/apache/datafusion/issues/17513
@adriangb has a proposed PR up to fix:
- https://github.com/apache/datafusion/pull/17520
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Re: [PR] Support from-first SQL syntax [datafusion]
Posted by "adriangb (via GitHub)" <gi...@apache.org>.
adriangb commented on PR #17295:
URL: https://github.com/apache/datafusion/pull/17295#issuecomment-3281124360
So maybe the answer is that we should make `select from t1;` equivalent to "select no columns from t1"
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