feat: enhance-CLI-query-header-for-cast-expressions-with-literals #15736
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qstommyshu
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datafusion/sql/src/parser.rs
Outdated
| DataType::Float(_) => "FLOAT", | ||
| DataType::Double(_) => "DOUBLE", | ||
| DataType::Text => "TEXT", | ||
| // TODO: need to support more DataType, probably use an Extension Trait |
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We need to support a full list of enum elements for DataType here, this DataType comes from an external library. This probably means everything we update this API, we need to make accommodation as well.
Or we can look into using strum crate to auto derive ToString for all DataType, we are currently using it for the datafusion proto crate.
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Currently, supported data type result would look like this:
select cast('1' as int);
+------------------+
| cast('1' as int) |
+------------------+
| 1 |
+------------------+
unsupported data type result would look like this:
select cast(1 as string);
+-------------------------+
| cast(1 as string(none)) |
+-------------------------+
| 1 |
+-------------------------+
datafusion/sql/src/parser.rs
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| Expr::Value(sqlparser::ast::ValueWithSpan { value: Value::Number(n, _), .. }) => { | ||
| n.clone() | ||
| }, | ||
| // TODO: need to take care of other types of values, like TimeStamp, etc... |
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This is currently only matching specific case for select cast('1' as int), we need to support other types as well if we want to go with this idea. I'm thinking about a way to generalize the Value extraction.
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For enum Value, there are 22 types to support, I can write them into a function if we want to go ahead with this.
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This whole code modification will be turn into several functions for code readability and maintainability, I'm leaving for now just to validate the idea.
Which issue does this PR close?
Rationale for this change
Stated in #5221
What changes are included in this PR?
SQL parser modification
Are these changes tested?
Not yet
Are there any user-facing changes?
Yes