sabir-akhadov-localstack commented on code in PR #2438:
URL:
https://github.com/apache/datafusion-sqlparser-rs/pull/2438#discussion_r4391124583
##########
src/parser/mod.rs:
##########
@@ -16862,6 +16892,16 @@ impl<'a> Parser<'a> {
// Stage reference: @mystage or @namespace.stage (e.g. Snowflake)
self.parse_snowflake_stage_table_factor()
} else {
+ // Handle pipe result references ($1, $2, ...) in FROM clause.
+ // See <https://docs.snowflake.com/en/sql-reference/operators-flow>
+ if self.dialect.supports_long_arrow_pipe_operator() {
+ if let Token::Placeholder(ref s) =
self.peek_token_ref().token.clone() {
+ if let Some(Ok(index @ 1..)) =
s.strip_prefix('$').map(str::parse::<u64>) {
+ self.next_token(); // consume the $n token
+ return Ok(TableFactor::PipeResultScan { index });
Review Comment:
Snowflake accepts an alias here: `SELECT 1 AS a ->> SELECT t.a FROM $1 AS t`
and `... ->> SELECT t.a, u.b FROM $2 AS t CROSS JOIN $1 AS u` both run on Cloud
but are rejected with `Expected: end of statement, found: AS`. Suggest an
`alias: Option<TableAlias>` on the variant via `maybe_parse_table_alias`, which
also removes the need for the parenthesized-alias error above.
##########
src/dialect/snowflake.rs:
##########
@@ -1100,6 +1106,11 @@ pub fn parse_create_table(
parser.prev_token();
break;
}
+ Token::LongArrow => {
+ // Snowflake pipe operator terminates the statement
Review Comment:
The same end-of-statement loops in `parse_copy_into` (`COPY INTO t FROM @s
->> SELECT * FROM $1`), `parse_alter_session` (`ALTER SESSION SET QUERY_TAG =
'x' ->> SELECT 1`, valid on Cloud) and `parse_key_value_options` in
`src/parser/mod.rs` (`CREATE WAREHOUSE w ->> SELECT 1`, `CREATE USER u ->>
SELECT 1`) still reject `->>`. A single end-of-statement predicate on `Parser`
that includes `->>` when the dialect supports it would cover all of them.
##########
src/ast/query.rs:
##########
@@ -1721,6 +1721,14 @@ pub enum TableFactor {
/// The alias for the table.
alias: Option<TableAlias>,
},
+ /// Snowflake pipe result reference: `$1`, `$2`, etc.
+ ///
+ /// Used in FROM clauses of pipe-chained statements to reference previous
results.
+ /// See <https://docs.snowflake.com/en/sql-reference/operators-flow>
+ PipeResultScan {
+ /// 1-based index of the previous statement whose result is referenced.
Review Comment:
Worth saying this counts back from the current statement (`$1` is the
immediately preceding one, `$2` the one before that), since `index` reads as
absolute.
##########
src/dialect/generic.rs:
##########
@@ -329,6 +329,10 @@ impl Dialect for GenericDialect {
true
}
+ fn supports_long_arrow_pipe_operator(&self) -> bool {
Review Comment:
In Generic `->>` still binds as the JSON operator whenever the previous
statement ends in an expression, so `SELECT 1 ->> SELECT 2` and `SELECT * FROM
t WHERE a = 1 ->> SELECT 1` fail while `SELECT * FROM t ->> SELECT 1` works.
Either drop Generic here or add a test documenting the partial support.
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