maropu commented on a change in pull request #23880: [SPARK-26976][SQL] Forbid
reserved keywords as table identifiers when ANSI mode is on
URL: https://github.com/apache/spark/pull/23880#discussion_r259705484
##########
File path:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/parser/AstBuilder.scala
##########
@@ -1404,6 +1404,15 @@ class AstBuilder(conf: SQLConf) extends
SqlBaseBaseVisitor[AnyRef] with Logging
}
}
+ override def visitIdentifier(ctx: IdentifierContext): String =
withOrigin(ctx) {
+ val keyword = ctx.getText
+ if (ctx.ansiReserved() != null) {
+ throw new ParseException(
+ s"'$keyword' is reserved and you cannot use this keyword as an
identifier.", ctx)
Review comment:
Oh, I see. But, if we just remove the rule, the two cases throw a parse
error since both colunm name rule and function name rule use `identifier`;
```
scala> sql("SET spark.sql.parser.ansi.enabled=false")
scala> sql("SELECT CURRENT_TIMESTAMP").show
+--------------------+
| current_timestamp()|
+--------------------+
|2019-02-25 16:26:...|
+--------------------+
scala> sql("SELECT CURRENT_TIMESTAMP()").show
+--------------------+
| current_timestamp()|
+--------------------+
|2019-02-25 16:26:...|
+--------------------+
scala> sql("SET spark.sql.parser.ansi.enabled=true")
scala> sql("SELECT CURRENT_TIMESTAMP").show
org.apache.spark.sql.catalyst.parser.ParseException:
no viable alternative at input 'CURRENT_TIMESTAMP'(line 1, pos 7)
== SQL ==
SELECT CURRENT_TIMESTAMP
-------^^^
scala> sql("SELECT CURRENT_TIMESTAMP()").show
rg.apache.spark.sql.catalyst.parser.ParseException:
no viable alternative at input 'CURRENT_TIMESTAMP'(line 1, pos 7)
== SQL ==
SELECT CURRENT_TIMESTAMP()
-------^^^
```
To be honest, I'm not 100% sure about what the ANSI reserved means.
For example, both postgresql and mysql reserve `current_timestamp`, but the
behviour is different;
```
postgres=# SELECT CURRENT_TIMESTAMP;
now
-------------------------------
2019-02-25 16:44:26.320698+09
(1 row)
postgres=# SELECT CURRENT_TIMESTAMP();
ERROR: syntax error at or near ")"
LINE 1: SELECT CURRENT_TIMESTAMP();
^
mysql> SELECT CURRENT_TIMESTAMP;
+---------------------+
| CURRENT_TIMESTAMP |
+---------------------+
| 2019-02-25 16:45:02 |
+---------------------+
mysql> SELECT CURRENT_TIMESTAMP();
+---------------------+
| CURRENT_TIMESTAMP() |
+---------------------+
| 2019-02-25 16:45:04 |
+---------------------+
```
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