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From "Till Rohrmann (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (FLINK-4241) Cryptic expression parser exceptions
Date Thu, 21 Jul 2016 13:32:20 GMT

     [ https://issues.apache.org/jira/browse/FLINK-4241?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Till Rohrmann updated FLINK-4241:
---------------------------------
    Description: 
The exceptions thrown when giving wrong SQL syntax to Flink's SQL parser is very cryptic and
should be improved. For example, the following code snippet:

{code}
inputTable.filter("a == 0");
{code}

gives the following exception:

{code}
Exception in thread "main" org.apache.flink.api.table.ExpressionParserException: Could not
parse expression: [1.4] failure: `-' expected but `=' found

a == 0
   ^
	at org.apache.flink.api.table.expressions.ExpressionParser$.parseExpression(ExpressionParser.scala:355)
	at org.apache.flink.api.table.Table.filter(table.scala:161)
	at com.dataartisans.streaming.SimpleTableAPIJob.main(SimpleTableAPIJob.java:32)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:497)
	at com.intellij.rt.execution.application.AppMain.main(AppMain.java:144)
{code}

>From this description it is very hard to understand that {{==}} is not a valid operator.

Another example is:

{code}
inputTable.select("*");
{code}

which gives

{code}
Exception in thread "main" org.apache.flink.api.table.ExpressionParserException: Could not
parse expression: Base Failure
	at org.apache.flink.api.table.expressions.ExpressionParser$.parseExpressionList(ExpressionParser.scala:342)
	at org.apache.flink.api.table.Table.select(table.scala:103)
	at com.dataartisans.streaming.SimpleTableAPIJob.main(SimpleTableAPIJob.java:33)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:497)
	at com.intellij.rt.execution.application.AppMain.main(AppMain.java:144)
{code}

I think it would considerably improve user experience if we print more helpful parsing exceptions.



  was:
The exceptions thrown when giving wrong SQL syntax to Flink's SQL parser is very cryptic and
should be improved. For example, the following code snippet:

{code}
inputTable.filter("a == 0");
{code}

gives the following exception:

{code}
Exception in thread "main" org.apache.flink.api.table.ExpressionParserException: Could not
parse expression: [1.4] failure: `-' expected but `=' found

a == 0
   ^
	at org.apache.flink.api.table.expressions.ExpressionParser$.parseExpression(ExpressionParser.scala:355)
	at org.apache.flink.api.table.Table.filter(table.scala:161)
	at com.dataartisans.streaming.SimpleTableAPIJob.main(SimpleTableAPIJob.java:32)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:497)
	at com.intellij.rt.execution.application.AppMain.main(AppMain.java:144)
{code}

>From this description it is very hard to understand that {{==}} is not a valid operator.

I think it would considerably improve user experience if we print more helpful parsing exceptions.




> Cryptic expression parser exceptions
> ------------------------------------
>
>                 Key: FLINK-4241
>                 URL: https://issues.apache.org/jira/browse/FLINK-4241
>             Project: Flink
>          Issue Type: Improvement
>          Components: Table API & SQL
>    Affects Versions: 1.1.0
>            Reporter: Till Rohrmann
>
> The exceptions thrown when giving wrong SQL syntax to Flink's SQL parser is very cryptic
and should be improved. For example, the following code snippet:
> {code}
> inputTable.filter("a == 0");
> {code}
> gives the following exception:
> {code}
> Exception in thread "main" org.apache.flink.api.table.ExpressionParserException: Could
not parse expression: [1.4] failure: `-' expected but `=' found
> a == 0
>    ^
> 	at org.apache.flink.api.table.expressions.ExpressionParser$.parseExpression(ExpressionParser.scala:355)
> 	at org.apache.flink.api.table.Table.filter(table.scala:161)
> 	at com.dataartisans.streaming.SimpleTableAPIJob.main(SimpleTableAPIJob.java:32)
> 	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
> 	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
> 	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
> 	at java.lang.reflect.Method.invoke(Method.java:497)
> 	at com.intellij.rt.execution.application.AppMain.main(AppMain.java:144)
> {code}
> From this description it is very hard to understand that {{==}} is not a valid operator.
> Another example is:
> {code}
> inputTable.select("*");
> {code}
> which gives
> {code}
> Exception in thread "main" org.apache.flink.api.table.ExpressionParserException: Could
not parse expression: Base Failure
> 	at org.apache.flink.api.table.expressions.ExpressionParser$.parseExpressionList(ExpressionParser.scala:342)
> 	at org.apache.flink.api.table.Table.select(table.scala:103)
> 	at com.dataartisans.streaming.SimpleTableAPIJob.main(SimpleTableAPIJob.java:33)
> 	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
> 	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
> 	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
> 	at java.lang.reflect.Method.invoke(Method.java:497)
> 	at com.intellij.rt.execution.application.AppMain.main(AppMain.java:144)
> {code}
> I think it would considerably improve user experience if we print more helpful parsing
exceptions.



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