[ 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. -- This message was sent by Atlassian JIRA (v6.3.4#6332)