information_schema should not fail for duplicate columns

[chadheyne]

I believe this is similar to https://github.com/prestodb/presto/pull/11847 and https://github.com/prestosql/presto/pull/568.

When I am running

SELECT table_schema, table_name, column_name
FROM information_schema.columns
WHERE table_schema NOT IN ('pg_catalog', 'information_schema')

The whole query fails with

Query 20190515_163812_00120_bynzu failed: Hive metadata for table myTable is invalid: Table descriptor contains duplicate columns
io.prestosql.spi.PrestoException: Hive metadata for table myTable is invalid: Table descriptor contains duplicate columns
    at io.prestosql.plugin.hive.HiveMetadata.columnMetadataGetter(HiveMetadata.java:2148)
    at io.prestosql.plugin.hive.HiveMetadata.doGetTableMetadata(HiveMetadata.java:442)
    at io.prestosql.plugin.hive.HiveMetadata.getTableMetadata(HiveMetadata.java:423)
    at io.prestosql.plugin.hive.HiveMetadata.listTableColumns(HiveMetadata.java:558)
    at io.prestosql.spi.connector.classloader.ClassLoaderSafeConnectorMetadata.listTableColumns(ClassLoaderSafeConnectorMetadata.java:246)
    at io.prestosql.metadata.MetadataManager.listTableColumns(MetadataManager.java:572)
    at io.prestosql.metadata.MetadataListing.listTableColumns(MetadataListing.java:93)
    at io.prestosql.connector.informationSchema.InformationSchemaPageSourceProvider.buildColumns(InformationSchemaPageSourceProvider.java:146)
    at io.prestosql.connector.informationSchema.InformationSchemaPageSourceProvider.getInformationSchemaTable(InformationSchemaPageSourceProvider.java:115)
    at io.prestosql.connector.informationSchema.InformationSchemaPageSourceProvider.getInternalTable(InformationSchemaPageSourceProvider.java:109)
    at io.prestosql.connector.informationSchema.InformationSchemaPageSourceProvider.createPageSource(InformationSchemaPageSourceProvider.java:81)
    at io.prestosql.split.PageSourceManager.createPageSource(PageSourceManager.java:56)
    at io.prestosql.operator.ScanFilterAndProjectOperator.getOutput(ScanFilterAndProjectOperator.java:221)
    at io.prestosql.operator.Driver.processInternal(Driver.java:379)
    at io.prestosql.operator.Driver.lambda$processFor$8(Driver.java:283)
    at io.prestosql.operator.Driver.tryWithLock(Driver.java:675)
    at io.prestosql.operator.Driver.processFor(Driver.java:276)
    at io.prestosql.execution.SqlTaskExecution$DriverSplitRunner.processFor(SqlTaskExecution.java:1075)
    at io.prestosql.execution.executor.PrioritizedSplitRunner.process(PrioritizedSplitRunner.java:163)
    at io.prestosql.execution.executor.TaskExecutor$TaskRunner.run(TaskExecutor.java:484)
    at io.prestosql.$gen.Presto_306____20190503_191743_1.run(Unknown Source)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
    at java.lang.Thread.run(Thread.java:748)

This happens when the partition key is named the same as a column in the table.

This is the first ticket I've opened here so please let me know if I missed anything or if y'all need any more details.

[electrum]

From a SQL perspective, these operations should have different behavior for an invalid table:

• Selecting from information_schema.columns should skip any invalid tables.
• Running SHOW COLUMNS should fail with error, similar to querying from the table.

The problem is that the latter is implemented as a rewrite against the former. This happens in ShowQueriesRewrite.Visitor#visitShowColumns. The columns table in turn calls ConnectorMetadata#listTableColumns.

This is how to fix it:

• Change visitShowColumns to get the table handle and then ask for metadata about the handle. It will need to call AccessControl#filterColumns which is currently done in MetadataListing#listTableColumns.
• Change connector implementations of ConnectorMetadata#listTableColumns to skip invalid tables. This has to be done at the connector level since that method returns all the columns at once.

One question is if we should also call AccessControl#filterTables. This happens today, but it seems to be more of a side effect of the implementation. The documentation for AccessControl#checkCanShowColumnsMetadata only mentions AccessControl#filterColumns.