Dynamic Table Queries in the Pinot Connector fail if targeting an empty partition

[lksvenoy-r7]

Seeing an issue with dynamic table queries through the Pinot connector for Trino version 379. When doing a query with a WHERE clause on the partition key without using a dynamic table query where there is no data for that key, 0 rows are returned (as expected). But when doing a dynamic table query of the same kind, the Pinot Trino connector hangs for a long time, and then returns

Query 20220920_202500_00441_6rt9p failed: Only 0 out of 0 servers responded for query select "field1", "field2", "field3", "field4", "field5", "time", "field6", "time2", "field7", "primaryKey", "field8", "field9" from table where ("primaryKey") = 'primary-key-which-does-not-exist' limit 10 with query .......

This is a result of executing the following trino query SELECT * FROM pinot.default."SELECT anyField FROM table WHERE primaryKey = 'primary-key-which-does-not-exist'";

Executing the same query outside of a dynamic table query works as expected, and returns 0 rows. In the Trino UI the error shows up as EXTERNAL ERROR — PINOT_INSUFFICIENT_SERVER_RESPONSE

Here is a stack trace

at io.trino.plugin.pinot.client.PinotClient.lambda$submitBrokerQueryJson$6(PinotClient.java:551)
	at io.trino.plugin.pinot.client.PinotClient.doWithRetries(PinotClient.java:616)
	at io.trino.plugin.pinot.client.PinotClient.submitBrokerQueryJson(PinotClient.java:532)
	at io.trino.plugin.pinot.client.PinotClient.createResultIterator(PinotClient.java:573)
	at io.trino.plugin.pinot.PinotBrokerPageSource.getNextPage(PinotBrokerPageSource.java:112)
	at io.trino.operator.ScanFilterAndProjectOperator$ConnectorPageSourceToPages.process(ScanFilterAndProjectOperator.java:392)
	at io.trino.operator.WorkProcessorUtils$ProcessWorkProcessor.process(WorkProcessorUtils.java:391)
	at io.trino.operator.WorkProcessorUtils.getNextState(WorkProcessorUtils.java:240)
	at io.trino.operator.WorkProcessorUtils$YieldingProcess.process(WorkProcessorUtils.java:182)
	at io.trino.operator.WorkProcessorUtils$ProcessWorkProcessor.process(WorkProcessorUtils.java:391)
	at io.trino.operator.WorkProcessorUtils$3.process(WorkProcessorUtils.java:325)
	at io.trino.operator.WorkProcessorUtils$ProcessWorkProcessor.process(WorkProcessorUtils.java:391)
	at io.trino.operator.WorkProcessorUtils$3.process(WorkProcessorUtils.java:325)
	at io.trino.operator.WorkProcessorUtils$ProcessWorkProcessor.process(WorkProcessorUtils.java:391)
	at io.trino.operator.WorkProcessorUtils$3.process(WorkProcessorUtils.java:325)
	at io.trino.operator.WorkProcessorUtils$ProcessWorkProcessor.process(WorkProcessorUtils.java:391)
	at io.trino.operator.WorkProcessorUtils$3.process(WorkProcessorUtils.java:325)
	at io.trino.operator.WorkProcessorUtils$ProcessWorkProcessor.process(WorkProcessorUtils.java:391)
	at io.trino.operator.WorkProcessorUtils.lambda$flatten$7(WorkProcessorUtils.java:296)
	at io.trino.operator.WorkProcessorUtils$3.process(WorkProcessorUtils.java:338)
	at io.trino.operator.WorkProcessorUtils$ProcessWorkProcessor.process(WorkProcessorUtils.java:391)
	at io.trino.operator.WorkProcessorUtils$3.process(WorkProcessorUtils.java:325)
	at io.trino.operator.WorkProcessorUtils$ProcessWorkProcessor.process(WorkProcessorUtils.java:391)
	at io.trino.operator.WorkProcessorUtils.getNextState(WorkProcessorUtils.java:240)
	at io.trino.operator.WorkProcessorUtils.lambda$processStateMonitor$3(WorkProcessorUtils.java:219)
	at io.trino.operator.WorkProcessorUtils$ProcessWorkProcessor.process(WorkProcessorUtils.java:391)
	at io.trino.operator.WorkProcessorUtils.getNextState(WorkProcessorUtils.java:240)
	at io.trino.operator.WorkProcessorUtils.lambda$finishWhen$4(WorkProcessorUtils.java:234)
	at io.trino.operator.WorkProcessorUtils$ProcessWorkProcessor.process(WorkProcessorUtils.java:391)
	at io.trino.operator.WorkProcessorSourceOperatorAdapter.getOutput(WorkProcessorSourceOperatorAdapter.java:150)
	at io.trino.operator.Driver.processInternal(Driver.java:388)
	at io.trino.operator.Driver.lambda$processFor$9(Driver.java:292)
	at io.trino.operator.Driver.tryWithLock(Driver.java:693)
	at io.trino.operator.Driver.processFor(Driver.java:285)
	at io.trino.execution.SqlTaskExecution$DriverSplitRunner.processFor(SqlTaskExecution.java:1092)
	at io.trino.execution.executor.PrioritizedSplitRunner.process(PrioritizedSplitRunner.java:163)
	at io.trino.execution.executor.TaskExecutor$TaskRunner.run(TaskExecutor.java:488)
	at io.trino.$gen.Trino_379____20220920_201245_2.run(Unknown Source)
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
	at java.base/java.lang.Thread.run(Thread.java:829)

In the Pinot broker itself, I can see these messages No server found for request 99: select.....

Interestingly enough, this seems to only happen if the entire partition is empty. So for example, if you have a Pinot table with 10 partitions, where partitions 0,1,2,3,4 have data, but partition 5,6,7,8,9 do not, then any query with a key which maps to the empty partitions will fail.

This means that the issue is not predicated on whether a table has data for the specified key or not, but whether the partition has any data at all.

Workaround I have worked around this issue by reducing the amount of partitions for my tables to 1. After this change, any query with a key which does not exist just returns 0 rows, as it maps to a partition which does have data, just not for that key.

[findepi]

cc @elonazoulay

[findepi]

cc @xiangfu0