gortiz commented on code in PR #13733:
URL: https://github.com/apache/pinot/pull/13733#discussion_r1752031714
##########
pinot-query-runtime/src/main/java/org/apache/pinot/query/runtime/QueryRunner.java:
##########
@@ -256,4 +262,66 @@ private Map<String, String>
consolidateMetadata(Map<String, String> customProper
public void cancel(long requestId) {
_opChainScheduler.cancel(requestId);
}
+
+ public StagePlan explainQuery(
+ WorkerMetadata workerMetadata, StagePlan stagePlan, Map<String, String>
requestMetadata) {
+
+ if (!workerMetadata.isLeafStageWorker()) {
+ LOGGER.debug("Explain query on intermediate stages is a NOOP");
+ return stagePlan;
+ }
+ long requestId =
Long.parseLong(requestMetadata.get(CommonConstants.Query.Request.MetadataKeys.REQUEST_ID));
+ long timeoutMs =
Long.parseLong(requestMetadata.get(CommonConstants.Broker.Request.QueryOptionKey.TIMEOUT_MS));
+ long deadlineMs = System.currentTimeMillis() + timeoutMs;
+
+ StageMetadata stageMetadata = stagePlan.getStageMetadata();
+ Map<String, String> opChainMetadata =
consolidateMetadata(stageMetadata.getCustomProperties(), requestMetadata);
+
+ if (PipelineBreakerExecutor.hasPipelineBreakers(stagePlan)) {
+ // TODO: Support pipeline breakers before merging this feature.
+ LOGGER.error("Pipeline breaker is not supported in explain query");
+ return stagePlan;
+ }
Review Comment:
The main problem is that in order to have the exact physical plan in this
case we would need to actually execute the pipeline breaker part. For example,
a query like:
```sql
select whatever from table1
where col1 in (select something from table2 where col2 = cte)
```
the actual physical plan will depend on the result of `(select something
from table2 where col2 = cte)`. Assuming that subquery is evaluated to [100,
200, 300], the query would be:
```sql
select whatever from table1
where col1 in (100, 200, 300)
```
Which could, for example, use a inverted index. I had the happy idea of
generating a random set of values on the `col1` type, but that could create
incorrect plans. For example imagine we randomly generate the set of values
`1,2`. The query we would be using to explain would be:
```sql
select whatever from table1
where col1 in (1, 2)
```
Now imagine that values of `col1` went from 100 to 200. That query would be
explained as `ALL_SEGMENTS_PRUNED_ON_SERVER` when the actual plan would be
probably different
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