# Stats Multi-stage stats are more complex but also more expressive than single-stage stats. While in single-stage stats Apache Pinot returns a single set of statistics for the query, in multi-stage stats Apache Pinot returns a set of statistics for each operator of the query execution. These stats can be seen when using Pinot controller UI by running the query and clicking on the `Show JSON format` button. Then the whole JSON response will be shown and the multi-stage stats will be in a field called `stageStats`. Different drivers may provide different ways to see the stats. For example the following query: ```sql SELECT playerName, teamName FROM baseballStats_OFFLINE as playerStats JOIN dimBaseballTeams_OFFLINE AS teams ON playerStats.teamID = teams.teamID LIMIT 10 ``` Returns the following `stageStats`: ```json { "type": "MAILBOX_RECEIVE", "executionTimeMs": 222, "emittedRows": 10, "fanIn": 3, "rawMessages": 4, "deserializedBytes": 1688, "upstreamWaitMs": 651, "children": [ { "type": "MAILBOX_SEND", "executionTimeMs": 210, "emittedRows": 10, "stage": 1, "parallelism": 3, "fanOut": 1, "rawMessages": 4, "serializedBytes": 338, "children": [ { "type": "SORT_OR_LIMIT", "executionTimeMs": 585, "emittedRows": 10, "children": [ { "type": "MAILBOX_RECEIVE", "executionTimeMs": 585, "emittedRows": 10, "fanIn": 3, "inMemoryMessages": 4, "rawMessages": 8, "deserializedBytes": 1775, "deserializationTimeMs": 1, "upstreamWaitMs": 1480, "children": [ { "type": "MAILBOX_SEND", "executionTimeMs": 397, "emittedRows": 30, "stage": 2, "parallelism": 3, "fanOut": 3, "inMemoryMessages": 4, "rawMessages": 8, "serializedBytes": 1108, "serializationTimeMs": 2, "children": [ { "type": "SORT_OR_LIMIT", "executionTimeMs": 379, "emittedRows": 30, "children": [ { "type": "TRANSFORM", "executionTimeMs": 377, "emittedRows": 5092, "children": [ { "type": "HASH_JOIN", "executionTimeMs": 376, "emittedRows": 5092, "timeBuildingHashTableMs": 167, "children": [ { "type": "MAILBOX_RECEIVE", "executionTimeMs": 206, "emittedRows": 10000, "fanIn": 1, "inMemoryMessages": 4, "rawMessages": 21, "deserializedBytes": 649374, "deserializationTimeMs": 3, "downstreamWaitMs": 5, "upstreamWaitMs": 390, "children": [ { "type": "MAILBOX_SEND", "executionTimeMs": 94, "emittedRows": 97889, "stage": 3, "parallelism": 1, "fanOut": 3, "inMemoryMessages": 4, "rawMessages": 20, "serializedBytes": 649076, "serializationTimeMs": 17, "children": [ { "type": "LEAF", "table": "baseballStats_OFFLINE", "executionTimeMs": 75, "emittedRows": 97889, "numDocsScanned": 97889, "numEntriesScannedPostFilter": 195778, "numSegmentsQueried": 1, "numSegmentsProcessed": 1, "numSegmentsMatched": 1, "totalDocs": 97889, "threadCpuTimeNs": 19888000 } ] } ] }, { "type": "MAILBOX_RECEIVE", "executionTimeMs": 163, "emittedRows": 51, "fanIn": 1, "inMemoryMessages": 2, "rawMessages": 4, "deserializedBytes": 2330, "downstreamWaitMs": 14, "upstreamWaitMs": 162, "children": [ { "type": "MAILBOX_SEND", "executionTimeMs": 17, "emittedRows": 51, "stage": 4, "parallelism": 1, "fanOut": 3, "inMemoryMessages": 1, "rawMessages": 4, "serializedBytes": 2092, "children": [ { "type": "LEAF", "table": "dimBaseballTeams_OFFLINE", "executionTimeMs": 62, "emittedRows": 51, "numDocsScanned": 51, "numEntriesScannedPostFilter": 102, "numSegmentsQueried": 1, "numSegmentsProcessed": 1, "numSegmentsMatched": 1, "totalDocs": 51, "threadCpuTimeNs": 1919000, "systemActivitiesCpuTimeNs": 4677167 } ] } ] } ] } ] } ] } ] } ] } ] } ] } ] } ``` Each node in the tree represents an operation that is executed and the tree structure form is similar (but not equal) to the logical plan of the query that can be obtained with the `EXPLAIN PLAN` command. As you can see, each operator has a type and the stats carried on the node depend on that type. You can learn more about each operator types and their stats in the [Operator Types](/release-1.2.0/for-users/user-guide-query/multi-stage-query/operator-types.md) section. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://docs.pinot.apache.org/release-1.2.0/for-users/user-guide-query/multi-stage-query/understanding-stage-stats.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.