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# EXPLAIN
The `EXPLAIN` command shows the logical and physical execution plan for the specified SQL statement.
## Syntax
<pre>
EXPLAIN [ANALYZE] [VERBOSE] [FORMAT format] statement
</pre>
## `EXPLAIN`
Shows the execution plan of a statement.
If you need more detailed output, use `EXPLAIN VERBOSE`.
Note that `EXPLAIN VERBOSE` only supports the `indent` format.
The optional `[FORMAT format]` clause controls how the plan is displayed as
explained below. If this clause is not specified, the plan is displayed using
the format from the [configuration value] `datafusion.explain.format`.
### `tree` format (default)
The `tree` format is modeled after [DuckDB plans] and is designed to be easier
to see the high level structure of the plan
[duckdb plans]: https://duckdb.org/docs/stable/guides/meta/explain.html
```sql
> EXPLAIN FORMAT TREE SELECT SUM(x) FROM t GROUP BY b;
+---------------+-------------------------------+
| plan_type | plan |
+---------------+-------------------------------+
| physical_plan | ┌───────────────────────────┐ |
| | │ ProjectionExec │ |
| | │ -------------------- │ |
| | │ sum(t.x): sum(t.x)@1 │ |
| | └─────────────┬─────────────┘ |
| | ┌─────────────┴─────────────┐ |
| | │ AggregateExec │ |
| | │ -------------------- │ |
| | │ aggr: sum(t.x) │ |
| | │ group_by: b@0 as b │ |
| | │ │ |
| | │ mode: │ |
| | │ FinalPartitioned │ |
| | └─────────────┬─────────────┘ |
| | ┌─────────────┴─────────────┐ |
| | │ CoalesceBatchesExec │ |
| | └─────────────┬─────────────┘ |
| | ┌─────────────┴─────────────┐ |
| | │ RepartitionExec │ |
| | │ -------------------- │ |
| | │ input_partition_count: │ |
| | │ 16 │ |
| | │ │ |
| | │ partitioning_scheme: │ |
| | │ Hash([b@0], 16) │ |
| | └─────────────┬─────────────┘ |
| | ┌─────────────┴─────────────┐ |
| | │ RepartitionExec │ |
| | │ -------------------- │ |
| | │ input_partition_count: │ |
| | │ 1 │ |
| | │ │ |
| | │ partitioning_scheme: │ |
| | │ RoundRobinBatch(16) │ |
| | └─────────────┬─────────────┘ |
| | ┌─────────────┴─────────────┐ |
| | │ AggregateExec │ |
| | │ -------------------- │ |
| | │ aggr: sum(t.x) │ |
| | │ group_by: b@1 as b │ |
| | │ mode: Partial │ |
| | └─────────────┬─────────────┘ |
| | ┌─────────────┴─────────────┐ |
| | │ DataSourceExec │ |
| | │ -------------------- │ |
| | │ bytes: 224 │ |
| | │ format: memory │ |
| | │ rows: 1 │ |
| | └───────────────────────────┘ |
| | |
+---------------+-------------------------------+
1 row(s) fetched.
Elapsed 0.016 seconds.
```
### `indent` format
The `indent` format shows both the logical and physical plan, with one line for
each operator in the plan. Child plans are indented to show the hierarchy.
See [Reading Explain Plans](../explain-usage.md) for more information on how to interpret these plans.
```sql
> CREATE TABLE t(x int, b int) AS VALUES (1, 2), (2, 3);
0 row(s) fetched.
Elapsed 0.004 seconds.
> EXPLAIN FORMAT INDENT SELECT SUM(x) FROM t GROUP BY b;
+---------------+-------------------------------------------------------------------------------+
| plan_type | plan |
+---------------+-------------------------------------------------------------------------------+
| logical_plan | Projection: sum(t.x) |
| | Aggregate: groupBy=[[t.b]], aggr=[[sum(CAST(t.x AS Int64))]] |
| | TableScan: t projection=[x, b] |
| physical_plan | ProjectionExec: expr=[sum(t.x)@1 as sum(t.x)] |
| | AggregateExec: mode=FinalPartitioned, gby=[b@0 as b], aggr=[sum(t.x)] |
| | CoalesceBatchesExec: target_batch_size=8192 |
| | RepartitionExec: partitioning=Hash([b@0], 16), input_partitions=16 |
| | RepartitionExec: partitioning=RoundRobinBatch(16), input_partitions=1 |
| | AggregateExec: mode=Partial, gby=[b@1 as b], aggr=[sum(t.x)] |
| | DataSourceExec: partitions=1, partition_sizes=[1] |
| | |
+---------------+-------------------------------------------------------------------------------+
2 row(s) fetched.
Elapsed 0.004 seconds.
```
### `pgjson` format
The `pgjson` format is modeled after [Postgres JSON] format.
You can use this format to visualize the plan in existing plan visualization
tools, such as [dalibo]
[postgres json]: https://www.postgresql.org/docs/current/sql-explain.html
[dalibo]: https://explain.dalibo.com/
```sql
> EXPLAIN FORMAT PGJSON SELECT SUM(x) FROM t GROUP BY b;
+--------------+----------------------------------------------------+
| plan_type | plan |
+--------------+----------------------------------------------------+
| logical_plan | [ |
| | { |
| | "Plan": { |
| | "Expressions": [ |
| | "sum(t.x)" |
| | ], |
| | "Node Type": "Projection", |
| | "Output": [ |
| | "sum(t.x)" |
| | ], |
| | "Plans": [ |
| | { |
| | "Aggregates": "sum(CAST(t.x AS Int64))", |
| | "Group By": "t.b", |
| | "Node Type": "Aggregate", |
| | "Output": [ |
| | "b", |
| | "sum(t.x)" |
| | ], |
| | "Plans": [ |
| | { |
| | "Node Type": "TableScan", |
| | "Output": [ |
| | "x", |
| | "b" |
| | ], |
| | "Plans": [], |
| | "Relation Name": "t" |
| | } |
| | ] |
| | } |
| | ] |
| | } |
| | } |
| | ] |
+--------------+----------------------------------------------------+
1 row(s) fetched.
Elapsed 0.008 seconds.
```
### `graphviz` format
The `graphviz` format uses the [DOT language] that can be used with [Graphviz] to
generate a visual representation of the plan.
[dot language]: https://graphviz.org/doc/info/lang.html
[graphviz]: https://graphviz.org/
```sql
> EXPLAIN FORMAT GRAPHVIZ SELECT SUM(x) FROM t GROUP BY b;
+--------------+------------------------------------------------------------------------------------------------------------------------------+
| plan_type | plan |
+--------------+------------------------------------------------------------------------------------------------------------------------------+
| logical_plan | |
| | // Begin DataFusion GraphViz Plan, |
| | // display it online here: https://dreampuf.github.io/GraphvizOnline |
| | |
| | digraph { |
| | subgraph cluster_1 |
| | { |
| | graph[label="LogicalPlan"] |
| | 2[shape=box label="Projection: sum(t.x)"] |
| | 3[shape=box label="Aggregate: groupBy=[[t.b]], aggr=[[sum(CAST(t.x AS Int64))]]"] |
| | 2 -> 3 [arrowhead=none, arrowtail=normal, dir=back] |
| | 4[shape=box label="TableScan: t projection=[x, b]"] |
| | 3 -> 4 [arrowhead=none, arrowtail=normal, dir=back] |
| | } |
| | subgraph cluster_5 |
| | { |
| | graph[label="Detailed LogicalPlan"] |
| | 6[shape=box label="Projection: sum(t.x)\nSchema: [sum(t.x):Int64;N]"] |
| | 7[shape=box label="Aggregate: groupBy=[[t.b]], aggr=[[sum(CAST(t.x AS Int64))]]\nSchema: [b:Int32;N, sum(t.x):Int64;N]"] |
| | 6 -> 7 [arrowhead=none, arrowtail=normal, dir=back] |
| | 8[shape=box label="TableScan: t projection=[x, b]\nSchema: [x:Int32;N, b:Int32;N]"] |
| | 7 -> 8 [arrowhead=none, arrowtail=normal, dir=back] |
| | } |
| | } |
| | // End DataFusion GraphViz Plan |
| | |
+--------------+------------------------------------------------------------------------------------------------------------------------------+
1 row(s) fetched.
Elapsed 0.010 seconds.
```
## `EXPLAIN ANALYZE`
Shows the execution plan and metrics of a statement. Note that `EXPLAIN ANALYZE`
only supports the `indent` format.
```sql
EXPLAIN ANALYZE SELECT SUM(x) FROM table GROUP BY b;
+-------------------+-----------------------------------------------------------------------------------------------------------------------------------------------------------+
| plan_type | plan |
+-------------------+-----------------------------------------------------------------------------------------------------------------------------------------------------------+
| Plan with Metrics | CoalescePartitionsExec, metrics=[] |
| | ProjectionExec: expr=[SUM(table.x)@1 as SUM(x)], metrics=[] |
| | HashAggregateExec: mode=FinalPartitioned, gby=[b@0 as b], aggr=[SUM(x)], metrics=[outputRows=2] |
| | CoalesceBatchesExec: target_batch_size=4096, metrics=[] |
| | RepartitionExec: partitioning=Hash([Column { name: "b", index: 0 }], 16), metrics=[sendTime=839560, fetchTime=122528525, repartitionTime=5327877] |
| | HashAggregateExec: mode=Partial, gby=[b@1 as b], aggr=[SUM(x)], metrics=[outputRows=2] |
| | RepartitionExec: partitioning=RoundRobinBatch(16), metrics=[fetchTime=5660489, repartitionTime=0, sendTime=8012] |
| | DataSourceExec: file_groups={1 group: [[/tmp/table.csv]]}, has_header=false, metrics=[] |
+-------------------+-----------------------------------------------------------------------------------------------------------------------------------------------------------+
```
By default `EXPLAIN ANALYZE` shows the aggregated metrics from all partitions for each operator. If you need to display per-partition metrics, use `EXPLAIN ANALYZE VERBOSE`.
You can also set `datafusion.explain.analyze_level` from the [configuration value] to control the detail level for the metrics displayed.
[configuration value]: ../configs.md