EXPLAIN#
Synopsis#
EXPLAIN [ ( option [, ...] ) ] statement
where option can be one of:
FORMAT { TEXT | GRAPHVIZ | JSON }
TYPE { LOGICAL | DISTRIBUTED | VALIDATE | IO }
Description#
Show the logical or distributed execution plan of a statement, or validate the statement. The distributed plan is shown by default. Each plan fragment of the distributed plan is executed by a single or multiple Trino nodes. Fragments separation represent the data exchange between Trino nodes. Fragment type specifies how the fragment is executed by Trino nodes and how the data is distributed between fragments:
SINGLEFragment is executed on a single node.
HASHFragment is executed on a fixed number of nodes with the input data distributed using a hash function.
ROUND_ROBINFragment is executed on a fixed number of nodes with the input data distributed in a round-robin fashion.
BROADCASTFragment is executed on a fixed number of nodes with the input data broadcasted to all nodes.
SOURCEFragment is executed on nodes where input splits are accessed.
Examples#
EXPLAIN (TYPE LOGICAL)#
Logical plan:
EXPLAIN (TYPE LOGICAL) SELECT regionkey, count(*) FROM nation GROUP BY 1;
Query Plan
-----------------------------------------------------------------------------------------------------------------
Output[regionkey, _col1]
│ Layout: [regionkey:bigint, count:bigint]
│ Estimates: {rows: ? (?), cpu: ?, memory: ?, network: ?}
│ _col1 := count
└─ RemoteExchange[GATHER]
│ Layout: [regionkey:bigint, count:bigint]
│ Estimates: {rows: ? (?), cpu: ?, memory: ?, network: ?}
└─ Aggregate(FINAL)[regionkey]
│ Layout: [regionkey:bigint, count:bigint]
│ Estimates: {rows: ? (?), cpu: ?, memory: ?, network: ?}
│ count := count("count_8")
└─ LocalExchange[HASH][$hashvalue] ("regionkey")
│ Layout: [regionkey:bigint, count_8:bigint, $hashvalue:bigint]
│ Estimates: {rows: ? (?), cpu: ?, memory: ?, network: ?}
└─ RemoteExchange[REPARTITION][$hashvalue_9]
│ Layout: [regionkey:bigint, count_8:bigint, $hashvalue_9:bigint]
│ Estimates: {rows: ? (?), cpu: ?, memory: ?, network: ?}
└─ Project[]
│ Layout: [regionkey:bigint, count_8:bigint, $hashvalue_10:bigint]
│ Estimates: {rows: ? (?), cpu: ?, memory: ?, network: ?}
│ $hashvalue_10 := "combine_hash"(bigint '0', COALESCE("$operator$hash_code"("regionkey"), 0))
└─ Aggregate(PARTIAL)[regionkey]
│ Layout: [regionkey:bigint, count_8:bigint]
│ count_8 := count(*)
└─ TableScan[tpch:nation:sf0.01]
Layout: [regionkey:bigint]
Estimates: {rows: 25 (225B), cpu: 225, memory: 0B, network: 0B}
regionkey := tpch:regionkey
EXPLAIN (TYPE LOGICAL, FORMAT JSON)#
Warning
The output format is not guaranteed to be backward compatible across Trino versions.
JSON Logical plan:
EXPLAIN (TYPE LOGICAL, FORMAT JSON) SELECT regionkey, count(*) FROM nation GROUP BY 1;
{
"id": "9",
"name": "Output",
"descriptor": {
"columnNames": "[regionkey, _col1]"
},
"outputs": [
{
"symbol": "regionkey",
"type": "bigint"
},
{
"symbol": "count",
"type": "bigint"
}
],
"details": [
"_col1 := count"
],
"estimates": [
{
"outputRowCount": "NaN",
"outputSizeInBytes": "NaN",
"cpuCost": "NaN",
"memoryCost": "NaN",
"networkCost": "NaN"
}
],
"children": [
{
"id": "145",
"name": "RemoteExchange",
"descriptor": {
"type": "GATHER",
"isReplicateNullsAndAny": "",
"hashColumn": ""
},
"outputs": [
{
"symbol": "regionkey",
"type": "bigint"
},
{
"symbol": "count",
"type": "bigint"
}
],
"details": [
],
"estimates": [
{
"outputRowCount": "NaN",
"outputSizeInBytes": "NaN",
"cpuCost": "NaN",
"memoryCost": "NaN",
"networkCost": "NaN"
}
],
"children": [
{
"id": "4",
"name": "Aggregate",
"descriptor": {
"type": "FINAL",
"keys": "[regionkey]",
"hash": ""
},
"outputs": [
{
"symbol": "regionkey",
"type": "bigint"
},
{
"symbol": "count",
"type": "bigint"
}
],
"details": [
"count := count(\"count_0\")"
],
"estimates": [
{
"outputRowCount": "NaN",
"outputSizeInBytes": "NaN",
"cpuCost": "NaN",
"memoryCost": "NaN",
"networkCost": "NaN"
}
],
"children": [
{
"id": "194",
"name": "LocalExchange",
"descriptor": {
"partitioning": "HASH",
"isReplicateNullsAndAny": "",
"hashColumn": "[$hashvalue]",
"arguments": "[\"regionkey\"]"
},
"outputs": [
{
"symbol": "regionkey",
"type": "bigint"
},
{
"symbol": "count_0",
"type": "bigint"
},
{
"symbol": "$hashvalue",
"type": "bigint"
}
],
"details":[],
"estimates": [
{
"outputRowCount": "NaN",
"outputSizeInBytes": "NaN",
"cpuCost": "NaN",
"memoryCost": "NaN",
"networkCost": "NaN"
}
],
"children": [
{
"id": "200",
"name": "RemoteExchange",
"descriptor": {
"type": "REPARTITION",
"isReplicateNullsAndAny": "",
"hashColumn": "[$hashvalue_1]"
},
"outputs": [
{
"symbol": "regionkey",
"type": "bigint"
},
{
"symbol": "count_0",
"type": "bigint"
},
{
"symbol": "$hashvalue_1",
"type": "bigint"
}
],
"details":[],
"estimates": [
{
"outputRowCount": "NaN",
"outputSizeInBytes": "NaN",
"cpuCost": "NaN",
"memoryCost": "NaN",
"networkCost": "NaN"
}
],
"children": [
{
"id": "226",
"name": "Project",
"descriptor": {}
"outputs": [
{
"symbol": "regionkey",
"type": "bigint"
},
{
"symbol": "count_0",
"type": "bigint"
},
{
"symbol": "$hashvalue_2",
"type": "bigint"
}
],
"details": [
"$hashvalue_2 := combine_hash(bigint '0', COALESCE(\"$operator$hash_code\"(\"regionkey\"), 0))"
],
"estimates": [
{
"outputRowCount": "NaN",
"outputSizeInBytes": "NaN",
"cpuCost": "NaN",
"memoryCost": "NaN",
"networkCost": "NaN"
}
],
"children": [
{
"id": "198",
"name": "Aggregate",
"descriptor": {
"type": "PARTIAL",
"keys": "[regionkey]",
"hash": ""
},
"outputs": [
{
"symbol": "regionkey",
"type": "bigint"
},
{
"symbol": "count_0",
"type": "bigint"
}
],
"details": [
"count_0 := count(*)"
],
"estimates":[],
"children": [
{
"id": "0",
"name": "TableScan",
"descriptor": {
"table": "hive:tpch_sf1_orc_part:nation"
},
"outputs": [
{
"symbol": "regionkey",
"type": "bigint"
}
],
"details": [
"regionkey := regionkey:bigint:REGULAR"
],
"estimates": [
{
"outputRowCount": 25,
"outputSizeInBytes": 225,
"cpuCost": 225,
"memoryCost": 0,
"networkCost": 0
}
],
"children": []
}
]
}
]
}
]
}
]
}
]
}
]
}
]
}
EXPLAIN (TYPE DISTRIBUTED)#
Distributed plan:
EXPLAIN (TYPE DISTRIBUTED) SELECT regionkey, count(*) FROM nation GROUP BY 1;
Query Plan
------------------------------------------------------------------------------------------------------
Fragment 0 [SINGLE]
Output layout: [regionkey, count]
Output partitioning: SINGLE []
Output[regionkey, _col1]
│ Layout: [regionkey:bigint, count:bigint]
│ Estimates: {rows: ? (?), cpu: ?, memory: ?, network: ?}
│ _col1 := count
└─ RemoteSource[1]
Layout: [regionkey:bigint, count:bigint]
Fragment 1 [HASH]
Output layout: [regionkey, count]
Output partitioning: SINGLE []
Aggregate(FINAL)[regionkey]
│ Layout: [regionkey:bigint, count:bigint]
│ Estimates: {rows: ? (?), cpu: ?, memory: ?, network: ?}
│ count := count("count_8")
└─ LocalExchange[HASH][$hashvalue] ("regionkey")
│ Layout: [regionkey:bigint, count_8:bigint, $hashvalue:bigint]
│ Estimates: {rows: ? (?), cpu: ?, memory: ?, network: ?}
└─ RemoteSource[2]
Layout: [regionkey:bigint, count_8:bigint, $hashvalue_9:bigint]
Fragment 2 [SOURCE]
Output layout: [regionkey, count_8, $hashvalue_10]
Output partitioning: HASH [regionkey][$hashvalue_10]
Project[]
│ Layout: [regionkey:bigint, count_8:bigint, $hashvalue_10:bigint]
│ Estimates: {rows: ? (?), cpu: ?, memory: ?, network: ?}
│ $hashvalue_10 := "combine_hash"(bigint '0', COALESCE("$operator$hash_code"("regionkey"), 0))
└─ Aggregate(PARTIAL)[regionkey]
│ Layout: [regionkey:bigint, count_8:bigint]
│ count_8 := count(*)
└─ TableScan[tpch:nation:sf0.01, grouped = false]
Layout: [regionkey:bigint]
Estimates: {rows: 25 (225B), cpu: 225, memory: 0B, network: 0B}
regionkey := tpch:regionkey
EXPLAIN (TYPE DISTRIBUTED, FORMAT JSON)#
Warning
The output format is not guaranteed to be backward compatible across Trino versions.
JSON Distributed plan:
EXPLAIN (TYPE DISTRIBUTED, FORMAT JSON) SELECT regionkey, count(*) FROM nation GROUP BY 1;
{
"0" : {
"id" : "9",
"name" : "Output",
"descriptor" : {
"columnNames" : "[regionkey, _col1]"
},
"outputs" : [ {
"symbol" : "regionkey",
"type" : "bigint"
}, {
"symbol" : "count",
"type" : "bigint"
} ],
"details" : [ "_col1 := count" ],
"estimates" : [ {
"outputRowCount" : "NaN",
"outputSizeInBytes" : "NaN",
"cpuCost" : "NaN",
"memoryCost" : "NaN",
"networkCost" : "NaN"
} ],
"children" : [ {
"id" : "145",
"name" : "RemoteSource",
"descriptor" : {
"sourceFragmentIds" : "[1]"
},
"outputs" : [ {
"symbol" : "regionkey",
"type" : "bigint"
}, {
"symbol" : "count",
"type" : "bigint"
} ],
"details" : [ ],
"estimates" : [ ],
"children" : [ ]
} ]
},
"1" : {
"id" : "4",
"name" : "Aggregate",
"descriptor" : {
"type" : "FINAL",
"keys" : "[regionkey]",
"hash" : "[]"
},
"outputs" : [ {
"symbol" : "regionkey",
"type" : "bigint"
}, {
"symbol" : "count",
"type" : "bigint"
} ],
"details" : [ "count := count(\"count_0\")" ],
"estimates" : [ {
"outputRowCount" : "NaN",
"outputSizeInBytes" : "NaN",
"cpuCost" : "NaN",
"memoryCost" : "NaN",
"networkCost" : "NaN"
} ],
"children" : [ {
"id" : "194",
"name" : "LocalExchange",
"descriptor" : {
"partitioning" : "SINGLE",
"isReplicateNullsAndAny" : "",
"hashColumn" : "[]",
"arguments" : "[]"
},
"outputs" : [ {
"symbol" : "regionkey",
"type" : "bigint"
}, {
"symbol" : "count_0",
"type" : "bigint"
} ],
"details" : [ ],
"estimates" : [ {
"outputRowCount" : "NaN",
"outputSizeInBytes" : "NaN",
"cpuCost" : "NaN",
"memoryCost" : "NaN",
"networkCost" : "NaN"
} ],
"children" : [ {
"id" : "227",
"name" : "Project",
"descriptor" : { },
"outputs" : [ {
"symbol" : "regionkey",
"type" : "bigint"
}, {
"symbol" : "count_0",
"type" : "bigint"
} ],
"details" : [ ],
"estimates" : [ {
"outputRowCount" : "NaN",
"outputSizeInBytes" : "NaN",
"cpuCost" : "NaN",
"memoryCost" : "NaN",
"networkCost" : "NaN"
} ],
"children" : [ {
"id" : "200",
"name" : "RemoteSource",
"descriptor" : {
"sourceFragmentIds" : "[2]"
},
"outputs" : [ {
"symbol" : "regionkey",
"type" : "bigint"
}, {
"symbol" : "count_0",
"type" : "bigint"
}, {
"symbol" : "$hashvalue",
"type" : "bigint"
} ],
"details" : [ ],
"estimates" : [ ],
"children" : [ ]
} ]
} ]
} ]
},
"2" : {
"id" : "226",
"name" : "Project",
"descriptor" : { },
"outputs" : [ {
"symbol" : "regionkey",
"type" : "bigint"
}, {
"symbol" : "count_0",
"type" : "bigint"
}, {
"symbol" : "$hashvalue_1",
"type" : "bigint"
} ],
"details" : [ "$hashvalue_1 := combine_hash(bigint '0', COALESCE(\"$operator$hash_code\"(\"regionkey\"), 0))" ],
"estimates" : [ {
"outputRowCount" : "NaN",
"outputSizeInBytes" : "NaN",
"cpuCost" : "NaN",
"memoryCost" : "NaN",
"networkCost" : "NaN"
} ],
"children" : [ {
"id" : "198",
"name" : "Aggregate",
"descriptor" : {
"type" : "PARTIAL",
"keys" : "[regionkey]",
"hash" : "[]"
},
"outputs" : [ {
"symbol" : "regionkey",
"type" : "bigint"
}, {
"symbol" : "count_0",
"type" : "bigint"
} ],
"details" : [ "count_0 := count(*)" ],
"estimates" : [ ],
"children" : [ {
"id" : "0",
"name" : "TableScan",
"descriptor" : {
"table" : "tpch:tiny:nation"
},
"outputs" : [ {
"symbol" : "regionkey",
"type" : "bigint"
} ],
"details" : [ "regionkey := tpch:regionkey" ],
"estimates" : [ {
"outputRowCount" : 25.0,
"outputSizeInBytes" : 225.0,
"cpuCost" : 225.0,
"memoryCost" : 0.0,
"networkCost" : 0.0
} ],
"children" : [ ]
} ]
} ]
}
}
EXPLAIN (TYPE VALIDATE)#
Validate:
EXPLAIN (TYPE VALIDATE) SELECT regionkey, count(*) FROM nation GROUP BY 1;
Valid
-------
true
EXPLAIN (TYPE IO)#
IO:
EXPLAIN (TYPE IO, FORMAT JSON) INSERT INTO test_lineitem
SELECT * FROM lineitem WHERE shipdate = '2020-02-01' AND quantity > 10;
Query Plan
-----------------------------------
{
inputTableColumnInfos: [
{
table: {
catalog: "hive",
schemaTable: {
schema: "tpch",
table: "test_orders"
}
},
columnConstraints: [
{
columnName: "orderkey",
type: "bigint",
domain: {
nullsAllowed: false,
ranges: [
{
low: {
value: "1",
bound: "EXACTLY"
},
high: {
value: "1",
bound: "EXACTLY"
}
},
{
low: {
value: "2",
bound: "EXACTLY"
},
high: {
value: "2",
bound: "EXACTLY"
}
}
]
}
},
{
columnName: "processing",
type: "boolean",
domain: {
nullsAllowed: false,
ranges: [
{
low: {
value: "false",
bound: "EXACTLY"
},
high: {
value: "false",
bound: "EXACTLY"
}
}
]
}
},
{
columnName: "custkey",
type: "bigint",
domain: {
nullsAllowed: false,
ranges: [
{
low: {
bound: "ABOVE"
},
high: {
value: "10",
bound: "EXACTLY"
}
}
]
}
}
],
estimate: {
outputRowCount: 2,
outputSizeInBytes: 40,
cpuCost: 40,
maxMemory: 0,
networkCost: 0
}
}
],
outputTable: {
catalog: "hive",
schemaTable: {
schema: "tpch",
table: "test_orders"
}
},
estimate: {
outputRowCount: "NaN",
outputSizeInBytes: "NaN",
cpuCost: "NaN",
maxMemory: "NaN",
networkCost: "NaN"
}
}