417/sql/explain.html


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        <li class="md-nav__item"><a href="#synopsis" class="md-nav__link">Synopsis</a>
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  <section id="explain">
<h1 id="sql-explain--page-root">EXPLAIN<a class="headerlink" href="#sql-explain--page-root" title="Permalink to this heading">#</a></h1>
<section id="synopsis">
<h2 id="synopsis">Synopsis<a class="headerlink" href="#synopsis" title="Permalink to this heading">#</a></h2>
<div class="highlight-text notranslate"><div class="highlight"><pre><span></span>EXPLAIN [ ( option [, ...] ) ] statement
</pre></div>
</div>
<p>where <code class="docutils literal notranslate"><span class="pre">option</span></code> can be one of:</p>
<div class="highlight-text notranslate"><div class="highlight"><pre><span></span>FORMAT { TEXT | GRAPHVIZ | JSON }
TYPE { LOGICAL | DISTRIBUTED | VALIDATE | IO }
</pre></div>
</div>
</section>
<section id="description">
<h2 id="description">Description<a class="headerlink" href="#description" title="Permalink to this heading">#</a></h2>
<p>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:</p>
<dl class="simple">
<dt><code class="docutils literal notranslate"><span class="pre">SINGLE</span></code></dt><dd><p>Fragment is executed on a single node.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">HASH</span></code></dt><dd><p>Fragment is executed on a fixed number of nodes with the input data
distributed using a hash function.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">ROUND_ROBIN</span></code></dt><dd><p>Fragment is executed on a fixed number of nodes with the input data
distributed in a round-robin fashion.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">BROADCAST</span></code></dt><dd><p>Fragment is executed on a fixed number of nodes with the input data
broadcasted to all nodes.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">SOURCE</span></code></dt><dd><p>Fragment is executed on nodes where input splits are accessed.</p>
</dd>
</dl>
</section>
<section id="examples">
<h2 id="examples">Examples<a class="headerlink" href="#examples" title="Permalink to this heading">#</a></h2>
<section id="explain-type-logical">
<h3 id="explain-type-logical">EXPLAIN (TYPE LOGICAL)<a class="headerlink" href="#explain-type-logical" title="Permalink to this heading">#</a></h3>
<p>Process the supplied query statement and create a logical plan in text format:</p>
<div class="highlight-sql notranslate"><div class="highlight"><pre><span></span><span class="k">EXPLAIN</span> <span class="p">(</span><span class="k">TYPE</span> <span class="n">LOGICAL</span><span class="p">)</span> <span class="k">SELECT</span> <span class="n">regionkey</span><span class="p">,</span> <span class="k">count</span><span class="p">(</span><span class="o">*</span><span class="p">)</span> <span class="k">FROM</span> <span class="n">nation</span> <span class="k">GROUP</span> <span class="k">BY</span> <span class="mi">1</span><span class="p">;</span>
</pre></div>
</div>
<div class="highlight-text notranslate"><div class="highlight"><pre><span></span>                                                   Query Plan
-----------------------------------------------------------------------------------------------------------------
 Trino version: version
 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
</pre></div>
</div>
</section>
<section id="explain-type-logical-format-json">
<h3 id="explain-type-logical-format-json">EXPLAIN (TYPE LOGICAL, FORMAT JSON)<a class="headerlink" href="#explain-type-logical-format-json" title="Permalink to this heading">#</a></h3>
<div class="admonition warning">
<p class="admonition-title">Warning</p>
<p>The output format is not guaranteed to be backward compatible across Trino versions.</p>
</div>
<p>Process the supplied query statement and create a logical plan in JSON format:</p>
<div class="highlight-sql notranslate"><div class="highlight"><pre><span></span><span class="k">EXPLAIN</span> <span class="p">(</span><span class="k">TYPE</span> <span class="n">LOGICAL</span><span class="p">,</span> <span class="n">FORMAT</span> <span class="n">JSON</span><span class="p">)</span> <span class="k">SELECT</span> <span class="n">regionkey</span><span class="p">,</span> <span class="k">count</span><span class="p">(</span><span class="o">*</span><span class="p">)</span> <span class="k">FROM</span> <span class="n">nation</span> <span class="k">GROUP</span> <span class="k">BY</span> <span class="mi">1</span><span class="p">;</span>
</pre></div>
</div>
<div class="highlight-json notranslate"><div class="highlight"><pre><span></span><span class="p">{</span>
   <span class="nt">"id"</span><span class="p">:</span> <span class="s2">"9"</span><span class="p">,</span>
   <span class="nt">"name"</span><span class="p">:</span> <span class="s2">"Output"</span><span class="p">,</span>
   <span class="nt">"descriptor"</span><span class="p">:</span> <span class="p">{</span>
      <span class="nt">"columnNames"</span><span class="p">:</span> <span class="s2">"[regionkey, _col1]"</span>
   <span class="p">},</span>
   <span class="nt">"outputs"</span><span class="p">:</span> <span class="p">[</span>
      <span class="p">{</span>
         <span class="nt">"symbol"</span><span class="p">:</span> <span class="s2">"regionkey"</span><span class="p">,</span>
         <span class="nt">"type"</span><span class="p">:</span> <span class="s2">"bigint"</span>
      <span class="p">},</span>
      <span class="p">{</span>
         <span class="nt">"symbol"</span><span class="p">:</span> <span class="s2">"count"</span><span class="p">,</span>
         <span class="nt">"type"</span><span class="p">:</span> <span class="s2">"bigint"</span>
      <span class="p">}</span>
   <span class="p">],</span>
   <span class="nt">"details"</span><span class="p">:</span> <span class="p">[</span>
      <span class="s2">"_col1 := count"</span>
   <span class="p">],</span>
   <span class="nt">"estimates"</span><span class="p">:</span> <span class="p">[</span>
      <span class="p">{</span>
         <span class="nt">"outputRowCount"</span><span class="p">:</span> <span class="s2">"NaN"</span><span class="p">,</span>
         <span class="nt">"outputSizeInBytes"</span><span class="p">:</span> <span class="s2">"NaN"</span><span class="p">,</span>
         <span class="nt">"cpuCost"</span><span class="p">:</span> <span class="s2">"NaN"</span><span class="p">,</span>
         <span class="nt">"memoryCost"</span><span class="p">:</span> <span class="s2">"NaN"</span><span class="p">,</span>
         <span class="nt">"networkCost"</span><span class="p">:</span> <span class="s2">"NaN"</span>
      <span class="p">}</span>
   <span class="p">],</span>
   <span class="nt">"children"</span><span class="p">:</span> <span class="p">[</span>
      <span class="p">{</span>
         <span class="nt">"id"</span><span class="p">:</span> <span class="s2">"145"</span><span class="p">,</span>
         <span class="nt">"name"</span><span class="p">:</span> <span class="s2">"RemoteExchange"</span><span class="p">,</span>
         <span class="nt">"descriptor"</span><span class="p">:</span> <span class="p">{</span>
            <span class="nt">"type"</span><span class="p">:</span> <span class="s2">"GATHER"</span><span class="p">,</span>
            <span class="nt">"isReplicateNullsAndAny"</span><span class="p">:</span> <span class="s2">""</span><span class="p">,</span>
            <span class="nt">"hashColumn"</span><span class="p">:</span> <span class="s2">""</span>
         <span class="p">},</span>
         <span class="nt">"outputs"</span><span class="p">:</span> <span class="p">[</span>
            <span class="p">{</span>
               <span class="nt">"symbol"</span><span class="p">:</span> <span class="s2">"regionkey"</span><span class="p">,</span>
               <span class="nt">"type"</span><span class="p">:</span> <span class="s2">"bigint"</span>
            <span class="p">},</span>
            <span class="p">{</span>
               <span class="nt">"symbol"</span><span class="p">:</span> <span class="s2">"count"</span><span class="p">,</span>
               <span class="nt">"type"</span><span class="p">:</span> <span class="s2">"bigint"</span>
            <span class="p">}</span>
         <span class="p">],</span>
         <span class="nt">"details"</span><span class="p">:</span> <span class="p">[</span>

         <span class="p">],</span>
         <span class="nt">"estimates"</span><span class="p">:</span> <span class="p">[</span>
            <span class="p">{</span>
               <span class="nt">"outputRowCount"</span><span class="p">:</span> <span class="s2">"NaN"</span><span class="p">,</span>
               <span class="nt">"outputSizeInBytes"</span><span class="p">:</span> <span class="s2">"NaN"</span><span class="p">,</span>
               <span class="nt">"cpuCost"</span><span class="p">:</span> <span class="s2">"NaN"</span><span class="p">,</span>
               <span class="nt">"memoryCost"</span><span class="p">:</span> <span class="s2">"NaN"</span><span class="p">,</span>
               <span class="nt">"networkCost"</span><span class="p">:</span> <span class="s2">"NaN"</span>
            <span class="p">}</span>
         <span class="p">],</span>
         <span class="nt">"children"</span><span class="p">:</span> <span class="p">[</span>
            <span class="p">{</span>
               <span class="nt">"id"</span><span class="p">:</span> <span class="s2">"4"</span><span class="p">,</span>
               <span class="nt">"name"</span><span class="p">:</span> <span class="s2">"Aggregate"</span><span class="p">,</span>
               <span class="nt">"descriptor"</span><span class="p">:</span> <span class="p">{</span>
                  <span class="nt">"type"</span><span class="p">:</span> <span class="s2">"FINAL"</span><span class="p">,</span>
                  <span class="nt">"keys"</span><span class="p">:</span> <span class="s2">"[regionkey]"</span><span class="p">,</span>
                  <span class="nt">"hash"</span><span class="p">:</span> <span class="s2">""</span>
               <span class="p">},</span>
               <span class="nt">"outputs"</span><span class="p">:</span> <span class="p">[</span>
                  <span class="p">{</span>
                     <span class="nt">"symbol"</span><span class="p">:</span> <span class="s2">"regionkey"</span><span class="p">,</span>
                     <span class="nt">"type"</span><span class="p">:</span> <span class="s2">"bigint"</span>
                  <span class="p">},</span>
                  <span class="p">{</span>
                     <span class="nt">"symbol"</span><span class="p">:</span> <span class="s2">"count"</span><span class="p">,</span>
                     <span class="nt">"type"</span><span class="p">:</span> <span class="s2">"bigint"</span>
                  <span class="p">}</span>
               <span class="p">],</span>
               <span class="nt">"details"</span><span class="p">:</span> <span class="p">[</span>
                  <span class="s2">"count := count(\"count_0\")"</span>
               <span class="p">],</span>
               <span class="nt">"estimates"</span><span class="p">:</span> <span class="p">[</span>
                  <span class="p">{</span>
                     <span class="nt">"outputRowCount"</span><span class="p">:</span> <span class="s2">"NaN"</span><span class="p">,</span>
                     <span class="nt">"outputSizeInBytes"</span><span class="p">:</span> <span class="s2">"NaN"</span><span class="p">,</span>
                     <span class="nt">"cpuCost"</span><span class="p">:</span> <span class="s2">"NaN"</span><span class="p">,</span>
                     <span class="nt">"memoryCost"</span><span class="p">:</span> <span class="s2">"NaN"</span><span class="p">,</span>
                     <span class="nt">"networkCost"</span><span class="p">:</span> <span class="s2">"NaN"</span>
                  <span class="p">}</span>
               <span class="p">],</span>
               <span class="nt">"children"</span><span class="p">:</span> <span class="p">[</span>
                  <span class="p">{</span>
                     <span class="nt">"id"</span><span class="p">:</span> <span class="s2">"194"</span><span class="p">,</span>
                     <span class="nt">"name"</span><span class="p">:</span> <span class="s2">"LocalExchange"</span><span class="p">,</span>
                     <span class="nt">"descriptor"</span><span class="p">:</span> <span class="p">{</span>
                        <span class="nt">"partitioning"</span><span class="p">:</span> <span class="s2">"HASH"</span><span class="p">,</span>
                        <span class="nt">"isReplicateNullsAndAny"</span><span class="p">:</span> <span class="s2">""</span><span class="p">,</span>
                        <span class="nt">"hashColumn"</span><span class="p">:</span> <span class="s2">"[$hashvalue]"</span><span class="p">,</span>
                        <span class="nt">"arguments"</span><span class="p">:</span> <span class="s2">"[\"regionkey\"]"</span>
                     <span class="p">},</span>
                     <span class="nt">"outputs"</span><span class="p">:</span> <span class="p">[</span>
                        <span class="p">{</span>
                           <span class="nt">"symbol"</span><span class="p">:</span> <span class="s2">"regionkey"</span><span class="p">,</span>
                           <span class="nt">"type"</span><span class="p">:</span> <span class="s2">"bigint"</span>
                        <span class="p">},</span>
                        <span class="p">{</span>
                           <span class="nt">"symbol"</span><span class="p">:</span> <span class="s2">"count_0"</span><span class="p">,</span>
                           <span class="nt">"type"</span><span class="p">:</span> <span class="s2">"bigint"</span>
                        <span class="p">},</span>
                        <span class="p">{</span>
                           <span class="nt">"symbol"</span><span class="p">:</span> <span class="s2">"$hashvalue"</span><span class="p">,</span>
                           <span class="nt">"type"</span><span class="p">:</span> <span class="s2">"bigint"</span>
                        <span class="p">}</span>
                     <span class="p">],</span>
                     <span class="nt">"details"</span><span class="p">:[],</span>
                     <span class="nt">"estimates"</span><span class="p">:</span> <span class="p">[</span>
                        <span class="p">{</span>
                           <span class="nt">"outputRowCount"</span><span class="p">:</span> <span class="s2">"NaN"</span><span class="p">,</span>
                           <span class="nt">"outputSizeInBytes"</span><span class="p">:</span> <span class="s2">"NaN"</span><span class="p">,</span>
                           <span class="nt">"cpuCost"</span><span class="p">:</span> <span class="s2">"NaN"</span><span class="p">,</span>
                           <span class="nt">"memoryCost"</span><span class="p">:</span> <span class="s2">"NaN"</span><span class="p">,</span>
                           <span class="nt">"networkCost"</span><span class="p">:</span> <span class="s2">"NaN"</span>
                        <span class="p">}</span>
                     <span class="p">],</span>
                     <span class="nt">"children"</span><span class="p">:</span> <span class="p">[</span>
                        <span class="p">{</span>
                           <span class="nt">"id"</span><span class="p">:</span> <span class="s2">"200"</span><span class="p">,</span>
                           <span class="nt">"name"</span><span class="p">:</span> <span class="s2">"RemoteExchange"</span><span class="p">,</span>
                           <span class="nt">"descriptor"</span><span class="p">:</span> <span class="p">{</span>
                              <span class="nt">"type"</span><span class="p">:</span> <span class="s2">"REPARTITION"</span><span class="p">,</span>
                              <span class="nt">"isReplicateNullsAndAny"</span><span class="p">:</span> <span class="s2">""</span><span class="p">,</span>
                              <span class="nt">"hashColumn"</span><span class="p">:</span> <span class="s2">"[$hashvalue_1]"</span>
                           <span class="p">},</span>
                           <span class="nt">"outputs"</span><span class="p">:</span> <span class="p">[</span>
                              <span class="p">{</span>
                                 <span class="nt">"symbol"</span><span class="p">:</span> <span class="s2">"regionkey"</span><span class="p">,</span>
                                 <span class="nt">"type"</span><span class="p">:</span> <span class="s2">"bigint"</span>
                              <span class="p">},</span>
                              <span class="p">{</span>
                                 <span class="nt">"symbol"</span><span class="p">:</span> <span class="s2">"count_0"</span><span class="p">,</span>
                                 <span class="nt">"type"</span><span class="p">:</span> <span class="s2">"bigint"</span>
                              <span class="p">},</span>
                              <span class="p">{</span>
                                 <span class="nt">"symbol"</span><span class="p">:</span> <span class="s2">"$hashvalue_1"</span><span class="p">,</span>
                                 <span class="nt">"type"</span><span class="p">:</span> <span class="s2">"bigint"</span>
                              <span class="p">}</span>
                           <span class="p">],</span>
                           <span class="nt">"details"</span><span class="p">:[],</span>
                           <span class="nt">"estimates"</span><span class="p">:</span> <span class="p">[</span>
                              <span class="p">{</span>
                                 <span class="nt">"outputRowCount"</span><span class="p">:</span> <span class="s2">"NaN"</span><span class="p">,</span>
                                 <span class="nt">"outputSizeInBytes"</span><span class="p">:</span> <span class="s2">"NaN"</span><span class="p">,</span>
                                 <span class="nt">"cpuCost"</span><span class="p">:</span> <span class="s2">"NaN"</span><span class="p">,</span>
                                 <span class="nt">"memoryCost"</span><span class="p">:</span> <span class="s2">"NaN"</span><span class="p">,</span>
                                 <span class="nt">"networkCost"</span><span class="p">:</span> <span class="s2">"NaN"</span>
                              <span class="p">}</span>
                           <span class="p">],</span>
                           <span class="nt">"children"</span><span class="p">:</span> <span class="p">[</span>
                              <span class="p">{</span>
                                 <span class="nt">"id"</span><span class="p">:</span> <span class="s2">"226"</span><span class="p">,</span>
                                 <span class="nt">"name"</span><span class="p">:</span> <span class="s2">"Project"</span><span class="p">,</span>
                                 <span class="nt">"descriptor"</span><span class="p">:</span> <span class="p">{}</span>
                                 <span class="s2">"outputs"</span><span class="p">:</span> <span class="p">[</span>
                                    <span class="p">{</span>
                                       <span class="nt">"symbol"</span><span class="p">:</span> <span class="s2">"regionkey"</span><span class="p">,</span>
                                       <span class="nt">"type"</span><span class="p">:</span> <span class="s2">"bigint"</span>
                                    <span class="p">},</span>
                                    <span class="p">{</span>
                                       <span class="nt">"symbol"</span><span class="p">:</span> <span class="s2">"count_0"</span><span class="p">,</span>
                                       <span class="nt">"type"</span><span class="p">:</span> <span class="s2">"bigint"</span>
                                    <span class="p">},</span>
                                    <span class="p">{</span>
                                       <span class="nt">"symbol"</span><span class="p">:</span> <span class="s2">"$hashvalue_2"</span><span class="p">,</span>
                                       <span class="nt">"type"</span><span class="p">:</span> <span class="s2">"bigint"</span>
                                    <span class="p">}</span>
                                 <span class="p">],</span>
                                 <span class="nt">"details"</span><span class="p">:</span> <span class="p">[</span>
                                    <span class="s2">"$hashvalue_2 := combine_hash(bigint '0', COALESCE(\"$operator$hash_code\"(\"regionkey\"), 0))"</span>
                                 <span class="p">],</span>
                                 <span class="nt">"estimates"</span><span class="p">:</span> <span class="p">[</span>
                                    <span class="p">{</span>
                                       <span class="nt">"outputRowCount"</span><span class="p">:</span> <span class="s2">"NaN"</span><span class="p">,</span>
                                       <span class="nt">"outputSizeInBytes"</span><span class="p">:</span> <span class="s2">"NaN"</span><span class="p">,</span>
                                       <span class="nt">"cpuCost"</span><span class="p">:</span> <span class="s2">"NaN"</span><span class="p">,</span>
                                       <span class="nt">"memoryCost"</span><span class="p">:</span> <span class="s2">"NaN"</span><span class="p">,</span>
                                       <span class="nt">"networkCost"</span><span class="p">:</span> <span class="s2">"NaN"</span>
                                    <span class="p">}</span>
                                 <span class="p">],</span>
                                 <span class="nt">"children"</span><span class="p">:</span> <span class="p">[</span>
                                    <span class="p">{</span>
                                       <span class="nt">"id"</span><span class="p">:</span> <span class="s2">"198"</span><span class="p">,</span>
                                       <span class="nt">"name"</span><span class="p">:</span> <span class="s2">"Aggregate"</span><span class="p">,</span>
                                       <span class="nt">"descriptor"</span><span class="p">:</span> <span class="p">{</span>
                                          <span class="nt">"type"</span><span class="p">:</span> <span class="s2">"PARTIAL"</span><span class="p">,</span>
                                          <span class="nt">"keys"</span><span class="p">:</span> <span class="s2">"[regionkey]"</span><span class="p">,</span>
                                          <span class="nt">"hash"</span><span class="p">:</span> <span class="s2">""</span>
                                       <span class="p">},</span>
                                       <span class="nt">"outputs"</span><span class="p">:</span> <span class="p">[</span>
                                          <span class="p">{</span>
                                             <span class="nt">"symbol"</span><span class="p">:</span> <span class="s2">"regionkey"</span><span class="p">,</span>
                                             <span class="nt">"type"</span><span class="p">:</span> <span class="s2">"bigint"</span>
                                          <span class="p">},</span>
                                          <span class="p">{</span>
                                             <span class="nt">"symbol"</span><span class="p">:</span> <span class="s2">"count_0"</span><span class="p">,</span>
                                             <span class="nt">"type"</span><span class="p">:</span> <span class="s2">"bigint"</span>
                                          <span class="p">}</span>
                                       <span class="p">],</span>
                                       <span class="nt">"details"</span><span class="p">:</span> <span class="p">[</span>
                                          <span class="s2">"count_0 := count(*)"</span>
                                       <span class="p">],</span>
                                       <span class="nt">"estimates"</span><span class="p">:[],</span>
                                       <span class="nt">"children"</span><span class="p">:</span> <span class="p">[</span>
                                          <span class="p">{</span>
                                             <span class="nt">"id"</span><span class="p">:</span> <span class="s2">"0"</span><span class="p">,</span>
                                             <span class="nt">"name"</span><span class="p">:</span> <span class="s2">"TableScan"</span><span class="p">,</span>
                                             <span class="nt">"descriptor"</span><span class="p">:</span> <span class="p">{</span>
                                                <span class="nt">"table"</span><span class="p">:</span> <span class="s2">"hive:tpch_sf1_orc_part:nation"</span>
                                             <span class="p">},</span>
                                             <span class="nt">"outputs"</span><span class="p">:</span> <span class="p">[</span>
                                                <span class="p">{</span>
                                                   <span class="nt">"symbol"</span><span class="p">:</span> <span class="s2">"regionkey"</span><span class="p">,</span>
                                                   <span class="nt">"type"</span><span class="p">:</span> <span class="s2">"bigint"</span>
                                                <span class="p">}</span>
                                             <span class="p">],</span>
                                             <span class="nt">"details"</span><span class="p">:</span> <span class="p">[</span>
                                                <span class="s2">"regionkey := regionkey:bigint:REGULAR"</span>
                                             <span class="p">],</span>
                                             <span class="nt">"estimates"</span><span class="p">:</span> <span class="p">[</span>
                                                <span class="p">{</span>
                                                   <span class="nt">"outputRowCount"</span><span class="p">:</span> <span class="mi">25</span><span class="p">,</span>
                                                   <span class="nt">"outputSizeInBytes"</span><span class="p">:</span> <span class="mi">225</span><span class="p">,</span>
                                                   <span class="nt">"cpuCost"</span><span class="p">:</span> <span class="mi">225</span><span class="p">,</span>
                                                   <span class="nt">"memoryCost"</span><span class="p">:</span> <span class="mi">0</span><span class="p">,</span>
                                                   <span class="nt">"networkCost"</span><span class="p">:</span> <span class="mi">0</span>
                                                <span class="p">}</span>
                                             <span class="p">],</span>
                                             <span class="nt">"children"</span><span class="p">:</span> <span class="p">[]</span>
                                          <span class="p">}</span>
                                       <span class="p">]</span>
                                    <span class="p">}</span>
                                 <span class="p">]</span>
                              <span class="p">}</span>
                           <span class="p">]</span>
                        <span class="p">}</span>
                     <span class="p">]</span>
                  <span class="p">}</span>
               <span class="p">]</span>
            <span class="p">}</span>
         <span class="p">]</span>
      <span class="p">}</span>
   <span class="p">]</span>
<span class="p">}</span>
</pre></div>
</div>
</section>
<section id="explain-type-distributed">
<h3 id="explain-type-distributed">EXPLAIN (TYPE DISTRIBUTED)<a class="headerlink" href="#explain-type-distributed" title="Permalink to this heading">#</a></h3>
<p>Process the supplied query statement and create a distributed plan in text
format. The distributed plan splits the logical plan into stages, and therefore
explicitly shows the data exchange between workers:</p>
<div class="highlight-sql notranslate"><div class="highlight"><pre><span></span><span class="k">EXPLAIN</span> <span class="p">(</span><span class="k">TYPE</span> <span class="n">DISTRIBUTED</span><span class="p">)</span> <span class="k">SELECT</span> <span class="n">regionkey</span><span class="p">,</span> <span class="k">count</span><span class="p">(</span><span class="o">*</span><span class="p">)</span> <span class="k">FROM</span> <span class="n">nation</span> <span class="k">GROUP</span> <span class="k">BY</span> <span class="mi">1</span><span class="p">;</span>
</pre></div>
</div>
<div class="highlight-text notranslate"><div class="highlight"><pre><span></span>                                              Query Plan
------------------------------------------------------------------------------------------------------
 Trino version: version
 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
</pre></div>
</div>
</section>
<section id="explain-type-distributed-format-json">
<h3 id="explain-type-distributed-format-json">EXPLAIN (TYPE DISTRIBUTED, FORMAT JSON)<a class="headerlink" href="#explain-type-distributed-format-json" title="Permalink to this heading">#</a></h3>
<div class="admonition warning">
<p class="admonition-title">Warning</p>
<p>The output format is not guaranteed to be backward compatible across Trino versions.</p>
</div>
<p>Process the supplied query statement and create a distributed plan in JSON
format. The distributed plan splits the logical plan into stages, and therefore
explicitly shows the data exchange between workers:</p>
<div class="highlight-sql notranslate"><div class="highlight"><pre><span></span><span class="k">EXPLAIN</span> <span class="p">(</span><span class="k">TYPE</span> <span class="n">DISTRIBUTED</span><span class="p">,</span> <span class="n">FORMAT</span> <span class="n">JSON</span><span class="p">)</span> <span class="k">SELECT</span> <span class="n">regionkey</span><span class="p">,</span> <span class="k">count</span><span class="p">(</span><span class="o">*</span><span class="p">)</span> <span class="k">FROM</span> <span class="n">nation</span> <span class="k">GROUP</span> <span class="k">BY</span> <span class="mi">1</span><span class="p">;</span>
</pre></div>
</div>
<div class="highlight-json notranslate"><div class="highlight"><pre><span></span><span class="p">{</span>
   <span class="nt">"0"</span> <span class="p">:</span> <span class="p">{</span>
      <span class="nt">"id"</span> <span class="p">:</span> <span class="s2">"9"</span><span class="p">,</span>
      <span class="nt">"name"</span> <span class="p">:</span> <span class="s2">"Output"</span><span class="p">,</span>
      <span class="nt">"descriptor"</span> <span class="p">:</span> <span class="p">{</span>
         <span class="nt">"columnNames"</span> <span class="p">:</span> <span class="s2">"[regionkey, _col1]"</span>
      <span class="p">},</span>
      <span class="nt">"outputs"</span> <span class="p">:</span> <span class="p">[</span> <span class="p">{</span>
         <span class="nt">"symbol"</span> <span class="p">:</span> <span class="s2">"regionkey"</span><span class="p">,</span>
         <span class="nt">"type"</span> <span class="p">:</span> <span class="s2">"bigint"</span>
      <span class="p">},</span> <span class="p">{</span>
         <span class="nt">"symbol"</span> <span class="p">:</span> <span class="s2">"count"</span><span class="p">,</span>
         <span class="nt">"type"</span> <span class="p">:</span> <span class="s2">"bigint"</span>
      <span class="p">}</span> <span class="p">],</span>
      <span class="nt">"details"</span> <span class="p">:</span> <span class="p">[</span> <span class="s2">"_col1 := count"</span> <span class="p">],</span>
      <span class="nt">"estimates"</span> <span class="p">:</span> <span class="p">[</span> <span class="p">{</span>
         <span class="nt">"outputRowCount"</span> <span class="p">:</span> <span class="s2">"NaN"</span><span class="p">,</span>
         <span class="nt">"outputSizeInBytes"</span> <span class="p">:</span> <span class="s2">"NaN"</span><span class="p">,</span>
         <span class="nt">"cpuCost"</span> <span class="p">:</span> <span class="s2">"NaN"</span><span class="p">,</span>
         <span class="nt">"memoryCost"</span> <span class="p">:</span> <span class="s2">"NaN"</span><span class="p">,</span>
         <span class="nt">"networkCost"</span> <span class="p">:</span> <span class="s2">"NaN"</span>
      <span class="p">}</span> <span class="p">],</span>
      <span class="nt">"children"</span> <span class="p">:</span> <span class="p">[</span> <span class="p">{</span>
         <span class="nt">"id"</span> <span class="p">:</span> <span class="s2">"145"</span><span class="p">,</span>
         <span class="nt">"name"</span> <span class="p">:</span> <span class="s2">"RemoteSource"</span><span class="p">,</span>
         <span class="nt">"descriptor"</span> <span class="p">:</span> <span class="p">{</span>
            <span class="nt">"sourceFragmentIds"</span> <span class="p">:</span> <span class="s2">"[1]"</span>
         <span class="p">},</span>
         <span class="nt">"outputs"</span> <span class="p">:</span> <span class="p">[</span> <span class="p">{</span>
            <span class="nt">"symbol"</span> <span class="p">:</span> <span class="s2">"regionkey"</span><span class="p">,</span>
            <span class="nt">"type"</span> <span class="p">:</span> <span class="s2">"bigint"</span>
         <span class="p">},</span> <span class="p">{</span>
            <span class="nt">"symbol"</span> <span class="p">:</span> <span class="s2">"count"</span><span class="p">,</span>
            <span class="nt">"type"</span> <span class="p">:</span> <span class="s2">"bigint"</span>
         <span class="p">}</span> <span class="p">],</span>
         <span class="nt">"details"</span> <span class="p">:</span> <span class="p">[</span> <span class="p">],</span>
         <span class="nt">"estimates"</span> <span class="p">:</span> <span class="p">[</span> <span class="p">],</span>
         <span class="nt">"children"</span> <span class="p">:</span> <span class="p">[</span> <span class="p">]</span>
      <span class="p">}</span> <span class="p">]</span>
   <span class="p">},</span>
   <span class="nt">"1"</span> <span class="p">:</span> <span class="p">{</span>
      <span class="nt">"id"</span> <span class="p">:</span> <span class="s2">"4"</span><span class="p">,</span>
      <span class="nt">"name"</span> <span class="p">:</span> <span class="s2">"Aggregate"</span><span class="p">,</span>
      <span class="nt">"descriptor"</span> <span class="p">:</span> <span class="p">{</span>
         <span class="nt">"type"</span> <span class="p">:</span> <span class="s2">"FINAL"</span><span class="p">,</span>
         <span class="nt">"keys"</span> <span class="p">:</span> <span class="s2">"[regionkey]"</span><span class="p">,</span>
         <span class="nt">"hash"</span> <span class="p">:</span> <span class="s2">"[]"</span>
      <span class="p">},</span>
      <span class="nt">"outputs"</span> <span class="p">:</span> <span class="p">[</span> <span class="p">{</span>
         <span class="nt">"symbol"</span> <span class="p">:</span> <span class="s2">"regionkey"</span><span class="p">,</span>
         <span class="nt">"type"</span> <span class="p">:</span> <span class="s2">"bigint"</span>
      <span class="p">},</span> <span class="p">{</span>
         <span class="nt">"symbol"</span> <span class="p">:</span> <span class="s2">"count"</span><span class="p">,</span>
         <span class="nt">"type"</span> <span class="p">:</span> <span class="s2">"bigint"</span>
      <span class="p">}</span> <span class="p">],</span>
      <span class="nt">"details"</span> <span class="p">:</span> <span class="p">[</span> <span class="s2">"count := count(\"count_0\")"</span> <span class="p">],</span>
      <span class="nt">"estimates"</span> <span class="p">:</span> <span class="p">[</span> <span class="p">{</span>
         <span class="nt">"outputRowCount"</span> <span class="p">:</span> <span class="s2">"NaN"</span><span class="p">,</span>
         <span class="nt">"outputSizeInBytes"</span> <span class="p">:</span> <span class="s2">"NaN"</span><span class="p">,</span>
         <span class="nt">"cpuCost"</span> <span class="p">:</span> <span class="s2">"NaN"</span><span class="p">,</span>
         <span class="nt">"memoryCost"</span> <span class="p">:</span> <span class="s2">"NaN"</span><span class="p">,</span>
         <span class="nt">"networkCost"</span> <span class="p">:</span> <span class="s2">"NaN"</span>
      <span class="p">}</span> <span class="p">],</span>
      <span class="nt">"children"</span> <span class="p">:</span> <span class="p">[</span> <span class="p">{</span>
         <span class="nt">"id"</span> <span class="p">:</span> <span class="s2">"194"</span><span class="p">,</span>
         <span class="nt">"name"</span> <span class="p">:</span> <span class="s2">"LocalExchange"</span><span class="p">,</span>
         <span class="nt">"descriptor"</span> <span class="p">:</span> <span class="p">{</span>
            <span class="nt">"partitioning"</span> <span class="p">:</span> <span class="s2">"SINGLE"</span><span class="p">,</span>
            <span class="nt">"isReplicateNullsAndAny"</span> <span class="p">:</span> <span class="s2">""</span><span class="p">,</span>
            <span class="nt">"hashColumn"</span> <span class="p">:</span> <span class="s2">"[]"</span><span class="p">,</span>
            <span class="nt">"arguments"</span> <span class="p">:</span> <span class="s2">"[]"</span>
         <span class="p">},</span>
         <span class="nt">"outputs"</span> <span class="p">:</span> <span class="p">[</span> <span class="p">{</span>
            <span class="nt">"symbol"</span> <span class="p">:</span> <span class="s2">"regionkey"</span><span class="p">,</span>
            <span class="nt">"type"</span> <span class="p">:</span> <span class="s2">"bigint"</span>
         <span class="p">},</span> <span class="p">{</span>
            <span class="nt">"symbol"</span> <span class="p">:</span> <span class="s2">"count_0"</span><span class="p">,</span>
            <span class="nt">"type"</span> <span class="p">:</span> <span class="s2">"bigint"</span>
         <span class="p">}</span> <span class="p">],</span>
         <span class="nt">"details"</span> <span class="p">:</span> <span class="p">[</span> <span class="p">],</span>
         <span class="nt">"estimates"</span> <span class="p">:</span> <span class="p">[</span> <span class="p">{</span>
            <span class="nt">"outputRowCount"</span> <span class="p">:</span> <span class="s2">"NaN"</span><span class="p">,</span>
            <span class="nt">"outputSizeInBytes"</span> <span class="p">:</span> <span class="s2">"NaN"</span><span class="p">,</span>
            <span class="nt">"cpuCost"</span> <span class="p">:</span> <span class="s2">"NaN"</span><span class="p">,</span>
            <span class="nt">"memoryCost"</span> <span class="p">:</span> <span class="s2">"NaN"</span><span class="p">,</span>
            <span class="nt">"networkCost"</span> <span class="p">:</span> <span class="s2">"NaN"</span>
         <span class="p">}</span> <span class="p">],</span>
         <span class="nt">"children"</span> <span class="p">:</span> <span class="p">[</span> <span class="p">{</span>
            <span class="nt">"id"</span> <span class="p">:</span> <span class="s2">"227"</span><span class="p">,</span>
            <span class="nt">"name"</span> <span class="p">:</span> <span class="s2">"Project"</span><span class="p">,</span>
            <span class="nt">"descriptor"</span> <span class="p">:</span> <span class="p">{</span> <span class="p">},</span>
            <span class="nt">"outputs"</span> <span class="p">:</span> <span class="p">[</span> <span class="p">{</span>
               <span class="nt">"symbol"</span> <span class="p">:</span> <span class="s2">"regionkey"</span><span class="p">,</span>
               <span class="nt">"type"</span> <span class="p">:</span> <span class="s2">"bigint"</span>
            <span class="p">},</span> <span class="p">{</span>
               <span class="nt">"symbol"</span> <span class="p">:</span> <span class="s2">"count_0"</span><span class="p">,</span>
               <span class="nt">"type"</span> <span class="p">:</span> <span class="s2">"bigint"</span>
            <span class="p">}</span> <span class="p">],</span>
            <span class="nt">"details"</span> <span class="p">:</span> <span class="p">[</span> <span class="p">],</span>
            <span class="nt">"estimates"</span> <span class="p">:</span> <span class="p">[</span> <span class="p">{</span>
               <span class="nt">"outputRowCount"</span> <span class="p">:</span> <span class="s2">"NaN"</span><span class="p">,</span>
               <span class="nt">"outputSizeInBytes"</span> <span class="p">:</span> <span class="s2">"NaN"</span><span class="p">,</span>
               <span class="nt">"cpuCost"</span> <span class="p">:</span> <span class="s2">"NaN"</span><span class="p">,</span>
               <span class="nt">"memoryCost"</span> <span class="p">:</span> <span class="s2">"NaN"</span><span class="p">,</span>
               <span class="nt">"networkCost"</span> <span class="p">:</span> <span class="s2">"NaN"</span>
            <span class="p">}</span> <span class="p">],</span>
            <span class="nt">"children"</span> <span class="p">:</span> <span class="p">[</span> <span class="p">{</span>
               <span class="nt">"id"</span> <span class="p">:</span> <span class="s2">"200"</span><span class="p">,</span>
               <span class="nt">"name"</span> <span class="p">:</span> <span class="s2">"RemoteSource"</span><span class="p">,</span>
               <span class="nt">"descriptor"</span> <span class="p">:</span> <span class="p">{</span>
                  <span class="nt">"sourceFragmentIds"</span> <span class="p">:</span> <span class="s2">"[2]"</span>
               <span class="p">},</span>
               <span class="nt">"outputs"</span> <span class="p">:</span> <span class="p">[</span> <span class="p">{</span>
                  <span class="nt">"symbol"</span> <span class="p">:</span> <span class="s2">"regionkey"</span><span class="p">,</span>
                  <span class="nt">"type"</span> <span class="p">:</span> <span class="s2">"bigint"</span>
               <span class="p">},</span> <span class="p">{</span>
                  <span class="nt">"symbol"</span> <span class="p">:</span> <span class="s2">"count_0"</span><span class="p">,</span>
                  <span class="nt">"type"</span> <span class="p">:</span> <span class="s2">"bigint"</span>
               <span class="p">},</span> <span class="p">{</span>
                  <span class="nt">"symbol"</span> <span class="p">:</span> <span class="s2">"$hashvalue"</span><span class="p">,</span>
                  <span class="nt">"type"</span> <span class="p">:</span> <span class="s2">"bigint"</span>
               <span class="p">}</span> <span class="p">],</span>
               <span class="nt">"details"</span> <span class="p">:</span> <span class="p">[</span> <span class="p">],</span>
               <span class="nt">"estimates"</span> <span class="p">:</span> <span class="p">[</span> <span class="p">],</span>
               <span class="nt">"children"</span> <span class="p">:</span> <span class="p">[</span> <span class="p">]</span>
            <span class="p">}</span> <span class="p">]</span>
         <span class="p">}</span> <span class="p">]</span>
      <span class="p">}</span> <span class="p">]</span>
   <span class="p">},</span>
   <span class="nt">"2"</span> <span class="p">:</span> <span class="p">{</span>
      <span class="nt">"id"</span> <span class="p">:</span> <span class="s2">"226"</span><span class="p">,</span>
      <span class="nt">"name"</span> <span class="p">:</span> <span class="s2">"Project"</span><span class="p">,</span>
      <span class="nt">"descriptor"</span> <span class="p">:</span> <span class="p">{</span> <span class="p">},</span>
      <span class="nt">"outputs"</span> <span class="p">:</span> <span class="p">[</span> <span class="p">{</span>
         <span class="nt">"symbol"</span> <span class="p">:</span> <span class="s2">"regionkey"</span><span class="p">,</span>
         <span class="nt">"type"</span> <span class="p">:</span> <span class="s2">"bigint"</span>
      <span class="p">},</span> <span class="p">{</span>
         <span class="nt">"symbol"</span> <span class="p">:</span> <span class="s2">"count_0"</span><span class="p">,</span>
         <span class="nt">"type"</span> <span class="p">:</span> <span class="s2">"bigint"</span>
      <span class="p">},</span> <span class="p">{</span>
         <span class="nt">"symbol"</span> <span class="p">:</span> <span class="s2">"$hashvalue_1"</span><span class="p">,</span>
         <span class="nt">"type"</span> <span class="p">:</span> <span class="s2">"bigint"</span>
      <span class="p">}</span> <span class="p">],</span>
      <span class="nt">"details"</span> <span class="p">:</span> <span class="p">[</span> <span class="s2">"$hashvalue_1 := combine_hash(bigint '0', COALESCE(\"$operator$hash_code\"(\"regionkey\"), 0))"</span> <span class="p">],</span>
      <span class="nt">"estimates"</span> <span class="p">:</span> <span class="p">[</span> <span class="p">{</span>
         <span class="nt">"outputRowCount"</span> <span class="p">:</span> <span class="s2">"NaN"</span><span class="p">,</span>
         <span class="nt">"outputSizeInBytes"</span> <span class="p">:</span> <span class="s2">"NaN"</span><span class="p">,</span>
         <span class="nt">"cpuCost"</span> <span class="p">:</span> <span class="s2">"NaN"</span><span class="p">,</span>
         <span class="nt">"memoryCost"</span> <span class="p">:</span> <span class="s2">"NaN"</span><span class="p">,</span>
         <span class="nt">"networkCost"</span> <span class="p">:</span> <span class="s2">"NaN"</span>
      <span class="p">}</span> <span class="p">],</span>
      <span class="nt">"children"</span> <span class="p">:</span> <span class="p">[</span> <span class="p">{</span>
         <span class="nt">"id"</span> <span class="p">:</span> <span class="s2">"198"</span><span class="p">,</span>
         <span class="nt">"name"</span> <span class="p">:</span> <span class="s2">"Aggregate"</span><span class="p">,</span>
         <span class="nt">"descriptor"</span> <span class="p">:</span> <span class="p">{</span>
            <span class="nt">"type"</span> <span class="p">:</span> <span class="s2">"PARTIAL"</span><span class="p">,</span>
            <span class="nt">"keys"</span> <span class="p">:</span> <span class="s2">"[regionkey]"</span><span class="p">,</span>
            <span class="nt">"hash"</span> <span class="p">:</span> <span class="s2">"[]"</span>
         <span class="p">},</span>
         <span class="nt">"outputs"</span> <span class="p">:</span> <span class="p">[</span> <span class="p">{</span>
            <span class="nt">"symbol"</span> <span class="p">:</span> <span class="s2">"regionkey"</span><span class="p">,</span>
            <span class="nt">"type"</span> <span class="p">:</span> <span class="s2">"bigint"</span>
         <span class="p">},</span> <span class="p">{</span>
            <span class="nt">"symbol"</span> <span class="p">:</span> <span class="s2">"count_0"</span><span class="p">,</span>
            <span class="nt">"type"</span> <span class="p">:</span> <span class="s2">"bigint"</span>
         <span class="p">}</span> <span class="p">],</span>
         <span class="nt">"details"</span> <span class="p">:</span> <span class="p">[</span> <span class="s2">"count_0 := count(*)"</span> <span class="p">],</span>
         <span class="nt">"estimates"</span> <span class="p">:</span> <span class="p">[</span> <span class="p">],</span>
         <span class="nt">"children"</span> <span class="p">:</span> <span class="p">[</span> <span class="p">{</span>
            <span class="nt">"id"</span> <span class="p">:</span> <span class="s2">"0"</span><span class="p">,</span>
            <span class="nt">"name"</span> <span class="p">:</span> <span class="s2">"TableScan"</span><span class="p">,</span>
            <span class="nt">"descriptor"</span> <span class="p">:</span> <span class="p">{</span>
               <span class="nt">"table"</span> <span class="p">:</span> <span class="s2">"tpch:tiny:nation"</span>
            <span class="p">},</span>
            <span class="nt">"outputs"</span> <span class="p">:</span> <span class="p">[</span> <span class="p">{</span>
               <span class="nt">"symbol"</span> <span class="p">:</span> <span class="s2">"regionkey"</span><span class="p">,</span>
               <span class="nt">"type"</span> <span class="p">:</span> <span class="s2">"bigint"</span>
            <span class="p">}</span> <span class="p">],</span>
            <span class="nt">"details"</span> <span class="p">:</span> <span class="p">[</span> <span class="s2">"regionkey := tpch:regionkey"</span> <span class="p">],</span>
            <span class="nt">"estimates"</span> <span class="p">:</span> <span class="p">[</span> <span class="p">{</span>
               <span class="nt">"outputRowCount"</span> <span class="p">:</span> <span class="mf">25.0</span><span class="p">,</span>
               <span class="nt">"outputSizeInBytes"</span> <span class="p">:</span> <span class="mf">225.0</span><span class="p">,</span>
               <span class="nt">"cpuCost"</span> <span class="p">:</span> <span class="mf">225.0</span><span class="p">,</span>
               <span class="nt">"memoryCost"</span> <span class="p">:</span> <span class="mf">0.0</span><span class="p">,</span>
               <span class="nt">"networkCost"</span> <span class="p">:</span> <span class="mf">0.0</span>
            <span class="p">}</span> <span class="p">],</span>
            <span class="nt">"children"</span> <span class="p">:</span> <span class="p">[</span> <span class="p">]</span>
         <span class="p">}</span> <span class="p">]</span>
      <span class="p">}</span> <span class="p">]</span>
   <span class="p">}</span>
<span class="p">}</span>
</pre></div>
</div>
</section>
<section id="explain-type-validate">
<h3 id="explain-type-validate">EXPLAIN (TYPE VALIDATE)<a class="headerlink" href="#explain-type-validate" title="Permalink to this heading">#</a></h3>
<p>Validate the supplied query statement for syntactical and semantic correctness.
Returns true if the statement is valid:</p>
<div class="highlight-sql notranslate"><div class="highlight"><pre><span></span><span class="k">EXPLAIN</span> <span class="p">(</span><span class="k">TYPE</span> <span class="n">VALIDATE</span><span class="p">)</span> <span class="k">SELECT</span> <span class="n">regionkey</span><span class="p">,</span> <span class="k">count</span><span class="p">(</span><span class="o">*</span><span class="p">)</span> <span class="k">FROM</span> <span class="n">nation</span> <span class="k">GROUP</span> <span class="k">BY</span> <span class="mi">1</span><span class="p">;</span>
</pre></div>
</div>
<div class="highlight-text notranslate"><div class="highlight"><pre><span></span> Valid
-------
 true
</pre></div>
</div>
<p>If the statement is not correct because a syntax error, such as an unknown
keyword, is found the error message details the problem:</p>
<div class="highlight-sql notranslate"><div class="highlight"><pre><span></span><span class="k">EXPLAIN</span> <span class="p">(</span><span class="k">TYPE</span> <span class="n">VALIDATE</span><span class="p">)</span> <span class="n">SELET</span> <span class="mi">1</span><span class="o">=</span><span class="mi">0</span><span class="p">;</span>
</pre></div>
</div>
<div class="highlight-text notranslate"><div class="highlight"><pre><span></span>Query 20220929_234840_00001_vjwxj failed: line 1:25: mismatched input 'SELET'.
Expecting: 'ALTER', 'ANALYZE', 'CALL', 'COMMENT', 'COMMIT', 'CREATE',
'DEALLOCATE', 'DELETE', 'DENY', 'DESC', 'DESCRIBE', 'DROP', 'EXECUTE',
'EXPLAIN', 'GRANT', 'INSERT', 'MERGE', 'PREPARE', 'REFRESH', 'RESET',
'REVOKE', 'ROLLBACK', 'SET', 'SHOW', 'START', 'TRUNCATE', 'UPDATE', 'USE',
&lt;query&gt;
</pre></div>
</div>
<p>Similarly if semantic issues are detected, such as an invalid object name
<code class="docutils literal notranslate"><span class="pre">nations</span></code> instead of <code class="docutils literal notranslate"><span class="pre">nation</span></code>, the error message returns useful
information:</p>
<div class="highlight-sql notranslate"><div class="highlight"><pre><span></span><span class="k">EXPLAIN</span><span class="p">(</span><span class="k">TYPE</span> <span class="n">VALIDATE</span><span class="p">)</span> <span class="k">SELECT</span> <span class="o">*</span> <span class="k">FROM</span> <span class="n">tpch</span><span class="p">.</span><span class="n">tiny</span><span class="p">.</span><span class="n">nations</span><span class="p">;</span>
</pre></div>
</div>
<div class="highlight-text notranslate"><div class="highlight"><pre><span></span>Query 20220929_235059_00003_vjwxj failed: line 1:15: Table 'tpch.tiny.nations' does not exist
SELECT * FROM tpch.tiny.nations
</pre></div>
</div>
</section>
<section id="explain-type-io">
<h3 id="explain-type-io">EXPLAIN (TYPE IO)<a class="headerlink" href="#explain-type-io" title="Permalink to this heading">#</a></h3>
<p>Process the supplied query statement and create a plan with input and output
details about the accessed objects in JSON format:</p>
<div class="highlight-sql notranslate"><div class="highlight"><pre><span></span><span class="k">EXPLAIN</span> <span class="p">(</span><span class="k">TYPE</span> <span class="n">IO</span><span class="p">,</span> <span class="n">FORMAT</span> <span class="n">JSON</span><span class="p">)</span> <span class="k">INSERT</span> <span class="k">INTO</span> <span class="n">test_lineitem</span>
<span class="k">SELECT</span> <span class="o">*</span> <span class="k">FROM</span> <span class="n">lineitem</span> <span class="k">WHERE</span> <span class="n">shipdate</span> <span class="o">=</span> <span class="s1">'2020-02-01'</span> <span class="k">AND</span> <span class="n">quantity</span> <span class="o">&gt;</span> <span class="mi">10</span><span class="p">;</span>
</pre></div>
</div>
<div class="highlight-text notranslate"><div class="highlight"><pre><span></span>            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"
   }
}
</pre></div>
</div>
</section>
</section>
<section id="see-also">
<h2 id="see-also">See also<a class="headerlink" href="#see-also" title="Permalink to this heading">#</a></h2>
<p><a class="reference internal" href="explain-analyze.html"><span class="doc">EXPLAIN ANALYZE</span></a></p>
</section>
</section>


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