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 <link rel="stylesheet" href="https://at-ui.github.io/feather-font/css/iconfont.css"><title data-react-helmet="true">Schema Evolution | Apache Hudi</title><meta data-react-helmet="true" name="twitter:card" content="summary_large_image"><meta data-react-helmet="true" property="og:url" content="https://hudi.apache.org/docs/next/schema_evolution"><meta data-react-helmet="true" name="docsearch:language" content="en"><meta data-react-helmet="true" name="docsearch:version" content="current"><meta data-react-helmet="true" name="docsearch:docusaurus_tag" content="docs-default-current"><meta data-react-helmet="true" property="og:title" content="Schema Evolution | Apache Hudi"><meta data-react-helmet="true" name="description" content="Schema evolution is an essential aspect of data management, and Hudi supports schema evolution on write out-of-the-box,"><meta data-react-helmet="true" property="og:description" content="Schema evolution is an essential aspect of data management, and Hudi supports schema evolution on write out-of-the-box,"><meta data-react-helmet="true" name="keywords" content="hudi,incremental,batch,stream,processing,schema,evolution"><link data-react-helmet="true" rel="icon" href="/assets/images/favicon.ico"><link data-react-helmet="true" rel="canonical" href="https://hudi.apache.org/docs/next/schema_evolution"><link data-react-helmet="true" rel="alternate" href="https://hudi.apache.org/docs/next/schema_evolution" hreflang="en"><link data-react-helmet="true" rel="alternate" href="https://hudi.apache.org/cn/docs/next/schema_evolution" hreflang="cn"><link data-react-helmet="true" rel="alternate" href="https://hudi.apache.org/docs/next/schema_evolution" hreflang="x-default"><link data-react-helmet="true" rel="preconnect" href="https://BH4D9OD16A-dsn.algolia.net" crossorigin="anonymous"><link rel="stylesheet" href="/assets/css/styles.ea681a30.css">
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theme-doc-sidebar-item-link-level-1 menu__list-item"><a class="menu__link" href="/docs/next/privacy">Privacy Policy</a></li></ul></nav></div></aside><main class="docMainContainer_Q970"><div class="container padding-top--md padding-bottom--lg"><div class="row"><div class="col docItemCol_zHA2"><div class="theme-doc-version-banner alert alert--warning margin-bottom--md" role="alert"><div>This is unreleased documentation for <!-- -->Apache Hudi<!-- --> <b>Current</b> version.</div><div class="margin-top--md">For up-to-date documentation, see the <b><a href="/docs/schema_evolution">latest version</a></b> (<!-- -->0.14.1<!-- -->).</div></div><div class="docItemContainer_oiyr"><article><span class="theme-doc-version-badge badge badge--secondary">Version: <!-- -->Current</span><div class="tocCollapsible_aw-L theme-doc-toc-mobile tocMobile_Tx6Y"><button type="button" class="clean-btn tocCollapsibleButton_zr6a">On this page</button></div><div class="theme-doc-markdown markdown"><header><h1>Schema Evolution</h1></header><p>Schema evolution is an essential aspect of data management, and Hudi supports schema evolution on write out-of-the-box,
 and experimental support for schema evolution on read. This page will discuss the schema evolution support in Hudi.</p><h2 class="anchor anchorWithStickyNavbar_y2LR" id="schema-evolution-on-write">Schema Evolution on Write<a class="hash-link" href="#schema-evolution-on-write" title="Direct link to heading"></a></h2><p>Hudi supports backwards-compatible schema evolution scenarios out of the box, such as adding a nullable field or promoting a field&#x27;s datatype.</p><div class="admonition admonition-info alert alert--info"><div class="admonition-heading"><h5><span class="admonition-icon"><svg xmlns="http://www.w3.org/2000/svg" width="14" height="16" viewBox="0 0 14 16"><path fill-rule="evenodd" d="M7 2.3c3.14 0 5.7 2.56 5.7 5.7s-2.56 5.7-5.7 5.7A5.71 5.71 0 0 1 1.3 8c0-3.14 2.56-5.7 5.7-5.7zM7 1C3.14 1 0 4.14 0 8s3.14 7 7 7 7-3.14 7-7-3.14-7-7-7zm1 3H6v5h2V4zm0 6H6v2h2v-2z"></path></svg></span>info</h5></div><div class="admonition-content"><p>We recommend employing this approach as much as possible. This is a practical and efficient way to evolve schemas, proven at large-scale
 data lakes at companies like Uber, Walmart, and LinkedIn. It is also implemented at scale by vendors like Confluent for streaming data.
 Given the continuous nature of streaming data, there are no boundaries to define a schema change that can be incompatible with
 the previous schema (e.g., renaming a column).   </p></div></div><p>Furthermore, the evolved schema is queryable across high-performance engines like Presto and Spark SQL without additional overhead for column ID translations or
 type reconciliations. The following table summarizes the schema changes compatible with different Hudi table types.</p><p>The incoming schema will automatically have missing columns added with null values from the table schema.
 For this we need to enable the following config
 <code>hoodie.write.set.null.for.missing.columns</code>, otherwise the pipeline will fail.</p><table><thead><tr><th align="left">Schema Change</th><th align="left">COW</th><th align="left">MOR</th><th align="left">Remarks</th></tr></thead><tbody><tr><td align="left">Add a new nullable column at root level at the end</td><td align="left">Yes</td><td align="left">Yes</td><td align="left"><code>Yes</code> means that a write with evolved schema succeeds and a read following the write succeeds to read entire dataset.</td></tr><tr><td align="left">Add a new nullable column to inner struct (at the end)</td><td align="left">Yes</td><td align="left">Yes</td><td align="left"></td></tr><tr><td align="left">Add a new complex type field with default (map and array)</td><td align="left">Yes</td><td align="left">Yes</td><td align="left"></td></tr><tr><td align="left">Add a new nullable column and change the ordering of fields</td><td align="left">No</td><td align="left">No</td><td align="left">Write succeeds but read fails if the write with evolved schema updated only some of the base files but not all. Currently, Hudi does not maintain a schema registry with history of changes across base files. Nevertheless, if the upsert touched all base files then the read will succeed.</td></tr><tr><td align="left">Add a custom nullable Hudi meta column, e.g. <code>_hoodie_meta_col</code></td><td align="left">Yes</td><td align="left">Yes</td><td align="left"></td></tr><tr><td align="left">Promote datatype for a field at root level</td><td align="left">Yes</td><td align="left">Yes</td><td align="left"></td></tr><tr><td align="left">Promote datatype for a nested field</td><td align="left">Yes</td><td align="left">Yes</td><td align="left"></td></tr><tr><td align="left">Promote datatype for a complex type (value of map or array)</td><td align="left">Yes</td><td align="left">Yes</td><td align="left"></td></tr><tr><td align="left">Add a new non-nullable column at root level at the end</td><td align="left">No</td><td align="left">No</td><td align="left">In case of MOR table with Spark data source, write succeeds but read fails. As a <strong>workaround</strong>, you can make the field nullable.</td></tr><tr><td align="left">Add a new non-nullable column to inner struct (at the end)</td><td align="left">No</td><td align="left">No</td><td align="left"></td></tr><tr><td align="left">Demote datatype for a field at root level</td><td align="left">No</td><td align="left">No</td><td align="left"></td></tr><tr><td align="left">Demote datatype for a nested field</td><td align="left">No</td><td align="left">No</td><td align="left"></td></tr><tr><td align="left">Demote datatype for a complex type (value of map or array)</td><td align="left">No</td><td align="left">No</td><td align="left"></td></tr></tbody></table><h3 class="anchor anchorWithStickyNavbar_y2LR" id="type-promotions">Type Promotions<a class="hash-link" href="#type-promotions" title="Direct link to heading"></a></h3><p>This chart shows what the table schema will be when an incoming column type has changed (X means that it is not allowed):</p><table><thead><tr><th>Incoming Schema <!-- -->↓<!-- --> \ Table Schema <!-- -->→</th><th>int</th><th>long</th><th>float</th><th>double</th><th>string</th><th>bytes</th></tr></thead><tbody><tr><td>int</td><td>int</td><td>long</td><td>float</td><td>double</td><td>string</td><td>X</td></tr><tr><td>long</td><td>long</td><td>long</td><td>float</td><td>double</td><td>string</td><td>X</td></tr><tr><td>float</td><td>float</td><td>float</td><td>float</td><td>double</td><td>string</td><td>X</td></tr><tr><td>double</td><td>double</td><td>double</td><td>double</td><td>double</td><td>string</td><td>X</td></tr><tr><td>string</td><td>string</td><td>string</td><td>string</td><td>string</td><td>string</td><td>bytes</td></tr><tr><td>bytes</td><td>X</td><td>X</td><td>X</td><td>X</td><td>string</td><td>bytes</td></tr></tbody></table><h2 class="anchor anchorWithStickyNavbar_y2LR" id="schema-evolution-on-read">Schema Evolution on read<a class="hash-link" href="#schema-evolution-on-read" title="Direct link to heading"></a></h2><p>There are often scenarios where it&#x27;s desirable to have the ability to evolve the schema more flexibly.
 For example,</p><ol><li>Columns (including nested columns) can be added, deleted, modified, and moved.</li><li>Renaming of columns (including nested columns).</li><li>Add, delete, or perform operations on nested columns of the Array type.</li></ol><p>Hudi has experimental support for allowing backward incompatible schema evolution scenarios on write while resolving
 it during read time. To enable this feature, <code>hoodie.schema.on.read.enable=true</code> needs to be set on the writer config (Datasource) or table property (SQL).</p><div class="admonition admonition-note alert alert--secondary"><div class="admonition-heading"><h5><span class="admonition-icon"><svg xmlns="http://www.w3.org/2000/svg" width="14" height="16" viewBox="0 0 14 16"><path fill-rule="evenodd" d="M6.3 5.69a.942.942 0 0 1-.28-.7c0-.28.09-.52.28-.7.19-.18.42-.28.7-.28.28 0 .52.09.7.28.18.19.28.42.28.7 0 .28-.09.52-.28.7a1 1 0 0 1-.7.3c-.28 0-.52-.11-.7-.3zM8 7.99c-.02-.25-.11-.48-.31-.69-.2-.19-.42-.3-.69-.31H6c-.27.02-.48.13-.69.31-.2.2-.3.44-.31.69h1v3c.02.27.11.5.31.69.2.2.42.31.69.31h1c.27 0 .48-.11.69-.31.2-.19.3-.42.31-.69H8V7.98v.01zM7 2.3c-3.14 0-5.7 2.54-5.7 5.68 0 3.14 2.56 5.7 5.7 5.7s5.7-2.55 5.7-5.7c0-3.15-2.56-5.69-5.7-5.69v.01zM7 .98c3.86 0 7 3.14 7 7s-3.14 7-7 7-7-3.12-7-7 3.14-7 7-7z"></path></svg></span>note</h5></div><div class="admonition-content"><p>Hudi versions &gt; 0.11 and Spark versions &gt; 3.1.x, and 3.2.1 are required. For Spark 3.2.1 and above,
 <code>spark.sql.catalog.spark_catalog</code> must also be set. If schema on read is enabled, it cannot be disabled again
 since the table would have accepted such schema changes already.</p></div></div><h3 class="anchor anchorWithStickyNavbar_y2LR" id="adding-columns">Adding Columns<a class="hash-link" href="#adding-columns" title="Direct link to heading"></a></h3><div class="codeBlockContainer_J+bg language-sql theme-code-block"><div class="codeBlockContent_csEI sql"><pre tabindex="0" class="prism-code language-sql codeBlock_rtdJ thin-scrollbar" style="color:#F8F8F2;background-color:#282A36"><code class="codeBlockLines_1zSZ"><span class="token-line" style="color:#F8F8F2"><span class="token comment" style="color:rgb(98, 114, 164)">-- add columns</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"></span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">ALTER</span><span class="token plain"> </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">TABLE</span><span class="token plain"> tableName </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">ADD</span><span class="token plain"> </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">COLUMNS</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token plain">col_spec</span><span class="token punctuation" style="color:rgb(248, 248, 242)">[</span><span class="token punctuation" style="color:rgb(248, 248, 242)">,</span><span class="token plain"> col_spec </span><span class="token punctuation" style="color:rgb(248, 248, 242)">.</span><span class="token punctuation" style="color:rgb(248, 248, 242)">.</span><span class="token punctuation" style="color:rgb(248, 248, 242)">.</span><span class="token punctuation" style="color:rgb(248, 248, 242)">]</span><span class="token punctuation" style="color:rgb(248, 248, 242)">)</span><br></span></code></pre><button type="button" aria-label="Copy code to clipboard" class="copyButton_M3SB clean-btn">Copy</button></div></div><p>Column specification consists of five field, next to each other. </p><table><thead><tr><th align="left">Parameter</th><th align="left">Description</th></tr></thead><tbody><tr><td align="left">col_name</td><td align="left">name of the new column. To add sub-column col1 to a nested map type column member map&lt;string, struct&lt;n: string, a: int&gt;&gt;, set this field to member.value.col1</td></tr><tr><td align="left">col_type</td><td align="left">type of the new column.</td></tr><tr><td align="left">nullable</td><td align="left">whether or not the new column allows null values. (optional)</td></tr><tr><td align="left">comment</td><td align="left">comment of the new column. (optional)</td></tr><tr><td align="left">col_position</td><td align="left">The position where the new column is added. The value can be <em>FIRST</em> or <em>AFTER origin_col</em>. If it is set to <em>FIRST</em>, the new column will be added before the first column of the table. If it is set to <em>AFTER origin_col</em>, the new column will be added after the original column.  <em>FIRST</em> can be used only when new sub-columns are added to nested columns and not in top-level columns. There are no restrictions on the usage of <em>AFTER</em>.</td></tr></tbody></table><p><strong>Examples</strong></p><div class="codeBlockContainer_J+bg language-sql theme-code-block"><div class="codeBlockContent_csEI sql"><pre tabindex="0" class="prism-code language-sql codeBlock_rtdJ thin-scrollbar" style="color:#F8F8F2;background-color:#282A36"><code class="codeBlockLines_1zSZ"><span class="token-line" style="color:#F8F8F2"><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">ALTER</span><span class="token plain"> </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">TABLE</span><span class="token plain"> h0 </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">ADD</span><span class="token plain"> </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">COLUMNS</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token plain">ext0 string</span><span class="token punctuation" style="color:rgb(248, 248, 242)">)</span><span class="token punctuation" style="color:rgb(248, 248, 242)">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"></span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">ALTER</span><span class="token plain"> </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">TABLE</span><span class="token plain"> h0 </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">ADD</span><span class="token plain"> </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">COLUMNS</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token plain">new_col </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">int</span><span class="token plain"> </span><span class="token operator">not</span><span class="token plain"> </span><span class="token boolean">null</span><span class="token plain"> </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">comment</span><span class="token plain"> </span><span class="token string" style="color:rgb(255, 121, 198)">&#x27;add new column&#x27;</span><span class="token plain"> </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">AFTER</span><span class="token plain"> col1</span><span class="token punctuation" style="color:rgb(248, 248, 242)">)</span><span class="token punctuation" style="color:rgb(248, 248, 242)">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"></span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">ALTER</span><span class="token plain"> </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">TABLE</span><span class="token plain"> complex_table </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">ADD</span><span class="token plain"> </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">COLUMNS</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token plain">col_struct</span><span class="token punctuation" style="color:rgb(248, 248, 242)">.</span><span class="token plain">col_name string </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">comment</span><span class="token plain"> </span><span class="token string" style="color:rgb(255, 121, 198)">&#x27;add new column to a struct col&#x27;</span><span class="token plain"> </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">AFTER</span><span class="token plain"> col_from_col_struct</span><span class="token punctuation" style="color:rgb(248, 248, 242)">)</span><span class="token punctuation" style="color:rgb(248, 248, 242)">;</span><br></span></code></pre><button type="button" aria-label="Copy code to clipboard" class="copyButton_M3SB clean-btn">Copy</button></div></div><h3 class="anchor anchorWithStickyNavbar_y2LR" id="altering-columns">Altering Columns<a class="hash-link" href="#altering-columns" title="Direct link to heading"></a></h3><p><strong>Syntax</strong></p><div class="codeBlockContainer_J+bg language-sql theme-code-block"><div class="codeBlockContent_csEI sql"><pre tabindex="0" class="prism-code language-sql codeBlock_rtdJ thin-scrollbar" style="color:#F8F8F2;background-color:#282A36"><code class="codeBlockLines_1zSZ"><span class="token-line" style="color:#F8F8F2"><span class="token comment" style="color:rgb(98, 114, 164)">-- alter table ... alter column</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"></span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">ALTER</span><span class="token plain"> </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">TABLE</span><span class="token plain"> tableName </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">ALTER</span><span class="token plain"> </span><span class="token punctuation" style="color:rgb(248, 248, 242)">[</span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">COLUMN</span><span class="token punctuation" style="color:rgb(248, 248, 242)">]</span><span class="token plain"> col_old_name </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">TYPE</span><span class="token plain"> column_type </span><span class="token punctuation" style="color:rgb(248, 248, 242)">[</span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">COMMENT</span><span class="token punctuation" style="color:rgb(248, 248, 242)">]</span><span class="token plain"> col_comment</span><span class="token punctuation" style="color:rgb(248, 248, 242)">[</span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">FIRST</span><span class="token operator">|</span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">AFTER</span><span class="token punctuation" style="color:rgb(248, 248, 242)">]</span><span class="token plain"> column_name</span><br></span></code></pre><button type="button" aria-label="Copy code to clipboard" class="copyButton_M3SB clean-btn">Copy</button></div></div><p><strong>Parameter Description</strong></p><table><thead><tr><th align="left">Parameter</th><th align="left">Description</th></tr></thead><tbody><tr><td align="left">tableName</td><td align="left">Table name.</td></tr><tr><td align="left">col_old_name</td><td align="left">Name of the column to be altered.</td></tr><tr><td align="left">column_type</td><td align="left">Type of the target column.</td></tr><tr><td align="left">col_comment</td><td align="left">Optional comments on the altered column.</td></tr><tr><td align="left">column_name</td><td align="left">The new position to place the altered column. For example, <em>AFTER</em> <strong>column_name</strong> indicates that the target column is placed after <strong>column_name</strong>.</td></tr></tbody></table><p><strong>Examples</strong></p><div class="codeBlockContainer_J+bg language-sql theme-code-block"><div class="codeBlockContent_csEI sql"><pre tabindex="0" class="prism-code language-sql codeBlock_rtdJ thin-scrollbar" style="color:#F8F8F2;background-color:#282A36"><code class="codeBlockLines_1zSZ"><span class="token-line" style="color:#F8F8F2"><span class="token comment" style="color:rgb(98, 114, 164)">--- Changing the column type</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"></span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">ALTER</span><span class="token plain"> </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">TABLE</span><span class="token plain"> table1 </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">ALTER</span><span class="token plain"> </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">COLUMN</span><span class="token plain"> a</span><span class="token punctuation" style="color:rgb(248, 248, 242)">.</span><span class="token plain">b</span><span class="token punctuation" style="color:rgb(248, 248, 242)">.</span><span class="token plain">c </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">TYPE</span><span class="token plain"> </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">bigint</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain" style="display:inline-block"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"></span><span class="token comment" style="color:rgb(98, 114, 164)">--- Altering other attributes</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"></span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">ALTER</span><span class="token plain"> </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">TABLE</span><span class="token plain"> table1 </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">ALTER</span><span class="token plain"> </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">COLUMN</span><span class="token plain"> a</span><span class="token punctuation" style="color:rgb(248, 248, 242)">.</span><span class="token plain">b</span><span class="token punctuation" style="color:rgb(248, 248, 242)">.</span><span class="token plain">c </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">COMMENT</span><span class="token plain"> </span><span class="token string" style="color:rgb(255, 121, 198)">&#x27;new comment&#x27;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"></span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">ALTER</span><span class="token plain"> </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">TABLE</span><span class="token plain"> table1 </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">ALTER</span><span class="token plain"> </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">COLUMN</span><span class="token plain"> a</span><span class="token punctuation" style="color:rgb(248, 248, 242)">.</span><span class="token plain">b</span><span class="token punctuation" style="color:rgb(248, 248, 242)">.</span><span class="token plain">c </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">FIRST</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"></span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">ALTER</span><span class="token plain"> </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">TABLE</span><span class="token plain"> table1 </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">ALTER</span><span class="token plain"> </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">COLUMN</span><span class="token plain"> a</span><span class="token punctuation" style="color:rgb(248, 248, 242)">.</span><span class="token plain">b</span><span class="token punctuation" style="color:rgb(248, 248, 242)">.</span><span class="token plain">c </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">AFTER</span><span class="token plain"> x</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"></span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">ALTER</span><span class="token plain"> </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">TABLE</span><span class="token plain"> table1 </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">ALTER</span><span class="token plain"> </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">COLUMN</span><span class="token plain"> a</span><span class="token punctuation" style="color:rgb(248, 248, 242)">.</span><span class="token plain">b</span><span class="token punctuation" style="color:rgb(248, 248, 242)">.</span><span class="token plain">c </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">DROP</span><span class="token plain"> </span><span class="token operator">NOT</span><span class="token plain"> </span><span class="token boolean">NULL</span><br></span></code></pre><button type="button" aria-label="Copy code to clipboard" class="copyButton_M3SB clean-btn">Copy</button></div></div><p><strong>column type change</strong></p><table><thead><tr><th>Source\Target</th><th>long</th><th>float</th><th>double</th><th>string</th><th>decimal</th><th>date</th><th>int</th></tr></thead><tbody><tr><td>int</td><td>Y</td><td>Y</td><td>Y</td><td>Y</td><td>Y</td><td>N</td><td>Y</td></tr><tr><td>long</td><td>Y</td><td>Y</td><td>Y</td><td>Y</td><td>Y</td><td>N</td><td>N</td></tr><tr><td>float</td><td>N</td><td>Y</td><td>Y</td><td>Y</td><td>Y</td><td>N</td><td>N</td></tr><tr><td>double</td><td>N</td><td>N</td><td>Y</td><td>Y</td><td>Y</td><td>N</td><td>N</td></tr><tr><td>decimal</td><td>N</td><td>N</td><td>N</td><td>Y</td><td>Y</td><td>N</td><td>N</td></tr><tr><td>string</td><td>N</td><td>N</td><td>N</td><td>Y</td><td>Y</td><td>Y</td><td>N</td></tr><tr><td>date</td><td>N</td><td>N</td><td>N</td><td>Y</td><td>N</td><td>Y</td><td>N</td></tr></tbody></table><h3 class="anchor anchorWithStickyNavbar_y2LR" id="deleting-columns">Deleting Columns<a class="hash-link" href="#deleting-columns" title="Direct link to heading"></a></h3><p><strong>Syntax</strong></p><div class="codeBlockContainer_J+bg language-sql theme-code-block"><div class="codeBlockContent_csEI sql"><pre tabindex="0" class="prism-code language-sql codeBlock_rtdJ thin-scrollbar" style="color:#F8F8F2;background-color:#282A36"><code class="codeBlockLines_1zSZ"><span class="token-line" style="color:#F8F8F2"><span class="token comment" style="color:rgb(98, 114, 164)">-- alter table ... drop columns</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"></span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">ALTER</span><span class="token plain"> </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">TABLE</span><span class="token plain"> tableName </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">DROP</span><span class="token plain"> </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">COLUMN</span><span class="token operator">|</span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">COLUMNS</span><span class="token plain"> cols</span><br></span></code></pre><button type="button" aria-label="Copy code to clipboard" class="copyButton_M3SB clean-btn">Copy</button></div></div><p><strong>Examples</strong></p><div class="codeBlockContainer_J+bg language-sql theme-code-block"><div class="codeBlockContent_csEI sql"><pre tabindex="0" class="prism-code language-sql codeBlock_rtdJ thin-scrollbar" style="color:#F8F8F2;background-color:#282A36"><code class="codeBlockLines_1zSZ"><span class="token-line" style="color:#F8F8F2"><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">ALTER</span><span class="token plain"> </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">TABLE</span><span class="token plain"> table1 </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">DROP</span><span class="token plain"> </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">COLUMN</span><span class="token plain"> a</span><span class="token punctuation" style="color:rgb(248, 248, 242)">.</span><span class="token plain">b</span><span class="token punctuation" style="color:rgb(248, 248, 242)">.</span><span class="token plain">c</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"></span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">ALTER</span><span class="token plain"> </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">TABLE</span><span class="token plain"> table1 </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">DROP</span><span class="token plain"> </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">COLUMNS</span><span class="token plain"> a</span><span class="token punctuation" style="color:rgb(248, 248, 242)">.</span><span class="token plain">b</span><span class="token punctuation" style="color:rgb(248, 248, 242)">.</span><span class="token plain">c</span><span class="token punctuation" style="color:rgb(248, 248, 242)">,</span><span class="token plain"> x</span><span class="token punctuation" style="color:rgb(248, 248, 242)">,</span><span class="token plain"> y</span><br></span></code></pre><button type="button" aria-label="Copy code to clipboard" class="copyButton_M3SB clean-btn">Copy</button></div></div><h3 class="anchor anchorWithStickyNavbar_y2LR" id="renaming-columns">Renaming columns<a class="hash-link" href="#renaming-columns" title="Direct link to heading"></a></h3><p><strong>Syntax</strong></p><div class="codeBlockContainer_J+bg language-sql theme-code-block"><div class="codeBlockContent_csEI sql"><pre tabindex="0" class="prism-code language-sql codeBlock_rtdJ thin-scrollbar" style="color:#F8F8F2;background-color:#282A36"><code class="codeBlockLines_1zSZ"><span class="token-line" style="color:#F8F8F2"><span class="token comment" style="color:rgb(98, 114, 164)">-- alter table ... rename column</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"></span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">ALTER</span><span class="token plain"> </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">TABLE</span><span class="token plain"> tableName </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">RENAME</span><span class="token plain"> </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">COLUMN</span><span class="token plain"> old_columnName </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">TO</span><span class="token plain"> new_columnName</span><br></span></code></pre><button type="button" aria-label="Copy code to clipboard" class="copyButton_M3SB clean-btn">Copy</button></div></div><p><strong>Examples</strong></p><div class="codeBlockContainer_J+bg language-sql theme-code-block"><div class="codeBlockContent_csEI sql"><pre tabindex="0" class="prism-code language-sql codeBlock_rtdJ thin-scrollbar" style="color:#F8F8F2;background-color:#282A36"><code class="codeBlockLines_1zSZ"><span class="token-line" style="color:#F8F8F2"><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">ALTER</span><span class="token plain"> </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">TABLE</span><span class="token plain"> table1 </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">RENAME</span><span class="token plain"> </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">COLUMN</span><span class="token plain"> a</span><span class="token punctuation" style="color:rgb(248, 248, 242)">.</span><span class="token plain">b</span><span class="token punctuation" style="color:rgb(248, 248, 242)">.</span><span class="token plain">c </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">TO</span><span class="token plain"> x</span><br></span></code></pre><button type="button" aria-label="Copy code to clipboard" class="copyButton_M3SB clean-btn">Copy</button></div></div><div class="admonition admonition-note alert alert--secondary"><div class="admonition-heading"><h5><span class="admonition-icon"><svg xmlns="http://www.w3.org/2000/svg" width="14" height="16" viewBox="0 0 14 16"><path fill-rule="evenodd" d="M6.3 5.69a.942.942 0 0 1-.28-.7c0-.28.09-.52.28-.7.19-.18.42-.28.7-.28.28 0 .52.09.7.28.18.19.28.42.28.7 0 .28-.09.52-.28.7a1 1 0 0 1-.7.3c-.28 0-.52-.11-.7-.3zM8 7.99c-.02-.25-.11-.48-.31-.69-.2-.19-.42-.3-.69-.31H6c-.27.02-.48.13-.69.31-.2.2-.3.44-.31.69h1v3c.02.27.11.5.31.69.2.2.42.31.69.31h1c.27 0 .48-.11.69-.31.2-.19.3-.42.31-.69H8V7.98v.01zM7 2.3c-3.14 0-5.7 2.54-5.7 5.68 0 3.14 2.56 5.7 5.7 5.7s5.7-2.55 5.7-5.7c0-3.15-2.56-5.69-5.7-5.69v.01zM7 .98c3.86 0 7 3.14 7 7s-3.14 7-7 7-7-3.12-7-7 3.14-7 7-7z"></path></svg></span>note</h5></div><div class="admonition-content"><p>When using hive metastore, please disable  <code>hive.metastore.disallow.incompatible.col.type.changes</code> if you encounter this error:
 <code>The following columns have types incompatible with the existing columns in their respective positions</code>.</p></div></div><h2 class="anchor anchorWithStickyNavbar_y2LR" id="schema-evolution-in-action">Schema Evolution in Action<a class="hash-link" href="#schema-evolution-in-action" title="Direct link to heading"></a></h2><p>Let us walk through an example to demonstrate the schema evolution support in Hudi. In the below example, we are going to add a new string field and change the datatype of a field from int to long.</p><div class="codeBlockContainer_J+bg language-scala theme-code-block"><div class="codeBlockContent_csEI scala"><pre tabindex="0" class="prism-code language-scala codeBlock_rtdJ thin-scrollbar" style="color:#F8F8F2;background-color:#282A36"><code class="codeBlockLines_1zSZ"><span class="token-line" style="color:#F8F8F2"><span class="token plain">scala&gt; :paste </span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">import org.apache.hudi.QuickstartUtils._</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">import scala.collection.JavaConversions._</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">import org.apache.spark.sql.SaveMode._</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">import org.apache.hudi.DataSourceReadOptions._</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">import org.apache.hudi.DataSourceWriteOptions._</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">import org.apache.hudi.config.HoodieWriteConfig._</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">import org.apache.spark.sql.types._</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">import org.apache.spark.sql.Row</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain" style="display:inline-block"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">val tableName = &quot;hudi_trips_cow&quot;</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">val basePath = &quot;file:///tmp/hudi_trips_cow&quot;</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">val schema = StructType( Array(</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">     StructField(&quot;rowId&quot;, StringType,true),</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">     StructField(&quot;partitionId&quot;, StringType,true),</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">     StructField(&quot;preComb&quot;, LongType,true),</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">     StructField(&quot;name&quot;, StringType,true),</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">     StructField(&quot;versionId&quot;, StringType,true),</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">     StructField(&quot;intToLong&quot;, IntegerType,true)</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">))</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">        </span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">        </span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">val data1 = Seq(Row(&quot;row_1&quot;, &quot;part_0&quot;, 0L, &quot;bob&quot;, &quot;v_0&quot;, 0),</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">                Row(&quot;row_2&quot;, &quot;part_0&quot;, 0L, &quot;john&quot;, &quot;v_0&quot;, 0),</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">                Row(&quot;row_3&quot;, &quot;part_0&quot;, 0L, &quot;tom&quot;, &quot;v_0&quot;, 0))</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">        </span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">var dfFromData1 = spark.createDataFrame(data1, schema)</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">dfFromData1.write.format(&quot;hudi&quot;).</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">   options(getQuickstartWriteConfigs).</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">   option(&quot;hoodie.datasource.write.precombine.field&quot;, &quot;preComb&quot;).</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">   option(&quot;hoodie.datasource.write.recordkey.field&quot;, &quot;rowId&quot;).</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">   option(&quot;hoodie.datasource.write.partitionpath.field&quot;, &quot;partitionId&quot;).</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">   option(&quot;hoodie.index.type&quot;,&quot;SIMPLE&quot;).</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">   option(&quot;hoodie.table.name&quot;, tableName).</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">   mode(Overwrite).</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">   save(basePath)</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain" style="display:inline-block"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">var tripsSnapshotDF1 = spark.read.format(&quot;hudi&quot;).load(basePath + &quot;/*/*&quot;)</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">tripsSnapshotDF1.createOrReplaceTempView(&quot;hudi_trips_snapshot&quot;)</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain" style="display:inline-block"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">ctrl+D</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain" style="display:inline-block"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">scala&gt; spark.sql(&quot;desc hudi_trips_snapshot&quot;).show()</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">    +--------------------+---------+-------+</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">    |            col_name|data_type|comment|</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">    +--------------------+---------+-------+</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">    | _hoodie_commit_time|   string|   null|</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">    |_hoodie_commit_seqno|   string|   null|</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">    |  _hoodie_record_key|   string|   null|</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">    |_hoodie_partition...|   string|   null|</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">    |   _hoodie_file_name|   string|   null|</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">    |               rowId|   string|   null|</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">    |         partitionId|   string|   null|</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">    |             preComb|   bigint|   null|</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">    |                name|   string|   null|</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">    |           versionId|   string|   null|</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">    |           intToLong|      int|   null|</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">    +--------------------+---------+-------+</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">    </span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">scala&gt; spark.sql(&quot;select rowId, partitionId, preComb, name, versionId, intToLong from hudi_trips_snapshot&quot;).show()</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">    +-----+-----------+-------+----+---------+---------+</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">    |rowId|partitionId|preComb|name|versionId|intToLong|</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">    +-----+-----------+-------+----+---------+---------+</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">    |row_3|     part_0|      0| tom|      v_0|        0|</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">    |row_2|     part_0|      0|john|      v_0|        0|</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">    |row_1|     part_0|      0| bob|      v_0|        0|</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">    +-----+-----------+-------+----+---------+---------+</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain" style="display:inline-block"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">// In the new schema, we are going to add a String field and </span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">// change the datatype `intToLong` field from  int to long.</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">scala&gt; :paste </span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">val newSchema = StructType( Array(</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">    StructField(&quot;rowId&quot;, StringType,true),</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">    StructField(&quot;partitionId&quot;, StringType,true),</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">    StructField(&quot;preComb&quot;, LongType,true),</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">    StructField(&quot;name&quot;, StringType,true),</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">    StructField(&quot;versionId&quot;, StringType,true),</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">    StructField(&quot;intToLong&quot;, LongType,true),</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">    StructField(&quot;newField&quot;, StringType,true)</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">))</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain" style="display:inline-block"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">val data2 = Seq(Row(&quot;row_2&quot;, &quot;part_0&quot;, 5L, &quot;john&quot;, &quot;v_3&quot;, 3L, &quot;newField_1&quot;),</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">               Row(&quot;row_5&quot;, &quot;part_0&quot;, 5L, &quot;maroon&quot;, &quot;v_2&quot;, 2L, &quot;newField_1&quot;),</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">               Row(&quot;row_9&quot;, &quot;part_0&quot;, 5L, &quot;michael&quot;, &quot;v_2&quot;, 2L, &quot;newField_1&quot;))</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain" style="display:inline-block"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">var dfFromData2 = spark.createDataFrame(data2, newSchema)</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">dfFromData2.write.format(&quot;hudi&quot;).</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">    options(getQuickstartWriteConfigs).</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">    option(&quot;hoodie.datasource.write.precombine.field&quot;, &quot;preComb&quot;).</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">    option(&quot;hoodie.datasource.write.recordkey.field&quot;, &quot;rowId&quot;).</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">    option(&quot;hoodie.datasource.write.partitionpath.field&quot;, &quot;partitionId&quot;).</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">    option(&quot;hoodie.index.type&quot;,&quot;SIMPLE&quot;).</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">    option(&quot;hoodie.table.name&quot;, tableName).</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">    mode(Append).</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">    save(basePath)</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain" style="display:inline-block"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">var tripsSnapshotDF2 = spark.read.format(&quot;hudi&quot;).load(basePath + &quot;/*/*&quot;)</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">tripsSnapshotDF2.createOrReplaceTempView(&quot;hudi_trips_snapshot&quot;)</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain" style="display:inline-block"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">Ctrl + D</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain" style="display:inline-block"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">scala&gt; spark.sql(&quot;desc hudi_trips_snapshot&quot;).show()</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">    +--------------------+---------+-------+</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">    |            col_name|data_type|comment|</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">    +--------------------+---------+-------+</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">    | _hoodie_commit_time|   string|   null|</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">    |_hoodie_commit_seqno|   string|   null|</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">    |  _hoodie_record_key|   string|   null|</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">    |_hoodie_partition...|   string|   null|</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">    |   _hoodie_file_name|   string|   null|</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">    |               rowId|   string|   null|</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">    |         partitionId|   string|   null|</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">    |             preComb|   bigint|   null|</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">    |                name|   string|   null|</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">    |           versionId|   string|   null|</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">    |           intToLong|   bigint|   null|</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">    |            newField|   string|   null|</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">    +--------------------+---------+-------+</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain" style="display:inline-block"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain" style="display:inline-block"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">scala&gt; spark.sql(&quot;select rowId, partitionId, preComb, name, versionId, intToLong, newField from hudi_trips_snapshot&quot;).show()</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">    +-----+-----------+-------+-------+---------+---------+----------+</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">    |rowId|partitionId|preComb|   name|versionId|intToLong|  newField|</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">    +-----+-----------+-------+-------+---------+---------+----------+</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">    |row_3|     part_0|      0|    tom|      v_0|        0|      null|</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">    |row_2|     part_0|      5|   john|      v_3|        3|newField_1|</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">    |row_1|     part_0|      0|    bob|      v_0|        0|      null|</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">    |row_5|     part_0|      5| maroon|      v_2|        2|newField_1|</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">    |row_9|     part_0|      5|michael|      v_2|        2|newField_1|</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">    +-----+-----------+-------+-------+---------+---------+----------+</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain" style="display:inline-block"></span><br></span></code></pre><button type="button" aria-label="Copy code to clipboard" class="copyButton_M3SB clean-btn">Copy</button></div></div><h2 class="anchor anchorWithStickyNavbar_y2LR" id="related-resources">Related Resources<a class="hash-link" href="#related-resources" title="Direct link to heading"></a></h2><h3>Videos</h3><ul><li><a href="https://youtu.be/s1_-zl3sfLE" target="_blank" rel="noopener noreferrer">Learn Schema Evolution in Apache Hudi Transaction Datalake with hands on labs</a></li><li><a href="https://www.youtube.com/watch?v=_i5G4ojpwlk" target="_blank" rel="noopener noreferrer">How do I identify Schema Changes in Hudi Tables and Send Email Alert when New Column added/removed</a></li></ul></div><footer class="theme-doc-footer docusaurus-mt-lg"><div 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