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160h396.8v204.8H313.6V160zm396.8 704H313.6V620.8h396.8V864zM864 665.6c0 25.6-19.2 44.8-44.8 44.8h-44.8V588.8c0-17.067-14.933-32-32-32H281.6c-17.067 0-32 14.933-32 32v121.6h-44.8c-25.6 0-44.8-19.2-44.8-44.8v-192c0-25.6 19.2-44.8 44.8-44.8h614.4c25.6 0 44.8 19.2 44.8 44.8v192z"></path></svg></button><div class="arrow end"></div></div><div class="vp-toc-wrapper"><ul class="vp-toc-list"><!--[--><li class="vp-toc-item"><a class="route-link vp-toc-link level3" href="#limit-of-offset-isn-t-working">LIMIT of OFFSET isn&#39;t working</a></li><!----><!--]--><!--[--><li class="vp-toc-item"><a class="route-link vp-toc-link level3" href="#where-in-clause-isn-t-working">WHERE IN clause isn&#39;t working</a></li><!----><!--]--><!--[--><li class="vp-toc-item"><a class="route-link vp-toc-link level3" href="#wrong-binary-data">Wrong binary data</a></li><!----><!--]--><!--[--><li class="vp-toc-item"><a class="route-link vp-toc-link level3" href="#cannot-insert-empty-array">Cannot insert empty ARRAY</a></li><!----><!--]--></ul><div class="vp-toc-marker" style="top:-1.7rem;"></div></div><!--[--><!----><!--]--></aside></div><!--[--><!----><!--]--><div class="theme-hope-content"><p>Here you can find most common questions and problems.</p><h3 id="limit-of-offset-isn-t-working" tabindex="-1"><a class="header-anchor" href="#limit-of-offset-isn-t-working"><span>LIMIT of OFFSET isn&#39;t working</span></a></h3><p>The main problem is PostgreSQL expects <code>LIMIT</code> and <code>OFFSET</code> to be BIGINT type but when you pass python <code>int</code> into <code>parameters</code> it converts to <code>INTEGER</code>.</p><h4 id="problem-and-solution" tabindex="-1"><a class="header-anchor" href="#problem-and-solution"><span>Problem and Solution:</span></a></h4><div class="language-python line-numbers-mode" data-ext="py" data-title="py"><pre class="language-python"><code><span class="token keyword">from</span> psqlpy <span class="token keyword">import</span> ConnectionPool
<span class="token keyword">from</span> psqlpy<span class="token punctuation">.</span>extra_types <span class="token keyword">import</span> BigInt

<span class="token comment"># --- Incorrect ---</span>
<span class="token keyword">async</span> <span class="token keyword">def</span> <span class="token function">main</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">-</span><span class="token operator">&gt;</span> <span class="token boolean">None</span><span class="token punctuation">:</span>
    pool <span class="token operator">=</span> ConnectionPool<span class="token punctuation">(</span><span class="token punctuation">)</span>
    <span class="token keyword">await</span> pool<span class="token punctuation">.</span>execute<span class="token punctuation">(</span>
        querystring<span class="token operator">=</span><span class="token string">&quot;SELECT * FROM users LIMIT $1 OFFSET $2&quot;</span><span class="token punctuation">,</span>
        parameters<span class="token operator">=</span><span class="token punctuation">[</span><span class="token number">10</span><span class="token punctuation">,</span> <span class="token number">100</span><span class="token punctuation">]</span><span class="token punctuation">,</span>
    <span class="token punctuation">)</span>


<span class="token comment"># --- Correct ---</span>
<span class="token keyword">async</span> <span class="token keyword">def</span> <span class="token function">main</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">-</span><span class="token operator">&gt;</span> <span class="token boolean">None</span><span class="token punctuation">:</span>
    pool <span class="token operator">=</span> ConnectionPool<span class="token punctuation">(</span><span class="token punctuation">)</span>
    <span class="token keyword">await</span> pool<span class="token punctuation">.</span>execute<span class="token punctuation">(</span>
        querystring<span class="token operator">=</span><span class="token string">&quot;SELECT * FROM users LIMIT $1 OFFSET $2&quot;</span><span class="token punctuation">,</span>
        parameters<span class="token operator">=</span><span class="token punctuation">[</span>BigInt<span class="token punctuation">(</span><span class="token number">10</span><span class="token punctuation">)</span><span class="token punctuation">,</span> BigInt<span class="token punctuation">(</span><span class="token number">100</span><span class="token punctuation">)</span><span class="token punctuation">]</span><span class="token punctuation">,</span>
    <span class="token punctuation">)</span>
</code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><h3 id="where-in-clause-isn-t-working" tabindex="-1"><a class="header-anchor" href="#where-in-clause-isn-t-working"><span>WHERE IN clause isn&#39;t working</span></a></h3><p>Instead of using <code>WHERE &lt;field&gt; IN ()</code> clause you must use <code>WHERE &lt;field&gt; = ANY()</code>.</p><h4 id="problem-and-solution-1" tabindex="-1"><a class="header-anchor" href="#problem-and-solution-1"><span>Problem and Solution:</span></a></h4><div class="language-python line-numbers-mode" data-ext="py" data-title="py"><pre class="language-python"><code><span class="token keyword">from</span> psqlpy <span class="token keyword">import</span> ConnectionPool

<span class="token comment"># --- Incorrect ---</span>
<span class="token keyword">async</span> <span class="token keyword">def</span> <span class="token function">main</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">-</span><span class="token operator">&gt;</span> <span class="token boolean">None</span><span class="token punctuation">:</span>
    pool <span class="token operator">=</span> ConnectionPool<span class="token punctuation">(</span><span class="token punctuation">)</span>
    <span class="token keyword">await</span> pool<span class="token punctuation">.</span>execute<span class="token punctuation">(</span>
        querystring<span class="token operator">=</span><span class="token string">&quot;SELECT * FROM users WHERE id IN ($1)&quot;</span><span class="token punctuation">,</span>
        parameters<span class="token operator">=</span><span class="token punctuation">[</span>
            <span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
        <span class="token punctuation">]</span><span class="token punctuation">,</span>
    <span class="token punctuation">)</span>


<span class="token comment"># --- Correct ---</span>
<span class="token keyword">async</span> <span class="token keyword">def</span> <span class="token function">main</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">-</span><span class="token operator">&gt;</span> <span class="token boolean">None</span><span class="token punctuation">:</span>
    pool <span class="token operator">=</span> ConnectionPool<span class="token punctuation">(</span><span class="token punctuation">)</span>
    <span class="token keyword">await</span> pool<span class="token punctuation">.</span>execute<span class="token punctuation">(</span>
        querystring<span class="token operator">=</span><span class="token string">&quot;SELECT * FROM users WHERE id = ANY($1)&quot;</span><span class="token punctuation">,</span>
        parameters<span class="token operator">=</span><span class="token punctuation">[</span>
            <span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
        <span class="token punctuation">]</span><span class="token punctuation">,</span>
    <span class="token punctuation">)</span>
</code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><h3 id="wrong-binary-data" tabindex="-1"><a class="header-anchor" href="#wrong-binary-data"><span>Wrong binary data</span></a></h3><p>Example error: <code>binary data has array element type 1043 (character varying) instead of expected 25 (text)</code>.</p><p>This exception tells you that you use wrong data type and you need to specify types explicitly.</p><p>For example, when we want to make <code>WHERE</code> clause with <code>ANY</code> and string values, we need to use <code>TextArray</code>, see example below:</p><h4 id="problem-and-solution-2" tabindex="-1"><a class="header-anchor" href="#problem-and-solution-2"><span>Problem and Solution:</span></a></h4><div class="language-python line-numbers-mode" data-ext="py" data-title="py"><pre class="language-python"><code><span class="token keyword">from</span> psqlpy <span class="token keyword">import</span> ConnectionPool
<span class="token keyword">from</span> psqlpy<span class="token punctuation">.</span>extra_types <span class="token keyword">import</span> TextArray

<span class="token comment"># --- Incorrect ---</span>
<span class="token keyword">async</span> <span class="token keyword">def</span> <span class="token function">main</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">-</span><span class="token operator">&gt;</span> <span class="token boolean">None</span><span class="token punctuation">:</span>
    pool <span class="token operator">=</span> ConnectionPool<span class="token punctuation">(</span><span class="token punctuation">)</span>
    <span class="token keyword">await</span> pool<span class="token punctuation">.</span>execute<span class="token punctuation">(</span>
        querystring<span class="token operator">=</span><span class="token string">&quot;SELECT * FROM users WHERE name = ANY($1)&quot;</span><span class="token punctuation">,</span>
        parameters<span class="token operator">=</span><span class="token punctuation">[</span>
            <span class="token punctuation">[</span><span class="token string">&quot;Foo&quot;</span><span class="token punctuation">,</span> <span class="token string">&quot;Bar&quot;</span><span class="token punctuation">,</span> <span class="token string">&quot;Cafe&quot;</span><span class="token punctuation">]</span><span class="token punctuation">,</span>
        <span class="token punctuation">]</span><span class="token punctuation">,</span>
    <span class="token punctuation">)</span>


<span class="token comment"># --- Correct ---</span>
<span class="token keyword">async</span> <span class="token keyword">def</span> <span class="token function">main</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">-</span><span class="token operator">&gt;</span> <span class="token boolean">None</span><span class="token punctuation">:</span>
    pool <span class="token operator">=</span> ConnectionPool<span class="token punctuation">(</span><span class="token punctuation">)</span>
    <span class="token keyword">await</span> pool<span class="token punctuation">.</span>execute<span class="token punctuation">(</span>
        querystring<span class="token operator">=</span><span class="token string">&quot;SELECT * FROM users WHERE name = ANY($1)&quot;</span><span class="token punctuation">,</span>
        parameters<span class="token operator">=</span><span class="token punctuation">[</span>
            TextArray<span class="token punctuation">(</span><span class="token punctuation">[</span><span class="token string">&quot;Foo&quot;</span><span class="token punctuation">,</span> <span class="token string">&quot;Bar&quot;</span><span class="token punctuation">,</span> <span class="token string">&quot;Cafe&quot;</span><span class="token punctuation">]</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
        <span class="token punctuation">]</span><span class="token punctuation">,</span>
    <span class="token punctuation">)</span>
</code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><h3 id="cannot-insert-empty-array" tabindex="-1"><a class="header-anchor" href="#cannot-insert-empty-array"><span>Cannot insert empty ARRAY</span></a></h3><p>To insert empty array use explicit <a class="route-link" href="/usage/types/array_types.html">Array Type</a>.</p><h4 id="problem-and-solution-3" tabindex="-1"><a class="header-anchor" href="#problem-and-solution-3"><span>Problem and Solution:</span></a></h4><p>Let&#39;s assume that we have table <code>arr_table</code> with field <code>some_array</code> of <code>VARCHAR ARRAY</code> type. The main problem that we cannot determine the type of the empty sequence passed from Python side.</p><div class="language-python line-numbers-mode" data-ext="py" data-title="py"><pre class="language-python"><code><span class="token keyword">from</span> psqlpy <span class="token keyword">import</span> ConnectionPool
<span class="token keyword">from</span> psqlpy<span class="token punctuation">.</span>extra_types <span class="token keyword">import</span> VarCharArray

<span class="token comment"># --- Incorrect ---</span>
<span class="token keyword">async</span> <span class="token keyword">def</span> <span class="token function">main</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">-</span><span class="token operator">&gt;</span> <span class="token boolean">None</span><span class="token punctuation">:</span>
    pool <span class="token operator">=</span> ConnectionPool<span class="token punctuation">(</span><span class="token punctuation">)</span>
    <span class="token keyword">await</span> pool<span class="token punctuation">.</span>execute<span class="token punctuation">(</span>
        querystring<span class="token operator">=</span><span class="token string">&quot;INSERT INTO arr_table (some_array) VALUES ($1)&quot;</span><span class="token punctuation">,</span>
        parameters<span class="token operator">=</span><span class="token punctuation">[</span>
            <span class="token punctuation">[</span><span class="token punctuation">]</span><span class="token punctuation">,</span>
        <span class="token punctuation">]</span><span class="token punctuation">,</span>
    <span class="token punctuation">)</span>


<span class="token comment"># --- Correct ---</span>
<span class="token keyword">async</span> <span class="token keyword">def</span> <span class="token function">main</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">-</span><span class="token operator">&gt;</span> <span class="token boolean">None</span><span class="token punctuation">:</span>
    pool <span class="token operator">=</span> ConnectionPool<span class="token punctuation">(</span><span class="token punctuation">)</span>
    <span class="token keyword">await</span> pool<span class="token punctuation">.</span>execute<span class="token punctuation">(</span>
        querystring<span class="token operator">=</span><span class="token string">&quot;INSERT INTO arr_table (some_array) VALUES ($1)&quot;</span><span class="token punctuation">,</span>
        parameters<span class="token operator">=</span><span class="token punctuation">[</span>
            VarCharArray<span class="token punctuation">(</span><span class="token punctuation">[</span><span class="token punctuation">]</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
        <span class="token punctuation">]</span><span class="token punctuation">,</span>
    <span class="token punctuation">)</span>
</code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div></div><!--[--><!----><!--]--><footer class="vp-page-meta"><div class="vp-meta-item edit-link"><a href="https://github.com/psqlpy-python/psqlpy/edit/main/faq.md" rel="noopener noreferrer" target="_blank" aria-label="Edit this page" class="nav-link vp-meta-label"><!--[--><svg xmlns="http://www.w3.org/2000/svg" class="icon edit-icon" viewBox="0 0 1024 1024" fill="currentColor" aria-label="edit icon"><path d="M430.818 653.65a60.46 60.46 0 0 1-50.96-93.281l71.69-114.012 7.773-10.365L816.038 80.138A60.46 60.46 0 0 1 859.225 62a60.46 60.46 0 0 1 43.186 18.138l43.186 43.186a60.46 60.46 0 0 1 0 86.373L588.879 565.55l-8.637 8.637-117.466 68.234a60.46 60.46 0 0 1-31.958 11.229z"></path><path d="M728.802 962H252.891A190.883 190.883 0 0 1 62.008 771.98V296.934a190.883 190.883 0 0 1 190.883-192.61h267.754a60.46 60.46 0 0 1 0 120.92H252.891a69.962 69.962 0 0 0-69.098 69.099V771.98a69.962 69.962 0 0 0 69.098 69.098h475.911A69.962 69.962 0 0 0 797.9 771.98V503.363a60.46 60.46 0 1 1 120.922 0V771.98A190.883 190.883 0 0 1 728.802 962z"></path></svg><!--]-->Edit this page<span><svg class="external-link-icon" xmlns="http://www.w3.org/2000/svg" aria-hidden="true" focusable="false" x="0px" y="0px" viewBox="0 0 100 100" width="15" height="15"><path fill="currentColor" d="M18.8,85.1h56l0,0c2.2,0,4-1.8,4-4v-32h-8v28h-48v-48h28v-8h-32l0,0c-2.2,0-4,1.8-4,4v56C14.8,83.3,16.6,85.1,18.8,85.1z"></path><polygon fill="currentColor" points="45.7,48.7 51.3,54.3 77.2,28.5 77.2,37.2 85.2,37.2 85.2,14.9 62.8,14.9 62.8,22.9 71.5,22.9"></polygon></svg><span class="external-link-icon-sr-only">open in new window</span></span><!----></a></div><div class="vp-meta-item git-info"><div class="update-time"><span class="vp-meta-label">Last update: </span><!----></div><div class="contributors"><span class="vp-meta-label">Contributors: </span><!--[--><!--[--><span class="vp-meta-info" title="email: chandr@chandr.net">chandr-andr (Kiselev Aleksandr)</span><!--]--><!--]--></div></div></footer><nav class="vp-page-nav"><a class="route-link nav-link prev" href="/benchmarks.html" aria-label="Benchmarks"><div class="hint"><span class="arrow start"></span>Prev</div><div class="link"><!---->Benchmarks</div></a><!----></nav><!----><!--[--><!----><!--]--><!--]--></main><!--]--><!----></div><!--]--><!--]--><!--[--><!----><!----><!--]--><!--]--></div>
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