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<div class="markdown-heading"><h1 class="heading-element">
<a href="https://www.postgresql.org" rel="nofollow">PostgreSQL</a> Views and Functions</h1><a id="user-content-postgresql-views-and-functions" class="anchor" aria-label="Permalink: PostgreSQL Views and Functions" href="#postgresql-views-and-functions"><span aria-hidden="true" class="octicon octicon-link"></span></a></div>
<p>The functions and views published in this repository are some of those, which I
regularly need in my daily job.</p>
<p>As these procedures are sort of essential, at least to me, I install them in the
public schema. That way they are available for everyone without having to know
a schema name.</p>
<p>All functions and views are covered by tests. The tests are done in simple SQL
statements. Each test does raise division by zero if it fails.</p>
<p>The tests have been done with PostgreSQL 12 up to 17.</p>
<p>All examples have been tested with PostgreSQL 17, differences in the behavior of previous versions are noted.</p>
<p><a href=""><img src="https://camo.githubusercontent.com/1042d1fc01ac97f78a8c307a3ee403e1eba45a812519c0290319e3b872b3ade1/68747470733a2f2f696d672e736869656c64732e696f2f62616467652f506f737467726553514c2d31322d626c75652e737667" alt="version" data-canonical-src="https://img.shields.io/badge/PostgreSQL-12-blue.svg" style="max-width: 100%;"></a>
<a href=""><img src="https://camo.githubusercontent.com/d2a89cd3f2051b2365b8b045ef9d3654181181b3abe1492d0399909e1509d747/68747470733a2f2f696d672e736869656c64732e696f2f62616467652f506f737467726553514c2d31332d626c75652e737667" alt="version" data-canonical-src="https://img.shields.io/badge/PostgreSQL-13-blue.svg" style="max-width: 100%;"></a>
<a href=""><img src="https://camo.githubusercontent.com/b2dd345d55c35062416aff03b72efd385599e03675909bdefb362d27c0d6e6bd/68747470733a2f2f696d672e736869656c64732e696f2f62616467652f506f737467726553514c2d31342d626c75652e737667" alt="version" data-canonical-src="https://img.shields.io/badge/PostgreSQL-14-blue.svg" style="max-width: 100%;"></a>
<a href=""><img src="https://camo.githubusercontent.com/2afe3e6dfa0535af3158334804ad3e1e6b09cfda81d51435d3f812fb05c62df1/68747470733a2f2f696d672e736869656c64732e696f2f62616467652f506f737467726553514c2d31352d626c75652e737667" alt="version" data-canonical-src="https://img.shields.io/badge/PostgreSQL-15-blue.svg" style="max-width: 100%;"></a>
<a href=""><img src="https://camo.githubusercontent.com/b6c9ddd95255ec3cbdf81d2069c3809387320b4f1489052dd8fba4544591ba33/68747470733a2f2f696d672e736869656c64732e696f2f62616467652f506f737467726553514c2d31362d626c75652e737667" alt="version" data-canonical-src="https://img.shields.io/badge/PostgreSQL-16-blue.svg" style="max-width: 100%;"></a>
<a href=""><img src="https://camo.githubusercontent.com/d4308dc0c9177c0ebe49205431eebc432e19f044dff1d87bc077e188fbdc9359/68747470733a2f2f696d672e736869656c64732e696f2f62616467652f506f737467726553514c2d31372d626c75652e737667" alt="version" data-canonical-src="https://img.shields.io/badge/PostgreSQL-17-blue.svg" style="max-width: 100%;"></a></p>
<p><a href=""><img src="https://camo.githubusercontent.com/e0d0f6996fdf3cba78960efb62417ee001bcefd28e8b4eeef2f3b4d31dfc7700/68747470733a2f2f696d672e736869656c64732e696f2f62616467652f4c616e67756167652d706c2f706753514c2d677265656e2e737667" alt="Lang" data-canonical-src="https://img.shields.io/badge/Language-pl/pgSQL-green.svg" style="max-width: 100%;"></a>
<a href=""><img src="https://camo.githubusercontent.com/5eb31bac795fead9fbd57443292b5dfaeaaa49f08fd856d0254192c8803a279e/68747470733a2f2f696d672e736869656c64732e696f2f62616467652f4c6963656e73652d506f737467726553514c2d677265656e2e737667" alt="PostgreSQL" data-canonical-src="https://img.shields.io/badge/License-PostgreSQL-green.svg" style="max-width: 100%;"></a>
<a href=""><img src="https://camo.githubusercontent.com/b09338ed28c485df31576dbdcd7c6da762ea2ee056e78f07f34642933e3a4198/68747470733a2f2f696d672e736869656c64732e696f2f62616467652f457874656e73696f6e2d506f737467726553514c2d677265656e2e737667" alt="Extension" data-canonical-src="https://img.shields.io/badge/Extension-PostgreSQL-green.svg" style="max-width: 100%;"></a></p>
<div class="markdown-heading"><h1 class="heading-element">Repositories</h1><a id="user-content-repositories" class="anchor" aria-label="Permalink: Repositories" href="#repositories"><span aria-hidden="true" class="octicon octicon-link"></span></a></div>
<p>The main repository is now on
<a href="https://gitlab.com/sjstoelting/pgsql-tweaks.git" rel="nofollow">GitLab</a>. A mirror will stay on <a href="https://github.com/sjstoelting/pgsql-tweaks">GitHub</a>.</p>
<p>If you discover any issue, please file them on
<a href="https://gitlab.com/sjstoelting/pgsql-tweaks/-/issues" rel="nofollow">https://gitlab.com/sjstoelting/pgsql-tweaks/-/issues</a>.</p>
<div class="markdown-heading"><h1 class="heading-element">Building the extension</h1><a id="user-content-building-the-extension" class="anchor" aria-label="Permalink: Building the extension" href="#building-the-extension"><span aria-hidden="true" class="octicon octicon-link"></span></a></div>
<p>Each function and test is organized into its own separate file for easy management. The shell script <code>create_sql.sh</code> is responsible for assembling these files into the appropriate SQL scripts needed for extension creation.</p>
<div class="markdown-heading"><h2 class="heading-element">Configuration</h2><a id="user-content-configuration" class="anchor" aria-label="Permalink: Configuration" href="#configuration"><span aria-hidden="true" class="octicon octicon-link"></span></a></div>
<p>Copy the example configuration file <code>build.cfg.example</code> to <code>build.cfg</code>.
Modify <code>build.cfg</code> to include the database connection information of your environment.</p>
<div class="markdown-heading"><h2 class="heading-element">Running the Script</h2><a id="user-content-running-the-script" class="anchor" aria-label="Permalink: Running the Script" href="#running-the-script"><span aria-hidden="true" class="octicon octicon-link"></span></a></div>
<p>The script automatically generates the necessary SQL scripts by combining the function and test files.
It is assumed that you have a <a href="https://www.postgresql.org/docs/current/static/libpq-pgpass.html" rel="nofollow"><code>.pgpass</code></a> file in your home directory, containing the database credentials matching the configuration. This file simplifies the login process during script execution.
Otherwise you have to login with credentials for each execution.</p>
<p>The test results are generated with messages and captions in your local language settings. In addition the <code>test/sql/out/pgsql-tweaks-test-[version number].out</code> file has timing on, you see the execution time for each test.</p>
<div class="markdown-heading"><h2 class="heading-element">Releasing</h2><a id="user-content-releasing" class="anchor" aria-label="Permalink: Releasing" href="#releasing"><span aria-hidden="true" class="octicon octicon-link"></span></a></div>
<p>The script accepts an optional argument to control whether a zip file for <a href="https://pgxn.org/" rel="nofollow">PGXN</a> (PostgreSQL Extension Network) is created. PGXN is also the prefered installation method.</p>
<p>You have to pass <code>'y'</code> as the first argument to the script. The language of the test results will be in English UTF8 en_EN.
In addition a zip archive is generated ready for submission to PGXN.</p>
<p>The <code>test/sql/out/pgsql-tweaks-test-[version number].out</code> file is generated without timing, otherwise the test results would not be comparable.</p>
<p>Example:</p>
<div class="highlight highlight-source-shell"><pre>./create_sql.sh y</pre></div>
<p>This will create a zip file of the extension in the <code>$HOME/tmp</code> directory with the pattern <code>pgsql-tweaks-[version number].zip</code>.
When the directory <code>$HOME/tmp</code> does not exist, it is created by the scirpt.
If no argument is provided, or if the argument is not <code>'y'</code>, the PGXN zip file is <strong>not</strong> created.</p>
<div class="markdown-heading"><h1 class="heading-element">Installation</h1><a id="user-content-installation" class="anchor" aria-label="Permalink: Installation" href="#installation"><span aria-hidden="true" class="octicon octicon-link"></span></a></div>
<p>You may either, install all functions as a package, or install single functions of your choice.</p>
<div class="markdown-heading"><h2 class="heading-element">Install the package from source</h2><a id="user-content-install-the-package-from-source" class="anchor" aria-label="Permalink: Install the package from source" href="#install-the-package-from-source"><span aria-hidden="true" class="octicon octicon-link"></span></a></div>
<p>Get the source by either, download the code as ZIP file, or by git clone.</p>
<div class="highlight highlight-source-shell"><pre><span class="pl-c1">cd</span> pgsql_tweaks
make install</pre></div>
<p>Afterwards you are able to create the extension in a database:</p>
<div class="highlight highlight-source-sql"><pre>CREATE EXTENSION pgsql_tweaks;</pre></div>
<div class="markdown-heading"><h2 class="heading-element">Install the package with PGXN</h2><a id="user-content-install-the-package-with-pgxn" class="anchor" aria-label="Permalink: Install the package with PGXN" href="#install-the-package-with-pgxn"><span aria-hidden="true" class="octicon octicon-link"></span></a></div>
<p>pgsql_tweaks is now available over the PostgreSQL extension management, <a href="https://pgxn.org/dist/pgsql_tweaks/" rel="nofollow">PGXN</a>.</p>
<p>The installation is done with the PGXN installer and it is the prefered installation.</p>
<div class="highlight highlight-source-shell"><pre>pgxn install pgsql_tweaks</pre></div>
<p>Afterwards you are able to create the extension in a database:</p>
<div class="highlight highlight-source-sql"><pre>CREATE EXTENSION pgsql_tweaks;</pre></div>
<div class="markdown-heading"><h2 class="heading-element">Testing</h2><a id="user-content-testing" class="anchor" aria-label="Permalink: Testing" href="#testing"><span aria-hidden="true" class="octicon octicon-link"></span></a></div>
<p>When your local language is not set LC_MESSAGES to en_EN, you have to execute the the test in the installation directory with an additional parameter to have comparable resutls.</p>
<div class="highlight highlight-source-shell"><pre>LC_MESSAGES=en_EN psql -f test/sql/out/pgsql-tweaks-[version number].sql <span class="pl-k">></span> pgsql-tweaks-test-[version number].out
diff pgsql-tweaks-[version number].out test/sql/out/pgsql-tweaks-test-[version number].out</pre></div>
<div class="markdown-heading"><h1 class="heading-element">Table of content</h1><a id="user-content-table-of-content" class="anchor" aria-label="Permalink: Table of content" href="#table-of-content"><span aria-hidden="true" class="octicon octicon-link"></span></a></div>
<p>1 <a href="#user-content-list-of-functions">List of functions</a></p>
<p>1.1 <a href="#user-content-functions-to-check-data-types">Functions to check data types</a><br>
1.1.1 <a href="#user-content-function-is_date">FUNCTION is_date</a><br>
1.1.2 <a href="#user-content-function-is_time">FUNCTION is_time</a><br>
1.1.3 <a href="#user-content-function-is_timestamp">FUNCTION is_timestamp</a><br>
1.1.4 <a href="#user-content-function-is_real">FUNCTION is_real</a><br>
1.1.5 <a href="#user-content-function-is_double_precision">FUNCTION is_double_precision</a><br>
1.1.6 <a href="#user-content-function-is_numeric">FUNCTION is_numeric</a><br>
1.1.7 <a href="#user-content-function-is_bigint">FUNCTION is_bigint</a><br>
1.1.8 <a href="#user-content-function-is_integer">FUNCTION is_integer</a><br>
1.1.9 <a href="#user-content-function-is_smallint">FUNCTION is_smallint</a><br>
1.1.10 <a href="#user-content-function-is_boolean">FUNCTION is_boolean</a><br>
1.1.11 <a href="#user-content-function-is_json">FUNCTION is_json</a><br>
1.1.12 <a href="#user-content-function-is_jsonb">FUNCTION is_jsonb</a><br>
1.1.13 <a href="#user-content-function-is_empty-or-is_empty_b">FUNCTION is_empty or is_empty_b</a><br>
1.1.14 <a href="#user-content-function-is_hex">FUNCTION is_hex</a></p>
<p>1.2 <a href="#user-content-functions-about-encryption">Functions about encryption</a><br>
1.2.1 <a href="#user-content-function-sha256">FUNCTION sha256</a></p>
<p>1.3 <a href="#user-content-functions-and-views-to-get-extended-system-information">Functions and views to get extended system information</a><br>
1.3.1 <a href="#user-content-function-pg_schema_size">FUNCTION pg_schema_size</a><br>
1.3.2 <a href="#user-content-view-pg_db_views">VIEW pg_db_views</a><br>
1.3.3 <a href="#user-content-view-pg_foreign_keys">VIEW pg_foreign_keys</a><br>
1.3.4 <a href="#user-content-view-pg_functions">VIEW pg_functions</a><br>
1.3.4 <a href="#user-content-view-pg_active_locks">VIEW pg_active_locks</a><br>
1.3.5 <a href="#user-content-view-pg_table_matview_infos">VIEW pg_table_matview_infos</a><br>
1.3.6 <a href="#user-content-view-pg_object_ownership">VIEW pg_object_ownership</a><br>
1.3.7 <a href="#user-content-view-pg_partitioned_tables_infos">VIEW pg_partitioned_tables_infos</a></p>
<p>1.4 <a href="#user-content-functions-about-encodings">Functions about encodings</a><br>
1.4.1 <a href="#user-content-function-is_encoding">FUNCTION is_encoding</a><br>
1.4.2 <a href="#user-content-function-is_latin1">FUNCTION is_latin1</a><br>
1.4.3 <a href="#user-content-function-return_not_part_of_latin1">FUNCTION return_not_part_of_latin1</a><br>
1.4.4 <a href="#user-content-function-replace_latin1">FUNCTION replace_latin1</a><br>
1.4.4.1 <a href="#user-content-replace_latin1-s-text-">replace_latin1(s text)</a><br>
1.4.4.2 <a href="#user-content-replace_latin1-s-text-replacement-text-">replace_latin1(s text, replacement text)</a><br>
1.4.4.3 <a href="#user-content-replace_latin1-s-text-s_search-text-s_replace-text-">replace_latin1(s text, s_search text[], s_replace text[])</a><br>
1.4.5 <a href="#user-content-function-return_not_part_of_encoding">FUNCTION return_not_part_of_encoding</a><br>
1.4.6 <a href="#user-content-function-replace_encoding">FUNCTION replace_encoding</a><br>
1.4.6.1 <a href="#user-content-replace_encoding-s-text-e-text-">replace_encoding(s text, e text)</a><br>
1.4.6.2 <a href="#user-content-replace_encoding-s-text-e-text-replacement-text-">replace_encoding(s text, e text, replacement text)</a><br>
1.4.6.3 <a href="#user-content-replace_encoding-s-text-s_search-text-s_replace-text-">replace_encoding(s text, s_search text[], s_replace text[])</a></p>
<p>1.5 <a href="#user-content-user-defined-aggregates">User defined aggregates</a><br>
1.5.1 <a href="#user-content-aggregate-gap_fill">AGGREGATE gap_fill</a><br>
1.5.2 <a href="#user-content-aggregate-array_min">AGGREGATE array_min</a><br>
1.5.3 <a href="#user-content-aggregate-array_max">AGGREGATE array_max</a><br>
1.5.4 <a href="#user-content-aggregate-array_avg">AGGREGATE array_avg</a><br>
1.5.5 <a href="#user-content-aggregate-array_sum">AGGREGATE array_sum</a></p>
<p>1.6 <a href="#user-content-format-functions">Format functions</a><br>
1.6.1 <a href="#user-content-function-date_de">FUNCTION date_de</a><br>
1.6.2 <a href="#user-content-function-datetime_de">FUNCTION datetime_de</a></p>
<p>1.7 <a href="#user-content-conversion-functions">Conversion functions</a><br>
1.7.1 <a href="#user-content-function-to_unix_timestamp">FUNCTION to_unix_timestamp</a><br>
1.7.2 <a href="#user-content-function-hex2bigint">FUNCTION hex2bigint</a></p>
<p>1.8 <a href="#user-content-other-functions">Other functions</a><br>
1.8.1 <a href="#user-content-function-array_trim">FUNCTION array_trim</a></p>
<div class="markdown-heading"><h1 class="heading-element">List of functions</h1><a id="user-content-list-of-functions" class="anchor" aria-label="Permalink: List of functions" href="#list-of-functions"><span aria-hidden="true" class="octicon octicon-link"></span></a></div>
<div class="markdown-heading"><h2 class="heading-element">Functions to check data types</h2><a id="user-content-functions-to-check-data-types" class="anchor" aria-label="Permalink: Functions to check data types" href="#functions-to-check-data-types"><span aria-hidden="true" class="octicon octicon-link"></span></a></div>
<div class="markdown-heading"><h3 class="heading-element">FUNCTION is_date</h3><a id="user-content-function-is_date" class="anchor" aria-label="Permalink: FUNCTION is_date" href="#function-is_date"><span aria-hidden="true" class="octicon octicon-link"></span></a></div>
<p>The function checks strings for being a date.<br>
You might pass a second parameter to use a format string. Without the format,
the default format of PostgreSQL is used.</p>
<p>There has been a behaviour change in PostgreSQL 10. A conversion is now handled
strict, as in previous versions the conversion tried to calculate dates.</p>
<div class="markdown-heading"><h4 class="heading-element">Example PostgreSQL < 10</h4><a id="user-content-example-postgresql--10" class="anchor" aria-label="Permalink: Example PostgreSQL < 10" href="#example-postgresql--10"><span aria-hidden="true" class="octicon octicon-link"></span></a></div>
<div class="highlight highlight-source-sql"><pre><span class="pl-k">SELECT</span> is_date(<span class="pl-s"><span class="pl-pds">'</span>31.02.2018<span class="pl-pds">'</span></span>, <span class="pl-s"><span class="pl-pds">'</span>DD.MM.YYYY<span class="pl-pds">'</span></span>) <span class="pl-k">AS</span> res;
<span class="pl-c"><span class="pl-c">--</span> Result is true because the conversion would return a valid result for</span>
<span class="pl-k">SELECT</span> to_date(<span class="pl-s"><span class="pl-pds">'</span>31.02.2018<span class="pl-pds">'</span></span>, <span class="pl-s"><span class="pl-pds">'</span>DD.MM.YYYY<span class="pl-pds">'</span></span>);</pre></div>
<p>Result PostgreSQL 9.6 and previous versions:</p>
<table>
<thead>
<tr>
<th>to_date</th>
</tr>
</thead>
<tbody>
<tr>
<td>2018-03-03</td>
</tr>
</tbody>
</table>
<div class="markdown-heading"><h4 class="heading-element">Examples</h4><a id="user-content-examples" class="anchor" aria-label="Permalink: Examples" href="#examples"><span aria-hidden="true" class="octicon octicon-link"></span></a></div>
<div class="highlight highlight-source-sql"><pre><span class="pl-c"><span class="pl-c">/*</span>*</span>
<span class="pl-c"> * Parameter is in PostgreSQL default format</span>
<span class="pl-c"> <span class="pl-c">*/</span></span>
<span class="pl-k">SELECT</span> is_date(<span class="pl-s"><span class="pl-pds">'</span>2018-01-01<span class="pl-pds">'</span></span>) <span class="pl-k">AS</span> res;</pre></div>
<p>Result:</p>
<table>
<thead>
<tr>
<th align="center">res</th>
</tr>
</thead>
<tbody>
<tr>
<td align="center">t</td>
</tr>
</tbody>
</table>
<div class="highlight highlight-source-sql"><pre><span class="pl-k">SELECT</span> is_date(<span class="pl-s"><span class="pl-pds">'</span>2018-02-31<span class="pl-pds">'</span></span>) <span class="pl-k">AS</span> res;</pre></div>
<p>Result:</p>
<table>
<thead>
<tr>
<th align="center">res</th>
</tr>
</thead>
<tbody>
<tr>
<td align="center">f</td>
</tr>
</tbody>
</table>
<div class="highlight highlight-source-sql"><pre><span class="pl-c"><span class="pl-c">/*</span>*</span>
<span class="pl-c"> * Parameter is in PostgreSQL German format</span>
<span class="pl-c"> <span class="pl-c">*/</span></span>
<span class="pl-k">SELECT</span> is_date(<span class="pl-s"><span class="pl-pds">'</span>01.01.2018<span class="pl-pds">'</span></span>, <span class="pl-s"><span class="pl-pds">'</span>DD.MM.YYYY<span class="pl-pds">'</span></span>) <span class="pl-k">AS</span> res;</pre></div>
<p>Result:</p>
<table>
<thead>
<tr>
<th align="center">res</th>
</tr>
</thead>
<tbody>
<tr>
<td align="center">t</td>
</tr>
</tbody>
</table>
<div class="highlight highlight-source-sql"><pre><span class="pl-k">SELECT</span> is_date(<span class="pl-s"><span class="pl-pds">'</span>31.02.2018<span class="pl-pds">'</span></span>, <span class="pl-s"><span class="pl-pds">'</span>DD.MM.YYYY<span class="pl-pds">'</span></span>) <span class="pl-k">AS</span> res;</pre></div>
<p>Result:</p>
<table>
<thead>
<tr>
<th align="center">res</th>
</tr>
</thead>
<tbody>
<tr>
<td align="center">f</td>
</tr>
</tbody>
</table>
<div class="markdown-heading"><h3 class="heading-element">FUNCTION is_time</h3><a id="user-content-function-is_time" class="anchor" aria-label="Permalink: FUNCTION is_time" href="#function-is_time"><span aria-hidden="true" class="octicon octicon-link"></span></a></div>
<p>The function checks strings for being a time.<br>
You might pass a second parameter to use a format string. Without the format,
the default format of PostgreSQL is used.</p>
<p>There has been a behaviour change in PostgreSQL 10. A conversion is now handled
strict, as in previous versions the conversion tried to calculate time.</p>
<div class="markdown-heading"><h4 class="heading-element">Example PostgreSQL < 10</h4><a id="user-content-example-postgresql--10-1" class="anchor" aria-label="Permalink: Example PostgreSQL < 10" href="#example-postgresql--10-1"><span aria-hidden="true" class="octicon octicon-link"></span></a></div>
<div class="highlight highlight-source-sql"><pre><span class="pl-k">SELECT</span> is_time(<span class="pl-s"><span class="pl-pds">'</span>25.33.55,456574<span class="pl-pds">'</span></span>, <span class="pl-s"><span class="pl-pds">'</span>HH24.MI.SS,US<span class="pl-pds">'</span></span>) <span class="pl-k">AS</span> res;
<span class="pl-c"><span class="pl-c">--</span> Result is true because the conversion would return a valid result for</span>
<span class="pl-k">SELECT</span> to_timestamp(<span class="pl-s"><span class="pl-pds">'</span>25.33.55,456574<span class="pl-pds">'</span></span>, <span class="pl-s"><span class="pl-pds">'</span>HH24.MI.SS,US<span class="pl-pds">'</span></span>)::<span class="pl-k">TIME</span>;</pre></div>
<p>Result PostgreSQL 9.6 and previous versions:</p>
<table>
<thead>
<tr>
<th>to_timestamp</th>
</tr>
</thead>
<tbody>
<tr>
<td>01:33:55.456574</td>
</tr>
</tbody>
</table>
<div class="markdown-heading"><h4 class="heading-element">Examples</h4><a id="user-content-examples-1" class="anchor" aria-label="Permalink: Examples" href="#examples-1"><span aria-hidden="true" class="octicon octicon-link"></span></a></div>
<div class="highlight highlight-source-sql"><pre><span class="pl-c"><span class="pl-c">/*</span>*</span>
<span class="pl-c"> * Parameter is in PostgreSQL default format</span>
<span class="pl-c"> <span class="pl-c">*/</span></span>
<span class="pl-k">SELECT</span> is_time(<span class="pl-s"><span class="pl-pds">'</span>14:33:55.456574<span class="pl-pds">'</span></span>) <span class="pl-k">AS</span> res;</pre></div>
<p>Result:</p>
<table>
<thead>
<tr>
<th align="center">res</th>
</tr>
</thead>
<tbody>
<tr>
<td align="center">t</td>
</tr>
</tbody>
</table>
<div class="highlight highlight-source-sql"><pre><span class="pl-k">SELECT</span> is_time(<span class="pl-s"><span class="pl-pds">'</span>25:33:55.456574<span class="pl-pds">'</span></span>) <span class="pl-k">AS</span> res;</pre></div>
<p>Result:</p>
<table>
<thead>
<tr>
<th align="center">res</th>
</tr>
</thead>
<tbody>
<tr>
<td align="center">f</td>
</tr>
</tbody>
</table>
<div class="highlight highlight-source-sql"><pre><span class="pl-c"><span class="pl-c">/*</span>*</span>
<span class="pl-c"> * Parameter is some time format</span>
<span class="pl-c"> <span class="pl-c">*/</span></span>
<span class="pl-k">SELECT</span> is_time(<span class="pl-s"><span class="pl-pds">'</span>14.33.55,456574<span class="pl-pds">'</span></span>, <span class="pl-s"><span class="pl-pds">'</span>HH24.MI.SS,US<span class="pl-pds">'</span></span>) <span class="pl-k">AS</span> res;</pre></div>
<p>Result:</p>
<table>
<thead>
<tr>
<th align="center">res</th>
</tr>
</thead>
<tbody>
<tr>
<td align="center">t</td>
</tr>
</tbody>
</table>
<div class="highlight highlight-source-sql"><pre><span class="pl-k">SELECT</span> is_time(<span class="pl-s"><span class="pl-pds">'</span>25.33.55,456574<span class="pl-pds">'</span></span>, <span class="pl-s"><span class="pl-pds">'</span>HH24.MI.SS,US<span class="pl-pds">'</span></span>) <span class="pl-k">AS</span> res;</pre></div>
<p>Result:</p>
<table>
<thead>
<tr>
<th align="center">res</th>
</tr>
</thead>
<tbody>
<tr>
<td align="center">f</td>
</tr>
</tbody>
</table>
<div class="markdown-heading"><h3 class="heading-element">FUNCTION is_timestamp</h3><a id="user-content-function-is_timestamp" class="anchor" aria-label="Permalink: FUNCTION is_timestamp" href="#function-is_timestamp"><span aria-hidden="true" class="octicon octicon-link"></span></a></div>
<p>The function checks strings for being a timestamp.<br>
You might pass a second parameter to use a format string. Without the format,
the default format of PostgreSQL is used.</p>
<p>There has been a behaviour change in PostgreSQL 10. A conversion is now handled
strict, as in previous versions the conversion tried to calculate a date.</p>
<div class="markdown-heading"><h4 class="heading-element">Example PostgreSQL < 10</h4><a id="user-content-example-postgresql--10-2" class="anchor" aria-label="Permalink: Example PostgreSQL < 10" href="#example-postgresql--10-2"><span aria-hidden="true" class="octicon octicon-link"></span></a></div>
<div class="highlight highlight-source-sql"><pre><span class="pl-k">SELECT</span> is_timestamp(<span class="pl-s"><span class="pl-pds">'</span>2018-01-01 25:00:00<span class="pl-pds">'</span></span>) <span class="pl-k">AS</span> res;
<span class="pl-c"><span class="pl-c">--</span> Result is true because the conversion would return a valid result for</span>
<span class="pl-k">SELECT</span> to_timestamp(<span class="pl-s"><span class="pl-pds">'</span>01.01.2018 25:00:00<span class="pl-pds">'</span></span>, <span class="pl-s"><span class="pl-pds">'</span>DD.MM.YYYY HH24.MI.SS<span class="pl-pds">'</span></span>)::<span class="pl-k">TIMESTAMP</span>;</pre></div>
<p>Result PostgreSQL 9.6 and previous versions:</p>
<table>
<thead>
<tr>
<th>to_timestamp</th>
</tr>
</thead>
<tbody>
<tr>
<td>2018-01-02 01:00:00</td>
</tr>
</tbody>
</table>
<div class="markdown-heading"><h4 class="heading-element">Examples</h4><a id="user-content-examples-2" class="anchor" aria-label="Permalink: Examples" href="#examples-2"><span aria-hidden="true" class="octicon octicon-link"></span></a></div>
<div class="highlight highlight-source-sql"><pre><span class="pl-c"><span class="pl-c">/*</span>*</span>
<span class="pl-c"> * Parameter is in PostgreSQL default format</span>
<span class="pl-c"> <span class="pl-c">*/</span></span>
<span class="pl-k">SELECT</span> is_timestamp(<span class="pl-s"><span class="pl-pds">'</span>2018-01-01 00:00:00<span class="pl-pds">'</span></span>) <span class="pl-k">AS</span> res;</pre></div>
<p>Result:</p>
<table>
<thead>
<tr>
<th align="center">res</th>
</tr>
</thead>
<tbody>
<tr>
<td align="center">t</td>
</tr>
</tbody>
</table>
<div class="highlight highlight-source-sql"><pre><span class="pl-k">SELECT</span> is_timestamp(<span class="pl-s"><span class="pl-pds">'</span>2018-01-01 25:00:00<span class="pl-pds">'</span></span>) <span class="pl-k">AS</span> res;
<span class="pl-c"><span class="pl-c">--</span> Result is false in PostgreSQL >= 10</span></pre></div>
<p>Result:</p>
<table>
<thead>
<tr>
<th align="center">res</th>
</tr>
</thead>
<tbody>
<tr>
<td align="center">f</td>
</tr>
</tbody>
</table>
<div class="highlight highlight-source-sql"><pre><span class="pl-c"><span class="pl-c">/*</span>*</span>
<span class="pl-c"> * Parameter is in PostgreSQL German format</span>
<span class="pl-c"> <span class="pl-c">*/</span></span>
<span class="pl-k">SELECT</span> is_timestamp(<span class="pl-s"><span class="pl-pds">'</span>01.01.2018 00:00:00<span class="pl-pds">'</span></span>, <span class="pl-s"><span class="pl-pds">'</span>DD.MM.YYYY HH24.MI.SS<span class="pl-pds">'</span></span>) <span class="pl-k">AS</span> res;</pre></div>
<p>Result:</p>
<table>
<thead>
<tr>
<th align="center">res</th>
</tr>
</thead>
<tbody>
<tr>
<td align="center">t</td>
</tr>
</tbody>
</table>
<div class="highlight highlight-source-sql"><pre><span class="pl-k">SELECT</span> is_timestamp(<span class="pl-s"><span class="pl-pds">'</span>01.01.2018 25:00:00<span class="pl-pds">'</span></span>, <span class="pl-s"><span class="pl-pds">'</span>DD.MM.YYYY HH24.MI.SS<span class="pl-pds">'</span></span>) <span class="pl-k">AS</span> res;</pre></div>
<p>Result:</p>
<table>
<thead>
<tr>
<th align="center">res</th>
</tr>
</thead>
<tbody>
<tr>
<td align="center">f</td>
</tr>
</tbody>
</table>
<div class="markdown-heading"><h3 class="heading-element">FUNCTION is_real</h3><a id="user-content-function-is_real" class="anchor" aria-label="Permalink: FUNCTION is_real" href="#function-is_real"><span aria-hidden="true" class="octicon octicon-link"></span></a></div>
<p>The function checks strings for being of data type REAL.</p>
<div class="markdown-heading"><h4 class="heading-element">Examples</h4><a id="user-content-examples-3" class="anchor" aria-label="Permalink: Examples" href="#examples-3"><span aria-hidden="true" class="octicon octicon-link"></span></a></div>
<div class="highlight highlight-source-sql"><pre><span class="pl-k">SELECT</span> is_real(<span class="pl-s"><span class="pl-pds">'</span>123.456<span class="pl-pds">'</span></span>) <span class="pl-k">AS</span> res;</pre></div>
<p>Result:</p>
<table>
<thead>
<tr>
<th align="center">res</th>
</tr>
</thead>
<tbody>
<tr>
<td align="center">t</td>
</tr>
</tbody>
</table>
<div class="highlight highlight-source-sql"><pre><span class="pl-k">SELECT</span> is_real(<span class="pl-s"><span class="pl-pds">'</span>123,456<span class="pl-pds">'</span></span>) <span class="pl-k">AS</span> res;
<span class="pl-c"><span class="pl-c">--</span> Result is false</span></pre></div>
<p>Result:</p>
<table>
<thead>
<tr>
<th align="center">res</th>
</tr>
</thead>
<tbody>
<tr>
<td align="center">f</td>
</tr>
</tbody>
</table>
<div class="markdown-heading"><h3 class="heading-element">FUNCTION is_double_precision</h3><a id="user-content-function-is_double_precision" class="anchor" aria-label="Permalink: FUNCTION is_double_precision" href="#function-is_double_precision"><span aria-hidden="true" class="octicon octicon-link"></span></a></div>
<p>The function checks strings for being of data type DOUBLE PRECISION.</p>
<div class="markdown-heading"><h4 class="heading-element">Examples</h4><a id="user-content-examples-4" class="anchor" aria-label="Permalink: Examples" href="#examples-4"><span aria-hidden="true" class="octicon octicon-link"></span></a></div>
<div class="highlight highlight-source-sql"><pre><span class="pl-k">SELECT</span> is_double_precision(<span class="pl-s"><span class="pl-pds">'</span>123.456<span class="pl-pds">'</span></span>) <span class="pl-k">AS</span> res;</pre></div>
<p>Result:</p>
<table>
<thead>
<tr>
<th align="center">res</th>
</tr>
</thead>
<tbody>
<tr>
<td align="center">t</td>
</tr>
</tbody>
</table>
<div class="highlight highlight-source-sql"><pre><span class="pl-k">SELECT</span> is_double_precision(<span class="pl-s"><span class="pl-pds">'</span>123,456<span class="pl-pds">'</span></span>) <span class="pl-k">AS</span> res;
<span class="pl-c"><span class="pl-c">--</span> Result is false</span></pre></div>
<p>Result:</p>
<table>
<thead>
<tr>
<th align="center">res</th>
</tr>
</thead>
<tbody>
<tr>
<td align="center">f</td>
</tr>
</tbody>
</table>
<div class="markdown-heading"><h3 class="heading-element">FUNCTION is_numeric</h3><a id="user-content-function-is_numeric" class="anchor" aria-label="Permalink: FUNCTION is_numeric" href="#function-is_numeric"><span aria-hidden="true" class="octicon octicon-link"></span></a></div>
<p>The function checks strings for being of data type NUMERIC.</p>
<div class="markdown-heading"><h4 class="heading-element">Examples</h4><a id="user-content-examples-5" class="anchor" aria-label="Permalink: Examples" href="#examples-5"><span aria-hidden="true" class="octicon octicon-link"></span></a></div>
<div class="highlight highlight-source-sql"><pre><span class="pl-k">SELECT</span> is_numeric(<span class="pl-s"><span class="pl-pds">'</span>123<span class="pl-pds">'</span></span>) <span class="pl-k">AS</span> res;</pre></div>
<p>Result:</p>
<table>
<thead>
<tr>
<th align="center">res</th>
</tr>
</thead>
<tbody>
<tr>
<td align="center">t</td>
</tr>
</tbody>
</table>
<div class="highlight highlight-source-sql"><pre><span class="pl-k">SELECT</span> is_numeric(<span class="pl-s"><span class="pl-pds">'</span>1 2<span class="pl-pds">'</span></span>) <span class="pl-k">AS</span> res;
<span class="pl-c"><span class="pl-c">--</span> Result is false</span></pre></div>
<p>Result:</p>
<table>
<thead>
<tr>
<th align="center">res</th>
</tr>
</thead>
<tbody>
<tr>
<td align="center">f</td>
</tr>
</tbody>
</table>
<div class="markdown-heading"><h3 class="heading-element">FUNCTION is_bigint</h3><a id="user-content-function-is_bigint" class="anchor" aria-label="Permalink: FUNCTION is_bigint" href="#function-is_bigint"><span aria-hidden="true" class="octicon octicon-link"></span></a></div>
<p>The function checks strings for being of data type BIGINT.</p>
<div class="markdown-heading"><h4 class="heading-element">Examples</h4><a id="user-content-examples-6" class="anchor" aria-label="Permalink: Examples" href="#examples-6"><span aria-hidden="true" class="octicon octicon-link"></span></a></div>
<div class="highlight highlight-source-sql"><pre><span class="pl-k">SELECT</span> is_bigint(<span class="pl-s"><span class="pl-pds">'</span>3243546343<span class="pl-pds">'</span></span>) <span class="pl-k">AS</span> res;
<span class="pl-c"><span class="pl-c">--</span> Result is true</span></pre></div>
<p>Result:</p>
<table>
<thead>
<tr>
<th align="center">res</th>
</tr>
</thead>
<tbody>
<tr>
<td align="center">t</td>
</tr>
</tbody>
</table>
<div class="highlight highlight-source-sql"><pre><span class="pl-k">SELECT</span> is_bigint(<span class="pl-s"><span class="pl-pds">'</span>123.456<span class="pl-pds">'</span></span>) <span class="pl-k">AS</span> res;
<span class="pl-c"><span class="pl-c">--</span> Result is false</span></pre></div>
<div class="markdown-heading"><h3 class="heading-element">FUNCTION is_integer</h3><a id="user-content-function-is_integer" class="anchor" aria-label="Permalink: FUNCTION is_integer" href="#function-is_integer"><span aria-hidden="true" class="octicon octicon-link"></span></a></div>
<p>The function checks strings for being of data type INTEGER.</p>
<div class="markdown-heading"><h4 class="heading-element">Examples</h4><a id="user-content-examples-7" class="anchor" aria-label="Permalink: Examples" href="#examples-7"><span aria-hidden="true" class="octicon octicon-link"></span></a></div>
<div class="highlight highlight-source-sql"><pre><span class="pl-k">SELECT</span> is_integer(<span class="pl-s"><span class="pl-pds">'</span>123<span class="pl-pds">'</span></span>) <span class="pl-k">AS</span> res;
<span class="pl-c"><span class="pl-c">--</span> Result is true</span></pre></div>
<p>Result:</p>
<table>
<thead>
<tr>
<th align="center">res</th>
</tr>
</thead>
<tbody>
<tr>
<td align="center">t</td>
</tr>
</tbody>
</table>
<div class="highlight highlight-source-sql"><pre><span class="pl-k">SELECT</span> is_integer(<span class="pl-s"><span class="pl-pds">'</span>123.456<span class="pl-pds">'</span></span>) <span class="pl-k">AS</span> res;
<span class="pl-c"><span class="pl-c">--</span> Result is false</span></pre></div>
<div class="markdown-heading"><h3 class="heading-element">FUNCTION is_smallint</h3><a id="user-content-function-is_smallint" class="anchor" aria-label="Permalink: FUNCTION is_smallint" href="#function-is_smallint"><span aria-hidden="true" class="octicon octicon-link"></span></a></div>
<p>The function checks strings for being of data type SMALLINT.</p>
<div class="markdown-heading"><h4 class="heading-element">Examples</h4><a id="user-content-examples-8" class="anchor" aria-label="Permalink: Examples" href="#examples-8"><span aria-hidden="true" class="octicon octicon-link"></span></a></div>
<div class="highlight highlight-source-sql"><pre><span class="pl-k">SELECT</span> is_smallint(<span class="pl-s"><span class="pl-pds">'</span>123<span class="pl-pds">'</span></span>) <span class="pl-k">AS</span> res;
<span class="pl-c"><span class="pl-c">--</span> Result is true</span></pre></div>
<p>Result:</p>
<table>
<thead>
<tr>
<th align="center">res</th>
</tr>
</thead>
<tbody>
<tr>
<td align="center">t</td>
</tr>
</tbody>
</table>
<div class="highlight highlight-source-sql"><pre><span class="pl-k">SELECT</span> is_smallint(<span class="pl-s"><span class="pl-pds">'</span>123.456<span class="pl-pds">'</span></span>) <span class="pl-k">AS</span> res;
<span class="pl-c"><span class="pl-c">--</span> Result is false</span></pre></div>
<p>Result:</p>
<table>
<thead>
<tr>
<th align="center">res</th>
</tr>
</thead>
<tbody>
<tr>
<td align="center">f</td>
</tr>
</tbody>
</table>
<div class="markdown-heading"><h3 class="heading-element">FUNCTION is_boolean</h3><a id="user-content-function-is_boolean" class="anchor" aria-label="Permalink: FUNCTION is_boolean" href="#function-is_boolean"><span aria-hidden="true" class="octicon octicon-link"></span></a></div>
<p>The function checks a string variable for containing valid BOOLEAN values.</p>
<table>
<thead>
<tr>
<th>boolean strings</th>
</tr>
</thead>
<tbody>
<tr>
<td>t</td>
</tr>
<tr>
<td>f</td>
</tr>
<tr>
<td>T</td>
</tr>
<tr>
<td>F</td>
</tr>
<tr>
<td>y</td>
</tr>
<tr>
<td>n</td>
</tr>
<tr>
<td>Y</td>
</tr>
<tr>
<td>N</td>
</tr>
<tr>
<td>true</td>
</tr>
<tr>
<td>false</td>
</tr>
<tr>
<td>TRUE</td>
</tr>
<tr>
<td>FALSE</td>
</tr>
<tr>
<td>yes</td>
</tr>
<tr>
<td>no</td>
</tr>
<tr>
<td>YES</td>
</tr>
<tr>
<td>NO</td>
</tr>
<tr>
<td>0</td>
</tr>
<tr>
<td>1</td>
</tr>
</tbody>
</table>
<div class="markdown-heading"><h4 class="heading-element">Examples</h4><a id="user-content-examples-9" class="anchor" aria-label="Permalink: Examples" href="#examples-9"><span aria-hidden="true" class="octicon octicon-link"></span></a></div>
<div class="highlight highlight-source-sql"><pre><span class="pl-k">SELECT</span> is_boolean(<span class="pl-s"><span class="pl-pds">'</span>t<span class="pl-pds">'</span></span>) <span class="pl-k">AS</span> res;
<span class="pl-c"><span class="pl-c">--</span> Result is true</span></pre></div>
<p>Result:</p>
<table>
<thead>
<tr>
<th align="center">res</th>
</tr>
</thead>
<tbody>
<tr>
<td align="center">t</td>
</tr>
</tbody>
</table>
<div class="highlight highlight-source-sql"><pre><span class="pl-k">SELECT</span> is_boolean(<span class="pl-s"><span class="pl-pds">'</span>F<span class="pl-pds">'</span></span>) <span class="pl-k">AS</span> res;
<span class="pl-c"><span class="pl-c">--</span> Result is true</span></pre></div>
<p>Result:</p>
<table>
<thead>
<tr>
<th align="center">res</th>
</tr>
</thead>
<tbody>
<tr>
<td align="center">t</td>
</tr>
</tbody>
</table>
<div class="highlight highlight-source-sql"><pre><span class="pl-k">SELECT</span> is_boolean(<span class="pl-s"><span class="pl-pds">'</span>True<span class="pl-pds">'</span></span>) <span class="pl-k">AS</span> res;
<span class="pl-c"><span class="pl-c">--</span> Result is true</span></pre></div>
<p>Result:</p>
<table>
<thead>
<tr>
<th align="center">res</th>
</tr>
</thead>
<tbody>
<tr>
<td align="center">t</td>
</tr>
</tbody>
</table>
<div class="highlight highlight-source-sql"><pre><span class="pl-k">SELECT</span> is_boolean(<span class="pl-s"><span class="pl-pds">'</span>False<span class="pl-pds">'</span></span>);
<span class="pl-c"><span class="pl-c">--</span> Result is true</span></pre></div>
<p>Result:</p>
<table>
<thead>
<tr>
<th align="center">res</th>
</tr>
</thead>
<tbody>
<tr>
<td align="center">t</td>
</tr>
</tbody>
</table>
<div class="highlight highlight-source-sql"><pre><span class="pl-k">SELECT</span> is_boolean(<span class="pl-s"><span class="pl-pds">'</span>0<span class="pl-pds">'</span></span>) <span class="pl-k">AS</span> res;
<span class="pl-c"><span class="pl-c">--</span> Result is true</span></pre></div>
<p>Result:</p>
<table>
<thead>
<tr>
<th align="center">res</th>
</tr>
</thead>
<tbody>
<tr>
<td align="center">t</td>
</tr>
</tbody>
</table>
<div class="highlight highlight-source-sql"><pre><span class="pl-k">SELECT</span> is_boolean(<span class="pl-s"><span class="pl-pds">'</span>1<span class="pl-pds">'</span></span>) <span class="pl-k">AS</span> res;
<span class="pl-c"><span class="pl-c">--</span> Result is true</span></pre></div>
<p>Result:</p>
<table>
<thead>
<tr>
<th align="center">res</th>
</tr>
</thead>
<tbody>
<tr>
<td align="center">t</td>
</tr>
</tbody>
</table>
<div class="highlight highlight-source-sql"><pre><span class="pl-k">SELECT</span> is_boolean(<span class="pl-s"><span class="pl-pds">'</span>-1<span class="pl-pds">'</span></span>) <span class="pl-k">AS</span> res;
<span class="pl-c"><span class="pl-c">--</span> Result is false</span></pre></div>
<p>Result:</p>
<table>
<thead>
<tr>
<th align="center">res</th>
</tr>
</thead>
<tbody>
<tr>
<td align="center">f</td>
</tr>
</tbody>
</table>
<div class="markdown-heading"><h3 class="heading-element">FUNCTION is_json</h3><a id="user-content-function-is_json" class="anchor" aria-label="Permalink: FUNCTION is_json" href="#function-is_json"><span aria-hidden="true" class="octicon octicon-link"></span></a></div>
<p>The function checks a string variable for containing a valid JSON.</p>
<div class="markdown-heading"><h4 class="heading-element">Examples</h4><a id="user-content-examples-10" class="anchor" aria-label="Permalink: Examples" href="#examples-10"><span aria-hidden="true" class="octicon octicon-link"></span></a></div>
<div class="highlight highlight-source-sql"><pre><span class="pl-k">SELECT</span> is_json(<span class="pl-s"><span class="pl-pds">'</span>{"review": {"date": "1970-12-30", "votes": 10, "rating": 5, "helpful_votes": 0}, "product": {"id": "1551803542", "group": "Book", "title": "Start and Run a Coffee Bar (Start & Run a)", "category": "Business & Investing", "sales_rank": 11611, "similar_ids": ["0471136174", "0910627312", "047112138X", "0786883561", "0201570483"], "subcategory": "General"}, "customer_id": "AE22YDHSBFYIP"}<span class="pl-pds">'</span></span>) <span class="pl-k">AS</span> res;</pre></div>
<p>Result:</p>
<table>
<thead>
<tr>
<th align="center">res</th>
</tr>
</thead>
<tbody>
<tr>
<td align="center">t</td>
</tr>
</tbody>
</table>
<div class="highlight highlight-source-sql"><pre><span class="pl-k">SELECT</span> is_json(<span class="pl-s"><span class="pl-pds">'</span>Not a JSON<span class="pl-pds">'</span></span>) <span class="pl-k">AS</span> res;</pre></div>
<p>Result:</p>
<table>
<thead>
<tr>
<th align="center">res</th>
</tr>
</thead>
<tbody>
<tr>
<td align="center">f</td>
</tr>
</tbody>
</table>
<div class="markdown-heading"><h3 class="heading-element">FUNCTION is_jsonb</h3><a id="user-content-function-is_jsonb" class="anchor" aria-label="Permalink: FUNCTION is_jsonb" href="#function-is_jsonb"><span aria-hidden="true" class="octicon octicon-link"></span></a></div>
<p>The function checks a string variable for containing a valid JSONB.</p>
<div class="markdown-heading"><h4 class="heading-element">Example</h4><a id="user-content-example" class="anchor" aria-label="Permalink: Example" href="#example"><span aria-hidden="true" class="octicon octicon-link"></span></a></div>
<div class="highlight highlight-source-sql"><pre><span class="pl-k">SELECT</span> is_jsonb(<span class="pl-s"><span class="pl-pds">'</span>{"review": {"date": "1970-12-30", "votes": 10, "rating": 5, "helpful_votes": 0}, "product": {"id": "1551803542", "group": "Book", "title": "Start and Run a Coffee Bar (Start & Run a)", "category": "Business & Investing", "sales_rank": 11611, "similar_ids": ["0471136174", "0910627312", "047112138X", "0786883561", "0201570483"], "subcategory": "General"}, "customer_id": "AE22YDHSBFYIP"}<span class="pl-pds">'</span></span>) <span class="pl-k">AS</span> res;</pre></div>
<p>Result:</p>
<table>
<thead>
<tr>
<th align="center">res</th>
</tr>
</thead>
<tbody>
<tr>
<td align="center">t</td>
</tr>
</tbody>
</table>
<div class="highlight highlight-source-sql"><pre><span class="pl-k">SELECT</span> is_jsonb(<span class="pl-s"><span class="pl-pds">'</span>Not a JSONB<span class="pl-pds">'</span></span>) <span class="pl-k">AS</span> res;</pre></div>
<p>Result:</p>
<table>
<thead>
<tr>
<th align="center">res</th>
</tr>
</thead>
<tbody>
<tr>
<td align="center">f</td>
</tr>
</tbody>
</table>
<div class="markdown-heading"><h3 class="heading-element">FUNCTION is_empty or is_empty_b</h3><a id="user-content-function-is_empty-or-is_empty_b" class="anchor" aria-label="Permalink: FUNCTION is_empty or is_empty_b" href="#function-is_empty-or-is_empty_b"><span aria-hidden="true" class="octicon octicon-link"></span></a></div>
<p>The function checks a string variable for being either, NULL or '' and is returing a boolean result.</p>
<p>The extension <a href="https://pgtap.org/" rel="nofollow">pgtap</a> has the same name for a function with the same purpose, but a different returning value.<br>
Therefore the function name differs, if pgtap is installed.</p>
<p>The function <strong>is_empty</strong>, when pgtap is not installed.</p>
<p>The function <strong>is_empty_b</strong>, when pgtap is not installed. The <strong>b</strong> stands for its boolean result.</p>
<div class="markdown-heading"><h4 class="heading-element">Examples</h4><a id="user-content-examples-11" class="anchor" aria-label="Permalink: Examples" href="#examples-11"><span aria-hidden="true" class="octicon octicon-link"></span></a></div>
<div class="highlight highlight-source-sql"><pre><span class="pl-k">SELECT</span> is_empty(<span class="pl-s"><span class="pl-pds">'</span>abc<span class="pl-pds">'</span></span>) <span class="pl-k">AS</span> res;
<span class="pl-c"><span class="pl-c">--</span> Result is false</span></pre></div>
<p>Result:</p>
<table>
<thead>
<tr>
<th align="center">res</th>
</tr>
</thead>
<tbody>
<tr>
<td align="center">f</td>
</tr>
</tbody>
</table>
<div class="highlight highlight-source-sql"><pre><span class="pl-k">SELECT</span> is_empty(<span class="pl-s"><span class="pl-pds">'</span><span class="pl-pds">'</span></span>) <span class="pl-k">AS</span> res;
<span class="pl-c"><span class="pl-c">--</span> Result is true</span></pre></div>
<p>Result:</p>
<table>
<thead>
<tr>
<th align="center">res</th>
</tr>
</thead>
<tbody>
<tr>
<td align="center">t</td>
</tr>
</tbody>
</table>
<div class="highlight highlight-source-sql"><pre><span class="pl-k">SELECT</span> is_empty(<span class="pl-k">NULL</span>) <span class="pl-k">AS</span> res;
<span class="pl-c"><span class="pl-c">--</span> Result is true</span></pre></div>
<p>Result:</p>
<table>
<thead>
<tr>
<th align="center">res</th>
</tr>
</thead>
<tbody>
<tr>
<td align="center">t</td>
</tr>
</tbody>
</table>
<div class="markdown-heading"><h3 class="heading-element">FUNCTION is_hex</h3><a id="user-content-function-is_hex" class="anchor" aria-label="Permalink: FUNCTION is_hex" href="#function-is_hex"><span aria-hidden="true" class="octicon octicon-link"></span></a></div>
<p>The function checks a string variable for being a hexadecimal number being a
bigint.</p>
<p>❗<span>This function needs to have
hex2bigint being installed!</span>❗</p>
<p>If you use the package, both functions are installed in the correct sort order.</p>
<div class="markdown-heading"><h4 class="heading-element">Examples</h4><a id="user-content-examples-12" class="anchor" aria-label="Permalink: Examples" href="#examples-12"><span aria-hidden="true" class="octicon octicon-link"></span></a></div>
<div class="highlight highlight-source-sql"><pre><span class="pl-k">SELECT</span> is_hex(<span class="pl-s"><span class="pl-pds">'</span>a1b0<span class="pl-pds">'</span></span>) <span class="pl-k">AS</span> res;
<span class="pl-c"><span class="pl-c">--</span> Result is true</span></pre></div>
<p>Result:</p>
<table>
<thead>
<tr>
<th align="center">res</th>
</tr>
</thead>
<tbody>
<tr>
<td align="center">t</td>
</tr>
</tbody>
</table>
<div class="highlight highlight-source-sql"><pre><span class="pl-k">SELECT</span> is_hex(<span class="pl-s"><span class="pl-pds">'</span>a1b0w<span class="pl-pds">'</span></span>) <span class="pl-k">AS</span> res;
<span class="pl-c"><span class="pl-c">--</span> Result is false</span></pre></div>
<p>Result:</p>
<table>
<thead>
<tr>
<th align="center">res</th>
</tr>
</thead>
<tbody>
<tr>
<td align="center">f</td>
</tr>
</tbody>
</table>
<div class="highlight highlight-source-sql"><pre><span class="pl-k">SELECT</span> is_hex(<span class="pl-s"><span class="pl-pds">'</span>a1b0c3c3c3c4b5d3<span class="pl-pds">'</span></span>) <span class="pl-k">AS</span> res;
<span class="pl-c"><span class="pl-c">--</span> Result is false (does not fit into a bigint)</span></pre></div>
<p>Result:</p>
<table>
<thead>
<tr>
<th align="center">res</th>
</tr>
</thead>
<tbody>
<tr>
<td align="center">f</td>
</tr>
</tbody>
</table>
<div class="markdown-heading"><h2 class="heading-element">Functions about encryption</h2><a id="user-content-functions-about-encryption" class="anchor" aria-label="Permalink: Functions about encryption" href="#functions-about-encryption"><span aria-hidden="true" class="octicon octicon-link"></span></a></div>
<div class="markdown-heading"><h3 class="heading-element">FUNCTION sha256</h3><a id="user-content-function-sha256" class="anchor" aria-label="Permalink: FUNCTION sha256" href="#function-sha256"><span aria-hidden="true" class="octicon octicon-link"></span></a></div>
<p>Creates a function which returns a SHA256 hash for the given string.<br>
The parameter has to be converted into a binary string of <a href="https://www.postgresql.org/docs/current/static/datatype-binary.html" rel="nofollow">bytea</a>.
:heavy_exclamation_mark:<span>The function needs the <a href="https://www.postgresql.org/docs/current/static/pgcrypto.html" rel="nofollow">pgcrypto</a> package</span>❗</p>
<p>❗This function has an external dependency and is only installed, if the package pgcrypto is installed❗</p>
<div class="markdown-heading"><h4 class="heading-element">Example</h4><a id="user-content-example-1" class="anchor" aria-label="Permalink: Example" href="#example-1"><span aria-hidden="true" class="octicon octicon-link"></span></a></div>
<div class="highlight highlight-source-sql"><pre><span class="pl-k">SELECT</span> sha256(<span class="pl-s"><span class="pl-pds">'</span>test-string<span class="pl-pds">'</span></span>::<span class="pl-k">bytea</span>) <span class="pl-k">AS</span> res;</pre></div>
<p>Result:</p>
<table>
<thead>
<tr>
<th align="center">res</th>
</tr>
</thead>
<tbody>
<tr>
<td align="center">ffe65f1d98fafedea3514adc956c8ada5980c6c5d2552fd61f48401aefd5c00e</td>
</tr>
</tbody>
</table>
<div class="markdown-heading"><h2 class="heading-element">Functions and views to get extended system information</h2><a id="user-content-functions-and-views-to-get-extended-system-information" class="anchor" aria-label="Permalink: Functions and views to get extended system information" href="#functions-and-views-to-get-extended-system-information"><span aria-hidden="true" class="octicon octicon-link"></span></a></div>
<div class="markdown-heading"><h3 class="heading-element">FUNCTION pg_schema_size</h3><a id="user-content-function-pg_schema_size" class="anchor" aria-label="Permalink: FUNCTION pg_schema_size" href="#function-pg_schema_size"><span aria-hidden="true" class="octicon octicon-link"></span></a></div>
<p>The function returns the size for schema given as parameter in bytes.</p>
<div class="markdown-heading"><h4 class="heading-element">Examples</h4><a id="user-content-examples-13" class="anchor" aria-label="Permalink: Examples" href="#examples-13"><span aria-hidden="true" class="octicon octicon-link"></span></a></div>
<div class="highlight highlight-source-sql"><pre><span class="pl-c"><span class="pl-c">--</span> Returns the size of the schema public in bytes</span>
<span class="pl-k">SELECT</span> pg_schema_size(<span class="pl-s"><span class="pl-pds">'</span>public<span class="pl-pds">'</span></span>);</pre></div>
<p>Result:</p>
<table>
<thead>
<tr>
<th align="right">pg_schema_size</th>
</tr>
</thead>
<tbody>
<tr>
<td align="right">348536832</td>
</tr>
</tbody>
</table>
<div class="highlight highlight-source-sql"><pre><span class="pl-c"><span class="pl-c">--</span> Returns the size of the schema public formatted</span>
<span class="pl-k">SELECT</span> pg_size_pretty(pg_schema_size(<span class="pl-s"><span class="pl-pds">'</span>public<span class="pl-pds">'</span></span>));</pre></div>
<p>Result:</p>
<table>
<thead>
<tr>
<th align="right">pg_schema_size</th>
</tr>
</thead>
<tbody>
<tr>
<td align="right">332 MB</td>
</tr>
</tbody>
</table>
<div class="markdown-heading"><h3 class="heading-element">VIEW pg_db_views</h3><a id="user-content-view-pg_db_views" class="anchor" aria-label="Permalink: VIEW pg_db_views" href="#view-pg_db_views"><span aria-hidden="true" class="octicon octicon-link"></span></a></div>
<p>Creates a view to get all views of the current database but excluding system views and all views which do start with "pg" or "_pg".</p>
<div class="highlight highlight-source-sql"><pre><span class="pl-k">SELECT</span> <span class="pl-k">*</span>
<span class="pl-k">FROM</span> pg_db_views;</pre></div>
<table>
<thead>
<tr>
<th>view_catalog</th>
<th>view_schema</th>
<th>view_name</th>
<th>view_definition</th>
</tr>
</thead>
<tbody>
<tr>
<td>chinook</td>
<td>public</td>
<td>v_json_artist_data</td>
<td>WITH tracks AS (</td>
</tr>
<tr>
<td></td>
<td></td>
<td></td>
<td>SELECT "Track"."AlbumId" AS album_id,</td>
</tr>
<tr>
<td></td>
<td></td>
<td></td>
<td>"Track"."TrackId" AS track_id,</td>
</tr>
<tr>
<td></td>
<td></td>
<td></td>
<td>"Track"."Name" AS track_name,</td>
</tr>
<tr>
<td></td>
<td></td>
<td></td>
<td>"Track"."MediaTypeId" AS media_type_id,</td>
</tr>
<tr>
<td></td>
<td></td>
<td></td>
<td>"Track"."Milliseconds" AS milliseconds,</td>
</tr>
<tr>
<td></td>
<td></td>
<td></td>
<td>"Track"."UnitPrice" AS unit_price</td>
</tr>
<tr>
<td></td>
<td></td>
<td></td>