From f1c779e2b9e48eab05ad471e4111eb17e7e6ad3a Mon Sep 17 00:00:00 2001
From: Bruce Momjian <bruce@momjian.us>
Date: Fri, 8 Jul 2022 20:23:35 -0400
Subject: [PATCH] doc: add examples for array_length() and
jsonb_array_length()
The examples show the output of array_length() and jsonb_array_length()
for empty arrays.
Discussion: https://postgr.es/m/CAKFQuwaoBmRuWdMLzLHDCFDJDX3wvfQ7egAF0bpik_BFgG1KWg@mail.gmail.com
Author: David G. Johnston
Backpatch-through: 13
---
doc/src/sgml/func.sgml | 13 +++++++++++++
1 file changed, 13 insertions(+)
diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
index 9a177a4e8c8..6ce54c1ee1f 100644
--- a/doc/src/sgml/func.sgml
+++ b/doc/src/sgml/func.sgml
@@ -15446,6 +15446,10 @@ table2-mapping
<para>
<literal>json_array_length('[1,2,3,{"f1":1,"f2":[5,6]},4]')</literal>
<returnvalue>5</returnvalue>
+ </para>
+ <para>
+ <literal>jsonb_array_length('[]')</literal>
+ <returnvalue>0</returnvalue>
</para></entry>
</row>
@@ -17887,10 +17891,19 @@ SELECT NULLIF(value, '(none)') ...
</para>
<para>
Returns the length of the requested array dimension.
+ (Produces NULL instead of 0 for empty or missing array dimensions.)
</para>
<para>
<literal>array_length(array[1,2,3], 1)</literal>
<returnvalue>3</returnvalue>
+ </para>
+ <para>
+ <literal>array_length(array[]::int[], 1)</literal>
+ <returnvalue>NULL</returnvalue>
+ </para>
+ <para>
+ <literal>array_length(array['text'], 2)</literal>
+ <returnvalue>NULL</returnvalue>
</para></entry>
</row>