postgres.git / summary / log / commit / refs

commit    bd606ed8ec65f7ad388c3dead9ba200bf0b4fa6a
Author:   Andrew Dunstan <andrew@dunslane.net>
Date:     Fri Jan 03 14:23:46 2025 +0000
First released in: 18.0, 13.19, 14.16, 15.11, 16.7, 17.3

    Document strange jsonb sort order for empty top level arrays
    
    Slightly faulty logic in the original jsonb code (commit d9134d0a355)
    results in an empty top level array sorting less than a json null. We
    can't change the sort order now since it would affect btree indexes over
    jsonb, so document the anomaly.
    
    Backpatch to all live branches (13 .. 17)
    
    In master, also add a code comment noting the anomaly.
    
    Reported-by: Yan Chengpen
    Reviewed-by: Jian He
    
    Discussion: https://postgr.es/m/OSBPR01MB45199DD8DA2D1CECD50518188E272@OSBPR01MB4519.jpnprd01.prod.outlook.com


 doc/src/sgml/json.sgml | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/doc/src/sgml/json.sgml b/doc/src/sgml/json.sgml
index 06e2d655f6a..b3340469464 100644
--- a/doc/src/sgml/json.sgml
+++ b/doc/src/sgml/json.sgml
@@ -584,12 +584,13 @@ SELECT jdoc->'guid', jdoc->'name' FROM api WHERE jdoc @@ '$.tags[*] == "qui"';
     The <literal>btree</literal> ordering for <type>jsonb</type> datums is seldom
     of great interest, but for completeness it is:
 <synopsis>
-<replaceable>Object</replaceable> > <replaceable>Array</replaceable> > <replaceable>Boolean</replaceable> > <replaceable>Number</replaceable> > <replaceable>String</replaceable> > <replaceable>Null</replaceable>
+<replaceable>Object</replaceable> > <replaceable>Array</replaceable> > <replaceable>Boolean</replaceable> > <replaceable>Number</replaceable> > <replaceable>String</replaceable> > <replaceable>null</replaceable>
 
 <replaceable>Object with n pairs</replaceable> > <replaceable>object with n - 1 pairs</replaceable>
 
 <replaceable>Array with n elements</replaceable> > <replaceable>array with n - 1 elements</replaceable>
 </synopsis>
+      with the exception that (for historical reasons) an empty top level array sorts less than <replaceable>null</replaceable>.
       Objects with equal numbers of pairs are compared in the order:
 <synopsis>
 <replaceable>key-1</replaceable>, <replaceable>value-1</replaceable>, <replaceable>key-2</replaceable> ...


[parent: 24a1948ad2b3]