postgres.git / summary / log / commit / refs

commit    9577dd523b3e3bb7fba66e708dfb9ca76e299b7e
Author:   Andrew Dunstan <andrew@dunslane.net>
Date:     Fri Jan 03 14:23:46 2025 +0000

    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 339fcba4f9e..c5818566692 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: 6a2440167a8b]