On Wed, 5 Jan 2005, Mage wrote: > "order by a asc b desc" > > how can I create an index for this?
You need to create an operator class for reversed comparison of whatever type b is and then use it on b in the index definition. Something like (however, you should really use a C function for the reverse comparison function rather than the sql one shown here): create function btint4cmprev(integer, integer) returns integer as 'select btint4cmp($2,$1);' language 'sql'; CREATE OPERATOR CLASS int4_desc_ops FOR TYPE int4 USING BTREE AS OPERATOR 1 >, OPERATOR 2 >=, OPERATOR 3 =, OPERATOR 4 <=, OPERATOR 5 <, FUNCTION 1 btint4cmprev(int4,int4); which you could then use something like: create index testindex on testtable(a, b int4_desc_ops); ---------------------------(end of broadcast)--------------------------- TIP 1: subscribe and unsubscribe commands go to [EMAIL PROTECTED]
