Changes between Version 4 and Version 5 of waue/2010/0128

Timestamp:

Jan 29, 2010, 6:01:17 PM (15 years ago)

Author:

waue

Comment:

--

waue/2010/0128

@@ -11 +11 @@
 = what is secondary index (distinguished to primary index) =
 
-Explain what is primary and secondary index.
+indexing with another field which is not primary key.
+
+內容與原本table 相似的另一張table，但key 不同，利於排列內容
+
+如： table1 (primary)
+ ||   || '''name''' || '''price'''  || '''description'''  || 
+ || 1 || apple || 10 || xxx || 
+ || 2 || orig || 5 || ooo || 
+ || 3 || banana || 15 || vvvv || 
+ || 4 || tomato || 8 || uuuu || 
+
+使用者想依售價做排序，則可以建立 secondary index table
+ ||  '''price'''   || '''name''' || '''description'''  || 
+ || 5 || orig  || ooo || 
+ || 8 || tomato || uuuu || 
+ || 10 || apple || xxx || 
+ || 15 || banana  || vvvv || 
+
+
+ == Explain what is primary and secondary index ==
 
 When you activate an object say ODS / DSO, the system automatically generate an index based on the key fields and this is primary index.