# javascript code 39 barcode generator JOIN CARDINALITY in Java Printing Code39 in Java JOIN CARDINALITY

CHAPTER 10 JOIN CARDINALITY
Encode Code 39 Extended In Java
Using Barcode maker for Java Control to generate, create ANSI/AIM Code 39 image in Java applications.
www.OnBarcode.com
USS Code 39 Reader In Java
Using Barcode recognizer for Java Control to read, scan read, scan image in Java applications.
www.OnBarcode.com
Intermediate to T3: the table with 150 rows: Join Selectivity = (120 - 10) / 120) * -- the CBO uses the t2 figures at one end (150 - 10) / 150) / -- of the join, and the t3 at the other. greater(11, 14) = 0.0611111 Join Cardinality = 0.061111 * 900 * 150 = 8,250 But the new-style 9i calculations look like this: T1 to T2: the tables with 100 and 120 rows respectively: Join Selectivity = 1 / greater(9, 11) = 0.09090909 Join Cardinality = 0.09090909 * 90 * 110 = 900 Intermediate to T3: the table with 150 rows: Join Selectivity = 1 / greater(11, 14) = 0.0714285 Join Cardinality = 0.0714285 * 900 * 140 = 9,000
Making Code 3 Of 9 In Java
Using Barcode creator for Java Control to generate, create ANSI/AIM Code 39 image in Java applications.
www.OnBarcode.com
Code 128 Generation In Java
Using Barcode creation for Java Control to generate, create Code 128A image in Java applications.
www.OnBarcode.com
(as required)
Printing EAN 128 In Java
Using Barcode drawer for Java Control to generate, create UCC-128 image in Java applications.
www.OnBarcode.com
UPCA Printer In Java
Using Barcode encoder for Java Control to generate, create GTIN - 12 image in Java applications.
www.OnBarcode.com
Note, with 9i, how we have factored the effects of the is not null predicates into the join cardinality line as the filtered cardinality of each of the individual tables. This gives us a more appropriate answer than the 8i strategy, which has factored the null count of n1 into the calculations twice, once in the first join and then again in the second join, and so produced a final cardinality that is too low. Of course, as you upgrade from 8i to 9i, queries involving multiple tables joining along the same nullable columns may suddenly change their execution plans because the computed cardinality goes up. If the computed cardinality has increased for one step of a query, the optimizer may decide that the next step should be a hash or merge join rather than a nested loop join. I can t think of a rationale why this change only applies when the null count exceeds 5% of the row count, as it seems to be reasonable to invoke the rule across the board. But perhaps the limit has been imposed to reduce the number of queries that might change path on upgrade.
Code 39 Full ASCII Creation In Java
Using Barcode printer for Java Control to generate, create Code 3 of 9 image in Java applications.
www.OnBarcode.com
Generate EAN-8 In Java
Using Barcode creation for Java Control to generate, create EAN-8 Supplement 2 Add-On image in Java applications.
www.OnBarcode.com
CHAPTER 10 JOIN CARDINALITY
Encode Code-39 In .NET Framework
Using Barcode creator for Reporting Service Control to generate, create Code39 image in Reporting Service applications.
www.OnBarcode.com
Draw Code39 In Java
Using Barcode maker for BIRT reports Control to generate, create Code 39 Full ASCII image in BIRT reports applications.
www.OnBarcode.com
Implementation Issues
Read Data Matrix In Visual C#
Using Barcode recognizer for VS .NET Control to read, scan read, scan image in .NET framework applications.
www.OnBarcode.com
Using Barcode scanner for Software Control to read, scan read, scan image in Software applications.
www.OnBarcode.com
There are many ways to implement Oracle systems badly, and as a general rule, anything that hides useful information from the optimizer is a bad idea. One of the simple, and highly popular, strategies for doing this is to stick all your reference data into a single table with a type column. The results can be catastrophic as far as the optimizer is concerned. Unless you are very lucky, the optimizer will calculate ridiculously inappropriate cardinalities for most simple joins to this reference table. For example (see script type_demo.sql in the online code suite): create table t1 as with generator as ( select --+ materialize rownum id from all_objects where rownum <= 3000 ) select trunc(dbms_random.value(0,20)) trunc(dbms_random.value(0,25)) rownum lpad(rownum,10,'0') from generator v1, generator v2 where rownum <= 500000 ;
Draw Barcode In Visual Studio .NET
Using Barcode drawer for ASP.NET Control to generate, create Barcode image in ASP.NET applications.
www.OnBarcode.com
Barcode Printer In None
Using Barcode generation for Font Control to generate, create Barcode image in Font applications.
www.OnBarcode.com
class1_code, class2_code, id, small_vc
Print Data Matrix 2d Barcode In VB.NET
Using Barcode generator for VS .NET Control to generate, create Data Matrix image in VS .NET applications.
www.OnBarcode.com
Scan UPC - 13 In Java
www.OnBarcode.com
We create a table of 500,000 rows that requires two lookups to expand meaningless code numbers into recognizable descriptions. I have restricted the test case to just a pair of reference sets with similar numbers of entries in each set to avoid some of the oddities that I mention in the next section, and to keep the arithmetic straightforward. Consider the following query: select t1.small_vc, type1.description from t1, type1 where and and and ; t1.id type1.id type1.type type1.description between 1000 and 1999 = t1.class1_code = 'CURRENCY' = 'GBP'
UPC A Creator In VS .NET
Using Barcode encoder for VS .NET Control to generate, create UPC-A Supplement 2 image in .NET applications.
www.OnBarcode.com
Barcode Maker In Visual Basic .NET
Using Barcode maker for VS .NET Control to generate, create Barcode image in Visual Studio .NET applications.
www.OnBarcode.com
CHAPTER 10 JOIN CARDINALITY
Barcode Printer In .NET Framework
Using Barcode encoder for Reporting Service Control to generate, create Barcode image in Reporting Service applications.
www.OnBarcode.com
Denso QR Bar Code Printer In None
Using Barcode generation for Software Control to generate, create QR Code image in Software applications.
www.OnBarcode.com
All this does is select some rows from my large table, and join to a reference table to translate a code into a description to eliminate data based on that description. This is typical of the way in which an end-user query would have to make use of the type table. (The SQL in the test case in the download does not use the literal values 'CURRENCY' and 'GBP', but I thought that a couple of meaningful code samples would help make the point of the example more clearly.) So what does the execution plan look like It depends on what you ve done with your reference tables. Here s one option for the reference table the currency data (or 'CLASS1' as it really was) is stored in a table all by itself: create table type1 as select rownum-1 'CLASS1' lpad(rownum-1,10,'0') from all_objects where rownum <= 20 ;