vb.net barcode component SIMPLE B-TREE ACCESS in Java

Printing Code 39 Extended in Java SIMPLE B-TREE ACCESS

CHAPTER 4 SIMPLE B-TREE ACCESS
Create ANSI/AIM Code 39 In Java
Using Barcode generator for Java Control to generate, create Code39 image in Java applications.
www.OnBarcode.com
Code 3 Of 9 Scanner In Java
Using Barcode scanner for Java Control to read, scan read, scan image in Java applications.
www.OnBarcode.com
REBUILDING INDEXES
Make Barcode In Java
Using Barcode maker for Java Control to generate, create Barcode image in Java applications.
www.OnBarcode.com
Barcode Creator In Java
Using Barcode printer for Java Control to generate, create Barcode image in Java applications.
www.OnBarcode.com
You can often reduce the number of leaf_blocks (and, very occasionally, the blevel) of an index by rebuilding the index; but rebuilding an index has no effect on the clustering_factor. Rebuilding an index may make that index appear more desirable to the optimizer, but the side effects may be good or bad. On the plus side, rebuilding an index may introduce a caching benefit for that index at query time but the downside is a possible contention penalty on DML, combined with an increase in leaf blocks splits and redo generated as the index tries to get back to its equilibrium state. Counterintuitively, an index may end up needing regular rebuilds because you ve started to rebuild it regularly (see script rebuild_test.sql in the online code suite for an artificial example demonstrating the concept). If you want to get the optimizer to behave properly, it is usually more important to check whether or not the clustering_factor represents the real data scattering and do something about that, rather than simply wedging the index into a tighter hole.
GS1 DataBar Expanded Drawer In Java
Using Barcode generation for Java Control to generate, create GS1 DataBar Truncated image in Java applications.
www.OnBarcode.com
2D Barcode Encoder In Java
Using Barcode printer for Java Control to generate, create 2D image in Java applications.
www.OnBarcode.com
Extending the Algorithm
Generate Code128 In Java
Using Barcode creator for Java Control to generate, create Code 128B image in Java applications.
www.OnBarcode.com
Encoding ISSN In Java
Using Barcode maker for Java Control to generate, create International Standard Serial Number image in Java applications.
www.OnBarcode.com
Let s take a look at some more general examples of costing. For example: How do you handle range-based tests (e.g., n2 between 1 and 3) How do you handle partial use of a multicolumn index What effects do in-lists have How special is an index full scan What does the optimizer do when you don t have to visit the table
Create Code 3/9 In Visual Studio .NET
Using Barcode generation for .NET framework Control to generate, create Code 3 of 9 image in VS .NET applications.
www.OnBarcode.com
ANSI/AIM Code 39 Recognizer In None
Using Barcode reader for Software Control to read, scan read, scan image in Software applications.
www.OnBarcode.com
How Do You Handle Range-based Tests (e.g., n2 between 1 and 3)
EAN-13 Scanner In None
Using Barcode reader for Software Control to read, scan read, scan image in Software applications.
www.OnBarcode.com
Recognizing QR Code In VS .NET
Using Barcode decoder for .NET Control to read, scan read, scan image in .NET applications.
www.OnBarcode.com
Let s try it and see. Try running the following query (btree_cost_02.sql in the online code suite) against our base data set with autotrace enabled: select /*+ index(t1) */ small_vc from t1 where and and ; n1 = 2 ind_pad = rpad('x',40) n2 between 1 and 3
PDF417 Printer In None
Using Barcode maker for Office Word Control to generate, create PDF 417 image in Office Word applications.
www.OnBarcode.com
Painting PDF 417 In None
Using Barcode creation for Software Control to generate, create PDF 417 image in Software applications.
www.OnBarcode.com
CHAPTER 4 SIMPLE B-TREE ACCESS
Code-39 Generator In None
Using Barcode creator for Online Control to generate, create Code 39 Extended image in Online applications.
www.OnBarcode.com
USS Code 39 Encoder In Java
Using Barcode encoder for Eclipse BIRT Control to generate, create Code-39 image in BIRT applications.
www.OnBarcode.com
Execution Plan (9.2.0.6 and 10.1.0.4) ---------------------------------------------------------0 SELECT STATEMENT Optimizer=ALL_ROWS (Cost=93 Card=82 Bytes=4756) 1 0 TABLE ACCESS (BY INDEX ROWID) OF 'T1' (Cost=93 Card=82 Bytes=4756) 2 1 INDEX (RANGE SCAN) OF 'T1_I1' (NON-UNIQUE) (Cost=12 Card=82) You ll note that I ve had to include an index hint with this statement, as the cost of using the index is rather higher than the cost of a tablescan. (The number of blocks below the table s high water mark was 371, and my setting for db_file_multiblock_read_count was 8, so in the absence of CPU costing, 9i calculated the tablescan cost as 1 + 371 / 6.588 = 58.) As ever, we need to think about selectivity. The individual selectivities on columns ind_pad and n1 are unchanged at 1 and 0.04 respectively, but we now have a range-based predicate on n2. Referring to 3, we can pull out the formula for the between predicate: selectivity (n2 between 1 and 3) = required range / total range + 1/num_distinct + 1/num_distinct = (3 1) / (19 0) + 1/20 + 1/20 = 0.205263 As with the previous example, every predicate applies to both the index and the table, so this number can be used in both places in the formula. Slotting the numbers in, then, we get the following: Effective index selectivity = 1 * 0.04 * 0.205263 = 0.0082105 Effective table selectivity = 1 * 0.04 * 0.205263 = 0.0082105 Cost = 2 + ceiling(1,111 * 0.0082105) + -- 10 ceiling(9,745 * 0.00082105) -- 81 = 12 (index line of plan) + 81 = 93 -- as required There was one little glitch in this test that I haven t disclosed. I labelled the execution plan with (9.2.0.6 and 10.1.0.4) . When I repeated the test under 8i, there was a small difference the cardinality changed from 82 to 83. The calculated cardinality is defined as Input rows * calculated selectivity 10,000 * 0.00882105 = 82.105 -- should this be 82, or 83 This is actually something we have seen before in 3. 8i always seems to round cardinality up (the ceiling() function, or as SQL puts it, the ceil() function), but 9i and 10g round to the nearest whole number (the round() function).
GS1 - 13 Maker In Java
Using Barcode encoder for Android Control to generate, create GS1 - 13 image in Android applications.
www.OnBarcode.com
Code 39 Full ASCII Generator In VS .NET
Using Barcode maker for ASP.NET Control to generate, create Code 39 Extended image in ASP.NET applications.
www.OnBarcode.com
Barcode Maker In VS .NET
Using Barcode maker for ASP.NET Control to generate, create Barcode image in ASP.NET applications.
www.OnBarcode.com
Scanning EAN / UCC - 13 In Visual Studio .NET
Using Barcode decoder for Visual Studio .NET Control to read, scan read, scan image in .NET framework applications.
www.OnBarcode.com
Copyright © OnBarcode.com . All rights reserved.