立即与支持人员聊天
与支持团队交流

SQL Optimizer for Oracle 10.0 - User Guide

Welcome to SQL Optimizer
About SQL Optimizer SQL Optimization Workflow New in This Release Additional Resources Database Privileges Database Privileges Script Connect to the Database Windows Layout Customize Toolbars Keyboard Shortcuts Support Bundle Register SQL Optimizer Check for Updates SQL Operations
ALL PARTITION ALTER INDEX AND EQUAL ANTI JOIN BITMAP AND BITMAP COMPACTION BITMAP CONSTRUCTION BITMAP CONVERSION BITMAP INDEX BITMAP JOIN INDEX UPDATE BITMAP JOIN INDEX UPDATE STATEMENT BITMAP KEY ITERATION BITMAP MERGE BITMAP MINUS BITMAP OR BUFFER SORT CARTESIAN JOIN COLLECTION ITERATOR CONCATENATION CONNECT BY CONNECT BY PUMP COUNT COUNT STOPKEY CREATE AS SELECT CUBE SCAN DDL STATEMENT DELETE DOMAIN INDEX FAST FULL INDEX SCAN FILTER FIRST ROWS FIXED INDEX FIXED TABLE FOR UPDATE FULL INDEX SCAN FULL INDEX SCAN DESCENDING FULL INDEX SCAN (MIN/MAX) HASH GROUP BY HASH GROUP BY PIVOT HASH JOIN HASH JOIN BUFFERED HASH PARTITION HASH UNIQUE INDEX INDEX BUILD NON UNIQUE INDEX RANGE SCAN INDEX RANGE SCAN DESCENDING INDEX RANGE SCAN (MIN/MAX) INDEX SAMPLE FAST FULL SCAN INDEX SKIP SCAN INDEX SKIP SCAN DESCENDING INDEX UNIQUE SCAN INLIST ITERATOR INLIST PARTITION INSERT INTERSECTION INTO INVALID PARTITION ITERATOR PARTITION LOAD AS SELECT MAT_VIEW ACCESS MAT_VIEW REWRITE ACCESS MERGE JOIN MINUS MULTI-TABLE INSERT NESTED LOOPS OUTER JOIN PARTITION PARTITION HASH EMPTY PARTITION LIST PARTITION RANGE PROJECTION PX BLOCK ITERATOR PX COORDINATOR PX ITERATOR PX PARTITION PX PARTITION HASH ALL PX PARTITION LIST ALL PX PARTITION RANGE ALL PX RECEIVE PX SEND RANGE PARTITION RECURSIVE EXECUTION RECURSIVE WITH PUMP REFERENCE MODEL REMOTE SELECT SEMI JOIN SEQUENCE SINGLE PARTITION SINGLE RANGE PARTITION SORT SORT AGGREGATE SORT GROUP BY SORT GROUP BY CUBE SORT GROUP BY NOSORT SORT GROUP BY ROLLUP SORT JOIN SORT ORDER BY SORT UNIQUE SQL MODEL TABLE ACCESS TABLE ACCESS BY GLOBAL INDEX ROWID TABLE ACCESS BY INDEX ROWID TABLE ACCESS BY LOCAL INDEX ROWID TABLE ACCESS BY ROWID TABLE ACCESS BY USER ROWID TABLE ACCESS CLUSTER TABLE ACCESS FULL TABLE ACCESS HASH TABLE ACCESS SAMPLE TABLE QUEUE TEMP TABLE GENERATION TEMP TABLE TRANSFORMATION UNION UNION ALL UNION ALL (RECURSIVE WITH) UNPIVOT UPDATE VIEW VIEW PUSHED PREDICATE WINDOW
Optimize SQL
Create Optimize SQL Sessions Open Optimizer SQL Sessions Rewrite SQL Generate Execution Plan Alternatives
Optimize Indexes Batch Optimize SQL Scan SQL Inspect SGA Analyze Impact Manage Plans Configure Options SQL Optimizer Tutorials About Us Legal Notices

BITMAP MINUS

Execution Plan image: image\Plan_Bitmap_Minus.gif

Row operation.

The BITMAP MINUS operation subtracts one bitmap from another.

 

Related Topics

 

BITMAP OR

Execution plan image: image\Plan_Bitmap_OR.gif

Row operation.

The BITMAP OR operation is a bit-wise OR between two bitmap indexes; if either bitmap index returns the entry, the BITMAP OR of the two indexes will return an entry. The result of the BITMAP OR operation is a list of all the values that are in either index. The BITMAP OR operation is functionally equivalent to the CONCATENATION operation between B-Tree indexes.

Example

Assume that both City and State columns each has a single-column bitmap index.

select Name, City, State
from COMPANY
where City = 'Portland'
and State = 'MD';

This query selects rows from the COMPANY Table for all companies in the state "MD" or in the city named "Portland."

Execution Plan

TABLE ACCESS (BY INDEX ROWID) OF 'COMPANY' (Cost=7 Card=26 Bytes=1040)
BITMAP CONVERSION (TO ROWIDS)
BITMAP OR
  BITMAP INDEX (SINGLE VALUE) OF 'COMPANY$CITY'
  BITMAP INDEX (SINGLE VALUE) OF 'COMPANY$STATE'         

Interpreting the Execution Plan

The Execution Plan shows that the bitmap index on the City Column is used to find a bitmap for all the rows in the COMPANY table that satisfy the WHERE clause condition (where City='Portland'). Another bitmap is created from the index on the State column (for the condition State='MD'). The two bitmaps are then united to one bitmap using a BITMAP OR operation. The resulting bitmap is converted to a list of ROWIDs to access the COMPANY table.

 

Related Topics

 

BUFFER SORT

Execution plan image:

The BUFFER SORT operation reads frequently accessed data during statement execution into private memory to reduce overhead.

 

 

CARTESIAN JOIN

Execution plan image: image\Plan_Connect_By_Cartesian.gif, image\Plan_Nested_Loops_Cartesian.gif, image\Plan_Merge_Join_Cartesian.gif or image\Plan_Hash_Join_Cartesian.gif   

Join operation.

A join with no join condition results in a CARTESIAN product, or a cross product. A CARTESIAN product is the set of all possible combinations of rows drawn from each table. In other words, for a join of two tables, each row in one table is matched with every row in the other. A CARTESIAN product for more than two tables is the result of pairing each row of one table with every row of the Cartesian product of the remaining tables.

All other kinds of joins are subsets of CARTESIAN products effectively created by deriving the CARTESIAN product and then excluding rows that fail the join condition.

Note: When using the ORDERED hint, it is important that the tables in the FROM clause are listed in the correct order to prevent CARTESIAN joins.

Hint: Consider using Oracle’s STAR query optimization when joining a very large "fact" table to smaller, unrelated "dimension" tables. You will need a concatenated index on the fact table and may need to specify the STAR hint.

 

 

相关文档

The document was helpful.

选择评级

I easily found the information I needed.

选择评级