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SQL Optimizer for Oracle 10.0 - User Guide

Welcome to SQL Optimizer
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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
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TABLE ACCESS BY ROWID

Execution Plan image: image\Plan_By_Rowid.gif  

Table Access operation.

TABLE ACCESS BY ROWID returns a single row from a table, based on the ROWID provided to the operation. This is the fastest way to return data from a table.

Note: TABLE ACCESS BY ROWID may also represent an implicit FILTER operation.

Example

select Name
from COMPANY
where Company_ID = 12345
and Active_Flag = 'Y';

Execution Plan

TABLE ACCESS BY ROWID COMPANY
INDEX UNIQUE SCAN COMPANY_PK

Interpreting the Execution Plan

As shown in the Execution Plan, the use of the Company_ID column in the query’s WHERE clause allowed the COMPANY_PK index to be used. That index does not also contain the Name column, so Oracle must access the COMPANY table, using the ROWID returned by the index, to get the Name value. An implicit FILTER is then performed to return only the rows with Active_Flag = 'Y'.

 

TABLE ACCESS BY USER ROWID

Execution Plan image: image\Plan_By_User_Rowid.gif   

Table Access operation.

TABLE ACCESS BY USER ROWID is used to access records using records provided by a bind variable, literal or WHERE CURRENT OF CURSOR clause.

 

Related Topics

TABLE ACCESS CLUSTER

Execution Plan image: image\Plan_Table_Access_Cluster.gif   

Table Access operation.

TABLE ACCESS CLUSTER returns rows from a table that is stored within a cluster, when the cluster key is used.

The query from the NESTED LOOPS topic is used here again as an example. For the purposes of this example, assume that the COMPANY table is stored in a cluster, named COMPANY_CLUSTER, and the cluster key is the Company_ID column. The name of the cluster key index (on Company_ID) is COMPANY_CLUSTER_NDX.

Example

select COMPANY.Name
from COMPANY, SALES
where COMPANY.Company_D = SALES.Company_ID
and SALES.Period_ID = 3
and SALES.Sales_Total>1000;

Execution Plan

NESTED LOOPS
TABLE ACCESS FULL SALES
TABLE ACCESS CLUSTER COMPANY
INDEX UNIQUE SCAN COMPANY_CLUSTER_NDX

Interpreting the Execution Plan

The Execution Plan shows that the SALES table is used as the driving table for the query. For each Company_ID value in the SALES table, there is an access to the COMPANY table using the cluster index on the Company_ID column.

 

Related Topics

 

TABLE ACCESS FULL

Execution Plan image: image\Plan_Table_Access_Full.gif   

Table Access operation.

TABLE ACCESS FULL returns rows from a table when the ROWID is not available for the row search. Oracle scans each block in the given table until all rows are read.

Example

select *
from COMPANY;

Execution Plan

TABLE ACCESS FULL COMPANY

Since no restraining conditions are placed on the query, all records and all columns are returned. Oracle sequentially reads through all of the Company table blocks and returns them to the user as output.

 

Related Topics

 

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