Analysis: hints mechanism for Oracle adjustment (1)

In Oracle, hints can be used to better control and optimize Oracle performance. Now let's learn about hints adjustment.

Spread_min_analysis

With this hint, you can ignore the Compilation Time Optimization rules for workbooks such as detailed graph analysis. Other optimizations, such as creating filters to selectively locate the workbook access structure and restrict the revision rules, are available.

Because the number of rules is very large, the workbook analysis will be very long. This prompt helps us reduce the resulting compilation time by hundreds of hours.

Example:

 
 

  
  
SELECT /*+ SPREAD_MIN_ANALYSIS */ ...   
  
  
spread_no_analysis   
  
  
 
 
 

With this hint, No workbook analysis is possible. Similarly, this hint can be used to ignore the revision rules and filter the generation. If a spreadsheet analysis exists, the Compilation Time can be minimized.

Example:

V this hint allows CBO to add a specific table to another original row through nested loops. A specific table is used as an internal table only in the following cases: if no label is specified, CBO must be able to use some labels, and at least one of these labels can be used as the index key value for judgment; otherwise, CBO must be able to add at least one tag as the index key value to the judgment.

Example:

 
 

  
  
SELECT /*+ USE_NL_WITH_INDEX (polrecpolrind) */ ...   
  
  
CARDINALITY   
  
  
 
 
 

This hint defines the base number returned by the query or query. Note that if no table is defined, the base number is the total number of rows returned by the entire query.

Example:

 
 

  
  
SELECT /*+ CARDINALITY ( [tablespec] card ) */   
  
  
SELECTIVITY   
  
  
 
 
 

This hint defines a selective evaluation of the query or query. If only one table is defined, the row part that satisfies all single table judgments in the defined table is optional. If a series of tables are defined, selectivity refers to the row section in the result after all tables that meet all available judgments in any order are merged.