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Oracle - Tables/Indexes

原创 Oracle 作者:nmtcolin 时间:2008-05-06 15:35:52 0 删除 编辑

Here are some scripts related to Tables/Indexes .

Tabs w/ Questionable Inds

TABLES WITH QUESTIONABLE INDEX(ES) NOTES:

  • Owner - Owner of the table
  • Table Name - Name of the table
  • Column - Name of the column in question

  • The above query shows all tables that have more than one index with the same leading column. These indexes can cause queries to use an inappropriate indexes; in other words, Oracle will use the index that was created most recently if two indexes are of equal ranking. This can cause different indexes to be used from one environment to the next (e.g., from DEV to TEST to PROD).
  • The information does not automatically indicate that an index is incorrect; however, you may need to justify the existence of each of the indexes above.

    select 	TABLE_OWNER,
    	TABLE_NAME,
    	COLUMN_NAME
    from  	dba_ind_columns 
    where  	COLUMN_POSITION=1
    and  	TABLE_OWNER not in ('SYS','SYSTEM')
    group  	by TABLE_OWNER, TABLE_NAME, COLUMN_NAME
    having  count(*) > 1 
    
    

    Tabs With More Than 5 Inds

    TABLES WITH MORE THAN 5 INDEXES NOTES:

  • Owner - Owner of the table
  • Table Name - Name of the table
  • Index Count - Number of indexes

    select 	OWNER,
    	TABLE_NAME,
    	COUNT(*) index_count
    from  	dba_indexes 
    where  	OWNER not in ('SYS','SYSTEM')
    group  	by OWNER, TABLE_NAME 
    having  COUNT(*) > 5 
    order 	by COUNT(*) desc, OWNER, TABLE_NAME
    
    

    Tables With No Indexes

    TABLES WITHOUT INDEXES NOTES:

  • Owner - Owner of the table
  • Table Name - Name of the table

    select 	OWNER,
    	TABLE_NAME
    from 
    (
    select 	OWNER, 
    	TABLE_NAME 
    from 	dba_tables
    minus
    select 	TABLE_OWNER, 
    	TABLE_NAME 
    from 	dba_indexes
    )
    orasnap_noindex
    where	OWNER not in ('SYS','SYSTEM')
    order 	by OWNER,TABLE_NAME
    
    

    Tables With No PK

    NO PRIMARY KEY NOTES:

  • Table Owner - Owner of the table
  • Table Name - Name of the table

    select  OWNER,
    	TABLE_NAME
    from    dba_tables dt
    where   not exists (
            select  'TRUE'
            from    dba_constraints dc
            where   dc.TABLE_NAME = dt.TABLE_NAME
            and     dc.CONSTRAINT_TYPE='P')
    and 	OWNER not in ('SYS','SYSTEM')
    order	by OWNER, TABLE_NAME
    
    

    Disabled Constraints

    DISABLED CONSTRAINT NOTES:

  • Owner - Owner of the table
  • Table Name - Name of the table
  • Constraint Name - Name of the constraint
  • Constraint Type - Type of constraint
  • Status - Current status of the constraint

    select  OWNER,
            TABLE_NAME,
            CONSTRAINT_NAME,
            decode(CONSTRAINT_TYPE, 'C','Check',
                                    'P','Primary Key',
                                    'U','Unique',
                                    'R','Foreign Key',
                                    'V','With Check Option') type,
            STATUS 
    from 	dba_constraints
    where 	STATUS = 'DISABLED'
    order 	by OWNER, TABLE_NAME, CONSTRAINT_NAME
    
    

    FK Constraints

    FOREIGN KEY CONSTRAINTS NOTES:

  • Table Owner - Owner of the table
  • Table Name - Name of the table
  • Constraint Name - Name of the constraint
  • Column Name - Name of the column
  • Referenced Table - Name of the referenced table
  • Reference Column - Name of the referenced column
  • Position - Position of the column

    select 	c.OWNER,
    	c.TABLE_NAME,
    	c.CONSTRAINT_NAME,
    	cc.COLUMN_NAME,
    	r.TABLE_NAME,
    	rc.COLUMN_NAME,
    	cc.POSITION
    from 	dba_constraints c, 
    	dba_constraints r, 
    	dba_cons_columns cc, 
    	dba_cons_columns rc
    where 	c.CONSTRAINT_TYPE = 'R'
    and 	c.OWNER not in ('SYS','SYSTEM')
    and 	c.R_OWNER = r.OWNER
    and 	c.R_CONSTRAINT_NAME = r.CONSTRAINT_NAME
    and 	c.CONSTRAINT_NAME = cc.CONSTRAINT_NAME
    and 	c.OWNER = cc.OWNER
    and 	r.CONSTRAINT_NAME = rc.CONSTRAINT_NAME
    and 	r.OWNER = rc.OWNER
    and 	cc.POSITION = rc.POSITION
    order 	by c.OWNER, c.TABLE_NAME, c.CONSTRAINT_NAME, cc.POSITION
    
    

    FK Index Problems

    FK CONSTRAINTS WITHOUT INDEX ON CHILD TABLE NOTES:

  • Owner - Owner of the table
  • Constraint Name - Name of the constraint
  • Column Name - Name of the column
  • Position - Position of the index
  • Problem - Nature of the problem

  • It is highly recommended that an index be created if the Foreign Key column is used in joining, or often used in a WHERE clause. Otherwise a table level lock will be placed on the parent table.

    select 	acc.OWNER,
    	acc.CONSTRAINT_NAME,
    	acc.COLUMN_NAME,
    	acc.POSITION,
    	'No Index' Problem
    from   	dba_cons_columns acc, 
    	dba_constraints ac
    where  	ac.CONSTRAINT_NAME = acc.CONSTRAINT_NAME
    and   	ac.CONSTRAINT_TYPE = 'R'
    and     acc.OWNER not in ('SYS','SYSTEM')
    and     not exists (
            select  'TRUE' 
            from    dba_ind_columns b
            where   b.TABLE_OWNER = acc.OWNER
            and     b.TABLE_NAME = acc.TABLE_NAME
            and     b.COLUMN_NAME = acc.COLUMN_NAME
            and     b.COLUMN_POSITION = acc.POSITION)
    order   by acc.OWNER, acc.CONSTRAINT_NAME, acc.COLUMN_NAME, acc.POSITION
    
    

    Inconsistent Column Names

    INCONSISTENT COLUMN DATATYPE NOTES:

  • Owner - Owner of the table
  • Column - Name of the column
  • Table Name - Name of the table
  • Datatype - Datatype of the column

    select 	OWNER,
    	COLUMN_NAME,
    	TABLE_NAME,
    	decode(DATA_TYPE, 'NUMBER', DATA_PRECISION, DATA_LENGTH) datatype
    from 	dba_tab_columns 
    where  	(COLUMN_NAME, OWNER) in
    		(select	COLUMN_NAME, 
    			OWNER
    	 	 from 	dba_tab_columns
    	 	 group	by COLUMN_NAME, OWNER
    	  	 having	min(decode(DATA_TYPE, 'NUMBER', DATA_PRECISION, DATA_LENGTH)) <
    		 	max(decode(DATA_TYPE, 'NUMBER', DATA_PRECISION, DATA_LENGTH)) )
    and 	OWNER not in ('SYS', 'SYSTEM')
    order	by COLUMN_NAME,DATA_TYPE 
    
    

    Object Extent Warning

    TABLES THAT CANNOT EXTEND NOTES:

  • Owner - Owner of the object
  • Object Name - Name of the object
  • Object Type - Type of object
  • Tablespace - Name of the tablespace
  • Next Extent - Size of next extent (bytes)

    select 	OWNER,
    	SEGMENT_NAME,
    	SEGMENT_TYPE,
    	TABLESPACE_NAME,
    	NEXT_EXTENT
    from (
    	select 	seg.OWNER, 
    		seg.SEGMENT_NAME,
    			seg.SEGMENT_TYPE, 
    		seg.TABLESPACE_NAME,
    			t.NEXT_EXTENT
    	from 	dba_segments seg,
    			dba_tables t
    	where 	(seg.SEGMENT_TYPE = 'TABLE'
    	and  	 seg.SEGMENT_NAME = t.TABLE_NAME
    	and  	 seg.owner = t.OWNER
    	and    NOT EXISTS (
    			select 	TABLESPACE_NAME
    				from 	dba_free_space free
    				where 	free.TABLESPACE_NAME = t.TABLESPACE_NAME
    				and 	BYTES >= t.NEXT_EXTENT))
    	union
    	select 	seg.OWNER, 
    		seg.SEGMENT_NAME,
    			seg.SEGMENT_TYPE, 
    		seg.TABLESPACE_NAME,
    			c.NEXT_EXTENT
    	from 	dba_segments seg,
    			dba_clusters c 
    	where  	(seg.SEGMENT_TYPE = 'CLUSTER'
    	and    	 seg.SEGMENT_NAME = c.CLUSTER_NAME
    	and    	 seg.OWNER = c.OWNER
    	and    	NOT EXISTS (
    			select 	TABLESPACE_NAME
    			from 	dba_free_space free
    			where 	free.TABLESPACE_NAME = c.TABLESPACE_NAME
    			and 	BYTES >= c.NEXT_EXTENT))
    	union
    	select 	seg.OWNER, 
    		seg.SEGMENT_NAME,
    			seg.SEGMENT_TYPE, 
    		seg.TABLESPACE_NAME,
    			i.NEXT_EXTENT
    	from 	dba_segments seg,
    			dba_indexes  i
    	where  	(seg.SEGMENT_TYPE = 'INDEX'
    	and    	 seg.SEGMENT_NAME = i.INDEX_NAME
    	and    	 seg.OWNER        = i.OWNER
    	and    	 NOT EXISTS (
    			select 	TABLESPACE_NAME
    					from 	dba_free_space free
    					where 	free.TABLESPACE_NAME = i.TABLESPACE_NAME
    			and 	BYTES >= i.NEXT_EXTENT))
    	union
    	select 	seg.OWNER, 
    		seg.SEGMENT_NAME,
    			seg.SEGMENT_TYPE, 
    		seg.TABLESPACE_NAME,
    			r.NEXT_EXTENT
    	from 	dba_segments seg,
    			dba_rollback_segs r
    	where  	(seg.SEGMENT_TYPE = 'ROLLBACK'
    	and    	 seg.SEGMENT_NAME = r.SEGMENT_NAME
    	and    	 seg.OWNER        = r.OWNER
    	and    	 NOT EXISTS (
    			select	TABLESPACE_NAME
    					from 	dba_free_space free
    					where 	free.TABLESPACE_NAME = r.TABLESPACE_NAME
                    and 	BYTES >= r.NEXT_EXTENT))
    )
    orasnap_objext_warn
    order 	by OWNER,SEGMENT_NAME
    
    

    Segment Fragmentation

    OBJECTS WITH MORE THAN 50% OF MAXEXTENTS NOTES:

  • Owner - Owner of the object
  • Tablespace Name - Name of the tablespace
  • Segment Name - Name of the segment
  • Segment Type - Type of segment
  • Size - Size of the object (bytes)
  • Extents - Current number of extents
  • Max Extents - Maximum extents for the segment
  • Percentage - Percentage of extents in use

  • As of v7.3.4, you can set MAXEXTENTS=UNLIMITED to avoid ORA-01631: max # extents (%s) reached in table $s.%s.
  • To calculate the MAXEXTENTS value on versions < 7.3.4 use the following equation: DBBLOCKSIZE / 16 - 7
  • Here are the MAXEXTENTS for common blocksizes: 1K=57, 2K=121, 4K=249, 8K=505, and 16K=1017
  • Multiple extents in and of themselves aren't bad. However, if you also have chained rows, this can hurt performance.

    select 	OWNER,
    	TABLESPACE_NAME,
    	SEGMENT_NAME,
    	SEGMENT_TYPE,
    	BYTES,
    	EXTENTS,
    	MAX_EXTENTS,
    	(EXTENTS/MAX_EXTENTS)*100 percentage
    from 	dba_segments
    where 	SEGMENT_TYPE in ('TABLE','INDEX')
    and 	EXTENTS > MAX_EXTENTS/2
    order 	by (EXTENTS/MAX_EXTENTS) desc
    
    

    Extents reaching maximum

    TABLES AND EXTENTS WITHIN 3 EXTENTS OF MAXIMUM :

  • Owner - Owner of the segment
  • Segment Name - Name of the segment

    select owner "Owner",
           segment_name "Segment Name",
           segment_type "Type",
           tablespace_name "Tablespace",
           extents "Ext",
           max_extents "Max"
    from dba_segments
    where ((max_extents - extents) <= 3) 
    and owner not in ('SYS','SYSTEM')
    order by owner, segment_name
    
    

    Analyzed Tables

    ANALYZED TABLE NOTES:

  • Owner - Owner of the table
  • Analyzed - Number of analyzed tables
  • Not Analyzed - Number of tables that have not be analyzed
  • Total - Total number of tables owned by user

  • The ANALYZE statement allows you to validate and compute statistics for an index, table, or cluster. These statistics are used by the cost-based optimizer when it calculates the most efficient plan for retrieval. In addition to its role in statement optimization, ANALYZE also helps in validating object structures and in managing space in your system. You can choose the following operations: COMPUTER, ESTIMATE, and DELETE. Early version of Oracle7 produced unpredicatable results when the ESTIMATE operation was used. It is best to compute your statistics.
  • A COMPUTE will cause a table-level lock to be placed on the table during the operation.

    select	OWNER,
    	sum(decode(nvl(NUM_ROWS,9999), 9999,0,1)) analyzed,
    	sum(decode(nvl(NUM_ROWS,9999), 9999,1,0)) not_analyzed,
    	count(TABLE_NAME) total
    from 	dba_tables
    where 	OWNER not in ('SYS', 'SYSTEM')
    group 	by OWNER
    
    

    Recently Analyzed Tables

    LAST ANALYZED TABLE NOTES:

  • Owner - Owner of the table
  • Table Name - Name of the table
  • Last Analyzed - Last analyzed date/time

    select 	OWNER,
    	TABLE_NAME,
    	to_char(LAST_ANALYZED,'MM/DD/YYYY HH24:MI:SS') last_analyzed
    from 	dba_tab_columns
    where 	OWNER not in ('SYS','SYSTEM')
    and 	LAST_ANALYZED is not null
    and	COLUMN_ID=1
    and 	(SYSDATE-LAST_ANALYZED) < 30
    order	by (SYSDATE-LAST_ANALYZED)
    
    

    Cached Tables

    CACHED TABLE NOTES:

  • Owner - Owner of the table
  • Table Name - Name of the table
  • Cache - Cached?

  • Oracle 7.1+ provides a mechanism for caching table in the buffer cache. Caching tables will speed up data access and improve performance by finding the data in memory and avoiding disk reads.

    select 	OWNER,
    	TABLE_NAME,
    	CACHE
    from dba_tables
    where OWNER not in ('SYS','SYSTEM')
    and CACHE like '%Y'
    order by OWNER,TABLE_NAME
    
    
  • [@more@]

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