98 DBMS_SPACE

Using DBMS_SPACE

• Security Model

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Security Model

This package runs with SYS privileges. The execution privilege is granted to PUBLIC. Subprograms in this package run under the caller security. The user must have ANALYZE privilege on the object.

Data Structures

The DBMS_SPACE package defines a RECORD type and a TABLE type.

RECORD Types

ASA_RECO_ROW Record Type

TABLE Types

ASA_RECO_ROW_TB Table Type

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ASA_RECO_ROW Record Type

This type contains the column type of individual columns returned by the ASA_RECOMMENDATIONS Function.

Syntax

TYPE asa_reco_row IS RECORD (
   tablespace_name       VARCHAR2(30),
   segment_owner         VARCHAR2(30),
   segment_name          VARCHAR2(30),   segment_type          VARCHAR2(18),
   partition_name        VARCHAR2(30),
   allocated_space       NUMBER,
   used_space            NUMBER,
   reclaimable_space     NUMBER,
   chain_rowexcess       NUMBER,
   recommendations       VARCHAR2(1000),
   c1                    VARCHAR2(1000),
   c2                    VARCHAR2(1000),
   c3                    VARCHAR2(1000),
   task_id               NUMBER,
   mesg_id               NUMBER);

Attributes

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ASA_RECO_ROW_TB Table Type

Syntax

TYPE asa_reco_row_tb IS TABLE OF asa_reco_row;

Summary of DBMS_SPACE Subprograms

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ASA_RECOMMENDATIONS Function

This function returns returns recommendations using the stored results of the auto segment advisor. This function returns results from the latest run on any given object.

Syntax

DBMS_SPACE.ASA_RECOMMENDATIONS (
   all_runs        IN    VARCHAR2 DEFAULT := TRUE,
   show_manual     IN    VARCHAR2 DEFAULT := TRUE,
   show_findings   IN    VARCHAR2 DEFAULT := FALSE)
 RETURN ASA_RECO_ROW_TB PIPELINED;

Parameters

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CREATE_INDEX_COST Procedure

This procedure determines the cost of creating an index on an existing table. The input is the DDL statement that will be used to create the index. The procedure will output the storage required to create the index.

Syntax

DBMS_SPACE.CREATE_INDEX_COST (
   ddl             IN    VARCHAR2,
   used_bytes      OUT   NUMBER,
   alloc_bytes     OUT   NUMBER,
   plan_table      IN    VARCHAR2 DEFAULT NULL);

Pragmas

pragma restrict_references(create_index_cost,WNDS);

Parameters

Usage Notes

• The table on which the index is created must already exist.

• The computation of the index size depends on statistics gathered on the segment.

• It is imperative that the table must have been analyzed recently.

• In the absence of correct statistics, the results may be inaccurate, although the procedure will not raise any errors.

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CREATE_TABLE_COST Procedures

This procedure is used in capacity planning to determine the size of the table given various attributes. The size of the object can vary widely based on the tablespace storage attributes, tablespace block size, and so on. There are two overloads of this procedure.

• The first version takes the column information of the table as argument and outputs the table size.

• The second version takes the average row size of the table as argument and outputs the table size.

This procedure can be used on tablespace of dictionary managed and locally managed extent management as well as manual and auto segment space management.

Syntax

DBMS_SPACE.CREATE_TABLE_COST (
   tablespace_name    IN VARCHAR2,
   avg_row_size       IN NUMBER,
   row_count          IN NUMBER,
   pct_free           IN NUMBER,
   used_bytes         OUT NUMBER,
   alloc_bytes        OUT NUMBER);

DBMS_SPACE.CREATE_TABLE_COST (
   tablespace_name    IN VARCHAR2,
   colinfos           IN CREATE_TABLE_COST_COLUMNS,
   row_count          IN NUMBER,
   pct_free           IN NUMBER,
   used_bytes         OUT NUMBER,
   alloc_bytes        OUT NUMBER);

CREATE TYPE create_table_cost_colinfo IS OBJECT (
   COL_TYPE   VARCHAR(200),
   COL_SIZE   NUMBER);

Parameters

Usage Notes

• The used_bytes represent the actual bytes used by the data. This includes the overhead due to the block metadata, pctfree etc.

• The alloc_bytes represent the size of the table when it is created in the tablespace. This takes into account, the size of the extents in the tablespace and tablespace extent management properties.

Examples

-- review the parameters 
SELECT argument_name, data_type, type_owner, type_name 
FROM all_arguments 
WHERE object_name = 'CREATE_TABLE_COST' 
AND overload = 2 
 
-- examine the input parameter type 
SELECT text 
FROM dba_source 
WHERE name = 'CREATE_TABLE_COST_COLUMNS'; 
 
-- drill down further into the input parameter type 
SELECT text 
FROM dba_source 
WHERE name = 'create_table_cost_colinfo'; 
 
set serveroutput on 
 
DECLARE 
 ub NUMBER; 
 ab NUMBER; 
 cl sys.create_table_cost_columns; 
BEGIN 
  cl := sys.create_table_cost_columns( sys.create_table_cost_colinfo('NUMBER',10), 
        sys.create_table_cost_colinfo('VARCHAR2',30), 
        sys.create_table_cost_colinfo('VARCHAR2',30), 
        sys.create_table_cost_colinfo('DATE',NULL)); 
 
  DBMS_SPACE.CREATE_TABLE_COST('SYSTEM',cl,100000,0,ub,ab); 
 
  DBMS_OUTPUT.PUT_LINE('Used Bytes: ' || TO_CHAR(ub)); 
  DBMS_OUTPUT.PUT_LINE('Alloc Bytes: ' || TO_CHAR(ab)); 
END; 
/ 

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FREE_BLOCKS Procedure

This procedure returns information about free blocks in an object (table, index, or cluster). See SPACE_USAGE Procedure for returning free block information in an auto segment space managed segment.

Syntax

DBMS_SPACE.FREE_BLOCKS (
   segment_owner     IN  VARCHAR2, 
   segment_name      IN  VARCHAR2,
   segment_type      IN  VARCHAR2,
   freelist_group_id IN  NUMBER,
   free_blks         OUT NUMBER,
   scan_limit        IN  NUMBER DEFAULT NULL,
   partition_name    IN  VARCHAR2 DEFAULT NULL);

Pragmas

pragma restrict_references(free_blocks,WNDS);

Parameters

Examples

The following uses the CLUS cluster in SCOTT schema with 4 freelist groups. It returns the number of blocks in freelist group 3 in CLUS.

DBMS_SPACE.FREE_BLOCKS('SCOTT', 'CLUS', 'CLUSTER', 3, :free_blocks); 

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OBJECT_DEPENDENT_SEGMENTS Function

This table function, given an object, returns the list of segments that are associated with the object.

Syntax

DBMS_SPACE.OBJECT_DEPENDENT_SEGMENTS(
   objowner    IN     VARCHAR2,
   objname     IN     VARCHAR2,
   partname    IN     VARCHAR2,
   objtype     IN     NUMBER) 
  RETURN dependent_segments_table PIPELINED; 

Parameters

Return Values

The content of one row of a dependent_segments_table:

TYPE object_dependent_segment IS RECORD (
   segment_owner      VARCHAR2(100),
   segment_name       VARCHAR2(100),
   segment_type       VARCHAR2(100),
   tablespace_name    VARCHAR2(100),
   partition_name     VARCHAR2(100),
   lob_column_name    VARCHAR2(100)); 

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OBJECT_GROWTH_TREND Function

This is a table function. The output will be in the form of one or more rows where each row describes the space usage of the object at a specific point in time. Either the space usage totals will be retrieved from Automatic Workload Repository Facilities (AWRF), or the current space usage will be computed and combined with space usage deltas retrieved from AWRF.

Syntax

DBMS_SPACE.OBJECT_GROWTH_TREND (
   object_owner           IN    VARCHAR2,
   object_name            IN    VARCHAR2,
   object_type            IN    VARCHAR2,
   partition_name         IN    VARCHAR2 DEFAULT NULL,
   start_time             IN    TIMESTAMP DEFAULT NULL,
   end_time               IN    TIMESTAMP DEFAULT NULL,
   interval               IN    DSINTERVAL_UNCONSTRAINED DEFAULT NULL,
   skip_interpolated      IN    VARCHAR2 DEFAULT 'FALSE',
   timeout_seconds        IN    NUMBER DEFAULT NULL,
   single_datapoint_flag  IN    VARCHAR2 DEFAULT 'TRUE') 
 RETURN object_growth_trend_table PIPELINED;  

Parameters

Return Values

The object_growth_trend_row and object_growth_trend_table are used by the OBJECT_GROWTH_TREND table function to describe its output.

TYPE object_growth_trend_row IS RECORD(
   timepoint      TIMESTAMP,
   space_usage    NUMBER,
   space_alloc    NUMBER,
   quality        VARCHAR(20)); 

TYPE object_growth_trend_table IS TABLE OF object_growth_trend_row;

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SPACE_USAGE Procedure

This procedure shows the space usage of data blocks under the segment High Water Mark. You can calculate usage for LOBS, LOB PARTITIONS and LOB SUBPARTITIONS. This procedure can only be used on tablespaces that are created with auto segment space management.The bitmap blocks, segment header, and extent map blocks are not accounted for by this procedure.

Syntax

DBMS_SPACE.SPACE_USAGE(
   segment_owner      IN  VARCHAR2,
   segment_name       IN  VARCHAR2,
   segment_type       IN  VARCHAR2,
   unformatted_blocks OUT NUMBER,
   unformatted_bytes  OUT NUMBER,
   fs1_blocks         OUT NUMBER,
   fs1_bytes          OUT NUMBER,
   fs2_blocks         OUT NUMBER,
   fs2_bytes          OUT NUMBER,
   fs3_blocks         OUT NUMBER,
   fs3_bytes          OUT NUMBER,
   fs4_blocks         OUT NUMBER,
   fs4_bytes          OUT NUMBER,
   full_blocks        OUT NUMBER,
   full_bytes         OUT NUMBER,
   partition_name     IN  VARCHAR2 DEFAULT NULL); 

Parameters

Examples

variable unf number; 
variable unfb number; 
variable fs1 number; 
variable fs1b number; 
variable fs2 number; 
variable fs2b number; 
variable fs3 number; 
variable fs3b number; 
variable fs4 number; 
variable fs4b number; 
variable full number; 
variable fullb number; 

begin 
dbms_space.space_usage('U1','T', 
                        'TABLE', 
                        :unf, :unfb, 
                        :fs1, :fs1b, 
                        :fs2, :fs2b, 
                        :fs3, :fs3b, 
                        :fs4, :fs4b, 
                        :full, :fullb); 
end; 
/ 
print unf ; 
print unfb ; 
print fs4 ; 
print fs4b; 
print fs3 ; 
print fs3b; 
print fs2 ; 
print fs2b; 
print fs1 ; 
print fs1b; 
print full; 
print fullb; 

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UNUSED_SPACE Procedure

This procedure returns information about unused space in an object (table, index, or cluster).

Syntax

DBMS_SPACE.UNUSED_SPACE (
   segment_owner              IN  VARCHAR2, 
   segment_name               IN  VARCHAR2,
   segment_type               IN  VARCHAR2,
   total_blocks               OUT NUMBER,
   total_bytes                OUT NUMBER,
   unused_blocks              OUT NUMBER,
   unused_bytes               OUT NUMBER,
   last_used_extent_file_id   OUT NUMBER,
   last_used_extent_block_id  OUT NUMBER,
   last_used_block            OUT NUMBER, 
   partition_name             IN  VARCHAR2 DEFAULT NULL);

Parameters

Examples

The following declares the necessary bind variables and executes.

DBMS_SPACE.UNUSED_SPACE('SCOTT', 'EMP', 'TABLE', :total_blocks, 
   :total_bytes,:unused_blocks, :unused_bytes, :lastextf,  
   :last_extb, :lastusedblock);