The DBMS_SPACE
package enables you to analyze segment growth and space requirements.
This chapter contains the following topics:
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.
The DBMS_SPACE
package defines a RECORD
type and a TABLE
type.
This type contains the column type of individual columns returned by the ASA_RECOMMENDATIONS Function.
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);
Table 98-1 ASA_RECO_ROW Attributes
Field | Description |
---|---|
|
Name of the tablespace containing the object |
|
Name of the schema |
|
Name of the object |
|
Type of the segment ' |
|
Name of the partition |
|
Space allocated to the segment |
|
Space actually used by the segment |
|
Reclaimable free space in the segment |
|
Percentage of excess chain row pieces that can be eliminated |
|
Recommendation or finding for this segment |
|
Command associated with the recommendation |
|
Command associated with the recommendation |
|
Command associated with the recommendation |
|
Advisor Task that processed this segment |
|
Message ID corresponding to the recommendation |
TYPE asa_reco_row_tb IS TABLE OF asa_reco_row;
Table 98-2 DBMS_SPACE Package Subprograms
Subprogram | Description |
---|---|
Returns recommendations/findings of segment advisor run automatically by the system or manually invoked by the user |
|
Determines the cost of creating an index on an existing table |
|
Determines the size of the table given various attributes |
|
Returns information about free blocks in an object (table, index, or cluster) |
|
Returns the list of segments that are associated with the object |
|
A table function where each row describes the space usage of the object at a specific point in time |
|
Returns information about free blocks in an auto segment space managed segment |
|
Returns information about unused space in an object (table, index, or cluster) |
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.
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;
Table 98-3 CREATE_INDEX_COST Procedure Parameters
Parameter | Description |
---|---|
|
If |
|
If |
|
Show only the findings instead of the recommendations |
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.
DBMS_SPACE.CREATE_INDEX_COST ( ddl IN VARCHAR2, used_bytes OUT NUMBER, alloc_bytes OUT NUMBER, plan_table IN VARCHAR2 DEFAULT NULL);
pragma restrict_references(create_index_cost,WNDS);
Table 98-4 CREATE_INDEX_COST Procedure Parameters
Parameter | Description |
---|---|
|
The create index DDL statement |
|
The number of bytes representing the actual index data |
|
Size of the index when created in the tablespace |
|
Which plan table to use, default |
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.
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.
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);
Table 98-5 CREATE_TABLE_COST Procedure Parameters
Parameter | Description |
---|---|
|
The tablespace in which the object will be created. The default is |
|
The anticipated average row size in the table |
|
The description of the columns |
|
The anticipated number of rows in the table |
|
The percentage of free space in each block for future expansion of existing rows due to updates |
|
The space used by user data |
|
The size of the object taking into account the tablespace extent characteristics |
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.
-- 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; /
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.
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);
pragma restrict_references(free_blocks,WNDS);
Table 98-6 FREE_BLOCKS Procedure Parameters
Parameter | Description |
---|---|
|
Schema name of the segment to be analyzed |
|
Segment name of the segment to be analyzed |
|
Type of the segment to be analyzed (
|
|
Freelist group (instance) whose free list size is to be computed |
|
Returns count of free blocks for the specified group |
|
Maximum number of free list blocks to read (optional). Use a scan limit of X you are interested only in the question, "Do I have X blocks on the free list?" |
|
Partition name of the segment to be analyzed. This is only used for partitioned tables; the name of subpartition should be used when partitioning is composite. |
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);
Note:
An error is raised ifscan_limit
is not a positive number.This table function, given an object, returns the list of segments that are associated with the object.
DBMS_SPACE.OBJECT_DEPENDENT_SEGMENTS( objowner IN VARCHAR2, objname IN VARCHAR2, partname IN VARCHAR2, objtype IN NUMBER) RETURN dependent_segments_table PIPELINED;
Table 98-7 OBJECT_DEPENDENT_SEGMENTS Function Parameters
Parameter | Description |
---|---|
|
The schema containing the object |
|
The name of the object |
|
The name of the partition |
|
Type of the object:
|
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));
Table 98-8 OBJECT_DEPENDENT_SEGMENT Type Parameters
Parameter | Description |
---|---|
|
The schema containing the segment |
|
The name of the segment |
|
The type of the segment, such as table, index or LOB |
|
The name of the tablespace |
|
The name of the partition, if any |
|
The name of the |
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.
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;
Table 98-9 OBJECT_GROWTH_TREND Function Parameters
Parameter | Description |
---|---|
|
The schema containing the object |
|
The name of the object |
|
The type of the object |
|
The name of the partition |
|
Statistics generated after this time will be used in generating the growth trend |
|
Statistics generated until this time will be used in generating the growth trend |
|
The interval at which to sample |
|
Whether interpolation of missing values should be skipped |
|
The time-out value for the function in seconds |
|
Whether in the absence of statistics the segment should be sampled |
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));
Table 98-10 OBJECT_GROWTH_TREND_ROW Type Parameters
Parameter | Description |
---|---|
|
The time at which the statistic was recorded |
|
The space used by data |
|
The size of the segment including overhead and unused space |
|
The quality of result: " |
TYPE object_growth_trend_table IS TABLE OF object_growth_trend_row;
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.
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);
Table 98-11 SPACE_USAGE Procedure Parameters
Parameter | Description |
---|---|
|
Schema name of the segment to be analyzed |
|
Name of the segment to be analyzed |
|
Partition name of the segment to be analyzed |
|
Type of the segment to be analyzed ( |
|
Total number of blocks that are unformatted |
|
Total number of bytes that are unformatted |
|
Number of blocks that has at least 0 to 25% free space |
|
Number of bytes that has at least 0 to 25% free space |
|
Number of blocks that has at least 25 to 50% free space |
|
Number of bytes that has at least 25 to 50% free space |
|
Number of blocks that has at least 50 to 75% free space |
|
Number of bytes that has at least 50 to 75% free space |
|
Number of blocks that has at least 75 to 100% free space |
|
Number of bytes that has at least 75 to 100% free space |
|
Total number of blocks that are full in the segment |
|
Total number of bytes that are full in the segment |
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;
This procedure returns information about unused space in an object (table, index, or cluster).
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);
Table 98-12 UNUSED_SPACE Procedure Parameters
Parameter | Description |
---|---|
|
Schema name of the segment to be analyzed. |
|
Segment name of the segment to be analyzed. |
|
Type of the segment to be analyzed (
|
|
Returns total number of blocks in the segment. |
|
Returns total number of blocks in the segment, in bytes. |
|
Returns number of blocks which are not used. |
|
Returns, in bytes, number of blocks which are not used. |
|
Returns the file ID of the last extent which contains data. |
|
Returns the starting block ID of the last extent which contains data. |
|
Returns the last block within this extent which contains data. |
|
Partition name of the segment to be analyzed. This is only used for partitioned tables; the name of subpartition should be used when partitioning is compose. |
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);