Sort Usage Analysis (vsortusage.sql)

What This Script Does

This script monitors active sort operations in temporary tablespaces, showing real-time space usage by sessions performing sorts. It provides essential information for troubleshooting sort-related performance issues, monitoring temporary tablespace consumption, and identifying resource-intensive sorting operations. The script helps optimize sort area sizing, temporary tablespace management, and query performance.

The Script

rem vsortusage.sql
rem
set linesize 132
rem
ttitle 'Sort Segment Usage'
rem
col tablespace format a10
col username format a10
col osuser format a10
col sid format 9999
col extents format 99,999,999
col module form a18
col blocks format 9,999,999,999
col kbytes format 9,999,999,999 heading 'KBYTES'
col sql_hash_value format 99999999999 heading 'HASH VALUE'
col sql_text format a54 trunc
rem
break on report on tablespace skip 1 on sid on username on osuser
compute sum avg max of extents kbytes on report tablespace
rem
select  /*+ ordered use_nl (p, su, s) */ /*, st) */
       su.tablespace,
       s.sid,
       s.username,
       s.osuser,
       s.module,
       sum(su.extents) extents,
       sum(su.blocks) * p.value /1024 kbytes,
       s.sql_hash_value
       -- , st.sql_text
from
     v$parameter p,
     v$sort_usage su,
     v$session s
     --, v$sqltext st
where s.saddr = su.session_addr
  and s.serial# = su.session_num
  -- and st.address(+) = s.sql_address
  -- and st.hash_value(+) = s.sql_hash_value
  -- and st.piece(+) = 0
  and p.name='db_block_size'
group by
       su.tablespace,
       s.sid,
       s.username,
       s.osuser,
       s.module,
       s.sql_hash_value,
       -- st.sql_text,
       p.value
order by
       su.tablespace,
       6 desc,
       s.sid
/

Key Features

Real-Time Sort Monitoring: Shows currently active sort operations
Space Usage Analysis: Displays extents and space consumption in KB
Session Identification: Shows user, OS user, and session details
Application Context: Displays module information for application correlation
SQL Correlation: Provides SQL hash values for statement identification
Tablespace Breakdown: Groups results by temporary tablespace
Summary Statistics: Calculates totals, averages, and maximums

Usage

@vsortusage.sql

No parameters required - displays all current sort operations.

Required Privileges

SELECT on V$PARAMETER
SELECT on V$SORT_USAGE
SELECT on V$SESSION

Sample Output

                                              Sort Segment Usage

TABLESPACE   SID USERNAME   OSUSER     MODULE                EXTENTS     KBYTES  HASH VALUE
---------- ----- ---------- ---------- ------------------ --------- ----------- -----------
TEMP         234 HR_USER    jsmith     HR_APPLICATION            45      57,600  1234567890
             456 SALES_APP  rjones     SALES_BATCH               128     163,840  2345678901
             789 REPORT_USR sreports   Crystal Reports           256     327,680  3456789012

sum                                                              429     549,120
avg                                                              143     183,040
max                                                              256     327,680

TEMP2        345 DBA_USER   admin      SQL*Plus                   32      40,960  4567890123
             567 BATCH_JOB  batch      ETL_PROCESS               512     655,360  5678901234

sum                                                              544     696,320
avg                                                              272     348,160
max                                                              512     655,360

Key Output Columns

TABLESPACE: Temporary tablespace name
SID: Session ID performing the sort
USERNAME: Database username
OSUSER: Operating system username
MODULE: Application module name
EXTENTS: Number of extents allocated for sort
KBYTES: Space consumed in kilobytes
HASH VALUE: SQL statement hash value

Understanding Sort Operations

Sort Types and Causes

Common Sort Operations

-- Operations requiring sorts:
-- ORDER BY clauses
-- GROUP BY operations
-- DISTINCT processing
-- Index creation and rebuilds
-- Sort-merge joins
-- Set operations (UNION, INTERSECT, MINUS)
-- Window functions with ORDER BY

Memory vs. Disk Sorts

-- Sort location factors:
-- Small sorts: Performed in memory (PGA)
-- Large sorts: Spill to temporary tablespace
-- Sort area size: Determines memory threshold
-- Work area size policy: Automatic or manual tuning

Common Use Cases

Sort Performance Troubleshooting
- Identify sessions with excessive sort usage
- Diagnose sort-related performance issues
- Support query optimization efforts
- Resolve temporary tablespace space issues
Temporary Tablespace Management
- Monitor temporary tablespace usage patterns
- Plan temporary tablespace sizing
- Identify peak usage periods
- Support capacity planning
Query Optimization
- Find queries requiring large sorts
- Identify candidates for index optimization
- Support SQL tuning efforts
- Analyze application sorting patterns
System Monitoring
- Real-time sort activity monitoring
- Resource utilization tracking
- Performance baseline establishment
- Alert system support

Optimization Strategies

Query-Level Optimization

Sort Elimination Techniques

-- Reduce sort requirements:
-- Use indexes for ORDER BY operations
-- Optimize GROUP BY with appropriate indexes
-- Consider materialized views for aggregations
-- Eliminate unnecessary DISTINCT operations

Sort Efficiency Improvement

-- Improve sort performance:
-- Increase sort area size
-- Use FIRST_ROWS hint for partial results
-- Consider parallel sorting
-- Optimize data types for sorting

System-Level Optimization

Memory Configuration

-- Memory tuning:
-- Increase PGA_AGGREGATE_TARGET
-- Optimize WORKAREA_SIZE_POLICY
-- Tune sort area size parameters
-- Monitor memory allocation efficiency

Temporary Tablespace Optimization

-- Tablespace optimization:
-- Add temporary tablespace datafiles
-- Use multiple temporary tablespaces
-- Optimize datafile placement
-- Configure appropriate extent sizes

Integration with SQL Analysis

SQL Statement Correlation

Hash Value Usage

-- Correlate with SQL statements:
SELECT sql_text
FROM v$sql
WHERE hash_value = <hash_value_from_output>;

-- Or use SQL ID for newer versions:
SELECT sql_text
FROM v$sql
WHERE sql_id = '<sql_id>';

Best Practices

Monitoring Strategy

Proactive Monitoring

-- Monitoring best practices:
-- Regular sort usage assessment
-- Peak period monitoring
-- Alert-based notification
-- Performance trend tracking

Performance Baselines

-- Baseline establishment:
-- Normal sort usage patterns
-- Typical space consumption
-- Expected sort durations
-- Performance benchmarks

vsortratio.sql - Sort ratio analysis
temp.sql - Temporary tablespace analysis
vsession.sql - Session analysis

Summary

This script is essential for:

Sort Performance Analysis - Real-time monitoring of sort operations and space usage
Temporary Tablespace Management - Understanding and optimizing temporary tablespace utilization
Query Optimization - Identifying and optimizing queries with inefficient sort operations
System Monitoring - Proactive monitoring of sort activity and resource consumption
Capacity Planning - Supporting temporary tablespace sizing and infrastructure planning decisions