B13 Investigating oracle by Julian Dyke

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Investigating
Oracle
Julian Dyke
Independent Consultant
DB Tech Showcase - Osaka
May 2013
juliandyke.com© 2013 Julian Dyke

About Me
 Worked with Oracle databases since 1989
 Independent Consultant for 8 years
 Regular presenter at Conferences, Seminars and Special Interest Groups
 Co-Author of Pro Oracle Database 10g RAC on Linux
 Member of Oak Table Network since 2003
 Member of UKOUG Council
 Former UKOUG director
 Former chair of UKOUG RAC & HA SIG
 Oracle ACE Expert
 Oracle Certified DBA – 7.3, 8, 8i, 9i and 10i
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juliandyke.com© 2013 Julian Dyke3
Investigating Oracle
Introduction
 This presentation describes various techniques for investigating Oracle
features
 Investigative techniques differ depending on feature under investigation
 Why investigate?
 Feature evaluation
 Performance
 Compatibility
 Licensing costs

Investigating Oracle
Agenda
 Initial Research
 Advanced Research
 Oracle Tools
 Execution Plans
 Trace
 Dumps
 Internals
 Operating System Tools
 Custom Tools
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Initial
Research

Initial Research
Read the Oracle Documentation
 Read ALL of the Oracle documentation for the feature
 Useful sources include:
 New Features Guide 11g Release 1 (11.2)
 Part Number E10881-01
 Other Oracle documents
 What's New in... sections
 White Papers
 Oracle Technology Network
 http://www.oracle.com/technetwork
 My Oracle Support
 http://support.oracle.com
 Review the SQL syntax that supports the feature in:
 SQL Language Reference
 PL/SQL Packages and Types Reference

Initial Research
Read Third Party Documentation
 Read any available third party documentation for the feature
 Blogs
 Websites
 Books
 Presentations
 White Papers
 Make information is accurate and credible
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Initial Research
Learn how the new feature works
 Build a test environment
 Build VMs
 Configure storage
 Install Oracle software
 Install required patch sets / one-offs
 Create database(s)
 Configure feature
 Set parameters
 Test feature
 DDL
 DML
 etc
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Initial Research
Licensing
 Check the licensing requirements for the feature being investigated
 Almost all recent new features have been licensed options
 Investigation may not be cost-effective
 Check the Oracle Licensing document
 Check the global pricing document
 Check your existing license agreement
 Gotchas include:
 VMWare environments
 Primary and standby configurations
 RAC/Exadata environments
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Advanced
Research

Advanced Research
Supported Parameters
 Supported parameter values are reported in
 V$PARAMETER
 V$SYSTEM_PARAMETER
 V$SPPARAMETER
 Normalized lists of values are reported in
 V$PARAMETER2
 V$SYSTEM_PARAMETER2
 In Oracle 10.1 and above, valid values for supported parameters are reported
in
 V$PARAMETER_VALID_VALUES

Advanced Research
Unsupported Parameters
 Unsupported parameter values are reported in
 X$KSPPI
 X$KSPPSV
 X$KSPPCV
 To print parameter name, description and values use:
 In Oracle 10.1 and above, valid values for unsupported parameters are
reported in
 X$KSPVLD_VALUES
SELECT i.ksppinm, i.ksppdesc, sv.ksppstvl
FROM x$ksppi i, x$ksppsv sv
WHERE i.indx = sv.indx
ORDER BY i.ksppinm;

Advanced Research Optimizer
Parameters
 In Oracle 10.1 and above, optimizer parameter values are reported at
 Instance-level
 Session-level
 Statement-level
 Dynamic performance views only report supported parameters
 Fixed (X$) tables include unsupported parameters:
Level Supported Parameters Unsupported Parameters
Instance V$SYS_OPTIMIZER_ENV X$QKSCESYS
Session V$SES_OPTIMIZER_ENV X$QKSCESES
Statement V$SQL_OPTIMIZER_ENV X$KQLFSQCE

Advanced Research
Data Dictionary View Definitions
 Data dictionary views are based on data dictionary objects
DBA_% Accessible by all users
ALL_% Accessible by current user
USER_% Accessible by users with DBA privilege only
 View definitions can be found in DBA_VIEWS
SET LONG 50000
SELECT text FROM dba_views WHERE view_name = 'DBA_INDEXES';
 Many views are defined in terms of other views e.g. DBA_SEGMENTS is now
based on SYS_DBA_SEGS

Advanced Research
Data Dictionary Objects
 The data dictionary is created in the SYSTEM tablespace
 Objects are owned by SYS
 Data dictionary tables include:
Table Name Description
OBJ$ Objects
TAB$ Tables
IND$ Indexes
COL$ Columns
USER$ Users
SEG$ Segments
FET$ Free Extents
UET$ Used Extents
TS$ Tablespaces
FILE$ Files

Advanced Research
Data Dictionary Index Clusters
 Many data dictionary objects are stored in index clusters
 For example C_OBJ# is a cluster containing the following tables:
ASSEMBLY$ ICOLDEP$ REFCON$
ATTRCOL$ IND$ SUBCOLTYPE$
CLU$ LIBRARY$ TAB$
COL$ LOB$ TYPE_MISC$
COLTYPE$ NTAB$ VIEWTRCOL$
ICOL$ OPQTYPE$
ICOLDEP$
 Other clusters include:
 C_USER#
 C_FILE#_BLOCK#
 C_TS#
 Index clusters increase complexity of:
 Trace files
 Redo/undo changes

Advanced Research
SQL.BSQ
 During database creation, data dictionary objects are defined in
$ORACLE_HOME/rdbms/admin/sql.bsq
 In Oracle 11.1 and above, sql.bsq has been divided into the following files:
dcore.bsq drac.bsq daw.bsq
dsqlddl.bsq dsec.bsq dsummgt.bsq
dmanage.bsq doptim.bsq dtools.bsq
dplsql.bsq dobj.bsq dexttab.bsq
dtxnspc.bsq djava.bsq ddm.bsq
dfmap.bsq dpart.bsq dlmnr.bsq
denv.bsq drep.bsq
 The core data dictionary tables (obj$, tab$, ind$, col$ etc) are specified in
dcore.bsq

Advanced Research
Dynamic Performance View Definitions
 Definitions reported by
 V$FIXED_VIEW_DEFINITION
 Global (GV$) view selects from underlying fixed (X$) tables
SELECT view_definition FROM v$fixed_view_definition
WHERE view_name = 'GV$RESULT_CACHE_MEMORY';
VIEW_DEFINITION
SELECT inst_id, qesrcmem_lad, qesrcmem_cnk, qesrcmem_blk,
DECODE (qesrcmem_sta, 0, 'NO', 1, 'YES'), qesrcmem_oid, qesrcmem_pos
FROM x$qesrcmem;
SELECT view_definition FROM v$fixed_view_definition
WHERE view_name = 'V$RESULT_CACHE_MEMORY';
VIEW_DEFINITION
SELECT id, chunk, offset, free, object_id, position
FROM gv$result_cache_memory
WHERE inst_id = USERENV ('Instance')
 Instance (V$) view selects from global (GV$) view

Advanced Research
PL/SQL Package Definitions
 PL/SQL package headers are distributed in $ORACLE_HOME/rdbms/admin
 For example:
 dbmsmntr.sql contains package header for DBMS_MONITOR
 dbmsxplan.sql contains package header for DBMS_XPLAN
 Names are not intuitive
 Use grep to find specific packages
 Package headers contain comments that can be useful when documentation
is inadequate e.g.:
 new parameters
 ambiguity
 Most package bodies are wrapped:
 Unwrap tools can be found on the internet
 Probably break terms of licence agreements
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Advanced Research
Error Messages
 Error messages describe what a feature does not support
 Can be useful to understand how feature is implemented
 See $ORACLE_HOME/rdbms/mesg/oraus.msg
 Contains all message and event definitions
 Individual messages reported by oerr on Unix platforms
 Binary file - on Unix use strings utility to inspect contents
$ strings $ORACLE_HOME/rdbms/mesg/oraus.msg > /tmp/oraus.txt
 A range of error numbers is initially allocated for each feature
 Some features have more than one range

Advanced Research
Fixed Tables and Views
 V$FIXED_TABLES reports all fixed objects including
 Fixed (X$) tables
 Derived fixed (X$) tables (fixed views)
 Global (GV$) dynamic performance views
 Instance (V$) dynamic performance views
 V$INDEXED_FIXED_COLUMN reports all indexed columns for
 Fixed (X$) tables

Advanced Research
Fixed Tables and Views
 Fixed (X$) tables are described in X$KQFTA
 Fixed (X$) derived tables are described in X$KQFDT
 Fixed (X$) table columns arev described in X$KQFCO
 Internal data type reported in KQFCODTY
 Indexes reported in KQFCOIDX and KQFCOIPO
SELECT co.kqfconam,
CASE co.kqfcodty
WHEN 2 THEN 'NUMBER'
WHEN 23 THEN 'RAW ('||kqfcosiz||')'
END
FROM x$kqfco co, x$kqfta ta
WHERE co.kqfcotab = ta.indx
AND ta.kqftanam = 'X$QESRCMEM'
ORDER BY co.kqfcocno;

Advanced Research
Fixed Tables
 X$KQFCO.KQFCODTY reports internal column data type
 Current values in Oracle 11.1
Value Description
1 VARCHAR2
2 NUMBER
12 DATE
23 RAW
112 CLOB
180 TIMESTAMP
181 TIMESTAMP WITH TIME ZONE
 See http://www.juliandyke.com for more comprehensive list of internal data
types (Internals/Internal Data Types)

Advanced Research
Shared Memory
 V$SGA
 reports SGA memory sizes
 V$SGAINFO
 reports SGA memory pool sizes
 introduced in Oracle 10.1
 V$SGASTAT
 reports SGA memory area sizes
 enhanced in Oracle 10.1

Advanced Research
Shared Memory
 X$KSMFSV
 Contents of fixed SGA
 X$KSMGE
 Reports granule allocation
 X$KSMMEM
 Contents of SGA presented as an array
 Usually fails in Windows
 Usually fails with Automatic Memory Management
 X$KSMSP
 Reports shared pool memory usage
 X$KSMHP
 Reports heap allocation

Advanced Research
AWR Tables
 Some AWR tables contain useful information including:
 DBA_HIST_PLAN_OPERATION_NAME
 Execution plan operations
 DBA_HIST_PLAN_OPTION_NAME
 Execution plan operation options
 DBA_HIST_SQLCOMMAND_NAME
 Command types and names – similar to AUDIT_ACTIONS
 DBA_HIST_TOPLEVELCALL_NAME
 Top level calls
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Advanced Research
Dynamic Performance Views
 V$BGPROCESS (X$KSBDD)
 List of background processes
 V$LATCHNAME (X$KSLLD)
 List of parent latches
 V$EVENT_NAME (X$KSLED)
 List of wait events
 V$LOCK_TYPE (X$KSIRESTYP)
 List of lock/enqueue types (Oracle 10.1 and above)
 V$SQL_HINT
 List of supported hints
 V$SQL_FEATURE
 List of supported features

Advanced Research
Dynamic Performance Views
 V$TYPE_SIZE (X$KQFSZ)
 Size in bytes of various data types
 V$RESERVED_WORDS (X$KWDDEF)
 List of keywords / reserved words
 X$MESSAGES
 List of messages exchanged between processes

Advanced Research
Standard Package
 $ORACLE_HOME/rdbms/admin/standard.sql
 Contains definitions of standard PL/SQL types, built-in functions and
exceptions
 For example:
 DECODE
 SUBSTR
 INSTR
 UPPER
 LOWER
 In Oracle 11.2 standard.sql calls
 stdspec.sql
 stdbody.sql

Oracle Tools
Execution Plans

Execution Plans
AUTOTRACE
 SQL*Plus feature
 Prints execution plans and execution statistics
$ORACLE_HOME/rdbms/admin/utlxplan.sql
 Requires PLUS_TRACE role
$ORACLE_HOME/sqlplus/admin/plustrce.sql
GRANT plustrce TO user1;
 In Oracle 10.1 and above execution plan output uses DBMS_XPLAN format:
 Automatically includes:
 Partition information
 Parallel execution information
 Requires access to a PLAN_TABLE

Execution Plans
AUTOTRACE
 Options are:
SET AUTOTRACE OFF No report generated - default
SET AUTOTRACE ON EXPLAIN Shows execution plan
SET AUTOTRACE ON STATISTICS Shows execution statistics
SET AUTOTRACE ON Shows output, execution plan and statistics
SET AUTOTRACE ON TRACEONLY Suppresses query output if executed
 The EXPLAIN option generates a new execution plan
 Optimizer environment may differ from user sessions
 SET AUTOTRACE TRACEONLY EXPLAIN
 Shows execution plan for SELECT statements
 Shows execution plan AND executes DML statements
Note that SET AUTOT TRACE EXP executes DML statements
Any changes must be rolled back manually
Alternatively explain the SELECT subquery only

Execution Plans
DBMS_XPLAN
 Introduced in Oracle 9.2
 Enhanced in subsequent releases
 Useful subroutines include
 DISPLAY - display a plan from a PLAN_TABLE
 DISPLAY_AWR - display a plan from the AWR
 DISPLAY_CURSOR - display a plan from the library cache
 DISPLAY_PLAN – returns plan as a CLOB
 DISPLAY_SQLSET – displays a plan from a SQL tuning set
 DISPLAY_SQLPLAN_BASELIN E – displays a plan from SQL baseline
 For example to display execution plan for statement most recently executed
by the current session:
SELECT * FROM TABLE (DBMS_XPLAN.DISPLAY_CURSOR);

Execution Plans
DBMS_XPLAN
 The FORMAT parameter specifies the output format for the execution plan
 There are four options:
 BASIC – minimum information - operation ID, operation name and option
only
 TYPICAL – default – most relevant information in plan – operation id,
operation name, option, #rows, # bytes, optimizer cost. Also pruning,
parallel and predicate information where applicable
 SERIAL – same as TYPICAL except parallel information is not displayed
even if plan executes in parallel
 ALL – same as TYPICAL. Also includes PROJECTION, ALIAS and
REMOTE SQL if applicable
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Execution Plans
DBMS_XPLAN
 The following keywords can be added to the FORMAT options for more fine-
grained control of output
 ROWS – number of rows estimated by optimizer
 BYTES – number of bytes estimated by optimizer
 COST – optimizer cost information
 PARTITION – partition pruning information
 PARALLEL – parallel execution information
 PREDICATE – predicate section
 PROJECTION – projection section
 ALIAS – Query Block Name / Object Alias section
 REMOTE – distributed query information
 NOTE - note section of plan
 Sections are only displayed if relevant
 To exclude a section prefix with minus e.g. -PROJECTION
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Execution Plans
DBMS_XPLAN
 For DISPLAY_CURSOR and DISPLAY_SQLSET, additional data can be output
using the following keywords:
 IOSTATS – shows IO statistics for all executions of the cursor
 MEMSTATS – displays memory management statistics including
 execution mode of operator
 how much memory was used
 number of bytes spilled to disk
 ALLSTATS – both IOSTATS and MEMSTATS
 LAST – only report statistics for last execution of cursor
 IOSTATS, ALLSTATS and LAST require basic plan statistics which are
collected by
 setting STATISTICS_LEVEL parameter to ALL
 specifying GATHER_PLAN_STATISTICS hint
 MEMSTATS requires PGA memory management to be enabled by:
 setting PGA_AGGREGATE_TARGET to non-zero value
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Oracle Tools
Trace

SQL Trace
Diagnostics Area
 In Oracle 11.1 and above trace files and alert logs are written to the
diagnostics area:
 Default location is $ORACLE_HOME/diag
 Trace files and alter log are written to
 $ORACLE_BASE/diag/rdbms/<database>/<instance>/trace
 For example for database TEST
 $ORACLE_BASE/diag/rdbms/test/TEST/trace
 BACKGROUND_DUMP_DEST and USER_DUMP_DEST parameters still
available in Oracle 11.2
 New dynamic performance view V$DIAG_INFO reports trace locations
 Trace file for current process can be identified using:
SELECT value FROM v$diag_info
WHERE name = 'Default Trace File';

SQL Trace
Trace File Identifier
 In Oracle 8.1.5 and above a suffix can be added to the trace file name using
TRACEFILE_IDENTIFIER parameter
For example given the following current trace filename:
ALTER SESSION SET tracefile_identifier = 'TEST1';
TEST_ora_24672.trc
 The following statement:
 will add the suffix "_TEST1" to the file name e.g.
TEST_ora_24672_TEST1.trc

DBMS_MONITOR
Overview
 Introduced in Oracle 10.1
 Contains the following subroutines:
 SESSION_TRACE_ENABLE
 SESSION_TRACE_DISABLE
 DATABASE_TRACE_ENABLE
 DATABASE_TRACE_DISABLE
 CLIENT_ID_TRACE_ENABLE
 CLIENT_ID_TRACE_DISABLE
 CLIENT_ID_STAT_ENABLE
 CLIENT_ID_STAT_DISABLE
 SERV_MOD_ACT_TRACE_ENABLE
 SERV_MOD_ACT_TRACE_DISABLE
 SERV_MOD_ACT_STAT_ENABLE
 SERV_MOD_ACT_STAT_DISABLE
 DBMS_MONITOR trace configuration is reported in DBA_ENABLED_TRACES

DBMS_MONITOR
Enabling and Disabling Trace
 To enable and disable trace in the current session use:
EXECUTE DBMS_MONITOR.SESSION_TRACE_ENABLE;
EXECUTE DBMS_MONITOR.SESSION_TRACE_DISABLE;
 To enable and disable trace in another session e.g. 42 use:
EXECUTE DBMS_MONITOR.SESSION_TRACE_ENABLE (SESSION_ID => 42);
EXECUTE DBMS_MONITOR.SESSION_TRACE_DISABLE (SESSION_ID => 42);
 To enable and disable trace for instance RAC1 use:
EXECUTE DBMS_MONITOR.DATABASE_TRACE_ENABLE (INSTANCE_NAME => 'RAC1');
EXECUTE DBMS_MONITOR.DATABASE_TRACE_DISABLE (INSTANCE_NAME => 'RAC1');
 To enable and disable trace for the entire database use:
EXECUTE DBMS_MONITOR.DATABASE_TRACE_ENABLE;
EXECUTE DBMS_MONITOR.DATABASE_TRACE_DISABLE;

DBMS_MONITOR
Client Identifiers
 Trace can be enabled for using client identifiers
 Useful when many sessions connect using the same Oracle user
 Useful with connection caches
 To set a client identifier use DBMS_SESSION.SET_IDENTIFIER e.g.:
 The client identifier is reported in V$SESSION.CLIENT_IDENTIFIER
DBMS_SESSION.SET_IDENTIFIER ('CLIENT42');
 To enable and disable trace for CLIENT42 use:
DBMS_MONITOR.CLIENT_ID_TRACE_ENABLE (CLIENT_ID => 'CLIENT42');
DBMS_MONITOR.CLIENT_ID_TRACE_DISABLE (CLIENT_ID => 'CLIENT42');
 To enable and disable statistics collection for CLIENT42 use:
DBMS_MONITOR.CLIENT_ID_STAT_ENABLE (CLIENT_ID => 'CLIENT42');
DBMS_MONITOR.CLIENT_ID_STAT_DISABLE (CLIENT_ID => 'CLIENT42');
 Client statistics are reported in V$CLIENT_STATS

DBMS_MONITOR
Services, Modules & Actions
 Trace can be enabled for a specific
 service
 service and module
 service, module and action
 Current module and action reported by
 V$SESSION.MODULE
 V$SESSION.ACTION
 To specify a new action within the current module use:
DBMS_APPLICATION_INFO.SET_ACTION
(ACTION_NAME=> 'ACTION2');
DBMS_APPLICATION_INFO.SET_MODULE
(MODULE_NAME => 'MODULE1', ACTION_NAME=> 'ACTION1');
 To specify a module and action with a session use:

DBMS_MONITOR
Services, Modules & Actions
 To enable trace for use:
 To enable statistics collection use:
DBMS_MONITOR.SERV_MOD_ACT_TRACE_ENABLE
(SERVICE_NAME => 'SERVICE1',MODULE_NAME => 'MODULE1',ACTION_NAME => 'ACTION1‘);
(SERVICE_NAME => 'SERVICE1',MODULE_NAME => 'MODULE1‘);
DBMS_MONITOR.SERV_MOD_ACT_STAT_ENABLE
(SERVICE_NAME => 'SERVICE1',MODULE_NAME => 'MODULE1',ACTION_NAME => 'ACTION1‘);
(SERVICE_NAME => 'SERVICE1',MODULE_NAME => 'MODULE1‘);
(SERVICE_NAME => 'SERVICE1');
(SERVICE_NAME => 'SERVICE1');
 Statistics are reported in V$SERV_MOD_ACT_STATS

DBMS_MONITOR
Row Source Statistics
 In Oracle 11.2 and above PLAN_STAT parameter is supported in:
 CLIENT_ID_TRACE_ENABLE
 DATABASE_TRACE_ENABLE
 SERV_MOD_ACT_TRACE_ENABLE
 SESSION_TRACE_ENABLE
 PLAN_STAT specifies frequency of row source statistic dumps. Can be:
 NEVER
 FIRST_EXECUTION (default)
 ALL_EXECUTIONS
 In Oracle 11.2 and above event 10046 level 16 also dumps row source
statistics for all executions
 To dump binds + waits + statistics use event 10046 level 28
ALTER SESSION SET EVENTS ‘10046 trace name context forever, level 28’’;

DBMS_MONITOR
Interpreting Trace
 Use TKPROF to sort and filter the trace file
 Avoid re-explaining execution plans
 Use TRCSESS to merge trace files
 Useful with shared server (MTS)
 See Metalink Note: 39817.1 Interpreting Raw SQL_TRACE and
DBMS_SUPPORT.START_TRACE output
 Describes contents of trace file
 See Optimizing Oracle Performance
Cary Millsap & Jeff Holt (O'Reilly)

Oracle Tools
Dumps

ORADEBUG
Overview
 Undocumented SQL*Plus feature
 Requires SQLDBA privilege
 Allows session to connect to other processes and execute commands
 A process must be specified for many ORADEBUG commands using one of:
 ORADEBUG SETMYPID – connect to local process
 ORADEBUG SETORAPID – connect using Oracle process ID
 ORADEBUG SETOSPID – connect using OS pid
 All commands are prefixed with ORADEBUG
 To obtain a list of commands use ORADEBUG HELP
 New functionality is frequently added
 Review in each new release

ORADEBUG
Dumps
 To list of available dumps can be obtained using ORADEBUG DUMPLIST
 Most dumps can be performed by
 ORADEBUG
 ALTER SYSTEM
 ALTER SESSION
 Some dumps can be very useful for specific investigations
 Dumps are mostly undocumented
 187 dumps listed in Oracle 11.2.0.3
 Some dumps modify database
 Only use on
 non-production databases
 when requested by Oracle Support

Memory Dumps
Trace Dumps
 Memory dumps can be taken using
 ORADEBUG
 ALTER SYSTEM
 ALTER SESSION
 For example to dump fixed SGA including contents
ALTER SESSION SET EVENTS
'immediate trace name global_area level 2‘;
 To dump summary of SGA heap use:
'immediate trace name heapdump level 2‘;
 To dump contents of a specific SGA subheap use:
'immediate trace name heapdump_addr level 2, addr <address>';

File Dumps
Redo Log Dumps
 To identify the current redo log use:
SELECT member FROM v$logfile
WHERE group# =
(
SELECT group# FROM v$log
WHERE status = 'CURRENT'
);
 To dump the contents of a redo log use:
ALTER SYSTEM DUMP LOGFILE '<logfilename>';
 Also works for archived log files

File Dumps
Redo Log Dumps
 Full syntax is:
ALTER SYSTEM DUMP LOGFILE 'FileName'
SCN MIN MinimumSCN
SCN MAX MaximumSCN
TIME MIN MinimumTime
TIME MAX MaximumTime
LAYER Layer
OPCODE Opcode
DBA MIN FileNumber . BlockNumber
DBA MAX FileNumber . BlockNumber
RBA MIN LogFileSequenceNumber . BlockNumber
RBA MAX LogFileSequenceNumber . BlockNumber;
 See MOS Note 1031381.6 for further details

File Dumps
Block Dumps
 To dump a database block in Oracle 8.0 or above:
ALTER SYSTEM DUMP DATAFILE <absolute_file_number>
BLOCK <block_number>;
ALTER SYSTEM DUMP DATAFILE <absolute_file_number>
BLOCK MIN <minimum_block_number>
BLOCK MAX <maximum_block_number>;
 To dump a range of database blocks:
 To dump a block from a datafile in a closed database:
ALTER SYSTEM DUMP DATAFILE '<file_name>'
BLOCK <block_number>;

Internals

Internals
Overview
 Oracle dumps often include data. Common data types include
 VARCHAR2
 CHAR
 NUMBER
 DATE
 ROWID
 Oracle dumps also include some common metadata structures including:
 SCN
 DBA
 UBA
 RBA
 SQLID
 Command Types
 Unix Time
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Internals
Internal Data Type
 Each data type has an internal number
 Internal data type numbers appear in many structures and dumps
 e.g. bind variables
 Examples include:
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Internal Type Description
1 VARCHAR2, NVARCHAR2
2 NUMBER
8 LONG
12 DATE
23 RAW
24 LONG RAW
58 ANYDATA
69 ROWID
96 CHAR, NCHAR
100 BINARY FLOAT
101 BINARY DOUBLE
111 XMLTYPE
Internal Type Description
112 CLOB, NCLOB
113 BLOB
114 BFILE
121 TYPE (User-defined)
122 TYPE (TABLE OF RECORD)
123 TYPE (VARRAY)
180 TIMESTAMP
181 TIMESTAMP WITH TZ
182 INTERVAL YEAR TO MONTH
183 INTERVAL DAY TO SECOND
208 UROWID
231 TIMESTAMP WITH LOCAL TZ

Internals
Hexadecimal Conversions
 To convert from hexadecimal to decimal use TO_NUMBER with the 'XXXX'
format mask e.g.
SELECT TO_NUMBER (100,'XXX') FROM dual;
TO_NUMBER(100,'XXX')
--------------------
256
 To convert from decimal to hexadecimal use TO_CHAR with the 'XXXX' format
mask e.g.
SELECT TO_CHAR (256,'XXX') FROM dual;
TO_NUMBER(256,'XXX')
--------------------
100

Internals
DUMP Function
 Column values can be dumped using the SQL DUMP function
 Syntax is:
58
FUNCTION DUMP (expr[,return_format[,start_position[,length]]])
 where RETURN_FORMAT is:
Format Description
8 Octal Notation
10 Decimal Notation
16 Hexadecimal Notation
17 Single Characters
 For example:
SELECT DUMP (10000,16) FROM dual;
DUMP(10000,16)
-----------------
Typ=2 Len=2: c3,2

Internals
String Data Types
 VARCHAR2 (Internal Type 1)
 Stores characters plus length byte(s)
 e.g. “Ferrari” in a VARCHAR2(20)
59
Len F e r r a r i
07 46 65 72 72 61 72 69
 CHAR (InternalType 96)
 Pads data with space characters
 e.g. “Ferrari” in a CHAR(20)
Len F e r r a r i
07 46 65 72 72 61 72 69 20 20 20 20 20 20 20 20 20 20 20 20 20

Internals
NUMBER Data Type
 NUMBER (Internal Type 2)
 Oracle proprietary number format
 Platform independent representation
 Designed to ensure numbers collate
 Up to 38 bytes can be stored
 Numbers are stored as base-100 digits
 Each digit is increased by 1 to ensure non-zero
 Numbers prefixed by
 Sign bit
 Exponent
60
Number Value
Positive Infinity FF 65
Zero 80
Negative Infinity 01 01 66

Internals
NUMBER Data Type
 Some examples:
61
Value Internal Representation
0 80
1 C1,02
2 C1,03
3 C1,04
8 C1,09
9 C1,0A
99 C1,64
100 C2,02
101 C2,02,02
102 C2,02,03
999 C2,02,64
1000 C2,0B
1001 C2,0B,2
Value Internal Representation
9999 C2,64,64
10000 C3,02
90000 C3,0A
100000 C3,0B
-1 3E,64,66
-2 3E,63,66
-3 3E,62,66
-4 3E,61,66
-99 3E,2,66
-100 3D,64,66
-101 3D,64,64,66
-102 3D,64,63,66
-103 3D,64,62,66

Internals
DATE Data Type
 DATE (Internal Type 12)
 Oracle can store dates ranging from Jan 1, 4712BC to Dec 31 4712AD
 Dates are always stored in 7 byte values
 Always prefixed by (redundant) length byte
 Format is:
62
Byte Value
0 Year / 100
1 Year % 100
2 Month
3 Day
4 Hour
5 Minute
6 Second
 For example 26May2013 05:06:38 is
Len 0 1 2 3 4 5 6
07 DD 07 05 1A 05 06 26

Internals
ROWID Data Type
 ROWID (Internal Type 69)
 Extended ROWIDs were introduced in Oracle 8.0
 Use relative file number / block number / slot number
 Absolute file number derived from relative file number and tablespace
number
 Can be accessed using DBMS_ROWID package
 Useful functions include:
 ROWID_RELATIVE_FNO
 ROWID_BLOCK_NUMBER
 ROWID_ROW_NUMBER
 ROWID_TO_ABSOLUTE_FNO

Internals
ROWID Data Type
 For example:
SELECT
ROWID,
dbms_rowid.rowid_relative_fno (ROWID) AS "File Number",
dbms_rowid.rowid_block_number (ROWID) AS "Block Number",
dbms_rowid.rowid_row_number (ROWID) AS "Row Number"
FROM gp.team;
ROWID File Number Block Number Row Number
------------------ ----------- ------------ ----------
AAAR1GAAGAAAAR4AAA 6 1144 0
AAAR1GAAGAAAAR4AAB 6 1144 1
AAAR1GAAGAAAAR4AAC 6 1144 2
AAAR1GAAGAAAAR4AAD 6 1144 3
......

Internals
Database Block Address
 Database Block Address (DBA)
 Address of block in database
 Always 32-bit value
 Even on 64 bit platform
 SMALLFILE tablespaces (default)
 Upper 10 bits represent relative file number
 Lower 22 bits represent block number
 For example if DBA is 0x01000227
65
 BIGFILE tablespaces
 All 32 bits represent block number
 Some dumps / tools may not report DBA correctly
File number = dba >> 22 = 4
Block number = dba & 0x3FFFFF = 551

Internals
SQLID
 13 character representation of a 64-bit unsigned integer
 Uses a mapping of 32 characters to 0..31
 Uses the characters 0-9 and a-z with the exception of e, i, l and o
 Used in Oracle 10.1 and above to identify SQL parent cursors
 Also used to generate database replay file names
 5-bit characters in SQL ID map to 8 bit characters in unsigned integer
 Right to left
 Top bit of left hand word is not used

Internals
SQLID Conversion
0 1 2 3 4 5 6 7
00000 00001 00010 00011 00100 00101 00110 00111
8 9 a b c d f g
01000 01001 01010 01011 01100 01101 01110 01111
h j k m n p q r
10000 10001 10010 10011 10100 10101 10110 10111
s t u v w x y z
11000 11001 11010 11011 11100 11101 11110 11111
 The following table shows the mapping between characters and byte values:

Internals
SQLID Conversion
 Example
 “6j02q68mxgzt4“ = 0xcdc4598000000001
6 j 0 2 q 6 8 m x g z t 4
00110 10001 00000 00010 10110 00110 01000 10011 11101 01111 11111 11001 00100
01101000 10000000 01010110 00110010 00100111 11010111 11111111 00100100
68 80 56 32 27 d7 ff 24

Internals
SQLID Conversion
 The following C function converts a 64-bit unsigned integer into a 13-
character SQL ID
void ConvertLongToSQLID (unsigned long l,char *s)
{
char *map = "0123456789abcdfghjkmnpqrstuvwxyz";
int i;
for (i = 0;i < 13;i++)
{
unsigned long k = (l >> (60 - i * 5)) & 0x1F;
s[i] = map[k];
}
s[13] = 0;
}

Internals
SQLID Conversion
 The following C function converts a 13-character SQL ID into a 64-bit
unsigned integer
void ConvertSQLIDToLong (char *s,unsigned long *l)
{
char *map = "0123456789abcdfghjkmnpqrstuvwxyz";
unsigned long res = 0;
int i,j;
for (i = 0;i < 13;i++)
{
for (j = 0;j < 32;j++)
{
if (s[i] == map[j]) break;
}
res = (res << 5) | j;
}
*l = res;
}

Internals
Command Types
 Command types are listed the SYS.AUDIT_ACTIONS table
Name Type
ACTION NUMBER
NAME VARCHAR2(28)
 Common actions include:
Action Name
1 CREATE TABLE
2 INSERT
3 SELECT
6 UPDATE
7 DELETE
9 CREATE INDEX
10 DROP INDEX
12 DROP TABLE
17 GRANT OBJECT
19 CREATE SYNONYM

Internals
Unix Time
 Unix (POSIX) time – time in seconds since the Epoch
 Not counting leap seconds
 Epoch was midnight on 1st January 1970
 To determine current Unix time on Linux:
#include <stdio.h>
#include <sys/time.h>
main ()
{
struct timeval tv;
struct timezone tz;
gettimeofday (&tv,&tz);
printf ("Seconds = %ld (0x%lx)¥n",tv.tv_sec, tv.tv_sec);
printf ("MicroSeconds = %ld (0x%lx)¥n",tv.tv_usec,tv.tv_usec);
}

Operating
System
Tools

Operating System Tools
strings and od
 On Unix and Linux useful operating system tools for investigations include:
 strings – print ASCII strings in a binary file
 default string length is 4 – may miss short strings
 use –n parameter to specify shorter minimum length e.g. –n 3
 od – dumps blocks from a file in specified format
 Formats include:
 -c – ASCII characters or backslash escapes
 -d – Unsigned decimal 2-byte units
 -o – Octal 2 byte units
 -x – Hexadecimal 2 byte units
74

Operating System Tools
tcpdump
 Allows packets to be captured and displayed
 On busy systems packets can be stored in a file and examined
subsequently
 Filters can be applied to
 Reduce number of packets captured
 Increase level of data captured
 Promiscuous - network packets between other network interfaces can be
captured
 Based on libpcap
 Similar to snoop on Solaris
 Useful for investigating
 RAC interconnect traffic
 Oracle Streams packets

Custom Tools

Custom Tools
 If no suitable tools exist you can always develop your own….
 C is the best language for most tools
 Oracle is developed in C
 Structures align better in C
 Avoids unnecessary indirection
 GNU compilers are usually available
 Ensure development platform is:
 Same architecture as target e.g. x86-64, SPARC, Itanium
 Same word size e.g. 32 or 64 bit
 Ensure correct compiler switches are specified
 Word size
 Word alignment
77

Custom Tools
 RedoAnalyzer
 Analyses online redo log / archive redo log
 Summarizes redo generation by:
 undo / redo
 object
 operation
 Version specific
 Usually requires porting for different platforms
 LogMiner provides similar functionality
 LogMiner has high memory requirements
 RedoAnalyzer is less-intrusive
 RedoAnalyzer is faster
78

Custom Tools
 Block Dumper
 Dumps database blocks
 Similar output format to ALTER SYSTEM DUMP command
 Can be adapted
 For example non-intrusive analysis of chaining and migration
 SGA Attach
 Attaches to shared memory
 Follows memory pointers from fixed SGA
 Dumps blocks of memory
 Dumps sessions, processes, parent and child cursors etc
 Dumps RAC structures
 Useful for research and for identifying bugs
79

Custom Tools
 TCP Dump
 Based on libpmap
 Intercepts and dumps messages
 Useful for
 Clusterware / RAC research
 Oracle Streams research
 IO Performance
 Reads random blocks from large files
 Measures I/O rates
 Fine grained
 Allows I/O rate to be calculated for
 buffered I/O
 SAN cache
 SAN disk
80

Custom Tools
 ReplayAnalyzer
 Extracts contents of database replay files (record and workload metadata)
 Writes output in pseudo-XML format
 Useful for understanding
 database capture – what is captured and what is omitted
 database replay – what can be replayed
 TrailAnalyzer
 Dumps contents of Oracle GoldenGate trail
 Very similar to Oracle GoldenGate logdump utility
81

Thank you for listening
info@juliandyke.com

Backup

Execution Plans
AUTOTRACE
 Statistics reported are:
Statistic Name
recursive calls
db block gets
consistent gets
physical reads
redo size
bytes sent via SQL*Net to client
bytes received via SQL*Net from client
SQL*Net roundtrips to/from client
sorts(memory)
sorts(disk)
rows processed

Execution Plans
AUTOTRACE
 In Oracle 9.2 and below execution plan consists of four columns:
Column Name Description
ID_PLUS_EXP ID of execution step
PARENT_ID_PLUS_EXP Parent ID of execution step
PLAN_PLUS_EXP Execution step
OBJECT_NODE_PLUS_EXP Database links or parallel query servers
 Output can optionally be suppressed e.g.:
COLUMN PARENT_ID_PLUS_EXP NOPRINT
 For parallel and remote operations additional information is displayed in
another section:
Column Name Description
OTHER_PLUS_EXP Shows the SQL query
OTHER_TAG_PLUS_EXP Shows reason for OTHER_PLUS_EXP

Parameters
Parameter Types
 Parameter types are reported numerically in
 V$PARAMETER.TYPE
 X$KSPPI.KSPPITY
 Values are:
Value Description
1 Boolean
2 String
3 Integer
4 File
6 Big Integer

Parameters
Optimizer Parameters
 Optimizer parameters are grouped in FID_QKSCESYROW
 For example in Oracle 11.1
FID_QKSCESYROW COUNT(*)
QKSFM_ALL 101
QKSFM_CBO 71
QKSFM_CVM 1
QKSFM_EXECUTION 1
QKSFM_FBA 1
QKSFM_INDEX 1
QKSFM_JPPD 3
QKSFM_OR_EXPAND 1
QKSFM_PQ 6
QKSFM_STAR_TRANS 3
QKSFM_TRANSFORMATION 70

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