Download System Administration Certification exam 918 for IBM Informix

System Administration Certification exam 918 for
IBM Informix Dynamic Server 11 prep, Part 2:
System activity monitoring
Skill Level: Intermediate
Manjula Panthagani ([email protected])
Advanced Support Engineer
IBM
Sergio R. Eng ([email protected])
Technical Support Engineer
IBM
16 May 2007
Learn to monitor database server activity for IBM® Informix® Dynamic Server (IDS).
Examine various tools to monitor, diagnose problems, and manipulate IDS data. The
second in a series of eight tutorials, use this tutorial to help prepare for the IDS 11
exam 918.
Section 1. Before you start
About this series
Thinking about seeking certification on System Administration for IBM IDS 11 (Exam
918)? If so, you're in the right spot. This series of eight IDS certification preparation
tutorials covers all the basics -- the topics you'll need to understand before you read
the first exam question. Even if you're not planning to seek certification right away,
this set of tutorials is a great place to start learning what's new in IDS 11.
About this tutorial
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Tuning and configuring an IDS database can be a complex process that sometimes
overwhelms new DBAs. There are, however, a great number of tools, functions, and
applications included with IDS that, once mastered, make this task simple.
This tutorial is designed to introduce you to the set of monitoring tools that are
available with IDS 11 and to show you how each is used to monitor how well (or how
poorly) your database system is operating. In this tutorial:
• Gain an understanding of how automatic monitoring works
• Learn how administration API enables you to monitor system activity
using SQL commands
• Find out how tasks and sensors are created in the scheduler and how
data is collected
• Understand how system monitoring interface is used to collect data
• Learn how onstat and oncheck utilities are used to monitor system
• See how the message log is used to diagnose system problems
This tutorial is the second in a series of eight tutorials that can help you prepare for
the System Administration for IBM IDS V11 Certification (Exam 918). The material in
this tutorial primarily covers the objectives in Section 2 of the test, entitled "System
Activity Monitoring."
Objectives
After completing this tutorial, you should be able to:
• Use automatic monitoring
• Use System-Monitoring Interface
• Use the onstat utility
• Use the oncheck utility
• Create and modify tasks in the scheduler
• Use operating system commands to monitor
Prerequisites
IDS 11 installation is covered in part 1 of this tutorial series. If you haven't already
done so, consider downloading and installing a copy of IBM IDS 11. Installing IDS
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will help you understand many of the concepts that are tested on the System
Administration for IBM IDS V11 Certification exam.
System requirements
You do not need a copy of IDS to complete this tutorial. However, you will get more
out of the tutorial if you download the free trial version of IBM IDS 11 to work along
with this tutorial.
Section 2. Automatic monitoring and corrective actions
You can use the administration API, the scheduler, and information stored in the
sysadmin database to manage automatic maintenance, monitoring, and
administrative tasks. These components of Dynamic Server enable you to simplify
the collection of information and maintenance of the server in complex systems.
Administration API
The SQL administration API enables you to perform remote administration using
various, specific SQL commands for tasks such as managing spaces, managing
configuration, running routine jobs, and system validation.
You can use EXECUTE FUNCTION statements to invoke the built-in admin( ) or
task( ) functions to accomplish administrative tasks that are equivalent to
executing various administrative utilities of Dynamic Server.
In the EXECUTE FUNCTION statements, items in the argument list specify the utility
and its command-line arguments. For example, the following SQL statement, which
is equivalent to the oncheck -ce command, instructs the database server to check
the extents:
EXECUTE FUNCTION admin('check extents');
Sysadmin database
The sysadmin database contains tables that store task properties. You use the task
properties (not configuration parameters) to define the information that the scheduler
collects and the statements that the scheduler runs.
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The sysadmin database also contains:
• The built-in task() function
• The built-in admin() function
• The command_history table
Table 1. Sysadmin database tables
Table
Description
PH_TASK
Contains information about how
and when each task will be
executed
PH_ALERT
Contains a list of errors, warnings,
or information messages that
must be monitored
PH_GROUP
Contains a list of group names.
Each task is a member of a
group.
PH_RUN
Lists tasks and contains
information about how and when
the database server will execute
each task
PH_THRESHOLD
Contains a list of thresholds that
you defined. If a threshold is met,
the task can decide to take a
different action, such as inserting
an alert in the PH_ALERT table.
Each row in the ph_task table is a separate task (defined as a single monitoring
event), and each column is a task property. The task properties indicate such items
as when to run an SQL statement, stored procedure, or UDR and how to handle the
task. An example of a task is the automatic running of a particular job every Monday
at midnight.
The scheduler
The scheduler enables the database server to execute database functions and
procedures at predefined times or as determined internally by the server. The
functions and procedures collect information, and monitor and adjust the server,
using an SQL-based administrative system and a set of tasks.
The scheduler manages and executes scheduled maintenance, monitoring, and
administration tasks. This tool enables you to monitor activities (for example, space
management or automatically backing up any new log data at timed intervals since
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the last log backup) and create corrective actions that run automatically.
The scheduler manages:
• Tasks, which provide the means for running a specific job at a specific
time or interval
• Sensors, which collect and save information
• Startup tasks, which run only once when the database server starts
• Startup sensors, which run only once when the database starts
A set of task properties, which define what needs to be collected or executed,
control the scheduler. The task properties are stored in the ph_task table in the
sysadmin database.
Each row in this table is a separate task, and each column is a task property. The
task properties indicate to the system such things as when to run an SQL statement,
stored procedure, or function and how to handle the task.
For example, you could define tasks to check free log space every hour from 9:00:00
to 19:00:00, daily.
Only task properties, not configuration parameters, define what the scheduler
collects and executes. The scheduler executes tasks at predefined times or as
determined internally, as required by the database server.
Table 2. Built-in tasks
Task
Description
mon_command_history
Purges the command history
table
mon_config
Saves any changes in the
ONCONFIG file
mon_config_startup
Saves the ONCONFIG file on
every server startup
mon_vps
Collects virtual processor
information
mon_checkpoint
Saves information about
checkpoints
mon_table_profile
Saves table profile information,
including the total number of
updates, inserts, and deletes that
occurred on this table
mon_table_names
Saves the table names along with
their creation time
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mon_users
Saves profile information about
each user
check_backup
Checks to ensure that backups
have run
You can modify these tasks and set up more tasks.
Setting up tasks
To set up a task, you need to plan the task first. You need to have:
• A description of the task you want to monitor
• The table where you want to store data
• The SQL command, stored procedure, or function to capture data
• Information on when and how often you want the task to run
You can use SQL to insert a new row into the ph_task table, as shown in the
following examples. Also include values that will be displayed in table columns.
The following example in Listing 1 shows the code for the creation of a table, called
mon_chunkio, that uses a stored procedure to collect and store data. This task
instructs the database server to collect data every five minutes by executing a stored
procedure called chunkio. The default scheduling policy (for example, 8:00 A.M. to
5:00 P.M., five days a week) is used, but the data expires and is deleted when it
becomes seven days old.
Listing 1. Creating a table that uses a stored procedure to collect and store
data
INSERT INTO ph_task
(
tk_description,
tk_result_table,
tk_create,
tk_execute,
tk_frequency,
tk_delete
)
VALUES
(
"Chunk I/O counts and space usage",
"mon_chunkio",
"create table mon_chunkio (ID integer, chunknum smallint,
free integer, size integer, reads integer, pagereads integer,
writes integer, pageswritten integer)",
"chunkio",
"0 0:05:00",
"7 0:00:00"
);
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Setting up sensors
A sensor is a specialized TASK for collecting and saving data. A sensor can be
created the same way as a task by inserting a row in the ph_task table, with some
additional information.
To set up a new sensor, you need to plan first. You need to have:
• A description of the sensor
• The result table to save collect information
• SQL object, stored procedure, or a function to collect information
• Information on when and how often the sensor needs to run
The following example in Listing 2 shows the code for a sensor that collects
information about the amount of memory that is being used and stores the
information in the mon_memory_system table. If that table does not exist, the task
creates it. This task, which runs every 30 minutes, deletes any data in the
mon_memory_system table that has existed for more than 30 days.
Listing 2. Collecting information about the amount of memory that is being
used and storing data in the mon_memory_system table
INSERT INTO ph_task
(tk_name, tk_type, tk_group, tk_description, tk_result_table, tk_create,
tk_execute, tk_stop_time, tk_start_time, tk_frequency, tk_delete )
VALUES
("mon_memory_system",
"SENSOR",
"MEMORY",
"Server memory consumption",
"mon_memory_system",
"create table mon_memory_system (ID integer, class smallint, size int8,
used int8, free int8 )",
"insert into mon_memory_system select $DATA_SEQ_ID, seg_class, seg_size,
seg_blkused, seg_blkfree FROM sysmaster:sysseglst",
NULL,
NULL,
INTERVAL ( 30 ) MINUTE TO MINUTE,
INTERVAL ( 30 ) DAY TO DAY);
Modifying tasks
You can modify the tasks by modifying the rows in the tables that begin with the
characters ph_ in the sysadmin database.
Go to the ph_task or other table that you want to modify in the sysadmin database.
Manually change the task information.
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Command history table
The command_history table in the sysadmin database contains historical information
about the SQL administration API commands executed on this data server.
Section 3. The system-monitoring interface
The system-monitoring interface (SMI) tables are special tables managed by the
database server that contain dynamic information about the state of the database
server. You can use SELECT statements on them to determine almost anything you
might want to know about your database server.
The buildsmi script
When you bring the database server up for the first time, it runs a script called
buildsmi, which is in the $INFORMIXDIR/etc directory. This script builds the
sysmaster database and tables that support SMI. The database server requires
approximately 1750 free pages of logical-log space to build the sysmaster database.
If you receive an error message that directs you to run the buildsmi script, a problem
probably occurred while the database server was building the SMI database, tables,
and views. When you use buildsmi, the existing sysmaster database is dropped and
then recreated.
The bldutil.sh script
The sysutils database is the place where OnBar stores information about every
backup/restore it performed. Backup information on every dbspaces and logical logs
is also stored here. OnBar utilizes these tables when performing warm restores.
When you initialize the database server for the first time, it runs a script called
bldutil.sh on UNIX® or bldutil.bat on Windows®. This script builds the sysutils
database. If it fails, the database server creates an output file in the tmp directory.
The output file is bldutil.process_id on UNIX and bldutil.out on Windows. The
messages in this output file reflect errors that occurred during the script execution.
The sysmaster database
The sysmaster database is described as a pseudo database. That means most of its
tables are not normal tables on disk, but pointers to shared memory structures in the
IDS engine. The sysmaster database contains over 120 tables. Only some of these
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tables are documented in the Informix Dynamic Server Administrators Guide. The
rest are undocumented and meant to be as such for internal use.
These are new tables introduced in Version 11. There are many others sysmaster
tables that you can find more details on in the manual.
Table 3. New sysmaster tables
Table
Description
syscheckpoint
The information about the
checkpoint and associated
statistics
systcblst
Modified the existing table to add
wait stats
sysenvses
View Informix s session
environment variables
sysenv
View the servers environment
variables
sysonlinelog
View the online.log for the server
sysscblst
Improvement to view the memory
used by session
sysnetworkio
View the network I/O generated
by database session
sysdual
Oracle compatibility feature
syssqlcacheprof
Displays the profile information
about each SQL cache
syssqltrace
The SQL statements that have
been recently executed on the
system
syssqltrace_itr
The list of iterators for the SQL
statement
syssqltrace_info
General information about the
SQL tracing
sysnetglobal
Global Network Information
sysnetclienttype
Network information based on
client type
sysbaract_log
The OnBar activity log file
sysrstcb
Improvement to view I/O and lock
wait information
Understanding the SMI tables
The SMI consists of tables and pseudo-tables that the database server maintains
automatically. While the SMI tables appear to the user as tables, they are not
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recorded on disk as normal tables are. Instead, the database server constructs the
tables in memory, on demand, based on information in shared memory at that
instant. When you query an SMI table, the database server reads information from
these shared-memory structures. Because the database server continually updates
the data in shared memory, the information that SMI provides lets you examine the
current state of your database server.
The SMI tables provide information about the following topics:
• Auditing
• Disk usage
• User profiling
• Database-logging status
• Tables
• Chunks
• Chunk I/O
• Dbspaces
• Locks
• Extents
• SQL statement cache statistics
• Virtual-processor CPU usage
• System profiling
The data in the SMI tables changes dynamically as users access and modify
databases that the database server manages.
Accessing SMI tables
Any user can use SQL SELECT statements to query an SMI table, but standard
users cannot execute statements other than SELECT. Attempts to do so result in
permission errors. The administrator can execute SQL statements other than
SELECT, but the results of such statements are unpredictable.
Dynamic Server provides the sysadtinfo and sysaudit tables. Only user informix on
UNIX or members of the Informix-Admin group on Windows can query sysadtinfo
and sysaudit.
You cannot use dbschema or dbexport on any of the tables in the sysmaster
database. If you do, the database server generates the following error message:
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Database has pseudo tables - can't build schema
You can use SELECT statements on SMI tables wherever you can use SELECT
against ordinary tables (from DBAccess, in an SPL routine, with ESQL/C, and so on)
with one restriction: You cannot (meaningfully) reference rowid when you query SMI
tables. SELECT statements that use rowid do not return an error, but the results are
unpredictable.
All standard SQL syntax, including joins between tables, sorting of output, and so
on, works with SMI tables. For example, if you want to join an SMI table with a
non-SMI table, name the SMI table with the following standard syntax:
sysmaster[@dbservername]:[owner.]tablename
Example
Intention:: List of users who had a database open and which workstation they were
using to connect to the database.
• The onstat -u utility would tell which users were connected to the
server, but not what database and what workstation they were using.
• Onstat -g ses would tell the user and workstation, but not the
database.
• Onstat -g sql would tell the session ID and database, but not the user
name and workstation.
Listing 3. Example
QUERY SELECT sysdatabases.name database,
syssessions.username,
syssessions.hostname, syslocks.owner sid FROM syslocks,
sysdatabases, outer
syssessions WHERE syslocks.tabname = "sysdatabases" AND
syslocks.rowidlk =
sysdatabases.rowid AND syslocks.owner = syssessions.sid;
OUTPUT database stores_demo username informix hostname
istation1 sid 27
database sysmaster username informix hostname istation1 sid 29
Section 4. The onstat utility
The onstat utility provides a way to monitor database server shared memory from
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the command line. The onstat utility reads data from shared memory and reports
statistics that are accurate for the instant during which the command executes. That
is, onstat provides information that changes dynamically during processing,
including changes in buffers, locks, indexes, and users.
Monitor the database server status
The onstat output heading indicates the database server status. Whenever the
database server is blocked, onstat displays the following line after the banner line:
All onstat output includes a header. The onstat - option displays only the output
header and is useful for checking the database server mode. The header takes the
following form:
Version--Mode (Type)--(Checkpnt)--Up Uptime--Sh_mem Kbytes
Syntax
Listing 4. Onstat syntax
>>-onstat------------------------------------------------------->
.-----------------------------. V (1)
>--+-+-----------------+----+-------------------------+-+------+->
'-filename_source-' +- -a---------------------+ +-b---------------------+
+- -B---------------------+ +- -c---------------------+ +-C---------------------+ +- -d---------------------+ +-D---------------------+ +- -f---------------------+ +-F---------------------+ +- -g--Monitoring options-+ +-G---------------------+ +- -i---------------------+ +-k---------------------+ +- -K---------------------+ +-l---------------------+ +- -m---------------------+ +-o--+---------------+--+ '-filename_dest-' +-O---------------------+ +-p---------------------+ +- -P---------------------+ +-r--+---------+--------+ '-seconds-' +-R---------------------+ +-s---------------------+ +- -t---------------------+ +-T---------------------+ +- -u---------------------+ +-x---------------------+ +- -X---------------------+ '-z---------------------' +---------------------------------------------------------+ '---------------------------------------------------------
Note: Only one occurrence of each item is allowed. More than one option can be
specified on a single onstat command invocation.
Table 4. Onstat options
Element
Purpose
-
Displays the output header
--
Displays a listing of all onstat
options and their functions
-a
Interpreted as onstat
-cuskbtdlp; displays output in
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that order
-b
Displays information about buffers
currently in use, including number
of resident pages in the buffer
pool
-B
Obtains information about all
database server buffers, not just
buffers currently in use. See the
entry for -b in this table
-c
Displays the ONCONFIG file: *
$INFORMIXDIR/etc/
$ONCONFIG for UNIX *
%INFORMIXDIR%\etc\
%ONCONFIG% for Windows
-C
Prints B-tree scanner information
-d
Displays information for chunks in
each storage space
-D
Displays page-read and
page-write information for the first
50 chunks in each dbspace
-f
Lists the dbspaces currently
affected by the DATASKIP
feature
-F
Displays a count for each type of
write that flushes pages to disk
-g
Provides monitoring options
-G
Prints global transaction IDs
-i
Puts the onstat utility into
interactive mode
-j
Prints the interactive status of the
active onpload process
-k
Displays information about active
locks
-l
Displays information about
physical and logical logs,
including page addresses
-m
Displays the 20 most recent lines
of the database server message
log
-o
Saves copies of the
shared-memory segments to
filename
-O
Displays information about the
Optical Subsystem memory
cache and staging-area
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blobspace
-p
Displays profile counts
-P
Displays for all partitions the
partition number and the break-up
of the buffer-pool pages that
belong to the partition
-r
Repeats the accompanying
onstat options after they wait
the specified seconds between
each execution. The default value
of seconds is five.
-R
Displays detailed information
about the LRU queues, FLRU
queues, and MLRU queues
-s
Displays general latch information
-t
Displays tblspace information,
including residency state, for
active tblspaces
-T
Displays tblspace information for
all tblspaces
-u
Prints a profile of user activity
-x
Displays information about
transactions
-X
Obtains precise information about
the threads that are sharing and
waiting for buffers
-z
Sets the profile counts to zero
filename_dest
Specifies destination file for the
copy of the shared-memory
segments
filename_source
Specifies file that onstat reads
as source for the requested
information
Monitoring options
Specifies which onstat -g
monitoring option to use
seconds
Specifies number of seconds
between each execution of the
onstat -r command
onstat g monitoring options
The following onstat -g options are provided for support and debugging only. You
can include only one of these options per onstat -g command. For more
information, see your IBM Informix Performance Guide.
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Table 5. onstat -g options
onstat -g option
Topic or function
-g act
Active threads. For example
output, see the onstat -g act
option.
-g afr pool name session id
Prints allocated memory
fragments for a specified session
or shared-memory pool. Each
session is allocated a pool of
shared memory. To obtain the
pool name, see the -mem option.
For example output, see the
onstat -g afr pool name
session id option.
-g all
Prints all multithreading
information
-g ath
Prints all threads. The sqlmain
threads represent client sessions.
The rstcb value corresponds to
the user field of the onstat -u
command. For example output,
see the onstat -g ath option.
For information on using onstat
-g ath to print Enterprise
Replication threads, see the IBM
Informix Dynamic Server
Enterprise Replication Guide.
-g cat [modifier]
Prints information from the
Enterprise Replication global
catalog. The global catalog
contains a summary of
information about the defined
servers, replicates, and replicate
sets on each of the servers within
the enterprise. For more
information and sample output,
see the onstat -g cat option.
-g cac agg
Prints the definitions for
user-defined aggregates that are
currently in the cache
-g cac stmt
Prints the contents of the SQL
statement cache. Prints the same
output as the -g ssc statement.
-g con
Prints conditions with waiters. For
example output, see the onstat
-g con option.
-g ddr
Prints the status of the Enterprise
Replication database log reader.
If log reading is blocked, data
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might not be replicated until the
problem is resolved. For more
information and sample output,
see the onstat -g ddr option.
-g dic table
Without any parameters, prints
one line of information for each
table cached in the
shared-memory dictionary. If
given a specific table name as a
parameter, prints internal SQL
information for that table. For
more information, see your IBM
Informix Performance Guide. For
sample output, see the onstat
-g dic table option.
-g dis
Prints a list of database servers
and their status, and information
about each database server,
INFORMIXDIR, sqlhosts file,
ONCONFIG file, and hostname.
For example output, see the
onstat -g dis option.
-g dll
Prints a list of dynamic libraries
that have been loaded. For
example output, see the onstat
-g dis option.
-g dri
Prints data-replication
information. See monitoring
High-Availability Data-Replication
status in the IBM Informix
Administrator's Guide. For
example output, see the onstat
-g dri option.
-g dsc
Prints data-distribution cache
information. For example output,
see the onstat -g dsc option.
-g dss [modifier]
Prints detailed statistical
information about the activity of
individual data sync threads and
about user-defined data types.
For more information and sample
output, see the onstat -g dss
option.
-g dtc
Prints statistics about the delete
table cleaner, which removes
rows from the delete table when
they are no longer needed. For
more information and sample
output, see the onstat -g dtc
option.
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-g env
Prints the values of environment
variables the database server
currently uses. For more
information, see the onstat -g
env option.
-g ffr pool name session id
Prints free fragments for a pool of
shared memory. For example
output, see the onstat -g ffr
pool name session id
option.
-g glo
Prints global multithreading
information. This information
includes CPU use information
about the virtual processors, the
total number of sessions, and
other multithreading global
counters. On Windows, the virtual
processors are operating system
threads. The values displayed
under the 'pid' field are thread ids,
not process ids (Windows). For
example output, see the onstat
-g glo option.
-g grp [modifier]
Prints statistics about the
Enterprise Replication grouper.
The grouper evaluates the log
records, rebuilds the individual log
records into the original
transaction, packages the
transaction, and queues the
transaction for transmission. For
more information and sample
output, see the onstat -g grp
option.
-g his
Prints information about the
SQLTrace configuration
parameter
-g imc
Prints information about
MaxConnect instances that are
connected to the database server.
If MaxConnect is not connected to
the database server, this
command displays No
MaxConnect servers are
connected.
-g ioa
Prints combined information from
-g ioq and -g iov. For
example output, see the onstat
-g ioa option.
-g iob
Prints the big buffer usage
summary. For example output,
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see the onstat -g iob option.
-g iof
Prints asynchronous I/O statistics
by chunk or file. This option is
similar to the -D option, except it
also displays information on
nonchunk, temporary, and
sort-work files. For example
output, see the onstat -g iof
option.
-g iog
Prints AIO global information. For
example output, see the onstat
-g iog option.
-g ioq queue name
Prints pending I/O operations for
the queue name. If given the gfd
or kaio queue name, a queue for
each CPU VP is displayed. If
queue name is omitted, I/O
statistics for all queues are
displayed. For example output,
see the onstat -g ioq queue
name option.
-g iov
Prints asynchronous I/O statistics
by virtual processor. For example
output, see the onstat -g iov
option.
-g ipl
Prints index page logging status
-g lmx
Prints all locked mutexes. For
example output, see the onstat
-g lmx option.
-g lsc
Displays information about light
scans
-g mem pool name session id
Prints statistics for a memory
pool. Also displays the pool
name, type of shared memory
segment that contains the pool,
the address of the pool, the total
size of the pool, the number of
bytes of free memory that it
contains, and the number of free
and allocated fragments in the
pool. If no argument is provided,
displays information about all
pools. The block pools are listed
in a separate section after the
main pool list. You also can use
ISA to obtain detailed information
about a memory pool. If you run
an SQL query that allocates
memory from the
PER_STMT_EXEC and
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PER_STMT_PREP memory
duration pools, onstat -g mem
displays information on the
PRP.sessionid.threadid pool and
the EXE.sessionid.threadid pool.
For example output, see the
onstat -g mem pool name
session id option. For more
information, see the IBM Informix
DataBlade API Programmer's
Guide.
-g mgm
Prints Memory Grant Manager
resource information. For
example output, see the onstat
-g mgm option.
-g nbm
Prints block bit map for the
nonresident segments, one bit per
8-kilobyte block. Bit set indicates
block free. For example output,
see the onstat -g nbm option.
-g nif [modifier]
Prints statistics about the network
interface. Useful to determine why
data is not replicating. For more
information and sample output,
see the onstat -g nif option.
-g nsc client id
Prints shared-memory status by
client id. If client id is omitted, all
client status areas are displayed.
This command prints the same
status data as the nss command.
For example output, see the
onstat -g nsc client_id
option.
-g nsd
Prints network shared-memory
data for poll threads. For example
output, see the onstat -g nsd
Option.
-g nss session id
Prints network shared-memory
status by session id. If session id
is omitted, all session status
areas are displayed. This
command prints the same status
data as the nsc command.
-g nta
Prints combined network statistics
from -g ntd, -g ntm, -g ntt,
and -g ntu. If MaxConnect is
installed, this command prints
statistics that you can use to tune
MaxConnect performance.
-g ntd
Prints network statistics by
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service. For example output, see
the onstat -g ntd option.
-g ntm
Prints network mail statistics. For
example output, see the onstat
-g ntm option.
-g ntt
Prints network user times. For
example output, see the onstat
-g ntt option.
-g ntu
Prints network user statistics. For
example output, see the onstat
-g ntu option.
-g pos
Prints $INFORMIXDIR/etc/
.infos.DBSERVERNAME file for
UNIX and %INFORMIXDIR%\etc\
.infos.DBSERVERNAME for
Windows. For example output,
see the onstat -g pos option.
-g ppf partition number 0
Prints partition profile for partition
number; 0 prints profiles for all
partitions. If TBLSPACE_STATS
configuration parameter is set to
0, displays: Partition profiles is
disabled. For example output, see
the onstat -g ppf
partition number 0 option.
-g prc
Prints information about SPL
routine cache. For example
output, see the onstat -g prc
option.
-g qst
Prints queue statistics
-g que
Prints statistics for the high-level
queue interface (which are
common to all the queues of the
Enterprise Replication Queue
Manager). For more information
and sample output, see the
onstat -g que option.
-g rbm
Prints block bit map for the
resident segment (communication
message area). For example
output, see the onstat -g rbm
option.
-g rcv [serverid]
Prints statistics about the receive
manager, which is a set of service
routines between the receive
queues and data sync. For more
information and sample output,
see the onstat -g rcv option.
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-g rea
Prints ready threads. For example
output, see the onstat -g rea
option.
-g rep [replname]
Prints events that are in the
queue for the schedule manager.
For more information and sample
output, see the onstat -g rep
option.
-g rqm [modifier]
Prints statistics and contents of
the low-level queues (each
individual queue) managed by the
Reliable Queue Manager (RQM).
For more information and sample
output, see the onstat -g rqm
option.
-g rwm
Prints read/write mutexes. For
example output, see the onstat
-g rwm option.
-g sch
Prints the number of semaphore
operations, spins, and busy waits
for each virtual processor. On
Windows, the virtual processors
are operating system threads.
The values displayed under the
'pid' field are thread ids not
process ids (Windows). For
example output, see the onstat
-g sch option.
-g seg
Prints shared-memory-segment
statistics. This option shows the
number and size of
shared-memory segments that
the database server is currently
using. For example output, see
the onstat -g seg option.
-g ses sessionid
Prints session information by
sessionid. If sessionid is missing,
a one-line summary of each
session prints. For more
information, see the onstat -g
ses option.
-g sle
Prints all sleeping threads. For
example output, see the onstat
-g sle option.
-g smb option
Prints detailed information about
sbspaces. For more information,
see the onstat -g smb option.
-g smxoption
Displays server multiplexer group
connections information
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-g spi
Prints spin locks that virtual
processors have spun more than
10,000 times to acquire. These
spin locks are called longspins.
The total number of longspins is
printed in the heading of the glo
command. Excessive longspins
might indicate an overloaded
system, too many virtual
processors for a given computer
or node, or an internal problem.
To reduce longspins, reduce the
number of virtual processors
(generally class CPU), reduce the
load on the computer, or use the
no-age or processor affinity
features.
-g sql session id
Prints SQL information by session
id. If session id is omitted, a
one-line summary for each
session prints. For more
information, see the onstat -g
sql option.
-g ssc
Monitors the number of times that
the database server reads the
SQL statement in the cache. For
example output, see the onstat
-g ssc option. Displays the
same output as onstat -g cac
stmt. For more information, see
improving query performance in
the IBM Informix Performance
Guide.
-g ssc all
Reports the key-only cache
entries as well as the fully cached
statements. If the value in the hits
column is less than the
STMT_CACHE_HITS value, that
entry is a key-only cache entry.
For more information, see
memory utilization in the IBM
Informix Performance Guide.
-g ssc pool
Reports usage of all memory
pools for the SQL statement
cache. The output displays
information on the name, class,
address, and total size of the
memory pools. For more
information, see improving query
performance in the IBM Informix
Performance Guide.
-g stk tid all
Dumps stack of thread specified
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by thread ID or stacks for all
threads. This option is not
supported on all platforms and is
not always accurate. For example
output, see the onstat -g stk
tid option.
-g stm [session id]
Displays the memory that each
prepared SQL statement uses.
For example output, see the
onstat -g stm option. For
more information, see memory
utilization and improving query
performance in the IBM Informix
Performance Guide.
-g sts
Prints maximum and current stack
use per thread. For example
output, see the onstat -g sts
option.
-g sync
Shows which sync is active. For
example output, see the onstat
-g sync option.
-g tpf tid
Prints thread profile for a specific
thread ID. For example output,
see the onstat -g tpf tid
option.
-g ufr pool name session id
Prints allocated fragments by use
-g vpcache
Returns information about CPU
VP memory block cache statistics
-g wai
Prints waiting threads; all threads
waiting on mutex or condition, or
yielding
-g wmx
Prints all mutexes with waiters.
For example output, see the
onstat -g wmx option.
-g wst
Prints wait statistics
Statistics called from source file
Use the filename_source parameter with other option flags to derive the
requested onstat statistics from the shared-memory segments that filename_source
contains. You must first use the onstat -o command to create a file that contains
the shared-memory segments.
Example
Listing 5. Calling statistics from source file
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Creating a snapshot of the shared memory for further analysis
onstat -o myfile
Checking some information, for example dbspace information
onstat -d myfile
Results
Dbspaces
address number
flags
owner
name
ad357e8 1
0x60001
informix rootdbs
b62a5b0 2
0x60001
informix dbsp1
2 active, 2047 maximum
fchunk
nchunks
pgsize
flags
1
1
2048
N
B
2
1
4096
N
B
Chunks
address chunk/dbs offset page Rd page Wr pathname
ad35948 1
1
0
493
5803
/local0/engines/ol_tuxedo/ifmxdata/rootdbs
b62a710 2
2
0
4
20
/local0/engines/ol_tuxedo/ifmxdata/dbsp1
2 active, 32766 maximum
NOTE: The values in the "page Rd" and "page Wr" columns for
DBspace chunks are
displayed in terms of system base page size.
Expanded chunk capacity mode: always
Interactive execution
To put the onstat utility in interactive mode, use the -i option. Interactive mode
allows you to enter multiple options, one after the other, without exiting the program.
For information on using interactive mode, see onstat -i.>
Continuous onstat execution
Use the seconds parameter with the -r option flag to cause all other flags to
execute repeatedly after they wait the specified seconds between each execution.
Section 5. The oncheck utility
The oncheck utility displays information about the database disk configuration and
usage, such as the number of pages used for a table, the contents of the reserved
pages, and the number of extents in a table.
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The oncheck utility is invoked by executing the oncheck command. The simplest
form of the command is shown in Listing 6, below:
Listing 6. Oncheck syntax
oncheck
<-option>
<database | database:owner.table | tablespacenum logical
pagenum ... >
<-x>
<-n>
<-y>
-x Places a shared lock on the table when you check and
print an index
-n Indicates that no index repair should be performed,
even if errors are detected Use with the index
repair options
(-ci, -cI, -pk, -pK, -pl, and -pL).
-y Repairs indexes when errors are detected.
Options
Table 6. Oncheck options
Option
Description
-cc
Checks system catalog tables for
the specified database
-cd
Reads all pages, except simple
large objects from the tblspace for
the specified database, table, or
fragment, and checks each page
for consistency. Also checks
tables that use a user-defined
access method. Does not check
simple or smart large objects.
-cD
Same as -cd, but also reads the
header of each blobpage and
checks it for consistency. Checks
simple large objects but not smart
large objects.
-ce
Checks each chunk-free list,
corresponding free space, and
each tblspace extent. Also checks
smart-large-object extents and
sbspace metadata. The oncheck
process verifies that the extents
on disk correspond to the current
control information that describes
them.
-ci
Checks the ordering of key values
and the consistency of horizontal
and vertical node links for all
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indexes associated with the
specified table. Also checks
indexes that use a user-defined
access method.
-cI
Same as -ci, but also checks
that the key value tied to a rowid
in an index is the same as the key
value in the row
-cr
Checks each of the root dbspace
reserved pages for several
conditions
-cR
Checks the root dbspace
reserved pages, physical-log
pages, and logical-log pages
-cs
Checks smart large object and
sbspace metadata for an sbspace
-cS
Checks smart large object and
sbspace metadata for an sbspace
as well as extents
-pB
Displays statistics that describe
the average fullness of blobspace
blobpages in a specified table.
These statistics provide a
measure of storage efficiency for
individual simple large objects in
a database or table. If a table or
fragment is not specified,
statistics are displayed for the
entire database.
-pc
Same as -cc, but also displays
the system catalog information as
it checks the system catalog
tables, including extent use for
each table None
-pd
Displays rows in hexadecimal
format
-pD
Displays rows in hexadecimal
format and simple-large-object
values stored in the tblspace or
header information for smart large
objects stored in an sbspace
sbpage, and simple large objects
stored in a blobspace blobpage
-pe
Same as -ce but also displays
the chunk and tblspace extent
information as it checks the chunk
free list, the corresponding free
space, and each tblspace extent
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-pk
Same as -ci, but also displays
the key values for all indexes on
the specified table as it checks
them
-pl
Same as -ci, but also displays
the key values. Only leaf-node
index pages are checked.
-pL
Same as -cI, but also displays
the key values and rowids for
leaf-node index pages only
-pp
Displays contents of a logical
page
-pP
Same as -pp, but requires a
chunk number and logical page
number or internal rowid as input
-pr
Same as -cr, but also displays
the reserved-page information as
it checks the reserved pages
-ps
Checks and displays
smart-large-object and sbspace
metadata for an sbspace
-pS
Checks and displays
smart-large-object and sbspace
metadata. Lists extents and
header information for individual
smart large objects.
-pt
Displays tblspace information for
a table or fragment
-pT
Same as -pt, but also displays
index-specific information and
page-allocation information by
page type (for dbspaces)
Check and repair
The oncheck utility can repair the following types of disk structures:
• Partition-page statistics
• Bitmap pages
• Partition blobpages
• Blobspace blobpages
• Indexes
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• Sbspace pages
• Metadata partitions for sbspaces
If oncheck detects inconsistencies in other structures, messages alert you to these
inconsistencies, but oncheck cannot resolve the problem.
Repairing indexes in sbspaces and external spaces
The oncheck utility can repair an index in an sbspace or external space if the index
is created using an access method that supports the oncheck -y option. Although
the oncheck utility does not repair fragmented indexes, user-defined access
methods can repair them.
Locking and oncheck
The oncheck utility places a shared lock on a table during the following operations,
so no other users can perform updates, inserts, or deletes until the check has
completed:
• When it checks data
• When it checks indexes (with -ci, -cI, -pk, -pK, -pl, or -pL), and the
table uses page locking
• When you specify the -x option with -ci, -cI, -pk, -pK, -pl, or -pL,
and the table uses row locking
If the table does not use page locking, the database server does not place a shared
lock on the table when you check an index with the oncheck -ci, -cI, -pk, -pK,
-pl, or -pL options. When no shared lock is on the table during an index check,
other users can update rows during the check.
By not placing a shared lock on tables using row locks during index checks, the
oncheck utility cannot be as accurate in the index check. For absolute assurance of
a complete index check, you can execute oncheck with the -x option. With the -x
option, oncheck places a shared lock on the table, and no other users can perform
updates, inserts, or deletes until the check has completed.
Section 6. Message log
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The database server message log is an operating system file. The messages
contained in the database server message log do not usually require immediate
action.
Location
To specify the message log path name, set the MSGPATH configuration parameter.
The changes to MSGPATH take effect after you shut down and restart the database
server.
Monitoring message log
You should monitor the message log once or twice a day to ensure that processing
is proceeding normally and that events are being logged as expected. Use the
onstat -m command to obtain the name of the message log and the 20 most
recent entries. Use a text editor to read the complete message log. Use an operating
system command (such as the UNIX command tail -f) to see the messages as
they occur.
Monitor the message log size, because the database server appends new entries to
this file. Edit the log as needed, or back it up to tape and delete it.
If the database server experiences a failure, the message log serves as an audit trail
for retracing the events that develop later into an unanticipated problem. Often the
database server provides the exact nature of the problem and the suggested
corrective action in the message log.
You can read the database server message log for a minute-by-minute account of
database server processing in order to catch events before a problem develops.
However, you do not need to perform this kind of monitoring.
Message categories
Four general categories of unnumbered messages exist, although some messages
fall into more than one category:
• Routine information
• Assertion-failed messages
• Administrative action needed
• Fatal error detected
Examples of message log messages
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Listing 7. Example of routine messages
Wed Apr 18 19:01:23 2007
22:56:00 Maximum server connections 284
22:56:03 Level 1 Archive started on dbsherm05
23:23:40 Logical Log 42173 Complete, timestamp: 0xeee826ad.
23:23:41 Logical Log 42173 - Backup Started
23:24:26 Logical Log 42173 - Backup Completed
23:26:30 Checkpoint Completed: duration was 29 seconds, 36019
buffers not flushed.
23:26:30 Checkpoint loguniq 42174, logpos 0x281d658,
timestamp: 0xeeece592
Listing 8. Example of assertion-failed messages
19:12:26
Who: Session(33, informix@rdbms2, 0, 25da90ba8)
Thread(63, xchg_1.6, 25da5d308, 1)
File: rspartn.c Line: 2426
19:12:26
Results: Could not complete operation on
'erv:"informix".stmy'
19:12:26
Action: Run 'oncheck -cDI
ermes:"informix".avvisi_out_tot_e2'
19:12:26 stack trace for pid 1474 written to
/appl/InformixDump/af.4274f8a
19:12:26
See Also: /appl/InformixDump/af.4274f8a
19:12:38 ptmap
19:12:38 Assert Failed: ptmap
Listing 9. Example of administrative action needed messages
11:05:49 Maximum server connections 4
11:08:05 Logical Log Files are Full -- Backup is Needed
Listing 10. Example of fatal error messages
15:24:33 IBM Informix Dynamic Server Started.
15:24:33 shmget: [EEXIST][17]: key 52584801: shared memory
already exists
15:24:33 mt_shm_init: can't create resident segment
15:40:09 Assert Failed: Unexpected virtual processor
termination,
pid = 526411, exit = 0x9
Event alarms
The database server provides a mechanism for automatically triggering
administrative actions based on an event that occurs in the database server
environment. This mechanism is the event-alarm feature. Events can be informative
(for example, backup complete) or can indicate an error condition that requires your
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attention (for example, unable to allocate memory). To use the event-alarm feature,
set the ALARMPROGRAM configuration parameter to the full pathname of an
executable file that performs the necessary administrative actions.
The database server can execute a program that operates either whenever certain
noteworthy event alarms occur or every time any event alarm occurs. Noteworthy
event alarms include failure of a database, table, index, chunk, or dbspace taken
offline, internal subsystem failure, start-up failure, and detection of long transaction.
You can receive notification of an event alarm through e-mail or pagermail.
Use the following parameters in Table 7 to specify:
• Whether the event-alarm program operates for all or only certain event
alarms
• What actions to take when alarm events occur
Table 7. Event-alarm parameters
Parameter
Description
ALRM_ALL_EVENTS
Specifies whether
ALARMPROGRAM runs for all
events that are logged in the
MSGPATH or only specified
noteworthy events
ALARMPROGRAM
Specifies the location of a file that
is executed when an event alarm
occurs
Section 7. Operating system tools
UNIX tools
System activity reporter (SAR)
The sar command is useful for monitoring CPU utilization, disk activity, and memory
utilization.
Listing 11. sar example
$ sar -u 60 10
09:42:17
%usr %sys %wio %idle
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09:43:17
09:44:17
09:45:17
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1
1
5
4
5
4
3
6
0
0
0
1
94
95
92
89
The example shown in Lising 11 monitors CPU utilization at intervals of 60 seconds
for 10 iterations.
To identify potential or actual performance bottlenecks or problems, it is necessary
to continuously monitor your system and capture these data points over an extended
period of time.
The UNIX sar command is particularly useful for creating and maintaining long-term
performance histories:
• sar is available on all IBM Informix IDS-hardware platforms
• When run with a named output file, a single binary-encoded file is created
from which all sar reports can be generated at a later time
time or timex
The time and timex commands allow you to time the running of a process. Both
time and timex report on real time as well as user and system CPU time.
ps
The ps command is a good source of snapshot information about system processes
currently running.
Listing 12. Process status (ps)
$
S
T
S
S
S
S
ps -el
UID
PID
root 0
root 1
root 434
root 435
root 445
PPID
0
0
1
434
434
STIME
08:59:54
08:59:57
09:03:51
09:03:53
09:06:02
TTY
?
?
?
?
?
TIME
0:01
0:00
0:05
0:00
0:00
CMD
sched
/etc/init
oninit
oninit
oninit
where PID is Process Id
STIME is process start time
TIME is accumulated CPU time for process
iostat
The iostat command provides highly accurate measures of throughput, utilization,
queue lengths, transaction rates, and service times.
Listing 13. The iostat command
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$ iostat -x 5 1
device
sd0
sd1
sd6
sd30
r/s
6.2
1.8
0.0
0.2
w/s
0.0
0.0
0.0
0.2
Kr/s
21.5
14.3
0.0
25.7
Kw/s
0.0
0.0
0.0
0.2
extended device statistics
wait
actv
svc_t
%w
%b
0.0
0.1
24.1
0
15
0.0
0.1
41.6
0
7
0.0
0.0
0.0
0
0
0.0
0.1
22.5
0
13
vmstat
The vmstat command provides information about the status of processes, memory
utilization, paging statistics, system activity, and CPU usage.
Listing 14. The iostat command
$ vmstat 5 4
procs
memory
r
4
2
3
4
b
1
3
2
2
w
0
0
0
0
swap
104512
105184
106688
104672
fre
1792
1952
1952
6240
page
re
8
4
7
4
mf
0
0
0
0
pi
288
96
256
384
disk
po ...
192 ...
128 ...
224 ...
32 ...
d0
4
0
4
3
d1
6
2
4
1
d2
1
1
12
3
faults
in
23
14
29
2
sy
15
15
21
75
...
...
...
...
...
where w is processes swapped out page outs
swap is Kbytes of swap space available
d0 is # of disk operations/sec
p0 is pageouts
Windows event viewer
The event viewer shows informational, warning, and error messages for the
operating system, other applications, and the database server.
To display database server messages on Windows:
1.
Choose Administrative Tools > Event Viewer.
2.
Choose Log > Security.
3.
Double-click any event for a more detailed message.
Windows utilities
The following Informix utilities simplify administration of the database server on
Windows.
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ixpasswd.exe
ixpasswd.exe changes the logon password for all services that log on as user
informix. You can change the password interactively or on the command line using
the -y option. This utility saves having to manually change the password for each
service whenever you change the informix password.
If you are logged on locally and run ixpasswd, it changes the password for services
that log on as the local informix user. If you are logged on domain and run ixpasswd,
it changes the password for services that log on as domain\informix.
Usage:
ixpasswd [-y new_password]
ixsu.exe
Launches a command-line window that runs as the specified user. The user is a
local user unless you specify a domain name. If you do not specify a user name, the
default user is informix. You no longer need to log off as the current user and log on
as informix to perform DBA tasks that need to be run as informix. The ixsu utility
requires advanced user rights:
Act as part of the operating system
• Increase quotas
• Replace a process-level token
• To configure advanced user rights on Windows NT:
1.
Select User Manager > Policies > User Rights
2.
Check the Advanced User Rights option.
Note: If you change the advanced user rights for the current user,
you need to log off and log back on for the new rights to take effect
Usage:
ixsu [[domain\]username]
The ixsu utility is equivalent to the Windows 2000 runas command. To use runas
to run a command shell as another user:
Usage:
runas /user:username cmd
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ntchname.exe
ntchname.exe changes the registry entries for Dynamic Server from the old
hostname to the new hostname. Run ntchname after you change the hostname.
This utility does not change user environment variables. After you execute
ntchname, edit the %INFORMIXDIR%\%INFORMIXSERVER%.cmd file and change
the INFORMIXSQLHOSTS entry to the new hostname.
Usage:
ntchname old_name new_name
Section 8. Conclusion
This tutorial introduced you to the set of monitoring tools that are available with IDS
11 and showed you how each are used to monitor how well (or how poorly) your
database system is operating. Database monitoring is a vital activity that, when
performed on a regular basis, provides continuous feedback on the health of a
database system.
The SQL administration API enables you to perform remote administration using
various, specific SQL commands for tasks such as managing spaces, managing
configuration, running routine jobs, and system validation.
The scheduler manages and executes scheduled maintenance, monitoring, and
administration tasks. This tool enables you to monitor activities (for example, space
management or automatically backing up any new log data at timed intervals since
the last log backup) and create corrective actions that run automatically.
The system-monitoring interface (SMI) tables are special tables managed by the
database server that contain dynamic information about the state of the database
server. You can use SELECT statements on them to determine almost anything you
might want to know about your database server.
The onstat utility provides a way to monitor database server shared memory from
the command line. The onstat utility reads data from shared memory and reports
statistics that are accurate for the instant during which the command executes. That
is, onstat provides information that changes dynamically during processing,
including changes in buffers, locks, indexes, and users.
The oncheck utility displays information about the database disk configuration and
usage, such as the number of pages used for a table, the contents of the reserved
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pages, and the number of extents in a table.
The database server message log is an operating system file. You can read the
database server message log for a minute-by-minute account of database server
processing in order to catch events before a problem develops.
Event alarm feature is the mechanism for automatically triggering administrative
actions based on an event that occurs in the database server environment.
Part 3 of the tutorial series helps you troubleshoot the database server problems.
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Resources
Learn
• developerWorks Informix zone: Read articles and tutorials and connect to other
resources to expand your Informix skills.
• IBM Informix Dynamic Server Information Center: Learn more about Informix.
• IBM Informix Dynamic Server 11 BETA Information Center: Learn more about
IDS 11.
• developerWorks IDS Experts blog: Find technical notes on Informix Dynamic
Server by a worldwide team of Development and Technical Support engineers.
• IBM Information Management certification page: Learn more about resources
for IDS certification.
• developerWorks Information Management zone: Learn more about Information
Management. Find technical documentation, how-to articles, education,
downloads, product information, and more.
• Stay current with developerWorks technical events and webcasts.
• Technology bookstore: Browse for books on these and other technical topics.
Get products and technologies
• Informix Dynamic Server Enterprise Edition V10.0: Download a free trial
version.
• Informix Dynamic Server 11: Download the free trial version to work along with
this tutorial.
• IBM product evaluation versions: Download and get your hands on application
development tools and middleware products from Information Management,
Lotus®, Rational®, Tivoli®, and WebSphere®.
Discuss
• Participate in the discussion forum for this content.
• Check out developerWorks blogs and get involved in the developerWorks
community.
About the authors
Manjula Panthagani
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Manjula Panthagani is an Advanced Support Engineer for Informix
Dynamic Server at IBM. She has been in this position supporting IDS
for over seven years and participated in the development of the IDS
Certification exam.
Sergio R. Eng
Sergio Eng has developed many database applications through the
years. He has also been a DBA and UNIX system administrator for
software development platforms. At IBM, Sergio has provided Informix
database support for IDS users for Versions 7, 9, and 10.
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