CS5226 Project
Database Performance Dashboard Report
Hu Weiwei A0068188N
Wang Fangda A0068212M
Zeng Zhong A0068960U
1 Introduction
In this project, we developed a web-based database performance dashboard to help DBAs
monitor the key statistics of the database more conveniently and efficiently. Our system is able
to offer useful monitoring and tuning information of the database to the DBAs. The web-based
interface is user-friendly and interactive, so that it can help DBAs look inside the database
performance in a clear and easy way. The web interface is developed mainly using ASP.Net and
the backend program is developed using java. The target database is Oracle 10g.
2 Project Admin
There are three members of our group and the key components done by each member is as
follows.
Hu Weiwei – Backend and the workload
Wang Fangda –
Zeng Zhong – Frontend program implementation
3 System Design
3.1 Overall Architecture
The overall architecture of our system is shown in Figure 1. As can be seen, there are mainly
four components, including the web UI, the Oracle DB, the workload and the backend monitor.
Oracle DB is based on the Oracle 10g. Workload program is written using java and select, insert
and delete queries are randomly generated to simulate a actual workload. Backend monitor
program is written using java and it analyzes the table every one minute to get the performance
statistics. Web UI is written using ASP.Net and it offers a web-based interface for DBAs to get
the result clearly and easily.
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Figure 1 Overall Architecture
3.2 Backend Monitor
The parameters monitored are described in Section 4 in detail. Here, we introduce the scheme
of the statistic table used to save all the parameters in Table 1.
create table statistic (
time date,
LIBRARY_CACHE_HIT_RATIO float,
DICTIONARY_CACHE_HIT_RATIO float,
BUFFER_CACHE_HIT_RATIO float,
REDO_BUFFER_ALLOCATION_RETRIES int,
REDO_ENTRIES int,
REDO_LOG_BUFFER_RATIO float,
REDO_LOG_SPACE_WAIT_TIME int,
SORT_DISK int,
SORT_MEMORY int,
SORT_AREA_RATIO float,
ROLLBACK_SEGMENT_WAIT_RATIO float,
primary key (time));
Table 1 Scheme of the Statistic Table
3.3 Web UI
The Web UI Component consists of 5 web pages. They are Home page, Parameter Monitored
page, Configuration page, On-demand Report page and Debug Interface page.
The Home page presents a brief guide of the Web UI Component to the users. In addition, the
users can test whether the Database in the backend is available.
The Parameter Monitored page presents a 3-level of breakdown for the key database
parameters. The top level shows the overall of the 7 key parameters. For each key parameter
there is a second-level breakdown to show the aggregated values during a certain time interval.
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The users can also set the smaller unit time block to monitor the parameter for a specific time
block within the time interval.
The Configuration page is used for users to set the alert and warning values of each parameter.
The effect can be monitored in Parameter Monitored page.
The On-demand Report page the DBA can view the history records of each parameter once
setting the starting date and ending date.
The Debug Interface page is an open interface between the DBA and backend database. The
DBA can issue queries directly on the database and obtain the result in the text window below.
4 Performance Statistics
We introduce the details on how the various statistics are computed and the SQL commands
used to obtain the statistics in this section. In total we choose six parameters that need to be
monitored, including shared pool, buffer cache, redo log buffer, redo log files, memory area
used for sorting and rollback segments.
4.1 Shared Pool
4.1.1 Concepts
The shared pool in Oracle is responsible for collecting, parsing, interpreting, and executing all of
the SQL statements that go against the Oracle database. Hence, the shared pool is a key
component, so it's necessary for the Oracle database administrator to check for shared pool
contention. Shared pool contains two main components, the library cache and the dictionary
cache and we will choose these two parameters as a indicator of the cache state of the
database system.
4.1.2 Parameters
We describe the two parameters, the computation methods, the SQL commands and the tuning
advice in the following table.
Parameter
Computation
Library Cache Hit Ratio
Library Cache Hit Ratio =
sum(PINHITS) / sum(PINS)
SQL
Select sum(PINHITS) / sum(PINS)
as lchr from V$LIBRARYCACHE;
Tuning advice
Enlarge the SHARED_POOL_SIZE
if the Library Cache Hit Ratio is in
the unhealthy level
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Dictionary Cache Hit Ratio
Dictionary Cache Hit Ratio =
sum(GETS – GETMISSES - FIXED)
/ sum(GETS)
Select sum(GETS – GETMISSES FIXED) / sum(GETS) as dchr from
V$ROWCACHE;
Enlarge the SHARED_POOL_SIZE
if the Dictionary Cache Hit Ratio
is in the unhealthy level
4.2 Buffer Cache
4.2.1 Concepts
The buffer cache is part of the SGA and it holds copies of data blocks so as they can be accessed
more quickly by Oracle than by reading them off disk. The purpose of the buffer cache is to
minimize physical I/O. When a block is read by Oracle, it places this block into the buffer cache,
because there is a chance that this block is needed again. Reading a block from the buffer cache
is less costly than reading it from the disk.
4.2.2 Parameters
We describe the parameter, the computation method, the SQL command and the tuning advice
in the following table.
Parameter
Computation
Buffer Cache Hit Ratio
Buffer Cache Hit Ratio = 1 – PHYSICAL_READS /
(CONSISTENT_GETS + DB_BLOCK_GETS)
Select (1 - PHYSICAL_READS / (CONSISTENT_GETS
+ DB_BLOCK_GETS)) as bchr from
V$BUFFER_POOL_STATISTICS;
Enlarge the DB_BLOCK_BUFFERS if the Buffer
Cache Hit Ratio is in the unhealthy level
SQL
Tuning advice
4.3 Redo Log Buffer/Files
4.3.1 Concepts
The redo log buffer is a RAM area that works to save changes to data, in case something fails
and Oracle has to put it back into its original state (a “rollback”). When Oracle SQL updates a
table, redo images are created and stored in the redo log buffer. Oracle will eventually flush the
redo log buffer to disk after a commit operation occurs. When you make changes in the
database you must commit them to make them permanent and visible to other users.
4.3.2 Parameters
We describe the parameter, the computation method, the SQL command and the tuning advice
in the following table.
Parameter
Computation
Redo Log Buffer Ratio between retries
and entries
Redo Log Buffer Ratio =
REDO_BUFFER_ALLOCATION_RETRIES /
REDO_ENTRIES
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Redo Log Space Wait Time
SQL
Tuning advice
Select value as REDO_ENTRIES from
V$SYSSTAT where name=’redo entries’;
Select value as
REDO_BUFFER_ALLOCATION_RETRIES
from V$SYSSTAT where name=’redo
buffer allocation retries’;
Enlarge LOG_BUFFER_SIZE if the Redo
Log Buffer Ratio is greater than 1%
Select value as
REDO_LOG_SPACE_WAIT_TIME from
V$SYSSTAT where name=’redo log
space wait time’;
Enlarge LOG_BUFFER_SIZE if the value
is in high
4.4 Memory area used for sorting
4.4.1 Concepts
The Oracle server processes will sort as much as they can in the memory sort area before using
any disk sort space. If the ratio of the disk sort space of the total sort space is greater than 5
percent, the sort area size will need to be enlarged.
4.4.2 Parameters
We describe the parameter, the computation method, the SQL command and the tuning advice
in the following table.
Parameter
Computation
Sort Area Ratio between Disk and Memory
Sort Area Ratio = SORTS_DISK / (SORTS_DISK +
SORTS_MEMORY)
Select value as SORTS_DISK from V$SYSSTAT
where name=’sorts (disk)’;
Select value as SORTS_MEMORY from
V$SYSSTAT where name=’sorts (memory)’;
Enlarge the SORT_AREA_SIZE if the Sort Area
Ratio is greater than 5%
SQL
Tuning advice
4.5 Rollback segments
4.5.1 Concepts
Rollback segments allow users to undo, or rollback transactions that have been made against a
database. It can ensure other transactions do not see uncommitted changes made to the
database and recover the database to a consistent state in case of failures. The rollback
segment wait ratio shows the number of times a process was delayed during the most recent
reporting interval while waiting to access the rollback segment.
4.5.2 Parameters
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We describe the parameter, the computation method, the SQL command and the tuning advice
in the following table.
Parameter
Computation
Rollback Segment Wait Ratio
Rollback Segment Wait Ratio = sum(WAITS) /
sum(GETS)
Select sum(WAITS) / sum(GETS) as rswr from
V$ROLLSTAT;
Add more rollback segments if the Rollback
Segment Wait Ratio is in the unhealthy level
SQL
Tuning advice
5. Screenshots of the Application
5.1 Home Page
One role of the home page is to help the DBA to use the Web UI application. As seen in the
Figure 2, for each page there is some respect brief information. Another role is to test the
connection to the Database. Once the connection test is successful, the home page will show
the version of the database. Otherwise, it will show the error message.
Figure 2
5.2 Parameter Monitored Page
There are 3 levels of breakdown for parameters to monitor the status of the database.
The top level breakdown shows the health of the all 7 database parameters being monitored.
Each parameter value is calculated as the average value for the last 24 hours. When it is above
the warning value, it implies that this parameter is currently healthy, the color for this row of
record is green; when it is below the warning value but resides above threshold value, it implies
that this parameter is unhealthy, the color for this row of record is yellow; however, when it
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falls below the threshold value, this indicates that the status of database for this parameter is
severely unsatisfied which should catch DBA’s attention. The color for the record is red. At this
time, there will be a tuning advice for the DBA’s reference.
Figure 3
In order to get detail information about one specific parameter, the DBA can click on the
parameter s/he is interested in to zoom in to the second level. In the second level breakdown,
the DBA can set the time interval and view the aggregated values for that parameter. Figure 4
show an interval of 30 min for parameter Dictionary Cache Hit Ratio.
If the DBA wants to further exploit the status of the parameter within the previous time
interval, s/he can click on the specific time interval on the second level to continuously zoom
into the third level. In that level, a unit time block is set by the DBA and the value of the
parameter for each unit time block will be shown as in Figure 5.
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Figure 4
Figure 5
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6. Conclusion
Aiming to optimize DBMS performance, database tuning is a necessary skill for DBAs.
Unfortunately, the chances are that the upfront work of obtaining important statistics is not
straightforward duo to considerable computation. In order to help DBAs perform work as
efficiently and rapidly as possible, a web-based database performance dashboard is designed
and implemented.
Our user-friendly application provides DBAs with not only a big picture of the health of the
database, but also detailed information for further monitoring. In our application, five
parameters – Shared Pool, Buffer Cache, Redo Log Buffer/Files, Memory area used for sorting
and Rollback segments -- gathered from an Oracle DBMS, can be investigated and tuned to
enhance performance. Additionally, the 3-level breakdown architecture and detailed reports
make monitoring work much easier.
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