maintenance plan - Page 23

Why You Need a Requirements-based Software Development Strategy

As IT departments continue to drive toward more efficient operations, a requirements-based plan is crucial

Is JQuery or Javascript are capable for image processing?

My plan is to develop a web based application in the future. I think, i can named it "Booth Reservation System" for the Events companies here in our country. One of the main functionality of the system and the most tricky part/ difficult part is the user can upload a "floor plan"(the design of the area were the booth is located in any image format) then the user can select on the specific location on the floor plan to reserve the booth. Also, the user can create floor plan on the system as another functionality of the system. What do you think? What programming language that i can use to accomplished the system? thanks!

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"Analyzing Performance"

Companies plan ahead with enterprise performance management.

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Symfony Form render with Self Referenced Entity

- by benarth

I have an Entity containing Self-Referenced mapping. class Category { /** * @var integer * * @ORM\Column(name="id", type="integer") * @ORM\Id * @ORM\GeneratedValue(strategy="AUTO") */ private $id; /** * @var string * * @ORM\Column(name="name", type="string", length=100) */ private $name; /** * @ORM\OneToMany(targetEntity="Category", mappedBy="parent") */ private $children; /** * @ORM\ManyToOne(targetEntity="Category", inversedBy="children") * @ORM\JoinColumn(name="parent_id", referencedColumnName="id") */ private $parent; } In my CategoryType I have this : public function buildForm(FormBuilderInterface $builder, array $options) { $plan = $this->plan; $builder->add('name'); $builder->add('parent', 'entity', array( 'class' => 'xxxBundle:Category', 'property' => 'name', 'empty_value' => 'Choose a parent category', 'required' => false, 'query_builder' => function(EntityRepository $er) use ($plan) { return $er->createQueryBuilder('u') ->where('u.plan = :plan') ->setParameter('plan', $plan) ->orderBy('u.id', 'ASC'); }, )); } Actually, when I render the form field Category this is something like Cat1 Cat2 Cat3 Subcat1 Subcat2 Cat4 I would like to know if it's possible and how to display something more like, a kind of a simple tree representation : Cat1 Cat2 Cat3 -- Subcat1 -- Subcat2 Cat4 Regards.

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Best way to limit results in MySQL with user subcategories

- by JM4

I am trying to essentially solve for the following: 1) Find all users in the system who ONLY have programID 1. 2) Find all users in the system who have programID 1 AND any other active program. My tables structures (in very simple terms are as follows): users userID | Name ================ 1 | John Smith 2 | Lewis Black 3 | Mickey Mantle 4 | Babe Ruth 5 | Tommy Bahama plans ID | userID | plan | status --------------------------- 1 | 1 | 1 | 1 2 | 1 | 2 | 1 3 | 1 | 3 | 1 4 | 2 | 1 | 1 5 | 2 | 3 | 1 6 | 3 | 1 | 0 7 | 3 | 2 | 1 8 | 3 | 3 | 1 9 | 3 | 4 | 1 10 | 4 | 2 | 1 11 | 4 | 4 | 1 12 | 5 | 1 | 1 I know I can easily find all members with a specific plan with something like the following: SELECT * FROM users a JOIN plans b ON (a.userID = b.userID) WHERE b.plan = 1 AND b.status = 1 but this will only tell me which users have an 'active' plan 1. How can I tell who ONLY has plan 1 (in this case only userID 5) and how to tell who has plan 1 AND any other active plan? Update: This is not to get a count, I will actually need the original member information, including all the plans they have so a COUNT(*) response may not be what I'm trying to achieve.

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"Optimal" game loop for 2D side-scroller

- by MrDatabase

Is it possible to describe an "optimal" (in terms of performance) layout for a 2D side-scroller's game loop? In this context the "game loop" takes user input, updates the states of game objects and draws the game objects. For example having a GameObject base class with a deep inheritance hierarchy could be good for maintenance... you can do something like the following: foreach(GameObject g in gameObjects) g.update(); However I think this approach can create performance issues. On the other hand all game objects' data and functions could be global. Which would be a maintenance headache but might be closer to an optimally performing game loop. Any thoughts? I'm interested in practical applications of near optimal game loop structure... even if I get a maintenance headache in exchange for great performance.

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JSR updates

- by heathervc

There were many JSR updates over the last week. See below. JSR 258, Mobile User Interface Customization API, has published a Maintenance Release. JSR 257, Contactless Communication API, has published a Maintenance Release 2. JSR 180, SIP API for J2ME, has published a Final Release 5. JSR 269, Pluggable Annotation Processing API, has published a Maintenance Release. JSR 344, JavaServerTM Faces 2.2, has published an Early Draft Review. The review closes on 8 December.

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How do I get to the maintenace shell?

- by Narida

I'm asking this because initially, my problem was this (power failure during installation, so I typed the following instructions in the maintenance shell: sudo mount -o remount,rw / sudo dpkg --configure a sudo mount -o remount,ro / sudo sync sudo reboot The first three lines worked, afterwards, my computer (a Dell Inspiron 530) got stalled for several hours, so I unplugged it. When I turned it on, the log in screen appeared, and after I try to write my password, it leads me back to the log screen. I must note that when I typed the first three lines during the maintenance shell mode, it said that the errors which were encountered during processing were: initscripts bluez gnome-bluetooth So, what do I have to do in order to get back to the maintenance shell so I can type code again? And, what code do I have to write in order to restore my computer? Thank you for your attention.

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Please advise on VPS config choice (with SQL Server Express)

- by tjeuten

Hi all, I might be interested in getting a VPS hosting plan for some small personal sites and .NET projects. Was thinking of Softsys Bronze Plan, as my current shared host plan is with them too. The stuff I want to host has grown beyond the capabilities of a Shared hosting plan, and I also want more control over the IIS/ASP.NET configuration, that's why I'm considering VPS. The main config details would be: Hyper-V 30 GB of diskspace 1 GB of RAM More info here: http://www.softsyshosting.com/Windows-VPS-HyperV.aspx Does anyone have experience with this plan (or something similar from another host), and maybe could answer these couple of questions: Bronze has a total diskspace of 30GB. Is the OS part of this quota or not ? If so, how much does a base configuration with Windows 2008 take up in diskspace ? Would you advise Windows 2008 R2 or Normal. Or would you advise to use Windows 2003 with this config. I'm planning on running a SQL Server Express install too. Would 1 GB of RAM be enough for both the Windows 2008 (R2) and SQL Express. The database load will not be that very high (a couple of 1000 records returned each day). The DB will most likely be far away from the 4GB limit, that's why I'd go for a SQL Express instead of paying extra licensing costs for a SQL Web install. But I'm more concerned about performance. Would you recommend Softsys as a VPS host ? I've been with them for one year for my Shared hosting plan, and have no complaints so far. Also, as I have no VPS experience, what are the pitfalls I need to be aware of, in terms of performance mainly, but maybe in other areas too ? Mathieu

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Get ID of the object saved with association

- by Pravin

Hi, Here is my scenario: I have three models Subscriber, Subscription, Plan, with has_many :through relationship between Subscriber and Plans. A subscriber can have multiple plans with one active plan. Whenever a subscriber selects a plan I save it using accepts_nested_attributes_for :subscriptions. I get one plan from the form. Now my problem is I want to get the ID of the record created in subscriptions table.

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New Oracle BI Applications released

- by THE

Oracle has just released two new Applications for Oracle Business Intelligence Analytics with the Normal 0 21 false false false DE X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman","serif";} 7.9.6.x Extension Pack: Normal 0 21 false false false DE X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman","serif";} · Oracle Manufacturing Analytics, part of the Oracle BI Applications product family, helps discrete and process manufacturing organizations optimize their supply networks by integrating data from across the enterprise value chain, thereby enabling executives, operations managers, cost accountants and production supervisors to make informed and actionable decisions related to manufacturing execution. Normal 0 21 false false false DE X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman","serif";} · Oracle Enterprise Asset Management Analytics, part of the Oracle BI Applications product family, offers complete and enhanced visibility to enterprise-wide maintenance information. Pre-built reports covering Maintenance History, Maintenance Cost Analysis and Maintenance Work Orders, provide Maintenance Managers information to maximize performance, identify potential issues much in advance, and address them before they escalate into serious problems. More Information about the existing Business Intelligence Analytics Applications can be found on this page: http://www.oracle.com/us/solutions/ent-performance-bi/bi-applications-066544.html If you are not familiar with Oracle Manufacturing or Oracle Enterprise Asset Management, these PDFs might get you started: http://www.oracle.com/us/products/applications/060289.pdf http://www.oracle.com/us/products/applications/057127.pdf

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WaterMark using c#

- by srk

I am working on a Kiosk application. There is a Maintenance mode in my application. When my application enters into Maintenance mode, i want to show the user a watermark "Maintenance Mode Commenced". I want this watermark to be shown through out my desktop. No matter what form is in focus. Is this possible ? Any ideas.... Note : This is Windows application using c#

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How to make maintaince document for a website?

- by metal-gear-solid

How to make maintenance document for a website? I've created a site using XHTML ,CSS, jQuery etc. it's big site. Now i have to write a maintenance document for a site for if any changes comes in future related to design, content and functionality then those things will be handled by someone else. How and what should i keep in maintenance document.

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If not following correct procedure?

- by ct2k7

Hi, I'm working on a Content Management System, and so far so good. I'm trying to get the system to work with a maintenance mode system. This is the code in the script to display the maintenance stuff: if ($maintenance['value'] == "1") {?> <div id="content"> <div id="errmsg"> <?php echo $maintenance['notes']; ?> </div> </div> <? } else {?> <h1><?php echo $title; ?></h1> <hr /><br /> <div id="content"> <?php echo $contents; if (!$content) { include ('includes/error/404.php');}?> </div> <? } ?> I can verify that the $maintenance['value'] variable is working as it should, but this portion o the script isn't working as it should. The value is currently set to 1, but it still displays the stuff in the else. Any ideas?

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So…is it a Seek or a Scan?

- by Paul White

You’re probably most familiar with the terms ‘Seek’ and ‘Scan’ from the graphical plans produced by SQL Server Management Studio (SSMS). The image to the left shows the most common ones, with the three types of scan at the top, followed by four types of seek. You might look to the SSMS tool-tip descriptions to explain the differences between them: Not hugely helpful are they? Both mention scans and ranges (nothing about seeks) and the Index Seek description implies that it will not scan the index entirely (which isn’t necessarily true). Recall also yesterday’s post where we saw two Clustered Index Seek operations doing very different things. The first Seek performed 63 single-row seeking operations; and the second performed a ‘Range Scan’ (more on those later in this post). I hope you agree that those were two very different operations, and perhaps you are wondering why there aren’t different graphical plan icons for Range Scans and Seeks? I have often wondered about that, and the first person to mention it after yesterday’s post was Erin Stellato (twitter | blog): Before we go on to make sense of all this, let’s look at another example of how SQL Server confusingly mixes the terms ‘Scan’ and ‘Seek’ in different contexts. The diagram below shows a very simple heap table with two columns, one of which is the non-clustered Primary Key, and the other has a non-unique non-clustered index defined on it. The right hand side of the diagram shows a simple query, it’s associated query plan, and a couple of extracts from the SSMS tool-tip and Properties windows. Notice the ‘scan direction’ entry in the Properties window snippet. Is this a seek or a scan? The different references to Scans and Seeks are even more pronounced in the XML plan output that the graphical plan is based on. This fragment is what lies behind the single Index Seek icon shown above: You’ll find the same confusing references to Seeks and Scans throughout the product and its documentation. Making Sense of Seeks Let’s forget all about scans for a moment, and think purely about seeks. Loosely speaking, a seek is the process of navigating an index B-tree to find a particular index record, most often at the leaf level. A seek starts at the root and navigates down through the levels of the index to find the point of interest: Singleton Lookups The simplest sort of seek predicate performs this traversal to find (at most) a single record. This is the case when we search for a single value using a unique index and an equality predicate. It should be readily apparent that this type of search will either find one record, or none at all. This operation is known as a singleton lookup. Given the example table from before, the following query is an example of a singleton lookup seek: Sadly, there’s nothing in the graphical plan or XML output to show that this is a singleton lookup – you have to infer it from the fact that this is a single-value equality seek on a unique index. The other common examples of a singleton lookup are bookmark lookups – both the RID and Key Lookup forms are singleton lookups (an RID lookup finds a single record in a heap from the unique row locator, and a Key Lookup does much the same thing on a clustered table). If you happen to run your query with STATISTICS IO ON, you will notice that ‘Scan Count’ is always zero for a singleton lookup. Range Scans The other type of seek predicate is a ‘seek plus range scan’, which I will refer to simply as a range scan. The seek operation makes an initial descent into the index structure to find the first leaf row that qualifies, and then performs a range scan (either backwards or forwards in the index) until it reaches the end of the scan range. The ability of a range scan to proceed in either direction comes about because index pages at the same level are connected by a doubly-linked list – each page has a pointer to the previous page (in logical key order) as well as a pointer to the following page. The doubly-linked list is represented by the green and red dotted arrows in the index diagram presented earlier. One subtle (but important) point is that the notion of a ‘forward’ or ‘backward’ scan applies to the logical key order defined when the index was built. In the present case, the non-clustered primary key index was created as follows: CREATE TABLE dbo.Example ( key_col INTEGER NOT NULL, data INTEGER NOT NULL, CONSTRAINT [PK dbo.Example key_col] PRIMARY KEY NONCLUSTERED (key_col ASC) ) ; Notice that the primary key index specifies an ascending sort order for the single key column. This means that a forward scan of the index will retrieve keys in ascending order, while a backward scan would retrieve keys in descending key order. If the index had been created instead on key_col DESC, a forward scan would retrieve keys in descending order, and a backward scan would return keys in ascending order. A range scan seek predicate may have a Start condition, an End condition, or both. Where one is missing, the scan starts (or ends) at one extreme end of the index, depending on the scan direction. Some examples might help clarify that: the following diagram shows four queries, each of which performs a single seek against a column holding every integer from 1 to 100 inclusive. The results from each query are shown in the blue columns, and relevant attributes from the Properties window appear on the right: Query 1 specifies that all key_col values less than 5 should be returned in ascending order. The query plan achieves this by seeking to the start of the index leaf (there is no explicit starting value) and scanning forward until the End condition (key_col < 5) is no longer satisfied (SQL Server knows it can stop looking as soon as it finds a key_col value that isn’t less than 5 because all later index entries are guaranteed to sort higher). Query 2 asks for key_col values greater than 95, in descending order. SQL Server returns these results by seeking to the end of the index, and scanning backwards (in descending key order) until it comes across a row that isn’t greater than 95. Sharp-eyed readers may notice that the end-of-scan condition is shown as a Start range value. This is a bug in the XML show plan which bubbles up to the Properties window – when a backward scan is performed, the roles of the Start and End values are reversed, but the plan does not reflect that. Oh well. Query 3 looks for key_col values that are greater than or equal to 10, and less than 15, in ascending order. This time, SQL Server seeks to the first index record that matches the Start condition (key_col >= 10) and then scans forward through the leaf pages until the End condition (key_col < 15) is no longer met. Query 4 performs much the same sort of operation as Query 3, but requests the output in descending order. Again, we have to mentally reverse the Start and End conditions because of the bug, but otherwise the process is the same as always: SQL Server finds the highest-sorting record that meets the condition ‘key_col < 25’ and scans backward until ‘key_col >= 20’ is no longer true. One final point to note: seek operations always have the Ordered: True attribute. This means that the operator always produces rows in a sorted order, either ascending or descending depending on how the index was defined, and whether the scan part of the operation is forward or backward. You cannot rely on this sort order in your queries of course (you must always specify an ORDER BY clause if order is important) but SQL Server can make use of the sort order internally. In the four queries above, the query optimizer was able to avoid an explicit Sort operator to honour the ORDER BY clause, for example. Multiple Seek Predicates As we saw yesterday, a single index seek plan operator can contain one or more seek predicates. These seek predicates can either be all singleton seeks or all range scans – SQL Server does not mix them. For example, you might expect the following query to contain two seek predicates, a singleton seek to find the single record in the unique index where key_col = 10, and a range scan to find the key_col values between 15 and 20: SELECT key_col FROM dbo.Example WHERE key_col = 10 OR key_col BETWEEN 15 AND 20 ORDER BY key_col ASC ; In fact, SQL Server transforms the singleton seek (key_col = 10) to the equivalent range scan, Start:[key_col >= 10], End:[key_col <= 10]. This allows both range scans to be evaluated by a single seek operator. To be clear, this query results in two range scans: one from 10 to 10, and one from 15 to 20. Final Thoughts That’s it for today – tomorrow we’ll look at monitoring singleton lookups and range scans, and I’ll show you a seek on a heap table. Yes, a seek. On a heap. Not an index! If you would like to run the queries in this post for yourself, there’s a script below. Thanks for reading! IF OBJECT_ID(N'dbo.Example', N'U') IS NOT NULL BEGIN DROP TABLE dbo.Example; END ; -- Test table is a heap -- Non-clustered primary key on 'key_col' CREATE TABLE dbo.Example ( key_col INTEGER NOT NULL, data INTEGER NOT NULL, CONSTRAINT [PK dbo.Example key_col] PRIMARY KEY NONCLUSTERED (key_col) ) ; -- Non-unique non-clustered index on the 'data' column CREATE NONCLUSTERED INDEX [IX dbo.Example data] ON dbo.Example (data) ; -- Add 100 rows INSERT dbo.Example WITH (TABLOCKX) ( key_col, data ) SELECT key_col = V.number, data = V.number FROM master.dbo.spt_values AS V WHERE V.[type] = N'P' AND V.number BETWEEN 1 AND 100 ; -- ================ -- Singleton lookup -- ================ ; -- Single value equality seek in a unique index -- Scan count = 0 when STATISTIS IO is ON -- Check the XML SHOWPLAN SELECT E.key_col FROM dbo.Example AS E WHERE E.key_col = 32 ; -- =========== -- Range Scans -- =========== ; -- Query 1 SELECT E.key_col FROM dbo.Example AS E WHERE E.key_col <= 5 ORDER BY E.key_col ASC ; -- Query 2 SELECT E.key_col FROM dbo.Example AS E WHERE E.key_col > 95 ORDER BY E.key_col DESC ; -- Query 3 SELECT E.key_col FROM dbo.Example AS E WHERE E.key_col >= 10 AND E.key_col < 15 ORDER BY E.key_col ASC ; -- Query 4 SELECT E.key_col FROM dbo.Example AS E WHERE E.key_col >= 20 AND E.key_col < 25 ORDER BY E.key_col DESC ; -- Final query (singleton + range = 2 range scans) SELECT E.key_col FROM dbo.Example AS E WHERE E.key_col = 10 OR E.key_col BETWEEN 15 AND 20 ORDER BY E.key_col ASC ; -- === TIDY UP === DROP TABLE dbo.Example; © 2011 Paul White email: [email protected] twitter: @SQL_Kiwi

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Basics of Join Predicate Pushdown in Oracle

- by Maria Colgan

Happy New Year to all of our readers! We hope you all had a great holiday season. We start the new year by continuing our series on Optimizer transformations. This time it is the turn of Predicate Pushdown. I would like to thank Rafi Ahmed for the content of this blog.Normally, a view cannot be joined with an index-based nested loop (i.e., index access) join, since a view, in contrast with a base table, does not have an index defined on it. A view can only be joined with other tables using three methods: hash, nested loop, and sort-merge joins. Introduction The join predicate pushdown (JPPD) transformation allows a view to be joined with index-based nested-loop join method, which may provide a more optimal alternative. In the join predicate pushdown transformation, the view remains a separate query block, but it contains the join predicate, which is pushed down from its containing query block into the view. The view thus becomes correlated and must be evaluated for each row of the outer query block. These pushed-down join predicates, once inside the view, open up new index access paths on the base tables inside the view; this allows the view to be joined with index-based nested-loop join method, thereby enabling the optimizer to select an efficient execution plan. The join predicate pushdown transformation is not always optimal. The join predicate pushed-down view becomes correlated and it must be evaluated for each outer row; if there is a large number of outer rows, the cost of evaluating the view multiple times may make the nested-loop join suboptimal, and therefore joining the view with hash or sort-merge join method may be more efficient. The decision whether to push down join predicates into a view is determined by evaluating the costs of the outer query with and without the join predicate pushdown transformation under Oracle's cost-based query transformation framework. The join predicate pushdown transformation applies to both non-mergeable views and mergeable views and to pre-defined and inline views as well as to views generated internally by the optimizer during various transformations. The following shows the types of views on which join predicate pushdown is currently supported. UNION ALL/UNION view Outer-joined view Anti-joined view Semi-joined view DISTINCT view GROUP-BY view Examples Consider query A, which has an outer-joined view V. The view cannot be merged, as it contains two tables, and the join between these two tables must be performed before the join between the view and the outer table T4. A: SELECT T4.unique1, V.unique3 FROM T_4K T4, (SELECT T10.unique3, T10.hundred, T10.ten FROM T_5K T5, T_10K T10 WHERE T5.unique3 = T10.unique3) VWHERE T4.unique3 = V.hundred(+) AND T4.ten = V.ten(+) AND T4.thousand = 5; The following shows the non-default plan for query A generated by disabling join predicate pushdown. When query A undergoes join predicate pushdown, it yields query B. Note that query B is expressed in a non-standard SQL and shows an internal representation of the query. B: SELECT T4.unique1, V.unique3 FROM T_4K T4, (SELECT T10.unique3, T10.hundred, T10.ten FROM T_5K T5, T_10K T10 WHERE T5.unique3 = T10.unique3 AND T4.unique3 = V.hundred(+) AND T4.ten = V.ten(+)) V WHERE T4.thousand = 5; The execution plan for query B is shown below. In the execution plan BX, note the keyword 'VIEW PUSHED PREDICATE' indicates that the view has undergone the join predicate pushdown transformation. The join predicates (shown here in red) have been moved into the view V; these join predicates open up index access paths thereby enabling index-based nested-loop join of the view. With join predicate pushdown, the cost of query A has come down from 62 to 32. As mentioned earlier, the join predicate pushdown transformation is cost-based, and a join predicate pushed-down plan is selected only when it reduces the overall cost. Consider another example of a query C, which contains a view with the UNION ALL set operator.C: SELECT R.unique1, V.unique3 FROM T_5K R, (SELECT T1.unique3, T2.unique1+T1.unique1 FROM T_5K T1, T_10K T2 WHERE T1.unique1 = T2.unique1 UNION ALL SELECT T1.unique3, T2.unique2 FROM G_4K T1, T_10K T2 WHERE T1.unique1 = T2.unique1) V WHERE R.unique3 = V.unique3 and R.thousand < 1; The execution plan of query C is shown below. In the above, 'VIEW UNION ALL PUSHED PREDICATE' indicates that the UNION ALL view has undergone the join predicate pushdown transformation. As can be seen, here the join predicate has been replicated and pushed inside every branch of the UNION ALL view. The join predicates (shown here in red) open up index access paths thereby enabling index-based nested loop join of the view. Consider query D as an example of join predicate pushdown into a distinct view. We have the following cardinalities of the tables involved in query D: Sales (1,016,271), Customers (50,000), and Costs (787,766). D: SELECT C.cust_last_name, C.cust_city FROM customers C, (SELECT DISTINCT S.cust_id FROM sales S, costs CT WHERE S.prod_id = CT.prod_id and CT.unit_price > 70) V WHERE C.cust_state_province = 'CA' and C.cust_id = V.cust_id; The execution plan of query D is shown below. As shown in XD, when query D undergoes join predicate pushdown transformation, the expensive DISTINCT operator is removed and the join is converted into a semi-join; this is possible, since all the SELECT list items of the view participate in an equi-join with the outer tables. Under similar conditions, when a group-by view undergoes join predicate pushdown transformation, the expensive group-by operator can also be removed. With the join predicate pushdown transformation, the elapsed time of query D came down from 63 seconds to 5 seconds. Since distinct and group-by views are mergeable views, the cost-based transformation framework also compares the cost of merging the view with that of join predicate pushdown in selecting the most optimal execution plan. Summary We have tried to illustrate the basic ideas behind join predicate pushdown on different types of views by showing example queries that are quite simple. Oracle can handle far more complex queries and other types of views not shown here in the examples. Again many thanks to Rafi Ahmed for the content of this blog post.

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Performance considerations for common SQL queries

- by Jim Giercyk

Originally posted on: http://geekswithblogs.net/NibblesAndBits/archive/2013/10/16/performance-considerations-for-common-sql-queries.aspxSQL offers many different methods to produce the same results. There is a never-ending debate between SQL developers as to the “best way” or the “most efficient way” to render a result set. Sometimes these disputes even come to blows….well, I am a lover, not a fighter, so I decided to collect some data that will prove which way is the best and most efficient. For the queries below, I downloaded the test database from SQLSkills: http://www.sqlskills.com/sql-server-resources/sql-server-demos/. There isn’t a lot of data, but enough to prove my point: dbo.member has 10,000 records, and dbo.payment has 15,554. Our result set contains 6,706 records. The following queries produce an identical result set; the result set contains aggregate payment information for each member who has made more than 1 payment from the dbo.payment table and the first and last name of the member from the dbo.member table. /*************/ /* Sub Query */ /*************/ SELECT a.[Member Number] , m.lastname , m.firstname , a.[Number Of Payments] , a.[Average Payment] , a.[Total Paid] FROM ( SELECT member_no 'Member Number' , AVG(payment_amt) 'Average Payment' , SUM(payment_amt) 'Total Paid' , COUNT(Payment_No) 'Number Of Payments' FROM dbo.payment GROUP BY member_no HAVING COUNT(Payment_No) > 1 ) a JOIN dbo.member m ON a.[Member Number] = m.member_no /***************/ /* Cross Apply */ /***************/ SELECT ca.[Member Number] , m.lastname , m.firstname , ca.[Number Of Payments] , ca.[Average Payment] , ca.[Total Paid] FROM dbo.member m CROSS APPLY ( SELECT member_no 'Member Number' , AVG(payment_amt) 'Average Payment' , SUM(payment_amt) 'Total Paid' , COUNT(Payment_No) 'Number Of Payments' FROM dbo.payment WHERE member_no = m.member_no GROUP BY member_no HAVING COUNT(Payment_No) > 1 ) ca /********/ /* CTEs */ /********/ ; WITH Payments AS ( SELECT member_no 'Member Number' , AVG(payment_amt) 'Average Payment' , SUM(payment_amt) 'Total Paid' , COUNT(Payment_No) 'Number Of Payments' FROM dbo.payment GROUP BY member_no HAVING COUNT(Payment_No) > 1 ), MemberInfo AS ( SELECT p.[Member Number] , m.lastname , m.firstname , p.[Number Of Payments] , p.[Average Payment] , p.[Total Paid] FROM dbo.member m JOIN Payments p ON m.member_no = p.[Member Number] ) SELECT * FROM MemberInfo /************************/ /* SELECT with Grouping */ /************************/ SELECT p.member_no 'Member Number' , m.lastname , m.firstname , COUNT(Payment_No) 'Number Of Payments' , AVG(payment_amt) 'Average Payment' , SUM(payment_amt) 'Total Paid' FROM dbo.payment p JOIN dbo.member m ON m.member_no = p.member_no GROUP BY p.member_no , m.lastname , m.firstname HAVING COUNT(Payment_No) > 1 We can see what is going on in SQL’s brain by looking at the execution plan. The Execution Plan will demonstrate which steps and in what order SQL executes those steps, and what percentage of batch time each query takes. SO….if I execute all 4 of these queries in a single batch, I will get an idea of the relative time SQL takes to execute them, and how it renders the Execution Plan. We can settle this once and for all. Here is what SQL did with these queries: Not only did the queries take the same amount of time to execute, SQL generated the same Execution Plan for each of them. Everybody is right…..I guess we can all finally go to lunch together! But wait a second, I may not be a fighter, but I AM an instigator. Let’s see how a table variable stacks up. Here is the code I executed: /********************/ /* Table Variable */ /********************/ DECLARE @AggregateTable TABLE ( member_no INT , AveragePayment MONEY , TotalPaid MONEY , NumberOfPayments MONEY ) INSERT @AggregateTable SELECT member_no 'Member Number' , AVG(payment_amt) 'Average Payment' , SUM(payment_amt) 'Total Paid' , COUNT(Payment_No) 'Number Of Payments' FROM dbo.payment GROUP BY member_no HAVING COUNT(Payment_No) > 1 SELECT at.member_no 'Member Number' , m.lastname , m.firstname , at.NumberOfPayments 'Number Of Payments' , at.AveragePayment 'Average Payment' , at.TotalPaid 'Total Paid' FROM @AggregateTable at JOIN dbo.member m ON m.member_no = at.member_no In the interest of keeping things in groupings of 4, I removed the last query from the previous batch and added the table variable query. Here’s what I got: Since we first insert into the table variable, then we read from it, the Execution Plan renders 2 steps. BUT, the combination of the 2 steps is only 22% of the batch. It is actually faster than the other methods even though it is treated as 2 separate queries in the Execution Plan. The argument I often hear against Table Variables is that SQL only estimates 1 row for the table size in the Execution Plan. While this is true, the estimate does not come in to play until you read from the table variable. In this case, the table variable had 6,706 rows, but it still outperformed the other queries. People argue that table variables should only be used for hash or lookup tables. The fact is, you have control of what you put IN to the variable, so as long as you keep it within reason, these results suggest that a table variable is a viable alternative to sub-queries. If anyone does volume testing on this theory, I would be interested in the results. My suspicion is that there is a breaking point where efficiency goes down the tubes immediately, and it would be interesting to see where the threshold is. Coding SQL is a matter of style. If you’ve been around since they introduced DB2, you were probably taught a little differently than a recent computer science graduate. If you have a company standard, I strongly recommend you follow it. If you do not have a standard, generally speaking, there is no right or wrong answer when talking about the efficiency of these types of queries, and certainly no hard-and-fast rule. Volume and infrastructure will dictate a lot when it comes to performance, so your results may vary in your environment. Download the database and try it!

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SQL SERVER – Solution – Puzzle – Statistics are not Updated but are Created Once

- by pinaldave

Earlier I asked puzzle why statistics are not updated. Read the complete details over here: Statistics are not Updated but are Created Once In the question I have demonstrated even though statistics should have been updated after lots of insert in the table are not updated.(Read the details SQL SERVER – When are Statistics Updated – What triggers Statistics to Update) In this example I have created following situation: Create Table Insert 1000 Records Check the Statistics Now insert 10 times more 10,000 indexes Check the Statistics – it will be NOT updated Auto Update Statistics and Auto Create Statistics for database is TRUE Now I have requested two things in the example 1) Why this is happening? 2) How to fix this issue? I have many answers – here is the how I fixed it which has resolved the issue for me. NOTE: There are multiple answers to this problem and I will do my best to list all. Solution: Create nonclustered Index on column City Here is the working example for the same. Let us understand this script and there is added explanation at the end. -- Execution Plans Difference -- Estimated Execution Plan Vs Actual Execution Plan -- Create Sample Database CREATE DATABASE SampleDB GO USE SampleDB GO -- Create Table CREATE TABLE ExecTable (ID INT, FirstName VARCHAR(100), LastName VARCHAR(100), City VARCHAR(100)) GO CREATE NONCLUSTERED INDEX IX_ExecTable1 ON ExecTable (City); GO -- Insert One Thousand Records -- INSERT 1 INSERT INTO ExecTable (ID,FirstName,LastName,City) SELECT TOP 1000 ROW_NUMBER() OVER (ORDER BY a.name) RowID, 'Bob', CASE WHEN ROW_NUMBER() OVER (ORDER BY a.name)%2 = 1 THEN 'Smith' ELSE 'Brown' END, CASE WHEN ROW_NUMBER() OVER (ORDER BY a.name)%20 = 1 THEN 'New York' WHEN ROW_NUMBER() OVER (ORDER BY a.name)%20 = 5 THEN 'San Marino' WHEN ROW_NUMBER() OVER (ORDER BY a.name)%20 = 3 THEN 'Los Angeles' WHEN ROW_NUMBER() OVER (ORDER BY a.name)%20 = 7 THEN 'La Cinega' WHEN ROW_NUMBER() OVER (ORDER BY a.name)%20 = 13 THEN 'San Diego' WHEN ROW_NUMBER() OVER (ORDER BY a.name)%20 = 17 THEN 'Las Vegas' ELSE 'Houston' END FROM sys.all_objects a CROSS JOIN sys.all_objects b GO -- Display statistics of the table sp_helpstats N'ExecTable', 'ALL' GO -- Select Statement SELECT FirstName, LastName, City FROM ExecTable WHERE City = 'New York' GO -- Display statistics of the table sp_helpstats N'ExecTable', 'ALL' GO -- Replace your Statistics over here DBCC SHOW_STATISTICS('ExecTable', IX_ExecTable1); GO -------------------------------------------------------------- -- Round 2 -- Insert One Thousand Records -- INSERT 2 INSERT INTO ExecTable (ID,FirstName,LastName,City) SELECT TOP 1000 ROW_NUMBER() OVER (ORDER BY a.name) RowID, 'Bob', CASE WHEN ROW_NUMBER() OVER (ORDER BY a.name)%2 = 1 THEN 'Smith' ELSE 'Brown' END, CASE WHEN ROW_NUMBER() OVER (ORDER BY a.name)%20 = 1 THEN 'New York' WHEN ROW_NUMBER() OVER (ORDER BY a.name)%20 = 5 THEN 'San Marino' WHEN ROW_NUMBER() OVER (ORDER BY a.name)%20 = 3 THEN 'Los Angeles' WHEN ROW_NUMBER() OVER (ORDER BY a.name)%20 = 7 THEN 'La Cinega' WHEN ROW_NUMBER() OVER (ORDER BY a.name)%20 = 13 THEN 'San Diego' WHEN ROW_NUMBER() OVER (ORDER BY a.name)%20 = 17 THEN 'Las Vegas' ELSE 'Houston' END FROM sys.all_objects a CROSS JOIN sys.all_objects b GO -- Select Statement SELECT FirstName, LastName, City FROM ExecTable WHERE City = 'New York' GO -- Display statistics of the table sp_helpstats N'ExecTable', 'ALL' GO -- Replace your Statistics over here DBCC SHOW_STATISTICS('ExecTable', IX_ExecTable1); GO -- Clean up Database DROP TABLE ExecTable GO When I created non clustered index on the column city, it also created statistics on the same column with same name as index. When we populate the data in the column the index is update – resulting execution plan to be invalided – this leads to the statistics to be updated in next execution of SELECT. This behavior does not happen on Heap or column where index is auto created. If you explicitly update the index, often you can see the statistics are updated as well. You can see this is for sure happening if you follow the tell of John Sansom. John Sansom‘s suggestion: That was fun! Although the column statistics are invalidated by the time the second select statement is executed, the query is not compiled/recompiled but instead the existing query plan is reused. It is the “next” compiled query against the column statistics that will see that they are out of date and will then in turn instantiate the action of updating statistics. You can see this in action by forcing the second statement to recompile. SELECT FirstName, LastName, City FROM ExecTable WHERE City = ‘New York’ option(RECOMPILE) GO Kevin Cross also have another suggestion: I agree with John. It is reusing the Execution Plan. Aside from OPTION(RECOMPILE), clearing the Execution Plan Cache before the subsequent tests will also work. i.e., run this before round 2: ————————————————————– – Clear execution plan cache before next test DBCC FREEPROCCACHE WITH NO_INFOMSGS; ————————————————————– Nice puzzle! Kevin As this was puzzle John and Kevin both got the correct answer, there was no condition for answer to be part of best practices. I know John and he is finest DBA around – his tremendous knowledge has always impressed me. John and Kevin both will agree that clearing cache either using DBCC FREEPROCCACHE and recompiling each query every time is for sure not good advice on production server. It is correct answer but not best practice. By the way, if you have better solution or have better suggestion please advise. I am open to change my answer and publish further improvement to this solution. On very separate note, I like to have clustered index on my Primary Key, which I have not mentioned here as it is out of the scope of this puzzle. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, Readers Contribution, Readers Question, SQL, SQL Authority, SQL Index, SQL Puzzle, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, T SQL, Technology Tagged: Statistics

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NHibernate and Composite Key References

- by Rich

I have a weird situation. I have three entities, Company, Employee, Plan and Participation (in retirement plan). Company PK: Company ID Plan PK: Company ID, Plan ID Employee PK: Company ID, SSN, Employee ID Participation PK: Company ID, SSN, Plan ID The problem is in linking the employee to the participation. From a DB perspective, participation should have Employee ID in the PK (it's not even in table). But it doesn't. NHibernate won't let me map the "has many" because the link expects 3 columns (since Employee PK has 3 columns), but I'd only provide 2. Any ideas on how to do this?

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Vodacom Call Center Management on the NetBeans Platform

- by Geertjan

If you live in South Africa, you know about Vodacom. Vodacom is one of the dominant mobile communication companies in South Africa, and beyond, providing voice, messaging, data, and similar mobile services. Inside Vodacom there's an application named Helios, which is a call centre application that had its inception in 2009 and consists of two parts. Firstly, a web-based front-end that allows a call centre agent to service subscribers using a Google-like search on a knowledge base structured as a collection of FAQs. The web-based front-end uses plain-old HTML + CSS + a good helping of JQuery and JQueryUI. This is delivered via JSR-168 portlets running on a cluster of IBM Portal 6 servers. In turn, the portlets communicate via RMI with several back-end EJB's containing the business logic. These EJB's are deployed on a cluster of Weblogic Application Servers, version 10.3.6. The second part is a NetBeans Platform application used for maintaining and constructing the knowledge base, i.e., the back-end of the web-based front-end. Helios is also used for a number of other maintenance functions, such as access permissions, user maintenance, and news bulletins. Below, in the web-based front-end, call centre agents can enter search terms and are presented with a number of FAQs from the knowledge base. Upon selecting a FAQ article, the agent is presented with the article text, the process to guide the subscriber, system checks that display information specific to the subscriber, and links to related applications and articles: Below, you can see that applications are searchable and can be accessed using the same web-based front-end as shown above. And, as can be seen below, knowledge base FAQs are maintained using the Helios Maintenance Application, which is the Vodacom application built on the NetBeans Platform: Several thousand call centre agent user accounts are administered using the Helios Maintenance Application. Below the main FAQ page is shown, together with the About dialog: Vodacom is happy with the back-end NetBeans Platform application. However, the front-end stack runs on quite old technology. Ideally Vodacom would like to migrate the portlets to Oracle Weblogic Portal or Oracle WebCenter, but this hasn't been accomplished yet. Migrating makes sense as the rest of the application server environment consists entirely of Oracle products.

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Vodacom Call Center Management on the NetBeans Platform

- by Geertjan

If you live in South Africa, you know about Vodacom. Vodacom is one of the dominant mobile communication companies in South Africa, and beyond, providing voice, messaging, data, and similar mobile services. Inside Vodacom there's an application named Helios, which is a call centre application that had its inception in 2009 and consists of two parts. Firstly, a web-based front-end that allows a call centre agent to service subscribers using a Google-like search on a knowledge base structured as a collection of FAQs. The web-based front-end uses plain-old HTML + CSS + a good helping of JQuery and JQueryUI. This is delivered via JSR-168 portlets running on a cluster of IBM Portal 6 servers. In turn, the portlets communicate via RMI with several back-end EJB's containing the business logic. These EJB's are deployed on a cluster of Weblogic Application Servers, version 10.3.6. The second part is a NetBeans Platform application used for maintaining and constructing the knowledge base, i.e., the back-end of the web-based front-end. Helios is also used for a number of other maintenance functions, such as access permissions, user maintenance, and news bulletins. Below, in the web-based front-end, call centre agents can enter search terms and are presented with a number of FAQs from the knowledge base. Upon selecting a FAQ article, the agent is presented with the article text, the process to guide the subscriber, system checks that display information specific to the subscriber, and links to related applications and articles: Below, you can see that applications are searchable and can be accessed using the same web-based front-end as shown above. And, as can be seen below, knowledge base FAQs are maintained using the Helios Maintenance Application, which is the Vodacom application built on the NetBeans Platform: Several thousand call centre agent user accounts are administered using the Helios Maintenance Application. Below the main FAQ page is shown, together with the About dialog: Vodacom is happy with the back-end NetBeans Platform application. However, the front-end stack runs on quite old technology. Ideally Vodacom would like to migrate the portlets to Oracle Weblogic Portal or Oracle WebCenter, but this hasn't been accomplished yet. Migrating makes sense as the rest of the application server environment consists entirely of Oracle products.

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T-SQL Tuesday #13: Clarifying Requirements

- by Alexander Kuznetsov

When we transform initial ideas into clear requirements for databases, we typically have to make the following choices: Frequent maintenance vs doing it once. As we are clarifying the requirements, we need to determine whether we want to concinue spending considerable time maintaining the system, or if we want to finish it up and move on to other tasks. Race car maintenance vs installing electric wiring is my favorite analogy for this kind of choice. In some cases we need to sqeeze every last bit...(read more)

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Organizing Your Department with CMMS Software

Computerized maintenance management (CMMS) software can help to organize any maintenance department no matter what the skill level of the employees are. One does not have to be a genius on the comput... [Author: Ashley Combs - Computers and Internet - April 01, 2010]

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CMMS Download Can Make Life Easier

Are you looking for a way to organize your maintenance department? Does your maintenance department need to run more efficiently? Would you like to be able to schedule the downtime for your equipment... [Author: Ashley Combs - Computers and Internet - April 11, 2010]

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WebCenter Customer Spotlight: Guizhou Power Grid Company

- by me

Author: Peter Reiser - Social Business Evangelist, Oracle WebCenter Solution SummaryGuizhou Power Grid Company is responsible for power grid planning, construction, management, and power distribution in Guizhou Province, serving 39 million people. Giuzhou has 49,823 employees and an annual revenue of over $5 Billion. The business objectives were to consolidate information contained in disparate systems into a single knowledge repository and provide a safe and efficient way for staff and managers to access, query, share, manage, and store business information. Guizhou Power Grid Company saved more than US$693,000 in storage costs, reduced average search times from 180 seconds to 5 seconds and solved 80% to 90% of technology and maintenance issues by searching the Oracle WebCenter Content management system. Company OverviewA wholly owned subsidiary of China Southern Power Grid Company Limited, Guizhou Power Grid Company is responsible for power grid planning, construction, management, and power distribution in Guizhou Province, serving 39 million people. Giuzhou has 49,823 employees and an annual revenue of over $5 Billion. Business ChallengesThe business objectives were to consolidate information contained in disparate systems, such as the customer relationship management and power grid management systems, into a single knowledge repository and provide a safe and efficient way for staff and managers to access, query, share, manage, and store business information. Solution DeployedGuizhou Power Grid Company implemented Oracle WebCenter Content to build a content management system that enabled the secure, integrated management and storage of information, such as documents, records, images, Web content, and digital assets. The content management solution was integrated with the power grid, customer service, maintenance, and other business systems, as well as the corporate Web site. Business Results Saved more than US$693,000 in storage costs and shortened the material distribution time by integrating the knowledge management solution with the power grid, customer service, maintenance, and other business systems, as well as the corporate Web site Enabled staff to search 31,650 documents using catalogs, multidimensional attributes, and knowledge maps, reducing average search times from 180 seconds to 5 seconds and saving approximately 1,539 hours in annual search time Gained comprehensive document management, format transformation, security, and auditing capabilities Enabled users to upload new documents and supervisors to check the accuracy of these documents online, resulting in improved information quality control Solved 80% to 90% of technology and maintenance issues by searching the Oracle content management system for information, ensuring IT staff can respond quickly to users’ technical problems Improved security by using role-based access controls to restrict access to confidential documents and information Supported the efficient classification of corporate knowledge by using Oracle’s metadata functions to collect, tag, and archive documents, images, Web content, and digital assets “We chose Oracle WebCenter Content, as it is an outstanding integrated content management platform. It has allowed us to establish a system to access, query, share, manage, and store our corporate assets. This has laid a solid foundation for Guizhou Power Grid Company to improve management practices.” Luo Sixi, Senior Information Consultant, Guizhou Power Grid Company Additional Information Guizhou Power Grid Company Customer Snapshot Oracle WebCenter Content

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