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• Using SQL Execution Plans to discover the Swedish alphabet

  - by Rob Farley

  SQL Server is quite remarkable in a bunch of ways. In this post, I’m using the way that the Query Optimizer handles LIKE to keep it SARGable, the Execution Plans that result, Collations, and PowerShell to come up with the Swedish alphabet. SARGability is the ability to seek for items in an index according to a particular set of criteria. If you don’t have SARGability in play, you need to scan the whole index (or table if you don’t have an index). For example, I can find myself in the phonebook easily, because it’s sorted by LastName and I can find Farley in there by moving to the Fs, and so on. I can’t find everyone in my suburb easily, because the phonebook isn’t sorted that way. I can’t even find people who have six letters in their last name, because also the book is sorted by LastName, it’s not sorted by LEN(LastName). This is all stuff I’ve looked at before, including in the talk I gave at SQLBits in October 2010. If I try to find everyone who’s names start with F, I can do that using a query a bit like: SELECT LastName FROM dbo.PhoneBook WHERE LEFT(LastName,1) = 'F'; Unfortunately, the Query Optimizer doesn’t realise that all the entries that satisfy LEFT(LastName,1) = 'F' will be together, and it has to scan the whole table to find them. But if I write: SELECT LastName FROM dbo.PhoneBook WHERE LastName LIKE 'F%'; then SQL is smart enough to understand this, and performs an Index Seek instead. To see why, I look further into the plan, in particular, the properties of the Index Seek operator. The ToolTip shows me what I’m after: You’ll see that it does a Seek to find any entries that are at least F, but not yet G. There’s an extra Predicate in there (a Residual Predicate if you like), which checks that each LastName is really LIKE F% – I suppose it doesn’t consider that the Seek Predicate is quite enough – but most of the benefit is seen by its working out the Seek Predicate, filtering to just the “at least F but not yet G” section of the data. This got me curious though, particularly about where the G comes from, and whether I could leverage it to create the Swedish alphabet. I know that in the Swedish language, there are three extra letters that appear at the end of the alphabet. One of them is ä that appears in the word Västerås. It turns out that Västerås is quite hard to find in an index when you’re looking it up in a Swedish map. I talked about this briefly in my five-minute talk on Collation from SQLPASS (the one which was slightly less than serious). So by looking at the plan, I can work out what the next letter is in the alphabet of the collation used by the column. In other words, if my alphabet were Swedish, I’d be able to tell what the next letter after F is – just in case it’s not G. It turns out it is… Yes, the Swedish letter after F is G. But I worked this out by using a copy of my PhoneBook table that used the Finnish_Swedish_CI_AI collation. I couldn’t find how the Query Optimizer calculates the G, and my friend Paul White (@SQL_Kiwi) tells me that it’s frustratingly internal to the QO. He’s particularly smart, even if he is from New Zealand. To investigate further, I decided to do some PowerShell, leveraging the Get-SqlPlan function that I blogged about recently (make sure you also have the SqlServerCmdletSnapin100 snap-in added). I started by indicating that I was going to use Finnish_Swedish_CI_AI as my collation of choice, and that I’d start whichever letter cam straight after the number 9. I figure that this is a cheat’s way of guessing the first letter of the alphabet (but it doesn’t actually work in Unicode – luckily I’m using varchar not nvarchar. Actually, there are a few aspects of this code that only work using ASCII, so apologies if you were wanting to apply it to Greek, Japanese, etc). I also initialised my $alphabet variable. $collation = 'Finnish_Swedish_CI_AI'; $firstletter = '9'; $alphabet = ''; Now I created the table for my test. A single field would do, and putting a Clustered Index on it would suffice for the Seeks. Invoke-Sqlcmd -server . -data tempdb -query "create table dbo.collation_test (col varchar(10) collate $collation primary key);" Now I get into the looping. $c = $firstletter; $stillgoing = $true; while ($stillgoing) { I construct the query I want, seeking for entries which start with whatever $c has reached, and get the plan for it: $query = "select col from dbo.collation_test where col like '$($c)%';"; [xml] $pl = get-sqlplan $query "." "tempdb"; At this point, my $pl variable is a scary piece of XML, representing the execution plan. A bit of hunting through it showed me that the EndRange element contained what I was after, and that if it contained NULL, then I was done. $stillgoing = ($pl.ShowPlanXML.BatchSequence.Batch.Statements.StmtSimple.QueryPlan.RelOp.IndexScan.SeekPredicates.SeekPredicateNew.SeekKeys.EndRange -ne $null); Now I could grab the value out of it (which came with apostrophes that needed stripping), and append that to my $alphabet variable.   if ($stillgoing)   {  $c=$pl.ShowPlanXML.BatchSequence.Batch.Statements.StmtSimple.QueryPlan.RelOp.IndexScan.SeekPredicates.SeekPredicateNew.SeekKeys.EndRange.RangeExpressions.ScalarOperator.ScalarString.Replace("'","");     $alphabet += $c;   } Finally, finishing the loop, dropping the table, and showing my alphabet! } Invoke-Sqlcmd -server . -data tempdb -query "drop table dbo.collation_test;"; $alphabet; When I run all this, I see that the Swedish alphabet is ABCDEFGHIJKLMNOPQRSTUVXYZÅÄÖ, which matches what I see at Wikipedia. Interesting to see that the letters on the end are still there, even with Case Insensitivity. Turns out they’re not just “letters with accents”, they’re letters in their own right. I’m sure you gave up reading long ago, and really aren’t that fazed about the idea of doing this using PowerShell. I chose PowerShell because I’d already come up with an easy way of grabbing the estimated plan for a query, and PowerShell does allow for easy navigation of XML. I find the most interesting aspect of this as the fact that the Query Optimizer uses the next letter of the alphabet to maintain the SARGability of LIKE. I’m hoping they do something similar for a whole bunch of operations. Oh, and the fact that you know how to find stuff in the IKEA catalogue. Footnote: If you are interested in whether this works in other languages, you might want to consider the following screenshot, which shows that in principle, it should work with Japanese. It might be a bit harder to run this in PowerShell though, as I’m not sure how it translates. In Hiragana, the Japanese alphabet starts ?, ?, ?, ?, ?, ...

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• Combination of Operating Mode and Commit Strategy

  - by Kevin Yang

  If you want to populate a source into multiple targets, you may also want to ensure that every row from the source affects all targets uniformly (or separately). Let’s consider the Example Mapping below. If a row from SOURCE causes different changes in multiple targets (TARGET_1, TARGET_2 and TARGET_3), for example, it can be successfully inserted into TARGET_1 and TARGET_3, but failed to be inserted into TARGET_2, and the current Mapping Property TLO (target load order) is “TARGET_1 -> TARGET_2 -> TARGET_3”. What should Oracle Warehouse Builder do, in order to commit the appropriate data to all affected targets at the same time? If it doesn’t behave as you intended, the data could become inaccurate and possibly unusable.                                               Example Mapping In OWB, we can use Mapping Configuration Commit Strategies and Operating Modes together to achieve this kind of requirements. Below we will explore the combination of these two features and how they affect the results in the target tables Before going to the example, let’s review some of the terms we will be using (Details can be found in white paper Oracle® Warehouse Builder Data Modeling, ETL, and Data Quality Guide11g Release 2): Operating Modes: Set-Based Mode: Warehouse Builder generates a single SQL statement that processes all data and performs all operations. Row-Based Mode: Warehouse Builder generates statements that process data row by row. The select statement is in a SQL cursor. All subsequent statements are PL/SQL. Row-Based (Target Only) Mode: Warehouse Builder generates a cursor select statement and attempts to include as many operations as possible in the cursor. For each target, Warehouse Builder inserts each row into the target separately. Commit Strategies: Automatic: Warehouse Builder loads and then automatically commits data based on the mapping design. If the mapping has multiple targets, Warehouse Builder commits and rolls back each target separately and independently of other targets. Use the automatic commit when the consequences of multiple targets being loaded unequally are not great or are irrelevant. Automatic correlated: It is a specialized type of automatic commit that applies to PL/SQL mappings with multiple targets only. Warehouse Builder considers all targets collectively and commits or rolls back data uniformly across all targets. Use the correlated commit when it is important to ensure that every row in the source affects all affected targets uniformly. Manual: select manual commit control for PL/SQL mappings when you want to interject complex business logic, perform validations, or run other mappings before committing data. Combination of the commit strategy and operating mode To understand the effects of each combination of operating mode and commit strategy, I’ll illustrate using the following example Mapping. Firstly we insert 100 rows into the SOURCE table and make sure that the 99th row and 100th row have the same ID value. And then we create a unique key constraint on ID column for TARGET_2 table. So while running the example mapping, OWB tries to load all 100 rows to each of the targets. But the mapping should fail to load the 100th row to TARGET_2, because it will violate the unique key constraint of table TARGET_2. With different combinations of Commit Strategy and Operating Mode, here are the results ¦ Set-based/ Correlated Commit: Configuration of Example mapping:                                                     Result:                                                      What’s happening: A single error anywhere in the mapping triggers the rollback of all data. OWB encounters the error inserting into Target_2, it reports an error for the table and does not load the row. OWB rolls back all the rows inserted into Target_1 and does not attempt to load rows to Target_3. No rows are added to any of the target tables. ¦ Row-based/ Correlated Commit: Configuration of Example mapping:                                                   Result:                                                  What’s happening: OWB evaluates each row separately and loads it to all three targets. Loading continues in this way until OWB encounters an error loading row 100th to Target_2. OWB reports the error and does not load the row. It rolls back the row 100th previously inserted into Target_1 and does not attempt to load row 100 to Target_3. Then, if there are remaining rows, OWB will continue loading them, resuming with loading rows to Target_1. The mapping completes with 99 rows inserted into each target. ¦ Set-based/ Automatic Commit: Configuration of Example mapping: Result: What’s happening: When OWB encounters the error inserting into Target_2, it does not load any rows and reports an error for the table. It does, however, continue to insert rows into Target_3 and does not roll back the rows previously inserted into Target_1. The mapping completes with one error message for Target_2, no rows inserted into Target_2, and 100 rows inserted into Target_1 and Target_3 separately. ¦ Row-based/Automatic Commit: Configuration of Example mapping: Result: What’s happening: OWB evaluates each row separately for loading into the targets. Loading continues in this way until OWB encounters an error loading row 100 to Target_2 and reports the error. OWB does not roll back row 100th from Target_1, does insert it into Target_3. If there are remaining rows, it will continue to load them. The mapping completes with 99 rows inserted into Target_2 and 100 rows inserted into each of the other targets. Note: Automatic Correlated commit is not applicable for row-based (target only). If you design a mapping with the row-based (target only) and correlated commit combination, OWB runs the mapping but does not perform the correlated commit. In set-based mode, correlated commit may impact the size of your rollback segments. Space for rollback segments may be a concern when you merge data (insert/update or update/insert). Correlated commit operates transparently with PL/SQL bulk processing code. The correlated commit strategy is not available for mappings run in any mode that are configured for Partition Exchange Loading or that include a Queue, Match Merge, or Table Function operator. If you want to practice in your own environment, you can follow the steps: 1. Import the MDL file: commit_operating_mode.mdl 2. Fix the location for oracle module ORCL and deploy all tables under it. 3. Insert sample records into SOURCE table, using below plsql code: begin     for i in 1..99     loop         insert into source values(i, 'col_'||i);     end loop;     insert into source values(99, 'col_99'); end; 4. Configure MAPPING_1 to any combinations of operating mode and commit strategy you want to test. And make sure feature TLO of mapping is open. 5. Deploy Mapping “MAPPING_1”. 6. Run the mapping and check the result.

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• Using a PreparedStatement to persist an array of Java Enums to an array of Postgres Enums

  - by McGin

  I have a Java Enum: public enum Equipment { Hood, Blinkers, ToungTie, CheekPieces, Visor, EyeShield, None;} and a corresponding Postgres enum: CREATE TYPE equipment AS ENUM ('Hood', 'Blinkers', 'ToungTie', 'CheekPieces', 'Visor', 'EyeShield', 'None'); Within my database I have a table which has a column containing an array of "equipment" items: CREATE TABLE "Entry" ( id bigint NOT NULL DEFAULT nextval('seq'::regclass), "date" character(10) NOT NULL, equipment equipment[] ); And finally when I am running my application I have an array of the "Equipment" enums which I want to persist to the database using a Prepared Statement, and for the life of me I can't figure out how to do it. StringBuffer sb = new StringBuffer("insert into \"Entry\" "); sb.append("( \"date\", \"equipment \" )"); sb.append(" values ( ?, ? )"); PreparedStatement ps = db.prepareStatement(sb.toString()); ps.setString("2010-10-10"); ps.set???????????

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• How to archive data from a table to a local or remote database in SQL 2005 and SQL 2008

  - by simonsabin

  Often you have the need to archive data from a table. This leads to a number of challenges 1. How can you do it without impacting users 2. How can I make it transactionally consistent, i.e. the data I put in the archive is the data I remove from the main table 3. How can I get it to perform well Points 1 is very much tied to point 3. If it doesn't perform well then the delete of data is going to cause lots of locks and thus potentially blocking. For points 1 and 3 refer to my previous posts DELETE-TOP-x-rows-avoiding-a-table-scan and UPDATE-and-DELETE-TOP-and-ORDER-BY---Part2. In essence you need to be removing small chunks of data from your table and you want to do that avoiding a table scan. So that deals with the delete approach but archiving is about inserting that data somewhere else. Well in SQL 2008 they introduced a new feature INSERT over DML (Data Manipulation Language, i.e. SQL statements that change data), or composable DML. The ability to nest DML statements within themselves, so you can past the results of an insert to an update to a merge. I've mentioned this before here SQL-Server-2008---MERGE-and-optimistic-concurrency. This feature is currently limited to being able to consume the results of a DML statement in an INSERT statement. There are many restrictions which you can find here http://msdn.microsoft.com/en-us/library/ms177564.aspx look for the section "Inserting Data Returned From an OUTPUT Clause Into a Table" Even with the restrictions what we can do is consume the OUTPUT from a DELETE and INSERT the results into a table in another database. Note that in BOL it refers to not being able to use a remote table, remote means a table on another SQL instance. To show this working use this SQL to setup two databases foo and fooArchive create database foo go --create the source table fred in database foo select * into foo..fred from sys.objects go create database fooArchive go if object_id('fredarchive',DB_ID('fooArchive')) is null begin     select getdate() ArchiveDate,* into fooArchive..FredArchive from sys.objects where 1=2       end go And then we can use this simple statement to archive the data insert into fooArchive..FredArchive select getdate(),d.* from (delete top (1)         from foo..Fred         output deleted.*) d         go In this statement the delete can be any delete statement you wish so if you are deleting by ids or a range of values then you can do that. Refer to the DELETE-TOP-x-rows-avoiding-a-table-scan post to ensure that your delete is going to perform. The last thing you want to do is to perform 100 deletes each with 5000 records for each of those deletes to do a table scan. For a solution that works for SQL2005 or if you want to archive to a different server then you can use linked servers or SSIS. This example shows how to do it with linked servers. [ONARC-LAP03] is the source server. begin transaction insert into fooArchive..FredArchive select getdate(),d.* from openquery ([ONARC-LAP03],'delete top (1)                     from foo..Fred                     output deleted.*') d commit transaction and to prove the transactions work try, you should get the same number of records before and after. select (select count(1) from foo..Fred) fred        ,(select COUNT(1) from fooArchive..FredArchive ) fredarchive   begin transaction insert into fooArchive..FredArchive select getdate(),d.* from openquery ([ONARC-LAP03],'delete top (1)                     from foo..Fred                     output deleted.*') d rollback transaction   select (select count(1) from foo..Fred) fred        ,(select COUNT(1) from fooArchive..FredArchive ) fredarchive The transactions are very important with this solution. Look what happens when you don't have transactions and an error occurs   select (select count(1) from foo..Fred) fred        ,(select COUNT(1) from fooArchive..FredArchive ) fredarchive   insert into fooArchive..FredArchive select getdate(),d.* from openquery ([ONARC-LAP03],'delete top (1)                     from foo..Fred                     output deleted.*                     raiserror (''Oh doo doo'',15,15)') d                     select (select count(1) from foo..Fred) fred        ,(select COUNT(1) from fooArchive..FredArchive ) fredarchive Before running this think what the result would be. I got it wrong. What seems to happen is that the remote query is executed as a transaction, the error causes that to rollback. However the results have already been sent to the client and so get inserted into the

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• Flex - How to call a webservice without crossdomain.xml file

  - by Stephane Grenier

  How can I consume a webservice that hasn't explicitely created a crossdomain.xml? I understand it's for security and to prevent cross-site scripting, but it does seem like a major limitation to the Flex framework. For example, if I want to consume a webservice, which is suppose to be language agnostic, then I can't with Flex. The webservice/server has to be specifically prepared for Flex/Flash. If it's not, then it cannot be consumed. That can't be right can it?

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• XBRL US Conference Highlights

  - by john.orourke(at)oracle.com

  Back in early November I had an opportunity to attend the XBRL US National Conference in Philadelphia.  At the event, XBRL US announced that Oracle had joined the initiative, so I had a chance to participate in a press conference and attend a number of sessions.  Oracle joined XBRL US so we can stay ahead of the standard and leverage it in our products, and to help drive awareness with customers and improve adoption of XBRL. There were roughly 250 attendees at the event, about half of which were vendors and consultants and the rest financial reporting staff from corporate filers.  Event sponsors included Ernst & Young, SWIFT and Fujitsu.  There were also a number of XBRL technology and service providers exhibiting at the conference.  On Monday Nov. 8th, the XBRL US Steering Committee meetings and Annual Members meeting and reception were held.  At the Annual Members meeting the big news was that current XBRL US President, Mark Bolgiano, is moving to a new position at Howard Hughes Medical Center.  Campbell Pryde, who had led the Taxonomy Development for XBRL US, is taking over as XBRL US President. Other items that were highlighted at the members meeting included: The US GAAP XBRL taxonomy is being used by over 1500 SEC filers and has now been handed over to the FASB to maintain and enhance 16 filer training events were held in 2010 XBRL Global Magazine was launched Corporate Actions proposal was submitted to the SEC with SWIFT in May XBRL Labs for iPhone, XBRL US Consistency Suite launched ISO 2022 Corporate Actions Alignment with XBRL achieved The XBRL Credit Rating taxonomy was accepted Tuesday Nov. 9th included Keynotes, General Sessions, Innovation Workshop for Governments and Securities Professionals, and an Opening Reception.  General sessions included: Lessons Learned from the SEC's rollout of XBRL.  More than 18,000 errors were identified in reviews of filings between June 2009 and September 2010.  Most of these related to negative values being used where they shouldn't have.  Also, the SEC feels there are too many taxonomy extensions being created - mostly in the Cash Flow Statements.  They emphasize using existing elements in the US GAAP taxonomy and advise filers not to  create extensions to improve the visual formatting of XBRL filings. Investors and XBRL - Setting the Standard for Data Quality.  In this panel discussion, the key learning was that CFA's, academics and the financial community are not using XBRL as expected.  The issues raised include the  accuracy and completeness of filings, number of taxonomy extensions, and limited number of tools available to help analyze XBRL data.  Another big issue that was raised is the lack of historic results in XBRL - most analysts need 10 quarters of historic data.  On the positive side, XBRL has the potential to eliminate re-keying of data and errors here and can improve analytic capabilities for financial analysts once more historic data is available and more companies are providing detailed tagging of their filings. A US Roadmap for XBRL Financial Reporting.  This was a panel discussion featuring Jeff Neumann(SEC), Campbell Pryde(XBRL US), and Louis Matherne(FASB).  Key points included the fact that XBRL is currently used by 1500 companies, with 8000 more companies coming in 2011.  XBRL for Mutual Fund Reporting will start in 2011 for 8000 funds, and a Credit Rating Taxonomy has now been submitted for review.  The XBRL tagging/filing process is improving each quarter - more education is helping here.  The FASB is looking at extensions to date, and potential additions to US GAAP taxonomy, while the SEC is evaluating filings for accuracy, consistency in tagging, and tools for analyzing data.  The big news is that the FASB 2011 US GAAP Taxonomy has been completed and reviewed by SEC.  The 2011 US GAAP Taxonomy supports new FASB accounting standards issued since 2009, has new taxonomy elements for certain industries (i.e airlines) and the elimination of 500 concepts.  (meaning they can't be used going forward but are still supported for historical comparison)  The 2011 US GAAP Taxonomy will be available for usage with Q2 2011 SEC filings.  More information about this can be found on the FASB web site.  http://www.fasb.org/home Accounting Firms and XBRL.  This session covered the Role of Audit Firms, which includes awareness and education, validation of XBRL filings, and in-house transition planning.  The main advice provided was that organizations should document XBRL mapping process, perform peer comparisons, and risk assessments on a regular basis. Wednesday Nov. 10th included more Keynotes, General Sessions on Corporate Actions, and XBRL Essentials Workshop Training for corporate filers.  The XBRL Essentials Training included: Getting Started Once you Have the Basics Detailed Footnote Tagging and Handling Tables Quality Control and Trust in the XBRL Process Bringing XBRL In-House:  What are the Options, What should you consider? The US GAAP Financial Reporting Taxonomy - Overview of the 2011 release The XBRL Essentials Training was well-attended with about 80 people.  This included a good overview of the SEC's XBRL mandate, limited liability issue, tagging levels, recommended planning process, internal vs. outsourced approach, and how to manage service providers.  I learned a lot from the session on detailed tagging.  This is the requirement that kicks in during a company's second year of XBRL filing with the SEC and applies to financial statements, footnotes and disclosures (it does not apply to MD&A, executive communications and other information).  The review of the Linkbase model, or dimensional table structure, was very interesting and can be complex to understand.  The key takeaway here is that using dimensional tables in XBRL filings can help limit the number of taxonomy extensions that are required.  The slides from this session are posted on the XBRL US web site. (http://xbrl.us/events/Pages/archive.aspx) For me, the main summary points and takeaways from the XBRL US conference are: XBRL for financial reporting has turned the corner and gone mainstream - with 1500 companies currently using it and 8000 more coming in 2011 The expected value is not being achieved by filers or consumers of XBRL data - this will improve when more companies are filing in XBRL, more history is available, and more software tools are available for analysis (hmm, sounds like an opportunity for Oracle) XBRL is becoming the global standard for all business communications beyond just the financials - i.e. adoption for mutual funds, corporate actions and others planned for the future If you would like to learn more about XBRL and the various training programs, services and software tools that are available check out the XBRL US web site and even better - become a member.  Here's a link:  http://xbrl.us/Pages/default.aspx

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• Best Practise to populate Fact and Dimension Tables from Transactional Flat DB

  - by alex25

  Hi! I want to populate a star schema / cube in SSIS / SSAS. I prepared all my dimension tables and my fact table, primary keys etc. The source is a 'flat' (item level) table and my problem is now how to split it up and get it from one into the respective tables. I did a fair bit of googling but couldn't find a satisfying solution to the problem. One would imagine that this is a rather common problem/situation in BI development?! Thanks, alexl

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• Is preg_match safe enaught in input satinization?

  - by DaNieL

  Im building a new web-app, LAMP environment... im wondering if preg_match can be trusted for user's input validation (+ prepared stmt, of course) for all the text-based fields (aka not html fields; phone, name, surname, etc..). For example, for a classic 'email field', if i check the input like: $email_pattern = "/^([a-zA-Z0-9_\-\.]+)@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.)" . "|(([a-zA-Z0-9\-]+\.)+))([a-zA-Z]{2,4}" . "|[0-9]{1,3})(\]?)$/"; $email = $_POST['email']; if(preg_match($email_pattern, $email)){ //go on, prepare stmt, execute, etc... }else{ //email not valid! do nothing except warn the user } can i sleep easy against the sql/xxs injection? I write the regexp to be the more restrictive as they can.

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• How can I condense stand-alone characters in Perl?

  - by brydgesk

  I'm trying to identify and condense single (uppercase) characters in a string. For example: "test A B test" - "test AB test" "test A B C test" - "test ABC test" "test A B test C D E test" - "test AB test CDE test" I have it working for single occurrences (as in the first above example), but cannot figure out how to chain it for multiple occurrences. $str =~ s/ ([A-Z]) ([A-Z]) / \1\2 /g; I'll probably feel stupid when I see the solution, but I'm prepared for that. Thanks in advance.

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• ClearCase: Versioning at file level

  - by Naveen

  Hi, I have a perculier problem about how to maintain a clearcase project. This project is a xml schema repository where each schema has a version. This repository is common and is used by all the apps in the enterprise. From clearcase prespective the project has a single component. Now the apps can be using different versions of the schema(s). So we are trying to figureout a way to setup the project in such way that a project can have a baseline of what versions of these files are included in a build. The only way we know of how to do this is to create a component for each schema or group of schemas and create a stream for each app to include the components they use. But that would result in too many components. Has anyone dealth with something like this before? We are prepared to restructre the whole project if necessary, so we are open to any idea. Thans for the help.

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• Using Sitecore RenderingContext Parameters as MVC controller action arguments

  - by Kyle Burns

  I have been working with the Technical Preview of Sitecore 6.6 on a project and have been for the most part happy with the way that Sitecore (which truly is an MVC implementation unto itself) has been expanded to support ASP.NET MVC. That said, getting up to speed with the combined platform has not been entirely without stumbles and today I want to share one area where Sitecore could have really made things shine from the "it just works" perspective. A couple days ago I was asked by a colleague about the usage of the "Parameters" field that is defined on Sitecore's Controller Rendering data template. Based on the standard way that Sitecore handles a field named Parameters, I was able to deduce that the field expected key/value pairs separated by the "&" character, but beyond that I wasn't sure and didn't see anything from a documentation perspective to guide me, so it was time to dig and find out where the data in the field was made available. My first thought was that it would be really nice if Sitecore handled the parameters in this field consistently with the way that ASP.NET MVC handles the various parameter collections on the HttpRequest object and automatically maps them to parameters of the action method executing. Being the hopeful sort, I configured a name/value pair on one of my renderings, added a parameter with matching name to the controller action and fired up the bugger to see... that the parameter was not populated. Having established that the field's value was not going to be presented to me the way that I had hoped it would, the next assumption that I would work on was that Sitecore would handle this field similar to how they handle other similar data and would plug it into some ambient object that I could reference from within the controller method. After a considerable amount of guessing, testing, and cracking code open with Redgate's Reflector (a must-have companion to Sitecore documentation), I found that the most direct way to access the parameter was through the ambient RenderingContext object using code similar to: string myArgument = string.Empty; var rc = Sitecore.Mvc.Presentation.RenderingContext.CurrentOrNull; if (rc != null) {     var parms = rc.Rendering.Parameters;     myArgument = parms["myArgument"]; } At this point, we know how this field is used out of the box from Sitecore and can provide information from Sitecore's Content Editor that will be available when the controller action is executing, but it feels a little dirty. In order to properly test the action method I would have to do a lot of setup work and possible use an isolation framework such as Pex and Moles to get at a value that my action method is dependent upon. Notice I said that my method is dependent upon the value but in order to meet that dependency I've accepted another dependency upon Sitecore's RenderingContext.  I'm a big believer in, when possible, ensuring that any piece of code explicitly advertises dependencies using the method signature, so I found myself still wanting this to work the same as if the parameters were in the request route, querystring, or form by being able to add a myArgument parameter to the action method and have this parameter populated by the framework. Lucky for us, the ASP.NET MVC framework is extremely flexible and provides some easy to grok and use extensibility points. ASP.NET MVC is able to provide information from the request as input parameters to controller actions because it uses objects which implement an interface called IValueProvider and have been registered to service the application. The most basic statement of responsibility for an IValueProvider implementation is "I know about some data which is indexed by key. If you hand me the key for a piece of data that I know about I give you that data". When preparing to invoke a controller action, the framework queries registered IValueProvider implementations with the name of each method argument to see if the ValueProvider can supply a value for the parameter. (the rest of this post will assume you're working along and make a lot more sense if you do) Let's pull Sitecore out of the equation for a second to simplify things and create an extremely simple IValueProvider implementation. For this example, I first create a new ASP.NET MVC3 project in Visual Studio, selecting "Internet Application" and otherwise taking defaults (I'm assuming that anyone reading this far in the post either already knows how to do this or will need to take a quick run through one of the many available basic MVC tutorials such as the MVC Music Store). Once the new project is created, go to the Index action of HomeController.  This action sets a Message property on the ViewBag to "Welcome to ASP.NET MVC!" and invokes the View, which has been coded to display the Message. For our example, we will remove the hard coded message from this controller (although we'll leave it just as hard coded somewhere else - this is sample code). For the first step in our exercise, add a string parameter to the Index action method called welcomeMessage and use the value of this argument to set the ViewBag.Message property. The updated Index action should look like: public ActionResult Index(string welcomeMessage) {     ViewBag.Message = welcomeMessage;     return View(); } This represents the entirety of the change that you will make to either the controller or view.  If you run the application now, the home page will display and no message will be presented to the user because no value was supplied to the Action method. Let's now write a ValueProvider to ensure this parameter gets populated. We'll start by creating a new class called StaticValueProvider. When the class is created, we'll update the using statements to ensure that they include the following: using System.Collections.Specialized; using System.Globalization; using System.Web.Mvc; With the appropriate using statements in place, we'll update the StaticValueProvider class to implement the IValueProvider interface. The System.Web.Mvc library already contains a pretty flexible dictionary-like implementation called NameValueCollectionValueProvider, so we'll just wrap that and let it do most of the real work for us. The completed class looks like: public class StaticValueProvider : IValueProvider {     private NameValueCollectionValueProvider _wrappedProvider;     public StaticValueProvider(ControllerContext controllerContext)     {         var parameters = new NameValueCollection();         parameters.Add("welcomeMessage", "Hello from the value provider!");         _wrappedProvider = new NameValueCollectionValueProvider(parameters, CultureInfo.InvariantCulture);     }     public bool ContainsPrefix(string prefix)     {         return _wrappedProvider.ContainsPrefix(prefix);     }     public ValueProviderResult GetValue(string key)     {         return _wrappedProvider.GetValue(key);     } } Notice that the only entry in the collection matches the name of the argument to our HomeController's Index action.  This is the important "secret sauce" that will make things work. We've got our new value provider now, but that's not quite enough to be finished. Mvc obtains IValueProvider instances using factories that are registered when the application starts up. These factories extend the abstract ValueProviderFactory class by initializing and returning the appropriate implementation of IValueProvider from the GetValueProvider method. While I wouldn't do so in production code, for the sake of this example, I'm going to add the following class definition within the StaticValueProvider.cs source file: public class StaticValueProviderFactory : ValueProviderFactory {     public override IValueProvider GetValueProvider(ControllerContext controllerContext)     {         return new StaticValueProvider(controllerContext);     } } Now that we have a factory, we can register it by adding the following line to the end of the Application_Start method in Global.asax.cs: ValueProviderFactories.Factories.Add(new StaticValueProviderFactory()); If you've done everything right to this point, you should be able to run the application and be presented with the home page reading "Hello from the value provider!". Now that you have the basics of the IValueProvider down, you have everything you need to enhance your Sitecore MVC implementation by adding an IValueProvider that exposes values from the ambient RenderingContext's Parameters property. I'll provide the code for the IValueProvider implementation (which should look VERY familiar) and you can use the work we've already done as a reference to create and register the factory: public class RenderingContextValueProvider : IValueProvider {     private NameValueCollectionValueProvider _wrappedProvider = null;     public RenderingContextValueProvider(ControllerContext controllerContext)     {         var collection = new NameValueCollection();         var rc = RenderingContext.CurrentOrNull;         if (rc != null && rc.Rendering != null)         {             foreach(var parameter in rc.Rendering.Parameters)             {                 collection.Add(parameter.Key, parameter.Value);             }         }         _wrappedProvider = new NameValueCollectionValueProvider(collection, CultureInfo.InvariantCulture);         }     public bool ContainsPrefix(string prefix)     {         return _wrappedProvider.ContainsPrefix(prefix);     }     public ValueProviderResult GetValue(string key)     {         return _wrappedProvider.GetValue(key);     } } In this post I've discussed the MVC IValueProvider used to map data to controller action method arguments and how this can be integrated into your Sitecore 6.6 MVC solution.

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• Run sql script from Ruby

  - by Chaker Nakhli

  Hi all, Using DBI::DatabaseHandle#execute or DBI::DatabaseHandle#prepare it's not possible to run an sql script (with mutiple sql statments). It fails with the following error : ERROR: cannot insert multiple commands into a prepared statement I tried to use the "unprepared" way using DBI::DatabaseHandle#do (the doc says it "goes straight to the DBD‘s implementation") but it keeps throwing the same error. code snippet: require 'dbd/pg' require 'dbi' DBI.connect("dbi:pg:database=dbname", db_user, db_password, db_params) do |dbh| schema = IO::read(schema_file) dbh.do(schema) end I'm using ruby 1.8.6 (2007-09-24 patchlevel 111) [i386-mswin32] dbi-0.4.3 dbd-pg-0.3.9 pg-0.9.0-x86-mswin32 Thank you!

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• How to make a spam tester

  - by aquero

  In my project I need to make a spam tester to check the spam score of the mails prepared to be sent. When I searched, I found Spam Assassin, which they say is used as sapm filters in many mail servers. Can I create a spam tester using Spam Assassin? Another option I found is one Litmus API, which is a paid service. Is there any options other than these two? Freeware is more preferred. My project is a J2EE web application using Spring.

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• Symlinking (ln) faster than moving (mv)?

  - by Chad Johnson

  When we build web software releases, we prepare the release in a temporary directory and then replace the release directory with the temporary one just prepared: # Move and replace existing release directory. mv /path/to/httpdocs /path/to/httpdocs.before mv /path/to/$newReleaseName /path/to/httpdocs Under this scheme, it happens that with about 1 in every 15 releases, a user was using a file in the original release directory exactly at the time the commands above are run, and a fatal error occurs for that user. I am wondering if using symlinking like follows would be significantly faster, in terms of processing time, thereby helping to lessen the likelihood of this problem: # Remove and replace existing release symlink. ln -sf /path/to/$newReleaseName path/to/httpdocs

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• Preserve images in Excel headers using Apache POI

  - by ddm

  I am trying to generate Excel reports using Apache POI 3.6 (latest). Since POI has limited support for header and footer generation (text only), I decided to start from a blank excel file with the header already prepared and fill the Excel cells using POI (cf. question 714172). Unfortunately, when opening the workbook with POI and writing it immediately to disk (without any cell manpulation), the header seems to be lost. Here is the code I used to test this behavior: public final class ExcelWorkbookCreator { public static void main(String[] args) { FileOutputStream outputStream = null; try { outputStream = new FileOutputStream(new File("dump.xls")); InputStream inputStream = ExcelWorkbookCreator.class.getResourceAsStream("report_template.xls"); HSSFWorkbook workbook = new HSSFWorkbook(inputStream, true); workbook.write(outputStream); } catch (Exception exception) { throw new RuntimeException(exception); } finally { if (outputStream != null) { try { outputStream.close(); } catch (IOException exception) { // Nothing much to do } } } } }

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• Full-text Indexing Books Online

  - by Most Valuable Yak (Rob Volk)

  While preparing for a recent SQL Saturday presentation, I was struck by a crazy idea (shocking, I know): Could someone import the content of SQL Server Books Online into a database and apply full-text indexing to it?  The answer is yes, and it's really quite easy to do. The first step is finding the installed help files.  If you have SQL Server 2012, BOL is installed under the Microsoft Help Library.  You can find the install location by opening SQL Server Books Online and clicking the gear icon for the Help Library Manager.  When the new window pops up click the Settings link, you'll get the following: You'll see the path under Library Location. Once you navigate to that path you'll have to drill down a little further, to C:\ProgramData\Microsoft\HelpLibrary\content\Microsoft\store.  This is where the help file content is kept if you downloaded it for offline use. Depending on which products you've downloaded help for, you may see a few hundred files.  Fortunately they're named well and you can easily find the "SQL_Server_Denali_Books_Online_" files.  We are interested in the .MSHC files only, and can skip the Installation and Developer Reference files. Despite the .MHSC extension, these files are compressed with the standard Zip format, so your favorite archive utility (WinZip, 7Zip, WinRar, etc.) can open them.  When you do, you'll see a few thousand files in the archive.  We are only interested in the .htm files, but there's no harm in extracting all of them to a folder.  7zip provides a command-line utility and the following will extract to a D:\SQLHelp folder previously created: 7z e –oD:\SQLHelp "C:\ProgramData\Microsoft\HelpLibrary\content\Microsoft\store\SQL_Server_Denali_Books_Online_B780_SQL_110_en-us_1.2.mshc" *.htm Well that's great Rob, but how do I put all those files into a full-text index? I'll tell you in a second, but first we have to set up a few things on the database side.  I'll be using a database named Explore (you can certainly change that) and the following setup is a fragment of the script I used in my presentation: USE Explore; GO CREATE SCHEMA help AUTHORIZATION dbo; GO -- Create default fulltext catalog for later FT indexes CREATE FULLTEXT CATALOG FTC AS DEFAULT; GO CREATE TABLE help.files(file_id int not null IDENTITY(1,1) CONSTRAINT PK_help_files PRIMARY KEY, path varchar(256) not null CONSTRAINT UNQ_help_files_path UNIQUE, doc_type varchar(6) DEFAULT('.xml'), content varbinary(max) not null); CREATE FULLTEXT INDEX ON help.files(content TYPE COLUMN doc_type LANGUAGE 1033) KEY INDEX PK_help_files; This will give you a table, default full-text catalog, and full-text index on that table for the content you're going to insert.  I'll be using the command line again for this, it's the easiest method I know: for %a in (D:\SQLHelp\*.htm) do sqlcmd -S. -E -d Explore -Q"set nocount on;insert help.files(path,content) select '%a', cast(c as varbinary(max)) from openrowset(bulk '%a', SINGLE_CLOB) as c(c)" You'll need to copy and run that as one line in a command prompt.  I'll explain what this does while you run it and watch several thousand files get imported: The "for" command allows you to loop over a collection of items.  In this case we want all the .htm files in the D:\SQLHelp folder.  For each file it finds, it will assign the full path and file name to the %a variable.  In the "do" clause, we'll specify another command to be run for each iteration of the loop.  I make a call to "sqlcmd" in order to run a SQL statement.  I pass in the name of the server (-S.), where "." represents the local default instance. I specify -d Explore as the database, and -E for trusted connection.  I then use -Q to run a query that I enclose in double quotes. The query uses OPENROWSET(BULK…SINGLE_CLOB) to open the file as a data source, and to treat it as a single character large object.  In order for full-text indexing to work properly, I have to convert the text content to varbinary. I then INSERT these contents along with the full path of the file into the help.files table created earlier.  This process continues for each file in the folder, creating one new row in the table. And that's it! 5 SQL Statements and 2 command line statements to unzip and import SQL Server Books Online!  In case you're wondering why I didn't use FILESTREAM or FILETABLE, it's simply because I haven't learned them…yet. I may return to this blog after I figure that out and update it with the steps to do so.  I believe that will make it even easier. In the spirit of exploration, I'll leave you to work on some fulltext queries of this content.  I also recommend playing around with the sys.dm_fts_xxxx DMVs (I particularly like sys.dm_fts_index_keywords, it's pretty interesting).  There are additional example queries in the download material for my presentation linked above. Many thanks to Kevin Boles (t) for his advice on (re)checking the content of the help files.  Don't let that .htm extension fool you! The 2012 help files are actually XML, and you'd need to specify '.xml' in your document type column in order to extract the full-text keywords.  (You probably noticed this in the default definition for the doc_type column.)  You can query sys.fulltext_document_types to get a complete list of the types that can be full-text indexed. I also need to thank Hilary Cotter for giving me the original idea. I believe he used MSDN content in a full-text index for an article from waaaaaaaaaaay back, that I can't find now, and had forgotten about until just a few days ago.  He is also co-author of Pro Full-Text Search in SQL Server 2008, which I highly recommend.  He also has some FTS articles on Simple Talk: http://www.simple-talk.com/sql/learn-sql-server/sql-server-full-text-search-language-features/ http://www.simple-talk.com/sql/learn-sql-server/sql-server-full-text-search-language-features,-part-2/

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• Google maps cluster manager

  - by Prashant

  Hello all I am using google maps in my application. I have to show 100 markers on map. First I prepared a markers array from these markers. When markers are added using addOverlay from markers array, it takes some time and they are being added in some animated way (in sequence). I want all of them to get added to map in a single shot, so no flickering effect. I tried MarkerClusterer but it shows a cluster of markers where the need be. Instead I want all the markers to appear, not a cluster. Only they should be added faster. var point = new GLatLng(latArr[i],lonArr[i]); var marker = new GMarker(point,markerOptions); markers[i] = marker; var markerCluster = new MarkerClusterer(map, markers); Any suggestions please? Thank you.

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• How fast can you make linear search?

  - by Mark Probst

  I'm looking to optimize this linear search: static int linear (const int *arr, int n, int key) { int i = 0; while (i < n) { if (arr [i] >= key) break; ++i; } return i; } The array is sorted and the function is supposed to return the index of the first element that is greater or equal to the key. They array is not large (below 200 elements) and will be prepared once for a large number of searches. Array elements after the n-th can if necessary be initialized to something appropriate, if that speeds up the search. No, binary search is not allowed, only linear search.

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• Inheritance Mapping Strategies with Entity Framework Code First CTP5: Part 2 – Table per Type (TPT)

  - by mortezam

  In the previous blog post you saw that there are three different approaches to representing an inheritance hierarchy and I explained Table per Hierarchy (TPH) as the default mapping strategy in EF Code First. We argued that the disadvantages of TPH may be too serious for our design since it results in denormalized schemas that can become a major burden in the long run. In today’s blog post we are going to learn about Table per Type (TPT) as another inheritance mapping strategy and we'll see that TPT doesn’t expose us to this problem. Table per Type (TPT)Table per Type is about representing inheritance relationships as relational foreign key associations. Every class/subclass that declares persistent properties—including abstract classes—has its own table. The table for subclasses contains columns only for each noninherited property (each property declared by the subclass itself) along with a primary key that is also a foreign key of the base class table. This approach is shown in the following figure: For example, if an instance of the CreditCard subclass is made persistent, the values of properties declared by the BillingDetail base class are persisted to a new row of the BillingDetails table. Only the values of properties declared by the subclass (i.e. CreditCard) are persisted to a new row of the CreditCards table. The two rows are linked together by their shared primary key value. Later, the subclass instance may be retrieved from the database by joining the subclass table with the base class table. TPT Advantages The primary advantage of this strategy is that the SQL schema is normalized. In addition, schema evolution is straightforward (modifying the base class or adding a new subclass is just a matter of modify/add one table). Integrity constraint definition are also straightforward (note how CardType in CreditCards table is now a non-nullable column). Another much more important advantage is the ability to handle polymorphic associations (a polymorphic association is an association to a base class, hence to all classes in the hierarchy with dynamic resolution of the concrete class at runtime). A polymorphic association to a particular subclass may be represented as a foreign key referencing the table of that particular subclass. Implement TPT in EF Code First We can create a TPT mapping simply by placing Table attribute on the subclasses to specify the mapped table name (Table attribute is a new data annotation and has been added to System.ComponentModel.DataAnnotations namespace in CTP5): public abstract class BillingDetail {     public int BillingDetailId { get; set; }     public string Owner { get; set; }     public string Number { get; set; } } [Table("BankAccounts")] public class BankAccount : BillingDetail {     public string BankName { get; set; }     public string Swift { get; set; } } [Table("CreditCards")] public class CreditCard : BillingDetail {     public int CardType { get; set; }     public string ExpiryMonth { get; set; }     public string ExpiryYear { get; set; } } public class InheritanceMappingContext : DbContext {     public DbSet<BillingDetail> BillingDetails { get; set; } } If you prefer fluent API, then you can create a TPT mapping by using ToTable() method: protected override void OnModelCreating(ModelBuilder modelBuilder) {     modelBuilder.Entity<BankAccount>().ToTable("BankAccounts");     modelBuilder.Entity<CreditCard>().ToTable("CreditCards"); } Generated SQL For QueriesLet’s take an example of a simple non-polymorphic query that returns a list of all the BankAccounts: var query = from b in context.BillingDetails.OfType<BankAccount>() select b; Executing this query (by invoking ToList() method) results in the following SQL statements being sent to the database (on the bottom, you can also see the result of executing the generated query in SQL Server Management Studio): Now, let’s take an example of a very simple polymorphic query that requests all the BillingDetails which includes both BankAccount and CreditCard types: projects some properties out of the base class BillingDetail, without querying for anything from any of the subclasses: var query = from b in context.BillingDetails             select new { b.BillingDetailId, b.Number, b.Owner }; -- var query = from b in context.BillingDetails select b; This LINQ query seems even more simple than the previous one but the resulting SQL query is not as simple as you might expect: -- As you can see, EF Code First relies on an INNER JOIN to detect the existence (or absence) of rows in the subclass tables CreditCards and BankAccounts so it can determine the concrete subclass for a particular row of the BillingDetails table. Also the SQL CASE statements that you see in the beginning of the query is just to ensure columns that are irrelevant for a particular row have NULL values in the returning flattened table. (e.g. BankName for a row that represents a CreditCard type) TPT ConsiderationsEven though this mapping strategy is deceptively simple, the experience shows that performance can be unacceptable for complex class hierarchies because queries always require a join across many tables. In addition, this mapping strategy is more difficult to implement by hand— even ad-hoc reporting is more complex. This is an important consideration if you plan to use handwritten SQL in your application (For ad hoc reporting, database views provide a way to offset the complexity of the TPT strategy. A view may be used to transform the table-per-type model into the much simpler table-per-hierarchy model.) SummaryIn this post we learned about Table per Type as the second inheritance mapping in our series. So far, the strategies we’ve discussed require extra consideration with regard to the SQL schema (e.g. in TPT, foreign keys are needed). This situation changes with the Table per Concrete Type (TPC) that we will discuss in the next post. References ADO.NET team blog Java Persistence with Hibernate book a { text-decoration: none; } a:visited { color: Blue; } .title { padding-bottom: 5px; font-family: Segoe UI; font-size: 11pt; font-weight: bold; padding-top: 15px; } .code, .typeName { font-family: consolas; } .typeName { color: #2b91af; } .padTop5 { padding-top: 5px; } .padTop10 { padding-top: 10px; } p.MsoNormal { margin-top: 0in; margin-right: 0in; margin-bottom: 10.0pt; margin-left: 0in; line-height: 115%; font-size: 11.0pt; font-family: "Calibri" , "sans-serif"; }

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• Benchmarking MySQL Replication with Multi-Threaded Slaves

  - by Mat Keep

  0 0 1 1145 6530 Homework 54 15 7660 14.0 Normal 0 false false false EN-US JA X-NONE /* 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-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:12.0pt; font-family:Cambria; mso-ascii-font-family:Cambria; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Cambria; mso-hansi-theme-font:minor-latin; mso-ansi-language:EN-US;} The objective of this benchmark is to measure the performance improvement achieved when enabling the Multi-Threaded Slave enhancement delivered as a part MySQL 5.6. As the results demonstrate, Multi-Threaded Slaves delivers 5x higher replication performance based on a configuration with 10 databases/schemas. For real-world deployments, higher replication performance directly translates to: · Improved consistency of reads from slaves (i.e. reduced risk of reading "stale" data) · Reduced risk of data loss should the master fail before replicating all events in its binary log (binlog) The multi-threaded slave splits processing between worker threads based on schema, allowing updates to be applied in parallel, rather than sequentially. This delivers benefits to those workloads that isolate application data using databases - e.g. multi-tenant systems deployed in cloud environments. Multi-Threaded Slaves are just one of many enhancements to replication previewed as part of the MySQL 5.6 Development Release, which include: · Global Transaction Identifiers coupled with MySQL utilities for automatic failover / switchover and slave promotion · Crash Safe Slaves and Binlog · Optimized Row Based Replication · Replication Event Checksums · Time Delayed Replication These and many more are discussed in the “MySQL 5.6 Replication: Enabling the Next Generation of Web & Cloud Services” Developer Zone article  Back to the benchmark - details are as follows. Environment The test environment consisted of two Linux servers: · one running the replication master · one running the replication slave. Only the slave was involved in the actual measurements, and was based on the following configuration: - Hardware: Oracle Sun Fire X4170 M2 Server - CPU: 2 sockets, 6 cores with hyper-threading, 2930 MHz. - OS: 64-bit Oracle Enterprise Linux 6.1 - Memory: 48 GB Test Procedure Initial Setup: Two MySQL servers were started on two different hosts, configured as replication master and slave. 10 sysbench schemas were created, each with a single table: CREATE TABLE `sbtest` (    `id` int(10) unsigned NOT NULL AUTO_INCREMENT,    `k` int(10) unsigned NOT NULL DEFAULT '0',    `c` char(120) NOT NULL DEFAULT '',    `pad` char(60) NOT NULL DEFAULT '',    PRIMARY KEY (`id`),    KEY `k` (`k`) ) ENGINE=InnoDB DEFAULT CHARSET=latin1 10,000 rows were inserted in each of the 10 tables, for a total of 100,000 rows. When the inserts had replicated to the slave, the slave threads were stopped. The slave data directory was copied to a backup location and the slave threads position in the master binlog noted. 10 sysbench clients, each configured with 10 threads, were spawned at the same time to generate a random schema load against each of the 10 schemas on the master. Each sysbench client executed 10,000 "update key" statements: UPDATE sbtest set k=k+1 WHERE id = <random row> In total, this generated 100,000 update statements to later replicate during the test itself. Test Methodology: The number of slave workers to test with was configured using: SET GLOBAL slave_parallel_workers=<workers> Then the slave IO thread was started and the test waited for all the update queries to be copied over to the relay log on the slave. The benchmark clock was started and then the slave SQL thread was started. The test waited for the slave SQL thread to finish executing the 100k update queries, doing "select master_pos_wait()". When master_pos_wait() returned, the benchmark clock was stopped and the duration calculated. The calculated duration from the benchmark clock should be close to the time it took for the SQL thread to execute the 100,000 update queries. The 100k queries divided by this duration gave the benchmark metric, reported as Queries Per Second (QPS). Test Reset: The test-reset cycle was implemented as follows: · the slave was stopped · the slave data directory replaced with the previous backup · the slave restarted with the slave threads replication pointer repositioned to the point before the update queries in the binlog. The test could then be repeated with identical set of queries but a different number of slave worker threads, enabling a fair comparison. The Test-Reset cycle was repeated 3 times for 0-24 number of workers and the QPS metric calculated and averaged for each worker count. MySQL Configuration The relevant configuration settings used for MySQL are as follows: binlog-format=STATEMENT relay-log-info-repository=TABLE master-info-repository=TABLE As described in the test procedure, the slave_parallel_workers setting was modified as part of the test logic. The consequence of changing this setting is: 0 worker threads:    - current (i.e. single threaded) sequential mode    - 1 x IO thread and 1 x SQL thread    - SQL thread both reads and executes the events 1 worker thread:    - sequential mode    - 1 x IO thread, 1 x Coordinator SQL thread and 1 x Worker thread    - coordinator reads the event and hands it to the worker who executes 2+ worker threads:    - parallel execution    - 1 x IO thread, 1 x Coordinator SQL thread and 2+ Worker threads    - coordinator reads events and hands them to the workers who execute them Results Figure 1 below shows that Multi-Threaded Slaves deliver ~5x higher replication performance when configured with 10 worker threads, with the load evenly distributed across our 10 x schemas. This result is compared to the current replication implementation which is based on a single SQL thread only (i.e. zero worker threads). Figure 1: 5x Higher Performance with Multi-Threaded Slaves The following figure shows more detailed results, with QPS sampled and reported as the worker threads are incremented. The raw numbers behind this graph are reported in the Appendix section of this post. Figure 2: Detailed Results As the results above show, the configuration does not scale noticably from 5 to 9 worker threads. When configured with 10 worker threads however, scalability increases significantly. The conclusion therefore is that it is desirable to configure the same number of worker threads as schemas. Other conclusions from the results: · Running with 1 worker compared to zero workers just introduces overhead without the benefit of parallel execution. · As expected, having more workers than schemas adds no visible benefit. Aside from what is shown in the results above, testing also demonstrated that the following settings had a very positive effect on slave performance: relay-log-info-repository=TABLE master-info-repository=TABLE For 5+ workers, it was up to 2.3 times as fast to run with TABLE compared to FILE. Conclusion As the results demonstrate, Multi-Threaded Slaves deliver significant performance increases to MySQL replication when handling multiple schemas. This, and the other replication enhancements introduced in MySQL 5.6 are fully available for you to download and evaluate now from the MySQL Developer site (select Development Release tab). You can learn more about MySQL 5.6 from the documentation  Please don’t hesitate to comment on this or other replication blogs with feedback and questions. Appendix – Detailed Results

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• Developing Schema Compare for Oracle (Part 1)

  - by Simon Cooper

  SQL Compare is one of Red Gate's most successful SQL Server tools; it allows developers and DBAs to compare and synchronize the contents of their databases. Although similar tools exist for Oracle, they are quite noticeably lacking in the usability and stability that SQL Compare is known for in the SQL Server world. We could see a real need for a usable schema comparison tools for Oracle, and so the Schema Compare for Oracle project was born. Over the next few weeks, as we come up to release of v1, I'll be doing a series of posts on the development of Schema Compare for Oracle. For the first post, I thought I would start with the main pitfalls that we stumbled across when developing the product, especially from a SQL Server background. 1. Schemas and Databases The most obvious difference is that the concept of a 'database' is quite different between Oracle and SQL Server. On SQL Server, one server instance has multiple databases, each with separate schemas. There is typically little communication between separate databases, and most databases are no more than about 1000-2000 objects. This means SQL Compare can register an entire database in a reasonable amount of time, and cross-database dependencies probably won't be an issue. It is a quite different scene under Oracle, however. The terms 'database' and 'instance' are used interchangeably, (although technically 'database' refers to the datafiles on disk, and 'instance' the running Oracle process that reads & writes to the database), and a database is a single conceptual entity. This immediately presents problems, as it is infeasible to register an entire database as we do in SQL Compare; in my Oracle install, using the standard recommended options, there are 63975 system objects. If we tried to register all those, not only would it take hours, but the client would probably run out of memory before we finished. As a result, we had to allow people to specify what schemas they wanted to register. This decision had quite a few knock-on effects for the design, which I will cover in a future post. 2. Connecting to Oracle The next obvious difference is in actually connecting to Oracle – in SQL Server, you can specify a server and database, and off you go. On Oracle things are slightly more complicated. SIDs, Service Names, and TNS A database (the files on disk) must have a unique identifier for the databases on the system, called the SID. It also has a global database name, which consists of a name (which doesn't have to match the SID) and a domain. Alternatively, you can identify a database using a service name, which normally has a 1-to-1 relationship with instances, but may not if, for example, using RAC (Real Application Clusters) for redundancy and failover. You specify the computer and instance you want to connect to using TNS (Transparent Network Substrate). The user-visible parts are a config file (tnsnames.ora) on the client machine that specifies how to connect to an instance. For example, the entry for one of my test instances is: SC_11GDB1 = (DESCRIPTION = (ADDRESS_LIST = (ADDRESS = (PROTOCOL = TCP)(HOST = simonctest)(PORT = 1521)) ) (CONNECT_DATA = (SID = 11gR1db1) ) ) This gives the hostname, port, and SID of the instance I want to connect to, and associates it with a name (SC_11GDB1). The tnsnames syntax also allows you to specify failover, multiple descriptions and address lists, and client load balancing. You can then specify this TNS identifier as the data source in a connection string. Although using ODP.NET (the .NET dlls provided by Oracle) was fine for internal prototype builds, once we released the EAP we discovered that this simply wasn't an acceptable solution for installs on other people's machines. Due to .NET assembly strong naming, users had to have installed on their machines the exact same version of the ODP.NET dlls as we had on our build server. We couldn't ship the ODP.NET dlls with our installer as the Oracle license agreement prohibited this, and we didn't want to force users to install another Oracle client just so they can run our program. To be able to list the TNS entries in the connection dialog, we also had to locate and parse the tnsnames.ora file, which was complicated by users with several Oracle client installs and intricate TNS entries. After much swearing at our computers, we eventually decided to use a third party Oracle connection library from Devart that we could ship with our program; this could use whatever client version was installed, parse the TNS entries for us, and also had the nice feature of being able to connect to an Oracle server without having any client installed at all. Unfortunately, their current license agreement prevents us from shipping an Oracle SDK, but that's a bridge we'll cross when we get to it. 3. Running synchronization scripts The most important difference is that in Oracle, DDL is non-transactional; you cannot rollback DDL statements like you can on SQL Server. Although we considered various solutions to this, including using the flashback archive or recycle bin, or generating an undo script, no reliable method of completely undoing a half-executed sync script has yet been found; so in this case we simply have to trust that the DBA or developer will check and verify the script before running it. However, before we got to that stage, we had to get the scripts to run in the first place... To run a synchronization script from SQL Compare we essentially pass the script over to the SqlCommand.ExecuteNonQuery method. However, when we tried to do the same for an OracleConnection we got a very strange error – 'ORA-00911: invalid character', even when running the most basic CREATE TABLE command. After much hair-pulling and Googling, we discovered that Oracle has got some very strange behaviour with semicolons at the end of statements. To understand what's going on, we need to take a quick foray into SQL and PL/SQL. PL/SQL is not T-SQL In SQL Server, T-SQL is the language used to interface with the database. It has DDL, DML, control flow, and many other nice features (like Turing-completeness) that you can mix and match in the same script. In Oracle, DDL SQL and PL/SQL are two completely separate languages, with different syntax, different datatypes and different execution engines within the instance. Oracle SQL is much more like 'pure' ANSI SQL, with no state, no control flow, and only the basic DML commands. PL/SQL is the Turing-complete language, but can only do DML and DCL (i.e. BEGIN TRANSATION commands). Any DDL or SQL commands that aren't recognised by the PL/SQL engine have to be passed back to the SQL engine via an EXECUTE IMMEDIATE command. In PL/SQL, a semicolons is a valid token used to delimit the end of a statement. In SQL, a semicolon is not a valid token (even though the Oracle documentation gives them at the end of the syntax diagrams) . When you execute the command CREATE TABLE table1 (COL1 NUMBER); in SQL*Plus the semicolon on the end is a command to SQL*Plus to execute the preceding statement on the server; it strips off the semicolon before passing it on. SQL Developer does a similar thing. When executing a PL/SQL block, however, the syntax is like so: BEGIN INSERT INTO table1 VALUES (1); INSERT INTO table1 VALUES (2); END; / In this case, the semicolon is accepted by the PL/SQL engine as a statement delimiter, and instead the / is the command to SQL*Plus to execute the current block. This explains the ORA-00911 error we got when trying to run the CREATE TABLE command – the server is complaining about the semicolon on the end. This also means that there is no SQL syntax to execute more than one DDL command in the same OracleCommand. Therefore, we would have to do a round-trip to the server for every command we want to execute. Obviously, this would cause lots of network traffic and be very slow on slow or congested networks. Our first attempt at a solution was to wrap every SQL statement (without semicolon) inside an EXECUTE IMMEDIATE command in a PL/SQL block and pass that to the server to execute. One downside of this solution is that we get no feedback as to how the script execution is going; we're currently evaluating better solutions to this thorny issue. Next up: Dependencies; how we solved the problem of being unable to register the entire database, and the knock-on effects to the whole product.

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• Are these two functions overkill for sanitization?

  - by jpjp

  function sanitizeString($var) { $var = stripslashes($var); $var = htmlentities($var); $var = strip_tags($var); return $var; } function sanitizeMySQL($var) { $var = mysql_real_escape_string($var); $var = sanitizeString($var); return $var; } I got these two functions from a book and the author says that by using these two, I can be extra safe against XSS(the first function) and sql injections(2nd func). Are all those necessary? Also for sanitizing, I use prepared statements to prevent sql injections. I would use it like this: $variable = sanitizeString($_POST['user_input']); $variable = sanitizeMySQL($_POST['user_input']);

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• Spring online repository for Maven

  - by Fortyrunner

  I've just installed Maven2 for the first time. By default it pulls down a few useful jars into a local project: jakarta-commons, junit etc. I wanted to pull in the latest Spring release (2.5.6 at the time of writing). But the online repositories I looked at (iBiblio and Maven) only had much older versions of Spring libraries. Are there any other repositories that are kept up to date? What is the best practice here; can we maintain them ourselves? I would be prepared to help out maintaining this stuff!

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• PostgreSQL 8.3 data types: xml vs varchar

  - by Sejanus

  There's xml data type in Postgres, I never used it before so I'd like to hear opinions. Downsides and upsides vs using regular varchar (or Text) column to store xml. The text I'm going to store is xml, well-formed, UTF-8. No need to search by it (I've read searching by xml is slow). This XML actually is data prepared for PDF generation with Apache FOP. XML can be generated dynamically from data found elsewhere (other Postgres tables), it's stored as is only so that I won't need to generate it twice. Kinda backup#2 for already generated PDF documents. Anything else to know? Good practices, performance, maintenance, etc?

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• HSQLDB Constraint Violation & SQL Query Log for an HSQLDB in-memory setup

  - by shipmaster

  We have a setup where we are using an embedded HSQLDB for backing Hibernate/JPA unit tests in java, and we are using the in-memory database mode since we simply want the database thrown away after the test run. My problem is that one of the tests is failing due to a constraint violation and HSQLDB lists the column as SYS_CT_286, and the query that appears in the log is the prepared statement where I cant see what the actual parameter values are (they are replaced by '?'). My questions are: 1- Is there a way in which I can see the actual SQL being executed? (like the mysql query log for example?). 2- What exactly is SYS_CT_286? it is not one of my columns, is it a generated column? is there something obvious that may be wrong with it? Thanks.

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