Search Results

Search found 18245 results on 730 pages for 'recursive query'.

facebook twitter digg google delicious technorati stumbleupon myspace wordpress linkedin gmail igoogle windows live tumblr viadeo yahoo buzz yahoo mail yahoo bookmarks favorites email print

Page 37/730 | < Previous Page | 33 34 35 36 37 38 39 40 41 42 43 44  | Next Page >

  • SQL SERVER MAXDOP Settings to Limit Query to Run on Specific CPU

    This is very simple and known tip. Query Hint MAXDOP – Maximum Degree Of Parallelism can be set to restrict query to run on a certain CPU. Please note that this query cannot restrict or dictate which CPU to be used, but for sure, it restricts the usage of number of CPUs in a single [...]...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

    Read the article

  • recursive grep started at / hangs

    - by Martin
    I have used following grep search pattern on multiple platforms: grep -r -I -D skip 'string_to_match' / For example on FreeBSD 8.0, FreeBSD 6.4 and Debian 6.0(squeeze). Command does a recursive search starting from root directory, assumes that binary files do not have the 'string_to_match' and skips devices, sockets and named pipes. FreeBSD 8.0 and FreeBSD 6.4 use GNU grep version 2.5.1 and Debian 6.0 uses GNU grep version 2.6.3. On FreeBSD 6.4, last information printed to stderr was "grep: /dev/cuad0: Device busy". After this grep just idles as according to "top -m io -o total" the I/O usage of grep is nonexistent. Same behavior is true under FreeBSD 8.0, but last information sent to stderr is "grep: /tmp/.wine-0: Permission denied" on my installation. In case of Debian, last output to stderr is "grep: /proc/sysrq-trigger: Input/output error". If I check the I/O usage of grep process under Debian, it is following: root@Debian:~# iotop -bp 22439 Total DISK READ: 0.00 B/s | Total DISK WRITE: 0.00 B/s TID PRIO USER DISK READ DISK WRITE SWAPIN IO COMMAND 22439 be/4 root 0.00 B/s 0.00 B/s 0.00 % 0.00 % grep -r -I -D skip 10.10.10.99 / Total DISK READ: 0.00 B/s | Total DISK WRITE: 0.00 B/s TID PRIO USER DISK READ DISK WRITE SWAPIN IO COMMAND 22439 be/4 root 0.00 B/s 0.00 B/s 0.00 % 0.00 % grep -r -I -D skip 10.10.10.99 / Total DISK READ: 0.00 B/s | Total DISK WRITE: 0.00 B/s TID PRIO USER DISK READ DISK WRITE SWAPIN IO COMMAND 22439 be/4 root 0.00 B/s 0.00 B/s 0.00 % 0.00 % grep -r -I -D skip 10.10.10.99 / ^Croot@Debian:~# What might cause this? Is there a way to view which file grep is currently processing in case lsof is not present? I'm able to use lsof under Debian and looks like the problematic file name there is "0xc6b2c230 file struct, ty=0, op=0xc0d34120". I'm not sure what this is.. I'm not able to use lsof or fstat under FreeBSD. PS: I know I could use find utility, but this is not the question.

    Read the article

  • Coherence Query Performance in Large Clusters

    - by jpurdy
    Large clusters (measured in terms of the number of storage-enabled members participating in the largest cache services) may introduce challenges when issuing queries. There is no particular cluster size threshold for this, rather a gradually increasing tendency for issues to arise. The most obvious challenges are that a client's perceived query latency will be determined by the slowest responder (more likely to be a factor in larger clusters) as well as the fact that adding additional cache servers will not increase query throughput if the query processing is not compute-bound (which would generally be the case for most indexed queries). If the data set can take advantage of the partition affinity features of Coherence, then the application can use a PartitionedFilter to target a query to a single server (using partition affinity to ensure that all data is in a single partition). If this can not be done, then avoiding an excessive number of cache server JVMs will help, as will ensuring that each cache server has sufficient CPU resources available and is also properly configured to minimize GC pauses (the most common cause of a slow-responding cache server).

    Read the article

  • Cannot make bind9 forward DNS query to subdomain unless recursive enabled

    - by PP.
    I am trying to develop my own dynamic DNS. I'm running my own custom DNS for the subdomain on port 5353. ASCII diagram: INET --->:53 Bind 9 --->:5353 node.js | V zone_files I have example.com. The node.js DNS is for dyn.example.com. In my /etc/bind/named.conf.local I have: zone "example.com" { type master; file "/etc/bind/db.com.example"; allow-transfer { zonetxfrsafe; }; }; zone "dyn.example.com" IN { # DYNAMIC type forward; forwarders { 127.0.0.1 port 5353; }; forward only; }; I've even gone so far as to add a NS in my example.com zone file: $TTL 86400 @ IN SOA ns.example.com. hostmaster.example.com. ( 2013070104 ; Serial 7200 ; Refresh 1200 ; Retry 2419200 ; Expire 86400 ) ; Negative Cache TTL ; NS ns ; inet of our nameserver ns A 1.2.3.4 ; NS record for subdomain dyn NS ns When I attempt to get a record from the subdomain server it doesn't get forwarded: dig @127.0.0.1 test.dyn.example.com However if I turn recursive on in /etc/bind/named.conf.options: options { recursion yes; } .. then I CAN see the request going to the subdomain server. But I don't want recursion yes; in my Bind configuration as it is poor security practice (and allows all-and-sundry requests that are not related to my managed zones). How does one forward (proxy) zone queries for just one zone? Or do I give up on Bind altogether and find a DNS server that can actually forward specific queries?

    Read the article

  • Why so much stack space used for each recursion?

    - by Harvey
    I have a simple recursive function RCompare() that calls a more complex function Compare() which returns before the recursive call. Each recursion level uses 248 bytes of stack space which seems like way more than it should. Here is the recursive function: void CMList::RCompare(MP n1) // RECURSIVE and Looping compare function { auto MP ne=n1->mf; while(StkAvl() && Compare(n1=ne->mb)) RCompare(n1); // Recursive call ! } StkAvl() is a simple stack space check function that compares the address of an auto variable to the value of an address near the end of the stack stored in a static variable. It seems to me that the only things added to the stack in each recursion are two pointer variables (MP is a pointer to a structure) and the stuff that one function call stores, a few saved registers, base pointer, return address, etc., all 32-bit (4 byte) values. There's no way that is 248 bytes is it? I don't no how to actually look at the stack in a meaningful way in Visual Studio 2008. Thanks

    Read the article

  • How to select a MAX value from column in Query Builder in Kohana framework?

    - by Victor Czechov
    I need to INSERT a data to table, but before a query I must to know the MAX value from column position, than to INSERT a data WHERE my SELECTED before position+1. Is it possible with query builder? following my first comment I did query: $p = DB::select(array(DB::expr('MAX(`position`)', 'p')))->from('supercategories')->execute(); echo $p; the error: ErrorException [ Notice ]: Undefined offset: 1 MODPATH\database\classes\kohana\database.php [ 505 ] 500 */ 501 public function quote_column($column) 502 { 503 if (is_array($column)) 504 { 505 list($column, $alias) = $column; 506 } 507 508 if ($column instanceof Database_Query) 509 { 510 // Create a sub-query

    Read the article

  • How can I choose different hints for different joins for a single table in a query hint?

    - by RenderIn
    Suppose I have the following query: select * from A, B, C, D where A.x = B.x and B.y = C.y and A.z = D.z I have indexes on A.x and B.x and B.y and C.y and D.z There is no index on A.z. How can I give a hint to this query to use an INDEX hint on A.x but a USE_HASH hint on A.z? It seems like hints only take the table name, not the specific join, so when using a single table with multiple joins I can only specify a single strategy for all of them. Alternative, suppose I'm using a LEADING or ORDERED hint on the above query. Both of these hints only take a table name as well, so how can I ensure that the A.x = B.x join takes place before the A.z = D.z one? I realize in this case I could list D first, but imagine D subsequently joins to E and that the D-E join is the last one I want in the entire query. A third configuration -- Suppose I want the A.x join to be the first of the entire query, and I want the A.z join to be the last one. How can I use a hint to have a single join from A to take place, followed by the B-C join, and the A-D join last?

    Read the article

  • will a mysql query run slower if one of the tables involved has no index defined??

    - by lock
    there's this already populated database which came from another dev im not sure what went on that dev's mind when he created the tables, but on one of our scripts there is this query involving 4 tables and it runs super slow SELECT a.col_1, a.col_2, a.col_3, a.col_4, a.col_5, a.col_6, a.col_7 FROM a, b, c, d WHERE a.id = b.id AND b.c_id = c.id AND c.id = d.c_id AND a.col_8 = '$col_8' AND d.g_id = '$g_id' AND c.private = '1' NOTE: $col_8 and $g_id are variables from a form its only my theory that it's due to tables b and c not having an index, although im guessing that the dev didnt think that it was necessary since those tables only tell relations between a and d, where b tells that the data in a belongs to a certain user, and c tells that the user belongs to a group in d as you can see, there's not even a join or other extensive query functions used but this query which returns only around 100 rows takes 2 minutes to execute. anyway my question is simply this post's title. will a mysql query run slower if one of the tables involved has no index defined??

    Read the article

  • What is the easiest way to find a sql query returns a result or not?

    - by bala3569
    Consider the following sql server query , DECLARE @Table TABLE( Wages FLOAT ) INSERT INTO @Table SELECT 20000 INSERT INTO @Table SELECT 15000 INSERT INTO @Table SELECT 10000 INSERT INTO @Table SELECT 45000 INSERT INTO @Table SELECT 50000 SELECT * FROM ( SELECT *, ROW_NUMBER() OVER(ORDER BY Wages DESC) RowID FROM @Table ) sub WHERE RowID = 3 The result of the query would be 20000 ..... Thats fine as of now i have to find the result of this query, SELECT * FROM ( SELECT *, ROW_NUMBER() OVER(ORDER BY Wages DESC) RowID FROM @Table ) sub WHERE RowID = 6 It will not give any result because there are only 5 rows in the table..... so now my question is What is the easiest way to find a sql query returns a result or not?

    Read the article

  • Kohana Database Library - How to Execute a Query with the Same Parameters More Than Once?

    - by Noah Goodrich
    With the following bit of code: $builder = ORM::factory('branch')->where('institution_id', $this->institution->id)->orderby('name'); I need to first execute: $count = $builder->count_all(); Then I need to execute: $rs = $builder->find_all($limit, $offset); However, it appears that when I execute the first query the stored query parameters are cleared so that a fresh query can be executed. Is there a way to avoid having the parameters cleared or at least copy them easily without having to reach directly into the Database driver object that stores the query parameters and copy them out? We are using Kohana 2.3.4 and upgrading is not an option.

    Read the article

  • How can I use a php array in a mysql search query?

    - by ThinkingInBits
    I was going to use the scuttle solution on: http://www.pui.ch/phred/archives/2005/04/tags-database-schemas.html for handling searches on my website. I was wondering how I could take the search input from a user and turn it into a single query. For instance, let's say a user inputted 'blue dogs' in their search query... How could I dynamically update the query to include ('blue', 'dogs') in union and intersection queries?

    Read the article

  • MySQL Query, limit output display according/only to associated ID!

    - by Jess
    So here's my situation. I have a books table and authors table. An author can have many books... In my authors page view, the user (logged in) can click an author in a tabled row and be directed to a page displaying the author's books (collected like this URI format: viewauthorbooks.php?author_id=23), very straight forward... However, in my query, I need to display the books for the author only, and not all books stored in the books table (as i currently have!) As I am a complete novice, I used the most simple query of: SELECT * FROM tasks_tb :)....this returns the books for me, but returns every single value (book) in the database, and not ones associated with the selected author. And when I click a different author the same books are displayed for them...I think everyone gets what I'm trying to achieve, I just don't know how to perform the query. I'm guessing that I need to start using more advanced query clauses like INNER JOIN etc. Anyone care to help me out :)

    Read the article

  • a reusable query with modifications?

    - by fusion
    i'm using this mysql query alongwith php to search for multiple keywords: $query = "SELECT cQuotes, vAuthor, cArabic, vReference FROM ".$table." WHERE ("; $countFields = count($arrayFields); while ($a < $countFields) { while ($b < $countSearch) { $query = $query."$arrayFields[$a] LIKE '%$arraySearch[$b]%'"; $b++; if ($b < $countSearch) { $query = $query." AND "; } } $b = 0; $a++; if ($a < $countFields) { $query = $query.") OR ("; } } $query = $query.")"; $result = mysql_query($query, $conn) i'd like to reuse this query with a few modifications to it (for instance, the WHERE clause remains the same, while i query the number of rows using COUNT), but it doesn't seem practical to repeat the code again for a few additions. any suggestions?

    Read the article

  • How can I get columns name from select query in php?

    - by Farshad Mehrvarzan
    I want to execute a SELECT query but I don't how many columns to select. Like: select name, family from persons; How can I know which columns to select? "I am currently designing a site for the execute query by users. So when the user executes this query, I won't know which columns selected. But when I want to show the results and draw a table for the user I should know which columns selected."

    Read the article

  • multiple mysql_real_query() in while loop

    - by Steve
    It seems that when I have one mysql_real_query() function in a continuous while loop, the query will get executed OK. However, if multiple mysql_real_query() are inside the while loop, one right after the other. Depending on the query, sometimes neither the first query nor second query will execute properly. This seems like a threading issue to me. I'm wondering if the mysql c api has a way of dealing with this? Does anyone know how to deal with this? mysql_free_result() doesn't work since I am not even storing the results. //keep polling as long as stop character '-' is not read while(szRxChar != '-') { // Check if a read is outstanding if (HasOverlappedIoCompleted(&ovRead)) { // Issue a serial port read if (!ReadFile(hSerial,&szRxChar,1, &dwBytesRead,&ovRead)) { DWORD dwErr = GetLastError(); if (dwErr!=ERROR_IO_PENDING) return dwErr; } } // Wait 5 seconds for serial input if (!(HasOverlappedIoCompleted(&ovRead))) { WaitForSingleObject(hReadEvent,RESET_TIME); } // Check if serial input has arrived if (GetOverlappedResult(hSerial,&ovRead, &dwBytesRead,FALSE)) { // Wait for the write GetOverlappedResult(hSerial,&ovWrite, &dwBytesWritten,TRUE); //load tagBuffer with byte stream tagBuffer[i] = szRxChar; i++; tagBuffer[i] = 0; //char arrays are \0 terminated //run query with tagBuffer if( strlen(tagBuffer)==PACKET_LENGTH ) { sprintf(query,"insert into scan (rfidnum) values ('"); strcat(query, tagBuffer); strcat(query, "')"); mysql_real_query(&mysql,query,(unsigned int)strlen(query)); i=0; } mysql_real_query(&mysql,"insert into scan (rfidnum) values ('2nd query')",(unsigned int)strlen("insert into scan (rfid) values ('2nd query')")); mysql_free_result(res); } }

    Read the article

  • Google App Engine query data store by a string start with ...

    - by Frank
    How to write a query that can find me all item_number start with a certain value ? For instance there are item_numbers like these : 123_abc 123_xyz ierireire 321_add 999_pop My current query looks like this : "select from "+PayPal_Message.class.getName()+" where item_number == '"+Item_Number+"' order by item_number desc" What's a query look like that can return all item_numbers start with "123_" ?

    Read the article

  • [Linq to sql] query result what should i use Count() or Any()...

    - by Pandiya Chendur
    I am checking login of a user by this repository method, public bool getLoginStatus(string emailId, string password) { var query = from r in taxidb.Registrations where (r.EmailId == emailId && r.Password==password) select r; if (query.Count() != 0) { return true; } return false; } I saw in one of the previous questions !query.Any() would be faster... Which should i use? Any suggestion....

    Read the article

  • SQL SERVER – Weekly Series – Memory Lane – #051

    - by Pinal Dave
    Here is the list of selected articles of SQLAuthority.com across all these years. Instead of just listing all the articles I have selected a few of my most favorite articles and have listed them here with additional notes below it. Let me know which one of the following is your favorite article from memory lane. 2007 Explanation and Understanding NOT NULL Constraint NOT NULL is integrity CONSTRAINT. It does not allow creating of the row where column contains NULL value. Most discussed questions about NULL is what is NULL? I will not go in depth analysis it. Simply put NULL is unknown or missing data. When NULL is present in database columns, it can affect the integrity of the database. I really do not prefer NULL in the database unless they are absolutely necessary. Three T-SQL Script to Create Primary Keys on Table I have always enjoyed writing about three topics Constraint and Keys, Backup and Restore and Datetime Functions. Primary Keys constraints prevent duplicate values for columns and provides a unique identifier to each column, as well it creates clustered index on the columns. 2008 Get Numeric Value From Alpha Numeric String – UDF for Get Numeric Numbers Only SQL is great with String operations. Many times, I use T-SQL to do my string operation. Let us see User Defined Function, which I wrote a few days ago, which will return only Numeric values from Alpha Numeric values. Introduction and Example of UNION and UNION ALL It is very much interesting when I get requests from blog reader to re-write my previous articles. I have received few requests to rewrite my article SQL SERVER – Union vs. Union All – Which is better for performance? with examples. I request you to read my previous article first to understand what is the concept and read this article to understand the same concept with an example. Downgrade Database for Previous Version The main questions is how they can downgrade the from SQL Server 2005 to SQL Server 2000? The answer is : Not Possible. Get Common Records From Two Tables Without Using Join Following is my scenario, Suppose Table 1 and Table 2 has same column e.g. Column1 Following is the query, 1. Select column1,column2 From Table1 2. Select column1 From Table2 I want to find common records from these tables, but I don’t want to use the Join clause because for that I need to specify the column name for Join condition. Will you help me to get common records without using Join condition? I am using SQL Server 2005. Retrieve – Select Only Date Part From DateTime – Best Practice – Part 2 A year ago I wrote a post about SQL SERVER – Retrieve – Select Only Date Part From DateTime – Best Practice where I have discussed two different methods of getting the date part from datetime. Introduction to CLR – Simple Example of CLR Stored Procedure CLR is an abbreviation of Common Language Runtime. In SQL Server 2005 and later version of it database objects can be created which are created in CLR. Stored Procedures, Functions, Triggers can be coded in CLR. CLR is faster than T-SQL in many cases. CLR is mainly used to accomplish tasks which are not possible by T-SQL or can use lots of resources. The CLR can be usually implemented where there is an intense string operation, thread management or iteration methods which can be complicated for T-SQL. Implementing CLR provides more security to the Extended Stored Procedure. 2009 Comic Slow Query – SQL Joke Before Presentation After Presentation Enable Automatic Statistic Update on Database In one of the recent projects, I found out that despite putting good indexes and optimizing the query, I could not achieve an optimized performance and I still received an unoptimized response from the SQL Server. On examination, I figured out that the culprit was statistics. The database that I was trying to optimize had auto update of the statistics was disabled. Recently Executed T-SQL Query Please refer to blog post  query to recently executed T-SQL query on database. Change Collation of Database Column – T-SQL Script – Consolidating Collations – Extention Script At some time in your DBA career, you may find yourself in a position when you sit back and realize that your database collations have somehow run amuck, or are faced with the ever annoying CANNOT RESOLVE COLLATION message when trying to join data of varying collation settings. 2010 Visiting Alma Mater – Delivering Session on Database Performance and Career – Nirma Institute of Technology Everyone always dreams of visiting their school and college, where they have studied once. It is a great feeling to see the college once again – where you have spent the wonderful golden years of your time. College time is filled with studies, education, emotions and several plans to build a future. I consider myself fortunate as I got the opportunity to study at some of the best places in the world. Change Column DataTypes There are times when I feel like writing that I am a day older in SQL Server. In fact, there are many who are looking for a solution that is simple enough. Have you ever searched online for something very simple. I often do and enjoy doing things which are straight forward and easy to change. 2011 Three DMVs – sys.dm_server_memory_dumps – sys.dm_server_services – sys.dm_server_registry In this blog post we will see three new DMVs which are introduced in Denali. The DMVs are very simple and there is not much to describe them. So here is the simple game. I will be asking a question back to you after seeing the result of the each of the DMV and you help me to complete this blog post. A Simple Quiz – T-SQL Brain Trick If you have some time, I strongly suggest you try this quiz out as it is for sure twists your brain. 2012 List All The Column With Specific Data Types in Database 5 years ago I wrote script SQL SERVER – 2005 – List All The Column With Specific Data Types, when I read it again, it is very much relevant and I liked it. This is one of the script which every developer would like to keep it handy. I have upgraded the script bit more. I have included few additional information which I believe I should have added from the beginning. It is difficult to visualize the final script when we are writing it first time. Find First Non-Numeric Character from String The function PATINDEX exists for quite a long time in SQL Server but I hardly see it being used. Well, at least I use it and I am comfortable using it. Here is a simple script which I use when I have to identify first non-numeric character. Finding Different ColumnName From Almost Identitical Tables Well here is the interesting example of how we can use sys.column catalogue views and get the details of the newly added column. I have previously written about EXCEPT over here which is very similar to MINUS of Oracle. Storing Data and Files in Cloud – Dropbox – Personal Technology Tip I thought long and hard about doing a Personal Technology Tips series for this blog.  I have so many tips I’d like to share.  I am on my computer almost all day, every day, so I have a treasure trove of interesting tidbits I like to share if given the chance.  The only thing holding me back – which tip to share first?  The first tip obviously has the weight of seeming like the most important.  But this would mean choosing amongst my favorite tricks and shortcuts.  This is a hard task. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Memory Lane, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

    Read the article

  • SQL Authority News – Play by Play with Pinal Dave – A Birthday Gift

    - by Pinal Dave
    Today is my birthday. Personal Note When I was young, I was always looking forward to my birthday as on this day, I used to get gifts from everybody. Now when I am getting old on each of my birthday, I have almost same feeling but the direction is different. Now on each of my birthday, I feel like giving gifts to everybody. I have received lots of support, love and respect from everybody; and now I must return it back.Well, on this birthday, I have very unique gifts for everybody – my latest course on SQL Server. How I Tune Performance I often get questions where I am asked how do I work on a normal day. I am often asked that how do I work when I have performance tuning project is assigned to me. Lots of people have expressed their desire that they want me to explain and demonstrate my own method of solving performance problem when I am facing real world problem. It is a pretty difficult task as in the real world, nothing goes as planned and usually planned demonstrations have no place there. The real world, demands real solutions and in a timely fashion. If a consultant goes to industry and does not demonstrate his/her capabilities in very first few minutes, it does not matter how much fame he/she is, the door is shown to them eventually. It is true and in my early career, I have faced it quite commonly. I have learned the trick to be honest from the start and request absolutely transparent communication from the organization where I am to consult. Play by Play Play by Play is a very unique setup. It is not planned and it is a step by step course. It is like a reality show – a very real encounter to the problem and real problem solving approach. I had a great time doing this course. Geoffrey Grosenbach (VP of Pluralsight) sits down with me to see what a SQL Server Admin does in the real world. This Play-by-Play focuses on SQL Server performance tuning and I go over optimizing queries and fine-tuning the server. The table of content of this course is very simple. Introduction In the introduction I explained my basic strategies when I am approached by a customer for performance tuning. Basic Information Gathering In this module I explain how I do gather various information for performance tuning project. It is very crucial to demonstrate to customers for consultant his capability of solving problem. I attempt to resolve a small problem which gives a big positive impact on performance, consultant have to gather proper information from the start. I demonstrate in this module, how one can collect all the important performance tuning metrics. Removing Performance Bottleneck In this module, I build upon the previous module’s statistics collected. I analysis various performance tuning measures and immediately start implementing various tweaks on the performance, which will start improving the performance of my server. This is a very effective method and it gives immediate return of efforts. Index Optimization Indexes are considered as a silver bullet for performance tuning. However, it is not true always there are plenty of examples where indexes even performs worst after implemented. The key is to understand a few of the basic properties of the index and implement the right things at the right time. In this module, I describe in detail how to do index optimizations and what are right and wrong with Index. If you are a DBA or developer, and if your application is running slow – this is must attend module for you. I have some really interesting stories to tell as well. Optimize Query with Rewrite Every problem has more than one solution, in this module we will see another very famous, but hard to master skills for performance tuning – Query Rewrite. There are few do’s and don’ts for any query rewrites. I take a very simple example and demonstrate how query rewrite can improve the performance of the query at many folds. I also share some real world funny stories in this module. This course is hosted at Pluralsight. You will need a valid login for Pluralsight to watch  Play by Play: Pinal Dave course. You can also sign up for FREE Trial of Pluralsight to watch this course. As today is my birthday – I will give 10 people (randomly) who will express their desire to learn this course, a free code. Please leave your comment and I will send you free code to watch this course for free. Reference: Pinal Dave (http://blog.sqlauthority.com)Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQL Training, SQLAuthority News, T SQL, Video

    Read the article

  • SQL SERVER – Weekly Series – Memory Lane – #053 – Final Post in Series

    - by Pinal Dave
    It has been a fantastic journey to write memory lane series for an entire year. This series gave me the opportunity to go back and see what I have contributed to this blog throughout the last 7 years. This was indeed fantastic series as this provided me the opportunity to witness how technology has grown throughout the year and how I have progressed in my career while writing this blog post. This series was indeed fantastic experience readers as many joined during the last few years and were not sure what they have missed in recent years. Let us continue with the final episode of the Memory Lane Series. Here is the list of selected articles of SQLAuthority.com across all these years. Instead of just listing all the articles I have selected a few of my most favorite articles and have listed them here with additional notes below it. Let me know which one of the following is your favorite article from memory lane. 2007 Get Current User – Get Logged In User Here is the straight script which list logged in SQL Server users. Disable All Triggers on a Database – Disable All Triggers on All Servers Question : How to disable all the triggers for a database? Additionally, how to disable all the triggers for all servers? For answer execute the script in the blog post. Importance of Master Database for SQL Server Startup I have received following questions many times. I will list all the questions here and answer them together. What is the purpose of Master database? Should our backup Master database? Which database is must have database for SQL Server for startup? Which are the default system database created when SQL Server 2005 is installed for the first time? What happens if Master database is corrupted? Answers to all of the questions are very much related. 2008 DECLARE Multiple Variables in One Statement SQL Server is a great product and it has many features which are very unique to SQL Server. Regarding feature of SQL Server where multiple variable can be declared in one statement, it is absolutely possible to do. 2009 How to Enable Index – How to Disable Index – Incorrect syntax near ‘ENABLE’ Many times I have seen that the index is disabled when there is a large update operation on the table. Bulk insert of very large file updates in any table using SSIS is usually preceded by disabling the index and followed by enabling the index. I have seen many developers running the following query to disable the index. 2010 List of all the Views from Database Many emails I received suggesting that they have hundreds of the view and now have no clue what is going on and how many of them have indexes and how many does not have an index. Some even asked me if there is any way they can get a list of the views with the property of Index along with it. Here is the quick script which does exactly the same. You can also include many other columns from the same view. Minimum Maximum Memory – Server Memory Options I was recently reading about SQL Server Memory Options over here. While reading this one line really caught my attention is minimum value allowed for maximum memory options. The default setting for min server memory is 0, and the default setting for max server memory is 2147483647. The minimum amount of memory you can specify for max server memory is 16 megabytes (MB). 2011 Fundamentals of Columnstore Index There are two kinds of storage in a database. Row Store and Column Store. Row store does exactly as the name suggests – stores rows of data on a page – and column store stores all the data in a column on the same page. These columns are much easier to search – instead of a query searching all the data in an entire row whether the data are relevant or not, column store queries need only to search a much lesser number of the columns. How to Ignore Columnstore Index Usage in Query In summary the question in simple words “How can we ignore using the column store index in selective queries?” Very interesting question – you can use I can understand there may be the cases when the column store index is not ideal and needs to be ignored the same. You can use the query hint IGNORE_NONCLUSTERED_COLUMNSTORE_INDEX to ignore the column store index. The SQL Server Engine will use any other index which is best after ignoring the column store index. 2012 Storing Variable Values in Temporary Array or Temporary List SQL Server does not support arrays or a dynamic length storage mechanism like list. Absolutely there are some clever workarounds and few extra-ordinary solutions but everybody can;t come up with such solution. Additionally, sometime the requirements are very simple that doing extraordinary coding is not required. Here is the simple case. Move Database Files MDF and LDF to Another Location It is not common to keep the Database on the same location where OS is installed. Usually Database files are in SAN, Separate Disk Array or on SSDs. This is done usually for performance reason and manageability perspective. Now the challenges comes up when database which was installed at not preferred default location and needs to move to a different location. Here is the quick tutorial how you can do it. UNION ALL and ORDER BY – How to Order Table Separately While Using UNION ALL If your requirement is such that you want your top and bottom query of the UNION resultset independently sorted but in the same result set you can add an additional static column and order by that column. Let us re-create the same scenario. Copy Data from One Table to Another Table – SQL in Sixty Seconds #031 – Video http://www.youtube.com/watch?v=FVWIA-ACMNo Reference: Pinal Dave (http://blog.sqlauthority.com)Filed under: Memory Lane, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

    Read the article

  • SQL SERVER – CXPACKET – Parallelism – Advanced Solution – Wait Type – Day 7 of 28

    - by pinaldave
    Earlier we discussed about the what is the common solution to solve the issue with CXPACKET wait time. Today I am going to talk about few of the other suggestions which can help to reduce the CXPACKET wait. If you are going to suggest that I should focus on MAXDOP and COST THRESHOLD – I totally agree. I have covered them in details in yesterday’s blog post. Today we are going to discuss few other way CXPACKET can be reduced. Potential Reasons: If data is heavily skewed, there are chances that query optimizer may estimate the correct amount of the data leading to assign fewer thread to query. This can easily lead to uneven workload on threads and may create CXPAKCET wait. While retrieving the data one of the thread face IO, Memory or CPU bottleneck and have to wait to get those resources to execute its tasks, may create CXPACKET wait as well. Data which is retrieved is on different speed IO Subsystem. (This is not common and hardly possible but there are chances). Higher fragmentations in some area of the table can lead less data per page. This may lead to CXPACKET wait. As I said the reasons here mentioned are not the major cause of the CXPACKET wait but any kind of scenario can create the probable wait time. Best Practices to Reduce CXPACKET wait: Refer earlier article regarding MAXDOP and Cost Threshold. De-fragmentation of Index can help as more data can be obtained per page. (Assuming close to 100 fill-factor) If data is on multiple files which are on multiple similar speed physical drive, the CXPACKET wait may reduce. Keep the statistics updated, as this will give better estimate to query optimizer when assigning threads and dividing the data among available threads. Updating statistics can significantly improve the strength of the query optimizer to render proper execution plan. This may overall affect the parallelism process in positive way. Bad Practice: In one of the recent consultancy project, when I was called in I noticed that one of the ‘experienced’ DBA noticed higher CXPACKET wait and to reduce them, he has increased the worker threads. The reality was increasing worker thread has lead to many other issues. With more number of the threads, more amount of memory was used leading memory pressure. As there were more threads CPU scheduler faced higher ‘Context Switching’ leading further degrading performance. When I explained all these to ‘experienced’ DBA he suggested that now we should reduce the number of threads. Not really! Lower number of the threads may create heavy stalling for parallel queries. I suggest NOT to touch the setting of number of the threads when dealing with CXPACKET wait. Read all the post in the Wait Types and Queue series. Note: The information presented here is from my experience and I no way claim it to be accurate. I suggest reading book on-line for further clarification. All the discussion of Wait Stats over here is generic and it varies by system to system. You are recommended to test this on development server before implementing to production server. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: DMV, Pinal Dave, PostADay, SQL, SQL Authority, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, SQL Wait Stats, SQL Wait Types, T SQL, Technology

    Read the article

  • Big Data – Data Mining with Hive – What is Hive? – What is HiveQL (HQL)? – Day 15 of 21

    - by Pinal Dave
    In yesterday’s blog post we learned the importance of the operational database in Big Data Story. In this article we will understand what is Hive and HQL in Big Data Story. Yahoo started working on PIG (we will understand that in the next blog post) for their application deployment on Hadoop. The goal of Yahoo to manage their unstructured data. Similarly Facebook started deploying their warehouse solutions on Hadoop which has resulted in HIVE. The reason for going with HIVE is because the traditional warehousing solutions are getting very expensive. What is HIVE? Hive is a datawarehouseing infrastructure for Hadoop. The primary responsibility is to provide data summarization, query and analysis. It  supports analysis of large datasets stored in Hadoop’s HDFS as well as on the Amazon S3 filesystem. The best part of HIVE is that it supports SQL-Like access to structured data which is known as HiveQL (or HQL) as well as big data analysis with the help of MapReduce. Hive is not built to get a quick response to queries but it it is built for data mining applications. Data mining applications can take from several minutes to several hours to analysis the data and HIVE is primarily used there. HIVE Organization The data are organized in three different formats in HIVE. Tables: They are very similar to RDBMS tables and contains rows and tables. Hive is just layered over the Hadoop File System (HDFS), hence tables are directly mapped to directories of the filesystems. It also supports tables stored in other native file systems. Partitions: Hive tables can have more than one partition. They are mapped to subdirectories and file systems as well. Buckets: In Hive data may be divided into buckets. Buckets are stored as files in partition in the underlying file system. Hive also has metastore which stores all the metadata. It is a relational database containing various information related to Hive Schema (column types, owners, key-value data, statistics etc.). We can use MySQL database over here. What is HiveSQL (HQL)? Hive query language provides the basic SQL like operations. Here are few of the tasks which HQL can do easily. Create and manage tables and partitions Support various Relational, Arithmetic and Logical Operators Evaluate functions Download the contents of a table to a local directory or result of queries to HDFS directory Here is the example of the HQL Query: SELECT upper(name), salesprice FROM sales; SELECT category, count(1) FROM products GROUP BY category; When you look at the above query, you can see they are very similar to SQL like queries. Tomorrow In tomorrow’s blog post we will discuss about very important components of the Big Data Ecosystem – Pig. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Big Data, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL

    Read the article

facebook twitter digg google delicious technorati stumbleupon myspace wordpress linkedin gmail igoogle windows live tumblr viadeo yahoo buzz yahoo mail yahoo bookmarks favorites email print

< Previous Page | 33 34 35 36 37 38 39 40 41 42 43 44  | Next Page >