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  • Database: Pipelined Functions

    - by Rachel
    I am new to the concept of Pipeline Functions. I have some questions regarding From Database point of view: What actually is Pipeline function ? What is the advantage of using Pipeline Function ? What challenges are solved using Pipeline Function ? Are the any optimization advantages of using Pipeline Function ? Thanks.

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  • Relational Database arrays (H2, Java)

    - by Daddy Warbox
    I seem to have two options on how to implement arrays, and I want to know which I should go with: Use the ARRAY data type and (from what I understand) effectively serialize data objects into the database (which in my case are just wrapped primitive types; don't know of another way to make this work). Use a separate table and map with foreign keys for each array item. If you have experience with this (especially with H2), which would you recommend?

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  • Wanted: Good examples of Scala database persistence

    - by Rydell
    I'm would like to use Scala to persist data to a relational database, so what I am looking for are examples of CRUD operations using Scala. I would like to code on a lower level of abstraction than an ORM like Hibernate/Toplink (read:JDBC), but between us, I would like to see examples of all types. Thanks folks.

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  • Database design 1 to 1 relationship

    - by Khou
    I design my database incorrectly, should I fix this while its in development? "user" table is suppose to have a 1.1 relationship with "userprofile" table however the actual design the "user" table has a 1.* relationship with "userprofile" table. Everything works! but should it be fixed anyways?

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  • Database web application

    - by Watergaite
    How would i go about creating a php application for my web page that can extract data from my database (i currently get the data in a CSV file). id also like the user to be able to filter the data by certain parameters. can u help

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  • java database backup and restore

    - by jawath
    How do I backup / restore any kind of databases inside my java application to flate files.Are there any tools framework available to backup database to flat file like CSV, XML, or secure encrypted file, or restore from csv or xml files to databases, it should be also capable of dumping table vise restore and backup also.

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  • WPF Application with Database.

    - by mike
    Hi, i would like to or need to use a database for my wpf project. It has to store "person" "team" "goals" and maybe 2 more things, nothing very big. Ive already used (worked) with databases in java / php (postgresql), but is there maybe an "easier" way to store the things.. i mean if the db is going to be big than i could use (postgre or mysql), but this one would be small.

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  • Good resource for studying Database High Availability techniques

    - by Invincible
    Hello Can anybody suggest some good resource/book on Database high availability techniques? Moreover, High-availability of system software like Intrusion Prevention system or Web servers. I am considering high-availability is global term which covers clustring, cloud computing, replication, replica management, distributed synchronization for cluster. Thanks in advance!

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  • Is it possible to download a large database using mysql query

    - by Rose
    i am downloading files from server using WinSCP.Is it possible to write a query to download a large database using mysql query? Or using any other method i have tried with this code but i am not able to get the whole database structure <?php if(file_exists('backup_sql/my_backup.zip')) { unlink('backup_sql/my_backup.zip'); } $tables='*'; $host='MY HOST NAME'; $user='MY_USERNAME'; $pass='MYPASSWORD'; $name='MY_DB_NAME'; $link = mysql_connect($host,$user,$pass); mysql_select_db($name,$link); //get all of the tables if($tables == '*') { $tables = array(); $result = mysql_query('SHOW TABLES'); while($row = mysql_fetch_row($result)) { $tables[] = $row[0]; } } else { $tables = is_array($tables) ? $tables : explode(',',$tables); } $return=''; //cycle through foreach($tables as $table) { $result = mysql_query('SELECT * FROM '.$table); $num_fields = mysql_num_fields($result); //$return.= 'DROP TABLE '.$table.';'; $row2 = mysql_fetch_row(mysql_query('SHOW CREATE TABLE '.$table)); $return.= "\n\n".$row2[1].";\n\n"; for ($i = 0; $i < $num_fields; $i++) { while($row = mysql_fetch_row($result)) { $return.= 'INSERT INTO '.$table.' VALUES('; for($j=0; $j<$num_fields; $j++) { $row[$j] = addslashes($row[$j]); //$row[$j] = ereg_replace("\n","\\n",$row[$j]); if (isset($row[$j])) { $return.= '"'.$row[$j].'"' ; } else { $return.= '""'; } if ($j<($num_fields-1)) { $return.= ','; } } $return.= ");\n"; } } $return.="\n\n\n"; } $rand_var=time(); $files_to_zip = array( "'backup_sql/db-backup-'.$rand_var.'.sql'", ); $name = 'db-backup-'.$rand_var.'.sql'; $data = $return; ?> any one please help me... thank you

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  • Database Design Question

    - by Soo
    Ok SO, I have a user table and want to define groups of users together. The best solution I have for this is to create three database tables as follows: UserTable user_id user_name UserGroupLink group_id member_id GroupInfo group_id group_name This method keeps the member and group information separate. This is just my way of thinking. Is there a better way to do this? Also, what is a good naming convention for tables that link two other tables?

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  • What should every developer know about databases?

    - by Aaronaught
    Whether we like it or not, many if not most of us developers either regularly work with databases or may have to work with one someday. And considering the amount of misuse and abuse in the wild, and the volume of database-related questions that come up every day, it's fair to say that there are certain concepts that developers should know - even if they don't design or work with databases today. So: What are the important concepts that developers and other software professionals ought to know about databases? Guidelines for Responses: Keep your list short. One concept per answer is best. Be specific. "Data modelling" may be an important skill, but what does that mean precisely? Explain your rationale. Why is your concept important? Don't just say "use indexes." Don't fall into "best practices." Convince your audience to go learn more. Upvote answers you agree with. Read other people's answers first. One high-ranked answer is a more effective statement than two low-ranked ones. If you have more to add, either add a comment or reference the original. Don't downvote something just because it doesn't apply to you personally. We all work in different domains. The objective here is to provide direction for database novices to gain a well-founded, well-rounded understanding of database design and database-driven development, not to compete for the title of most-important.

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  • Hibernate database integrity with multiple java applications

    - by Austen
    We have 2 java web apps both are read/write and 3 standalone java read/write applications (one loads questions via email, one processes an xml feed, one sends email to subscribers) all use hibernate and share a common code base. The problem we have recently come across is that questions loaded via email sometimes overwrite questions created in one of the web apps. We originally thought this to be a caching issue. We've tried turning off the second level cache, but this doesn't make a difference. We are not explicitly opening and closing sessions, but rather let hibernate manage them via Util.getSessionFactory().getCurrentSession(), which thinking about it, may actually be the issue. We'd rather not setup a clustered 2nd level cache at this stage as this creates another layer of complexity and we're more than happy with the level of performance we get from the app as a whole. So does implementing a open-session-in-view pattern in the web apps and manually managing the sessions in the standalone apps sound like it would fix this? Or any other suggestions/ideas please? <property name="hibernate.transaction.factory_class">org.hibernate.transaction.JDBCTransactionFactory</property> <property name="hibernate.current_session_context_class">thread</property> <property name="hibernate.cache.use_second_level_cache">false</property>

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  • MySQL Database Design with Internationalization

    - by Some name
    Hello, I'm going to start work on a medium sized application, and i'm planning it's db design. One thing that I'm not sure about is this. I will have many tables which will need internationalization, such as: "membership_options, gender_options, language_options etc" Each of these tables will share common i18n fields, like: "title, alternative_title, short_description, description" In your opinion which is the best way to do it? Have an i18n table with the same fields for each of the tables that will need them? or do something like: Membership table Gender table ---------------- -------------- id | created_at id | created_at 1 - 22.03.2001 1 - 14.08.2002 2 - 22.03.2001 2 - 14.08.2002 General translation table ------------------------- record_id | table_name | string_name | alternative_title| .... |id_language 1 - membership regular null 1 (english) 1 - membership normale null 2 (italian) 1 - gender man null 1(english) 1 -gender uomo null 2(italian) This would avoid me repeating something like: membership_translation table ----------------------------- membership_id | name | alternative_title | id_lang 1 regular null 1 1 normale null 2 gender_translation table ----------------------------- gender_id | name | alternative_title | id_lang 1 man null 1 1 uomo null 2 and so on, so i would probably reduce the number of db tables, but i'm not sure about performance.I'm not much of a DB designer, so please let me know.

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  • Database layout for an application with geocoding features using geokit

    - by vooD
    I'm developing a real estate web catalogue and want to geocode every ad using geokit gem. My question is what would be the best database layout from the performance point if i want to make search by country, city of the selected country, administrative area or nearest metro station of the selected city. Available countries, cities, administrative areas and metro sations should be defined by the administrator of catalogue and must be validated by geocoding. I came up with single table: create_table "geo_locations", :force => true do |t| t.integer "geo_location_id" #parent geo location (ex. country is parent geo location of city t.string "country", :null => false #necessary for any geo location t.string "city", #not null for city geo location and it's children t.string "administrative_area" #not null for administrative_area geo location and it's children t.string "thoroughfare_name" #not null for metro station or street name geo location and it's children t.string "premise_number" #house number t.float "lng", :null => false t.float "lat", :null => false t.float "bound_sw_lat", :null => false t.float "bound_sw_lng", :null => false t.float "bound_ne_lat", :null => false t.float "bound_ne_lng", :null => false t.integer "mappable_id" t.string "mappable_type" t.string "type" #country, city, administrative area, metro station or address end Final geo location is address it contains all neccessary information to put marker of the real estate ad on the map. But i'm still stuck on search functionality. Any help would be highly appreciated.

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  • SQL SERVER – FIX : ERROR : 4214 BACKUP LOG cannot be performed because there is no current database

    - by pinaldave
    I recently got following email from one of the reader. Hi Pinal, Even thought my database is in full recovery mode when I try to take log backup I am getting following error. BACKUP LOG cannot be performed because there is no current database backup. (Microsoft.SqlServer.Smo) How to fix it? Thanks, [name and email removed as requested] Solution / Fix: This error can happen when you have never taken full backup of your database and you try to attempt to take backup of the log only. Take full backup once and attempt to take log back up. If the name of your database is MyTestDB follow procedure as following. BACKUP DATABASE [MyTestDB] TO DISK = N'C:\MyTestDB.bak' GO BACKUP LOG [MyTestDB] TO DISK = N'C:\MyTestDB.bak' GO Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, SQL, SQL Authority, SQL Backup and Restore, SQL Error Messages, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, T SQL, Technology Tagged: SQL Log

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  • WebLogic Server Performance and Tuning: Part I - Tuning JVM

    - by Gokhan Gungor
    Each WebLogic Server instance runs in its own dedicated Java Virtual Machine (JVM) which is their runtime environment. Every Admin Server in any domain executes within a JVM. The same also applies for Managed Servers. WebLogic Server can be used for a wide variety of applications and services which uses the same runtime environment and resources. Oracle WebLogic ships with 2 different JVM, HotSpot and JRocket but you can choose which JVM you want to use. JVM is designed to optimize itself however it also provides some startup options to make small changes. There are default values for its memory and garbage collection. In real world, you will not want to stick with the default values provided by the JVM rather want to customize these values based on your applications which can produce large gains in performance by making small changes with the JVM parameters. We can tell the garbage collector how to delete garbage and we can also tell JVM how much space to allocate for each generation (of java Objects) or for heap. Remember during the garbage collection no other process is executed within the JVM or runtime, which is called STOP THE WORLD which can affect the overall throughput. Each JVM has its own memory segment called Heap Memory which is the storage for java Objects. These objects can be grouped based on their age like young generation (recently created objects) or old generation (surviving objects that have lived to some extent), etc. A java object is considered garbage when it can no longer be reached from anywhere in the running program. Each generation has its own memory segment within the heap. When this segment gets full, garbage collector deletes all the objects that are marked as garbage to create space. When the old generation space gets full, the JVM performs a major collection to remove the unused objects and reclaim their space. A major garbage collect takes a significant amount of time and can affect system performance. When we create a managed server either on the same machine or on remote machine it gets its initial startup parameters from $DOMAIN_HOME/bin/setDomainEnv.sh/cmd file. By default two parameters are set:     Xms: The initial heapsize     Xmx: The max heapsize Try to set equal initial and max heapsize. The startup time can be a little longer but for long running applications it will provide a better performance. When we set -Xms512m -Xmx1024m, the physical heap size will be 512m. This means that there are pages of memory (in the state of the 512m) that the JVM does not explicitly control. It will be controlled by OS which could be reserve for the other tasks. In this case, it is an advantage if the JVM claims the entire memory at once and try not to spend time to extend when more memory is needed. Also you can use -XX:MaxPermSize (Maximum size of the permanent generation) option for Sun JVM. You should adjust the size accordingly if your application dynamically load and unload a lot of classes in order to optimize the performance. You can set the JVM options/heap size from the following places:     Through the Admin console, in the Server start tab     In the startManagedWeblogic script for the managed servers     $DOMAIN_HOME/bin/startManagedWebLogic.sh/cmd     JAVA_OPTIONS="-Xms1024m -Xmx1024m" ${JAVA_OPTIONS}     In the setDomainEnv script for the managed servers and admin server (domain wide)     USER_MEM_ARGS="-Xms1024m -Xmx1024m" When there is free memory available in the heap but it is too fragmented and not contiguously located to store the object or when there is actually insufficient memory we can get java.lang.OutOfMemoryError. We should create Thread Dump and analyze if that is possible in case of such error. The second option we can use to produce higher throughput is to garbage collection. We can roughly divide GC algorithms into 2 categories: parallel and concurrent. Parallel GC stops the execution of all the application and performs the full GC, this generally provides better throughput but also high latency using all the CPU resources during GC. Concurrent GC on the other hand, produces low latency but also low throughput since it performs GC while application executes. The JRockit JVM provides some useful command-line parameters that to control of its GC scheme like -XgcPrio command-line parameter which takes the following options; XgcPrio:pausetime (To minimize latency, parallel GC) XgcPrio:throughput (To minimize throughput, concurrent GC ) XgcPrio:deterministic (To guarantee maximum pause time, for real time systems) Sun JVM has similar parameters (like  -XX:UseParallelGC or -XX:+UseConcMarkSweepGC) to control its GC scheme. We can add -verbosegc -XX:+PrintGCDetails to monitor indications of a problem with garbage collection. Try configuring JVM’s of all managed servers to execute in -server mode to ensure that it is optimized for a server-side production environment.

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  • CakePHP Missing Database Table Error

    - by BRADINO
    I am baking a new project management application at work and added a couple new tables to the database today. When I went into the console to bake the new models, they were not in the list... php /path/cake/console/cake.php bake all -app /path/app/ So I manually typed in the model name and I got a missing database table for model error. I checked and double-checked and the database table was named properly. Turns out that some files inside the /app/tmp/cache/ folder were causing Cake not to recognize that I had added new tables to my database. Once I deleted the cache files cake instantly recognized my new database tables and I was baking away! rm -Rf /path/app/tmp/cache/cake*

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  • PHP OCI8 and Oracle 11g DRCP Connection Pooling in Pictures

    - by christopher.jones
    Here is a screen shot from a PHP OCI8 connection pooling demo that I like to run. It graphically shows how little database host memory is needed when using DRCP connection pooling with Oracle Database 11g. Migrating to DRCP can be as simple as starting the pool and changing the connection string in your PHP application. The script that generated the data for this graph was a simple "Parts" query application being run under various simulated user loads. I was running the database on a small Oracle Linux server with just 2G of memory. I used PHP OCI8 1.4. Apache is in pre-fork mode, as needed for PHP. Each graph has time on the horizontal access in arbitrary 'tick' time units. Click the image to see it full sized. Pooled connections Beginning with the top left graph, At tick time 65 I used Apache's 'ab' tool to start 100 concurrent 'users' running the application. These users connected to the database using DRCP: $c = oci_pconnect('phpdemo', 'welcome', 'myhost/orcl:pooled'); A second hundred DRCP users were added to the system at tick 80 and a final hundred users added at tick 100. At about tick 110 I stopped the test and restarted Apache. This closed all the connections. The bottom left graph shows the number of statements being executed by the database per second, with some spikes for background database activity and some variability for this small test. Each extra batch of users adds another 'step' of load to the system. Looking at the top right Server Process graph shows the database server processes doing the query work for each web user. As user load is added, the DRCP server pool increases (in green). The pool is initially at its default size 4 and quickly ramps up to about (I'm guessing) 35. At tick time 100 the pool increases to my configured maximum of 40 processes. Those 40 processes are doing the query work for all 300 web users. When I stopped the test at tick 110, the pooled processes remained open waiting for more users to connect. If I had left the test quiet for the DRCP 'inactivity_timeout' period (300 seconds by default), the pool would have shrunk back to 4 processes. Looking at the bottom right, you can see the amount of memory being consumed by the database. During the initial quiet period about 500M of memory was in use. The absolute number is just an indication of my particular DB configuration. As the number of pooled processes increases, each process needs more memory. You can see the shape of the memory graph echoes the Server Process graph above it. Each of the 300 web users will also need a few kilobytes but this is almost too small to see on the graph. Non-pooled connections Compare the DRCP case with using 'dedicated server' processes. At tick 140 I started 100 web users who did not use pooled connections: $c = oci_pconnect('phpdemo', 'welcome', 'myhost/orcl'); This connection string change is the only difference between the two tests. At ticks 155 and 165 I started two more batches of 100 simulated users each. At about tick 195 I stopped the user load but left Apache running. Apache then gradually returned to its quiescent state, killing idle httpd processes and producing the downward slope at the right of the graphs as the persistent database connection in each Apache process was closed. The Executions per Second graph on the bottom left shows the same step increases as for the earlier DRCP case. The database is handling this load. But look at the number of Server processes on the top right graph. There is now a one-to-one correspondence between Apache/PHP processes and DB server processes. Each PHP processes has one DB server processes dedicated to it. Hence the term 'dedicated server'. The memory required on the database is proportional to all those database server processes started. Almost all my system's memory was consumed. I doubt it would have coped with any more user load. Summary Oracle Database 11g DRCP connection pooling significantly reduces database host memory requirements allow more system memory to be allocated for the SGA and allowing the system to scale to handled thousands of concurrent PHP users. Even for small systems, using DRCP allows more web users to be active. More information about PHP and DRCP can be found in the PHP Scalability and High Availability chapter of The Underground PHP and Oracle Manual.

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