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  • Is there an "embedded DBMS" to support multiple writer applications (processes) on the same db files

    - by Amir Moghimi
    I need to know if there is any embedded DBMS (preferably in Java and not necessarily relational) which supports multiple writer applications (processes) on the same set of db files. BerkeleyDB supports multiple readers but just one writer. I need multiple writers and multiple readers. UPDATE: It is not a multiple connection issue. I mean I do not need multiple connections to a running DBMS application (process) to write data. I need multiple DBMS applications (processes) to commit on the same storage files. HSQLDB, H2, JavaDB (Derby) and MongoDB do not support this feature. I think that there may be some File System limitations that prohibit this. If so, is there a File System that allows multiple writers on a single file? Use Case: The use case is a high-throughput clustered system that intends to store its high-volume business log entries into a SAN storage. Storing business logs in separate files for each server does not fit because query and indexing capabilities are needed on the whole biz logs. Because "a SAN typically is its own network of storage devices that are generally not accessible through the regular network by regular devices", I want to use SAN network bandwidth for logging while cluster LAN bandwidth is being used for other server to server and client to server communications.

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  • What is the proper query to get all the children in a tree?

    - by Nathan Adams
    Lets say I have the following MySQL structure: CREATE TABLE `domains` ( `id` INT(10) UNSIGNED NOT NULL AUTO_INCREMENT, `domain` CHAR(50) NOT NULL, `parent` INT(11) DEFAULT NULL, PRIMARY KEY (`id`) ) ENGINE=MYISAM AUTO_INCREMENT=10 DEFAULT CHARSET=latin1 insert into `domains`(`id`,`domain`,`parent`) values (1,'.com',0); insert into `domains`(`id`,`domain`,`parent`) values (2,'example.com',1); insert into `domains`(`id`,`domain`,`parent`) values (3,'sub1.example.com',2); insert into `domains`(`id`,`domain`,`parent`) values (4,'sub2.example.com',2); insert into `domains`(`id`,`domain`,`parent`) values (5,'s1.sub1.example.com',3); insert into `domains`(`id`,`domain`,`parent`) values (6,'s2.sub1.example.com',3); insert into `domains`(`id`,`domain`,`parent`) values (7,'sx1.s1.sub1.example.com',5); insert into `domains`(`id`,`domain`,`parent`) values (8,'sx2.s2.sub1.example.com',6); insert into `domains`(`id`,`domain`,`parent`) values (9,'x.sub2.example.com',4); In my mind that is enough to emulate a simple tree structure: .com | example / \ sub1 sub2 ect My problem is that give sub1.example.com I want to know all the children of sub1.example.com without using multiple queries in my code. I have tried joining the table to itself and tried to use subqueries, I can't think of anything that will reveal all the children. At work we are using MPTT to keep in hierarchal order a list of domains/subdomains however, I feel that there is an easier way to do it. I did some digging and someone did something similar but they required the use of a function in MySQL. I don't think for something simple like this we would need a whole function. Maybe I am just dumb and not seeing some sort of obvious solution. Also, feel free to alter the structure.

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  • Troubleshooting PG Function

    - by Grasper
    I have this function: CREATE OR REPLACE FUNCTION CREATE_AIRSPACE_AVAILABILITY_RECORD (cur_user VARCHAR, start_time VARCHAR, start_date VARCHAR, end_time VARCHAR, end_date VARCHAR, airspace_name VARCHAR) RETURNS VOID AS ' DECLARE c_user ALIAS for $1; BEGIN IF start_time IS NULL OR start_date IS NULL OR end_time IS NULL OR end_date IS NULL THEN INSERT INTO c_user.AIRSPACE_AVAILABILITY (ASP_AIRSPACE_NM, ASA_TIME_ID, ASA_START_DT, ASA_END_DT) SELECT airspace_name, 1, ABP.ABP_START_DT, ABP.ABP_STOP_DT FROM ABP WHERE EXISTS (SELECT ASP.ASP_AIRSPACE_NM FROM AIRSPACE ASP WHERE ASP.ASP_AIRSPACE_NM = airspace_name); ELSIF start_time IS NOT NULL AND start_date IS NOT NULL AND end_time IS NOT NULL AND end_date IS NOT NULL THEN INSERT INTO c_user.AIRSPACE_AVAILABILITY (ASP_AIRSPACE_NM, ASA_TIME_ID, ASA_START_DT, ASA_END_DT) SELECT airspace_name, 1, TO_DATE(start_date||start_time,''YYMMDDHH24MI''), TO_DATE(end_date||end_time,''YYMMDDHH24MI'') FROM DUAL WHERE EXISTS (SELECT ASP.ASP_AIRSPACE_NM FROM c_user.AIRSPACE ASP WHERE ASP.ASP_AIRSPACE_NM = airspace_name); END IF; END ; ' LANGUAGE plpgsql; I try calling it like so: select * from CREATE_AIRSPACE_AVAILABILITY_RECORD('user1','','','','',''); and I get this error: ERROR: schema "c_user" does not exist SQL state: 3F000 Context: SQL statement "INSERT INTO c_user.AIRSPACE_AVAILABILITY (ASP_AIRSPACE_NM, ASA_TIME_ID, ASA_START_DT, ASA_END_DT) SELECT $1 , 1, TO_DATE( $2 || $3 ,'YYMMDDHH24MI'), TO_DATE( $4 || $5 ,'YYMMDDHH24MI') FROM DUAL WHERE EXISTS (SELECT ASP.ASP_AIRSPACE_NM FROM c_user.AIRSPACE ASP WHERE ASP.ASP_AIRSPACE_NM = $1 )" PL/pgSQL function "create_airspace_availability_record" line 23 at SQL statement Why isn't c_user being replaced with my param (user1)?

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  • Synchronising tables across remote Access databases

    - by Paul H
    Hi folks, I'm helping out a business by providing an Access DB to manage requests of various types. As they are a construction company, they have one machine in an 'office' on the building site, plus 3 based in their main office. The machine on site has no internet connectivity. Is there any (reasonably simple) way to synchronise these databases every so often? I realise the tables could be merged, but each has an autoincrement field which must be synced between instances (i.e. when merging two tables the autoincrement should be reassigned based on the combination of records). Cheers in advance, Paul

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  • Tokyo Tyrant indexes

    - by viraptor
    I was wondering about size requirements for Tokyo Tyrant indexes. If I have an index on field x and insert a record with fields y and z only, does the x index grow? Also: does the insert time grow in that case?

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  • One check constraint or multiple check constraints?

    - by RenderIn
    Any suggestions on whether fewer check constraints are better, or more? How should they be grouped if at all? Suppose I have 3 columns which are VARCHAR2(1 BYTE), each of which is a 'T'/'F' flag. I want to add a check constraint to each column specifying that only characters IN ('T', 'F') are allowed. Should I have 3 separate check constraints, one for each column: COL_1 IN ('T', 'F') COL_2 IN ('T', 'F') COL_3 IN ('T', 'F') Or a single check constraint: COL_1 IN ('T', 'F') AND COL_2 IN ('T', 'F') AND COL_3 IN ('T', 'F') My thoughts are it is best to keep these three separate, as the columns are logically unrelated to each other. The only case I would have a check constraint that examines more than one column is if there was some relationship between the value in one and the value in another, e.g.: (PARENT_CNT > 0 AND PRIMARY_PARENT IS NOT NULL) OR (PARENT_CNT = 0 AND PRIMARY_PARENT IS NULL)

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  • moving to NoSql

    - by radi
    hi , i recently read this article nosql-vs-rdbms and i dont know too much about nosql and i didnt use it in my projects , so i have some questions : what is the main feature that nosql has over Rdbms ? if you think that it is best than rdbms : where and how i can learn about it (books - tutorials)? i want to be a DBA , what this career will be after moving to nosql ? thanks

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  • moving to NoSql

    - by radi
    hi , i recently read this article nosql-vs-rdbms and i dont know too much about nosql and i didnt use it in my projects , so i have some questions : what is the main feature that nosql has over Rdbms ? if you think that it is best than rdbms : where and how i can learn about it (books - tutorials)? i want to be a DBA , what this career will be after moving to nosql ? thanks

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  • Activity tracking usecase for login tracking.

    - by Mdillion
    Creating an activity tracking system for a social site. All user activiti from pooint of login til logoff are to be tracked. This means the first use case is the user's login. Every activity will have the same format so once I figure out how to track one activity then I can create chema for all activities. Currently for login I have steps like: Two solutions I have: Activity 1: User attempts to login Activity 2 A: User has successfully logged in Activity 2 B: User failed to login. Activity 2 B A: User failed to login due to invalid password Activity 2 B B: User failed to login due to locked account. OR Activty 1: User login - with result = Pass or Fail and if Fail reason = flag_id of reason. Accordingly I have to create the schema. For now I have it like this: activity_id object_id (fk) session_id (fk) user_id (fk) flag_id (fk) created_dt friend_id (fk) result (pass/fail) But ofcourse this a work in progress.

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  • Retrieving Data related to a top-level object from parse.com using PHP

    - by Albeert Tw
    I am retrieve related data using parse.com and PHP I get the top-leve object without problems but I can't access related data. ([myRelation] => stdClass Object ( [__type] => Relation [className] => other)) Please refer to my code below: $className = "myClass"; $url = 'https://api.parse.com/1/classes/' . $className; $appId = 'xxxxxx'; $restKey = 'xxxxxxx'; $relatedParams = urlencode('include=people'); $rest = curl_init(); curl_setopt($rest, CURLOPT_SSL_VERIFYPEER, false); curl_setopt($rest, CURLOPT_URL, $url .'/io1GzkzErH/'.$relatedParams); curl_setopt($rest, CURLOPT_HTTPGET, true); curl_setopt($rest, CURLOPT_RETURNTRANSFER, true); curl_setopt($rest, CURLOPT_HTTPHEADER, array("X-Parse-Application-Id: " . $appId, "X-Parse-REST-API-Key: " . $restKey, "Content-Type: application/json")); $response = curl_exec($rest); echo $response; I want to see related objects into myRelation. Current answer is: I get this answer: stdClass Object ( [Altres] => loremipsum. [Cartell] => stdClass Object ( [__type] => File [name] => f29efff4-5db1-451a-ab42-7569fbb955a7-cartell.jpg [url] => loremipsum.jpg ) [CartellURL] => [Categoria] => Comedia [Durada] => 120min [Estat] => Al teatre [Final] => stdClass Object ( [__type] => Date [iso] => 2014-06-18T22:00:00.000Z ) [Inici] => stdClass Object ( [__type] => Date [iso] => 2014-04-25T22:00:00.000Z ) [Nom] => Losers [Prioritat] => 0 [Sala] => loremipsum [Sinopsis] => loremipsum [TrailerURL] => loremipsum.com [URLEntrada] => loremipsum.com [URLProductora] => http://www.loremipsum.com [Visible] => 1 [createdAt] => 2014-05-20T12:01:06.094Z [objectId] => io1GzkzErH [people] => stdClass Object ( [__type] => Relation [className] => persones ) [updatedAt] => 2014-05-20T12:07:22.758Z ) loremipsum But I need to know what are in [people] = stdClass Object ( [__type] = Relation [className] = persones )

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  • Automatic Adjusting Range Table

    - by Bradford
    I have a table with a start date range, an end date range, and a few other additional columns. On input of a new record, I want to automatically adjust any overlapping date ranges (shrinking them to allow for the new input). I also want to ensure that no overlapping records can accidentally be inserted into this table. I'm using Oracle and Java for my application code. How should I enforce the prevention of overlapping date ranges and also allow for automatically adjusting overlapping ranges? Should I create an AFTER INSERT trigger, with a dbms_lock to serialize access, to prevent the overlapping data. Then in Java, apply the logic to auto adjust everything? Or should that part be in PL/SQL in stored procedure call? This is something that we need for a couple other tables so it'd be nice to abstract. If anyone has something like this already written, please share :) I did find this reference: http://asktom.oracle.com/pls/asktom/f?p=100:11:0::::P11_QUESTION_ID:474221407101 Here's an example of how each of the 4 overlapping cases should be handled for adjustment on insert: = Example 1 = In DB (Start, End, Value): (0, 10, 'X') **(30, 100, 'Z') (200, 500, 'Y') Input (20, 50, 'A') Gives (0, 10, 'X') **(20, 50, 'A') **(51, 100, 'Z') (200, 500, 'Y') = Example 2 = In DB (Start, End, Value): (0, 10, 'X') **(30, 100, 'Z') (200, 500, 'Y') Input (40, 80, 'A') Gives (0, 10, 'X') **(30, 39, 'Z') **(40, 80, 'A') **(81, 100, 'Z') (200, 500, 'Y') = Example 3 = In DB (Start, End, Value): (0, 10, 'X') **(30, 100, 'Z') (200, 500, 'Y') Input (50, 120, 'A') Gives (0, 10, 'X') **(30, 49, 'Z') **(50, 120, 'A') (200, 500, 'Y') = Example 4 = In DB (Start, End, Value): (0, 10, 'X') **(30, 100, 'Z') (200, 500, 'Y') Input (20, 120, 'A') Gives (0, 10, 'X') **(20, 120, 'A') (200, 500, 'Y') The algorithm is as follows: given range = g; input range = i; output range set = o if i.start <= g.start if i.end >= g.end o_1 = i else o_1 = i o_2 = (o.end + 1, g.end) else if i.end >= g.end o_1 = (g.start, i.start - 1) o_2 = i else o_1 = (g.start, i.start - 1) o_2 = i o_3 = (i.end + 1, i.end)

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  • Speed Difference between native OLE DB and ADO.NET

    - by weijiajun
    I'm looking for suggestions as well as any benchmarks or observations people have. We are looking to rewrite our data access layer and are trying to decide between native C++ OLEDB or ADO.NET for connecting with databases. Currently we are specifically targeting Oracle which would mean we would use the Oracle OLE DB provider and the ODP.NET. Requirements: 1. All applications will be in managed code so using native C++ OLEDB would require C++/CLI to work (no PInvoke way to slow). 2. Application must work with multiple databases in the future, currently just targeting Oracle specifically. Question: 1. Would it be more performant to use ADO.NET to accomplish this or use native C++ OLE DB wrapped in a Managed C++ interface for managed code to access? Any ideas, or help or places to look on the web would be greatly appreciated.

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  • Starting out NLP - Python + large data set

    - by pencilNero
    Hi, I've been wanting to learn python and do some NLP, so have finally gotten round to starting. Downloaded the english wikipedia mirror for a nice chunky dataset to start on, and have been playing around a bit, at this stage just getting some of it into a sqlite db (havent worked with dbs in the past unfort). But I'm guessing sqlite is not the way to go for a full blown nlp project(/experiment :) - what would be the sort of things I should look at ? HBase (.. and hadoop) seem interesting, i guess i could run then im java, prototype in python and maybe migrate the really slow bits to java... alternatively just run Mysql.. but the dataset is 12gb, i wonder if that will be a problem? Also looked at lucene, but not sure how (other than breaking the wiki articles into chunks) i'd get that to work.. What comes to mind for a really flexible NLP platform (i dont really know at this stage WHAT i want to do.. just want to learn large scale lang analysis tbh) ? Many thanks.

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  • Stringtemplate: is it ok to Apply Templates, in which HashMap uses, To Multi-Valued Attributes

    - by user1071830
    There is two template in my .stg file, and both of them apply on multi-value a HashMap. The HashMap is employed as an injected object. And I need those instance of HashMap can be injected for many times. My trouble is, when I switch to another template, ANTLR seems to consider the second HashMap as a List -- multipul objects and null value. Part of my .stg file shows as follows: tpl_hash(BAR, FOO) ::= << <FOO:foo(); separator="\n"> <BAR:bar(); separator="\n"> >> foo(nn) ::= << foo: <nn.name; null="NULL"> . <nn.national; null="NULL"> >> bar(mm) ::= << bar: <mm.name> @ <mm.national> >> Part of my .g file shows: HashMap hm = new HashMap(); hm.put("name", $name.text); hm.put("national", "German"); tpl_hash.add("FOO",new HashMap(hm)); HashMap hm2 = new HashMap(); hm2.put("name", $name.text); hm2.put("national", "German"); tpl_hash.add("BAR",new HashMap(hm2)); The result I expect is : bar: Kant @ German foo: Russell @ England But, I got: foo: NULL . NULL foo: NULL . NULL bar: @ bar: @ If we replace BAR with FOO, as is, keeping FOO and BAR with identical template, the output is right, like the following. bar: Russell @ German bar: Russell @ German In docs, "synchronized ST add (String name, Object value) in org.stringtemplate.v4.ST" said: "If you send in a List and then inject a single value element, add() copies original list and adds the new value." What about a HashMap? Does ANTLR consider the HashMap, key/value pair access, an object purposely, as a List and as multi-value injected by mistake? Thanks a lot in advance.

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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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  • MS Access 2003 - Help understanding the structure of mdb, mde and be.....

    - by Justin
    Hi. I was just wanting some explanation as to what is going on once you have split your tables out into a back end file, and set an mde out for use. When a user accesses the mde, is the mdb still required to get to the tabes (or in order to make it work)? Let say I put these access apps on a shared drive for folks to use. If I split the be end on to the shared drive, and placed the mde on the shared drive, would I the mdb have to exist for that version mde to work (communicate with the tables)? Or does the mde sort of speak to the mdb which speaks to the tables? Hope this question makes sense. Thanks

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  • insert or update on table violates foreign key constraint

    - by sprasad12
    Hi, I have two tables entitytype and project. Here are the create table statements: Create table project ( pname varchar(20) not null, primary key(pname) ); create table entitytype( entityname varchar(20) not null, toppos char(100), leftpos char(100), pname varchar(20) not null, primary key(entityname), foreign key(pname) references project(pname) on delete cascade on update cascade ); Now when i try to insert any values into entitytype table i am getting the following error: ERROR: insert or update on table "entitytype" violates foreign key constraint "entitytype_pname_fkey" Detail: Key (pname)=(494) is not present in table "project". Can someone please shed some light on what i am doing wrong. Any input will be of great help. Thank you.

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  • SQL Server: pulling and updating local data

    - by SDReyes
    Hi guys, I have two SQL Server 2008 databases called Anna and Bob. Bob has to pull and transform data from Anna to keep updated his tables. Ideally Bob will be always synchronized with Anna, but some delay would be acceptable. What is the best way to do this? Thanks in advance.

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  • SQL Server 2008 Express Edition Connection Problem

    - by waqasahmed
    I have VS 2008 Professional Edition. After the installation (which included SQL Server 2008), I decided to install SQL Server 2008 Express Edition with Advanced Tools (so I could get SQL Server Management Studio on it). So I uninstalled the SQL Express that came with VS 2008, and installed the standalone SQL Server Express 2008 version with advanced tools. However, When I try to logon onto SQL Server Management Studio using: .\SQLEXPRESS as Server name and Windows Authentication as the authentication, I get the following message: TITLE: Connect to Server ------------------------------ Cannot connect to .\SQLEXPRESS. ------------------------------ ADDITIONAL INFORMATION: A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: SQL Network Interfaces, error: 26 - Error Locating Server/Instance Specified) (Microsoft SQL Server, Error: -1) For help, click: http//go.microsoft.com/fwlink?ProdName=Microsoft+SQL+Server&EvtSrc=MSSQLServer&EvtID=-1&LinkId=20476 ------------------------------ BUTTONS: OK ------------------------------ Any suggestions on how to get it to work? I have tried disabling Windows Firewall as well and still no luck. I am using WIndows Vista and SQL Server 2008 Express SP1 Patch has also been applied recently.

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  • The woes of (sometimes) storing "date only" in datetimes

    - by Heinzi
    We have two fields from and to (of type datetime), where the user can store the begin time and the end time of a business trip, e.g.: From: 2010-04-14 09:00 To: 2010-04-16 16:30 So, the duration of the trip is 2 days and 7.5 hours. Often, the exact times are not known in advance, so the user enters the dates without a time: From: 2010-04-14 To: 2010-04-16 Internally, this is stored as 2010-04-14 00:00 and 2010-04-16 00:00, since that's what most modern class libraries (e.g. .net) and databases (e.g. SQL Server) do when you store a "date only" in a datetime structure. Usually, this makes perfect sense. However, when entering 2010-04-16 as the to date, the user clearly did not mean 2010-04-16 00:00. Instead, the user meant 2010-04-16 24:00, i.e., calculating the duration of the trip should output 3 days, not 2 days. I can think of a few (more or less ugly) workarounds for this problem (add "23:59" in the UI layer of the to field if the user did not enter a time component; add a special "dates are full days" Boolean field; store "2010-04-17 00:00" in the DB but display "2010-04-16 24:00" to the user if the time component is "00:00"; ...), all having advantages and disadvantages. Since I assume that this is a fairly common problem, I was wondering: Is there a "standard" best-practice way of solving it? If there isn't, have you experienced a similar requirement, how did you solve it and what were the pros/cons of that solution?

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  • Optimize mysql table ?

    - by fabien-barbier
    Here is my actual table schema (I'm using Mysql) : Table experiment : code(int) sample_1_id sample_2_id ... until ... sample_12_id rna_1_id rna_2_id ... until ... rna_12_id experiment_start How can I optimize both part : sample_n_id and rna_n_id (all are bigint(20) and allow null=true) ? About values : we can have : ex : sample_1_id = 2 , Sample_2_id = 5 , ... Note : values can be updated. Ideas ? Thanks.

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  • How to evaluate query by DBMS?

    - by Kevinniceguy
    Sorry...I mean what question will be for this query? SELECT SUM(price) FROM Room r, Hotel h WHERE r.hotelNo = h.hotelNo and hotelName = 'Paris Hilton' and roomNo NOT IN (SELECT roomNo FROM Booking b, Hotel h WHERE (dateFrom <= CURRENT_DATE AND dateTo >= CURRENT_DATE) AND b.hotelNo = h.hotelNo AND hotelName = 'Paris Hilton');

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