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  • Hibernate design to speed up querying of large dataset

    - by paddydub
    I currently have the below tables representing a bus network mapped in hibernate, accessed from a Spring MVC based bus route planner I'm trying to make my route planner application perform faster, I load all the above tables into Lists to perform the route planner logic. I would appreciate if anyone has any ideas of how to speed my performace Or any suggestions of another method to approach this problem of handling a large set of data Coordinate Connections Table (INT,INT,INT, DOUBLE)( Containing 50,000 Coordinate Connections) ID, FROMCOORDID, TOCOORDID, DISTANCE 1 1 2 0.383657 2 1 17 0.173201 3 1 63 0.258781 4 1 64 0.013726 5 1 65 0.459829 6 1 95 0.458769 Coordinate Table (INT,DECIMAL, DECIMAL) (Containing 4700 Coordinates) ID , LAT, LNG 0 59.352669 -7.264341 1 59.352669 -7.264341 2 59.350012 -7.260653 3 59.337585 -7.189798 4 59.339221 -7.193582 5 59.341408 -7.205888 Bus Stop Table (INT, INT, INT)(Containing 15000 Stops) StopID RouteID COORDINATEID 1000100001 100 17 1000100002 100 18 1000100003 100 19 1000100004 100 20 1000100005 100 21 1000100006 100 22 1000100007 100 23 This is how long it takes to load all the data from each table: stop.findAll = 148ms, stops.size: 15670 Hibernate: select coordinate0_.COORDINATEID as COORDINA1_2_, coordinate0_.LAT as LAT2_, coordinate0_.LNG as LNG2_ from COORDINATES coordinate0_ coord.findAll = 51ms , coordinates.size: 4704 Hibernate: select coordconne0_.COORDCONNECTIONID as COORDCON1_3_, coordconne0_.DISTANCE as DISTANCE3_, coordconne0_.FROMCOORDID as FROMCOOR3_3_, coordconne0_.TOCOORDID as TOCOORDID3_ from COORDCONNECTIONS coordconne0_ coordinateConnectionDao.findAll = 238ms ; coordConnectioninates.size:48132 Hibernate Annotations @Entity @Table(name = "STOPS") public class Stop implements Serializable { @Id @GeneratedValue(strategy = GenerationType.AUTO) @Column(name = "STOPID") private int stopID; @Column(name = "ROUTEID", nullable = false) private int routeID; @ManyToOne(fetch = FetchType.LAZY) @JoinColumn(name = "COORDINATEID", nullable = false) private Coordinate coordinate; } @Table(name = "COORDINATES") public class Coordinate { @Id @GeneratedValue @Column(name = "COORDINATEID") private int CoordinateID; @Column(name = "LAT") private double latitude; @Column(name = "LNG") private double longitude; } @Entity @Table(name = "COORDCONNECTIONS") public class CoordConnection { @Id @GeneratedValue @Column(name = "COORDCONNECTIONID") private int CoordinateID; @ManyToOne(fetch = FetchType.LAZY) @JoinColumn(name = "FROMCOORDID", nullable = false) private Coordinate fromCoordID; @ManyToOne(fetch = FetchType.LAZY) @JoinColumn(name = "TOCOORDID", nullable = false) private Coordinate toCoordID; @Column(name = "DISTANCE", nullable = false) private double distance; }

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  • postgresql syntax while exists loop

    - by veilig
    I'm working at function from Joe Celkos book - Trees and Hierarchies in SQL for Smarties I'm trying to delete a subtree from an adjacency list but part my function is not working yet. WHILE EXISTS –– mark leaf nodes (SELECT * FROM OrgChart WHERE boss_emp_nbr = -99999 AND emp_nbr > -99999) LOOP –– get list of next level subordinates DELETE FROM WorkingTable; INSERT INTO WorkingTable SELECT emp_nbr FROM OrgChart WHERE boss_emp_nbr = -99999; –– mark next level of subordinates UPDATE OrgChart SET emp_nbr = -99999 WHERE boss_emp_nbr IN (SELECT emp_nbr FROM WorkingTable); END LOOP; my question: is the WHILE EXISTS correct for use w/ postgresql? I appear to be stumbling and getting caught in an infinite loop in this part. Perhaps there is a more correct syntax I am unaware of.

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  • Data Modeling Help - Do I add another table, change existing table's usage, or something else?

    - by StackOverflowNewbie
    Assume I have the following tables and relationships: Person - Id (PK) - Name A Person can have 0 or more pets: Pet - Id (PK) - PersonId (FK) - Name A person can have 0 or more attributes (e.g. age, height, weight): PersonAttribute _ Id (PK) - PersonId (FK) - Name - Value PROBLEM: I need to represent pet attributes, too. As it turns out, these pet attributes are, in most cases, identical to the attributes of a person (e.g. a pet can have an age, height, and weight too). How do I represent pet attributes? Do I create a PetAttribute table? PetAttribute Id (PK) PetId (FK) Name Value Do I change PersonAttribute to GenericAttribute and have 2 foreign keys in it - one connecting to Person, the other connecting to Pet? GenericAttribute Id (PK) PersonId (FK) PetId (FK) Name Value NOTE: if PersonId is set, then PetId is not set. If PetId is set, PersonId is not set. Do something else?

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  • Is the set of data always normalized in one form or the other in Databases

    - by manugupt1
    Suppose I have a set of data, given the data and the relation schemas can I assume that the set of data is normalized in one form or the other. In my opinion raw data given, has to be normalized into some form. However a discussion with a friend has led to ask me this question here. To expound more on the question, I would say given a set of functional dependencies for a relation or table, is it guaranteed that the table would atleast be in 1NF if not others

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  • What does ER_WARN_FIELD_RESOLVED mean?

    - by VolkerK
    When SHOW WARNINGS after a EXPLAIN EXTENDED shows a Note 1276 Field or reference 'test.foo.bar' of SELECT #2 was resolved in SELECT #1 what exactly does that mean and what impact does it have? In my case it prevents mysql from using what seems to be a perfectly good index. But it's not about fixing that specific query (as it is an irrelevant test). I found http://dev.mysql.com/doc/refman/5.0/en/error-messages-server.html butError: 1276 SQLSTATE: HY000 (ER_WARN_FIELD_RESOLVED) Message: Field or reference '%s%s%s%s%s' of SELECT #%d was resolved in SELECT #%d isn't much of an explaination.

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  • I want define tables from a part of my ER Diagram.

    - by M R Jafari
    I have a ER-Diagram (Show in http://www.4freeimagehost.com/show.php?i=f82997ca4d5d.png). In the diagram you see 2 entities and a 1:N relataion together. Project has 2 columns as ProjectID, ProjectName. Employee has 3 colums as EmployeeID, EmployeeName and ProjectID. A project has ONLY 1 project-manager and project-manager is a employee. What columns add them?

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  • Low cost way to host a large table yet keep the performance scalable?

    - by Leo Liang
    I have a growing table storing time series data, 500M entries now, and 200K new records every day. The total size is around 15GB for now. My clients are querying the table via a PHP script mostly, and the size of the result set is around 10K records (not very large). select * from T where timestamp > X and timestamp < Y and additionFilters And I want this operation cheap. Currently my table is hosting in Postgres 7, on a single 16G memory Box, and I would love to see some good suggestion for me to host this in low cost and also allow me to scale up for performance if needed. The table serves: 1. Query: 90% 2. Insert: 9.9% 2. Update: 0.1% <-- very rare.

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  • Define tables from a part of my ER Diagram.

    - by M R Jafari
    I have a ER-Diagram (Show in http://www.4freeimagehost.com/show.php?i=f82997ca4d5d.png). In the diagram you see 2 entities and a 1:N relataion together. Project has 2 columns as ProjectID, ProjectName. Employee has 3 colums as EmployeeID, EmployeeName and ProjectID. A project has ONLY 1 project-manager and project-manager is a employee. What columns add them?

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  • MySQL triggers cannot update rows in same table the trigger is assigned to. Suggested workaround?

    - by Cory House
    MySQL doesn't currently support updating rows in the same table the trigger is assigned to since the call could become recursive. Does anyone have suggestions on a good workaround/alternative? Right now my plan is to call a stored procedure that performs the logic I really wanted in a trigger, but I'd love to hear how others have gotten around this limitation. Edit: A little more background as requested. I have a table that stores product attribute assignments. When a new parent product record is inserted, I'd like the trigger to perform a corresponding insert in the same table for each child record. This denormalization is necessary for performance. MySQL doesn't support this and throws: Can't update table 'mytable' in stored function/trigger because it is already used by statement which invoked this stored function/trigger. A long discussion on the issue on the MySQL forums basically lead to: Use a stored proc, which is what I went with for now. Thanks in advance!

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  • How to store data in mysql, to get the fastest performance?

    - by Oden
    Hey, I'm thinking about it, witch of the following two query types would give me the fastest performance for a user messaging module inside my site: The first one i thought about is a multi table setup, witch has a connection table, and a main table. The connection table holds the connection between accounts, and the messaging table. In this case a query would look like following, to get some data of the author, and the messages he has sent: SELECT m.*, a.username FROM messages AS m LEFT JOIN connection_table ON (message_id = m.id) LEFT JOIN accounts AS a ON (account_id = a.id) WHERE m.id = '32341' Inserting into it is a little bit more "complicated". My other idea, and in my thought the better solution of this problem is that i store the data i would use in a connection table in the same table where is store the data of the mail. Sounds like i would get lots of duplicated entries, but no, because i have a field witch has text type and holds user ids like this: *24*32*249* If I want to query them, i use the mysql LIKE method. Deleting is an other problem, but for this i have one more field where i store who has deleted the post. Sad about that i don't know how to join this. So what would you recommend? Are there other ways?

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  • how to design a schema where the columns of a table are not fixed

    - by hIpPy
    I am trying to design a schema where the columns of a table are not fixed. Ex: I have an Employee table where the columns of the table are not fixed and vary (attributes of Employee are not fixed and vary). Nullable columns in the Employee table itself i.e. no normalization Instead of adding nullable columns, separate those columns out in their individual tables ex: if Address is a column to be added then create table Address[EmployeeId, AddressValue]. Create tables ExtensionColumnName [EmployeeId, ColumnName] and ExtensionColumnValue [EmployeeId, ColumnValue]. ExtensionColumnName would have ColumnName as "Address" and ExtensionColumnValue would have ColumnValue as address value. Employee table EmployeeId Name ExtensionColumnName table ColumnNameId EmployeeId ColumnName ExtensionColumnValue table EmployeeId ColumnNameId ColumnValue There is a drawback is the first two ways as the schema changes with every new attribute. Note that adding a new attribute is frequent. I am not sure if this is the good or bad design. If someone had a similar decision to make, please give an insight on things like foreign keys / data integrity, indexing, performance, reporting etc.

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  • What is the best schema design for child collection with a "primary" entity

    - by erg39
    Here is the scenario: You have a Persons table with a one-to-many relationship with an Addresses table, where one of the Address rows is the "primary" Address. Is it better in a normalized schema to Use a Persons.PrimaryAddressID to access the "primary" Address for a Person or Use an Addresses.IsPrimary bit column to reference the "primary" Address for a Person via Addresses.PersonID or Other and why?

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  • How to maintain an ordered table with Core Data (or SQL) with insertions/deletions?

    - by Jean-Denis Muys
    This question is in the context of Core Data, but if I am not mistaken, it applies equally well to a more general SQL case. I want to maintain an ordered table using Core Data, with the possibility for the user to: reorder rows insert new lines anywhere delete any existing line What's the best data model to do that? I can see two ways: 1) Model it as an array: I add an int position property to my entity 2) Model it as a linked list: I add two one-to-one relations, next and previous from my entity to itself 1) makes it easy to sort, but painful to insert or delete as you then have to update the position of all objects that come after 2) makes it easy to insert or delete, but very difficult to sort. In fact, I don't think I know how to express a Sort Descriptor (SQL ORDER BY clause) for that case. Now I can imagine a variation on 1): 3) add an int ordering property to the entity, but instead of having it count one-by-one, have it count 100 by 100 (for example). Then inserting is as simple as finding any number between the ordering of the previous and next existing objects. The expensive renumbering only has to occur when the 100 holes have been filled. Making that property a float rather than an int makes it even better: it's almost always possible to find a new float midway between two floats. Am I on the right track with solution 3), or is there something smarter?

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  • InnoDB or MyISAM - Why not both?

    - by Skoder
    Hey. I'm new to databases, and I've read various threads about which is better between InnoDB and MyISAM. It seems that the debates are to use or the other. Is it not possible to use both, depending on the table? What would be the disadvantages in doing this? As far as I can tell, the engine can be set during the CREATE TABLE command. Therefore, certain tables which are often read can be set to MyISAM, but tables that need transaction support can use InnoDB. I'm sure there must be a problem, otherwise this would be the ultimate answer :).

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  • How do I create a free server-side database to be accessed via Windows forms and/or browser?

    - by NoCatharsis
    I have no formal education in databasing or programming, but I've learned enough SQL, C++, and C# to at least get started setting up a small database on my company's server. Using MS SQL Server 2008 R2, I have created the database and set up columns with proper data types. However, there seems to be a lot of tweaks and details that are way over my head. Since I would like these data to be accessible to the other 7 or 8 people in my office (preferably via web browser), I'm wondering whether this is the best setup for my situation. The other option I've read about is a LAMPP server, which I assume is the competing free option to Microsoft's Express packages. I know nothing of LAMP servers except from the articles I've read on how to set them up (and I believe I even saw a detailed tutorial somewhere). To summarize, my question is this: Which of these (or any other) server setups would best suit my purposes, keeping in mind that I'm a true novice (but willing to learn), and would like to keep it free until I get more experience?

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  • Relational MySQL - fetched properties?

    - by Kelso.b
    I'm currently using the following PHP code: // Get all subordinates $subords = array(); $supervisorID = $this->session->userdata('supervisor_id'); $result = $this->db->query(sprintf("SELECT * FROM users WHERE supervisor_id=%d AND id!=%d",$supervisorID, $supervisorID)); $user_list_query = 'user_id='.$supervisorID; foreach($result->result() as $user){ $user_list_query .= ' OR user_id='.$user->id; $subords[$user->id] = $user; } // Get Submissions $submissionsResult = $this->db->query(sprintf("SELECT * FROM submissions WHERE %s", $user_list_query)); $submissions = array(); foreach($submissionsResult->result() as $submission){ $entriesResult = $this->db->query(sprintf("SELECT * FROM submittedentries WHERE timestamp=%d", $submission->timestamp)); $entries = array(); foreach($entriesResult->result() as $entries) $entries[] = $entry; $submissions[] = array( 'user' => $subords[$submission->user_id], 'entries' => $entries ); $entriesResult->free_result(); } Basically I'm getting a list of users that are subordinates of a given supervisor_id (every user entry has a supervisor_id field), then grabbing entries belonging to any of those users. I can't help but think there is a more elegant way of doing this, like SELECT FROM tablename where user->supervisor_id=2222 Is there something like this with PHP/MySQL? Should probably learn relational databases properly sometime. :(

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  • Is it possible to listen to relational database update?

    - by Morgan Cheng
    Is it possible to listen to relation database update? For example, my web app want to send data update to client through Comet technology. I can have the program to poll the database periodically, but that would not be performant and scalable. If app can hood to a "event handler" of database, then app can get notification every time given database table data is updated. This sounds more promising, but I didn't find any concrete example for it. This is listener pattern. Does common relational database support such feature?

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  • Whats the best solution for a database used in conjunction with Maps in Android?

    - by Andrew
    Could someone please point me in the right direction. My project involves a database where users enter their address and other info from my website. This database is then referenced in my android application to show the locations of these addresses in my database. I have yet to start and just came up with this idea. My question is, what would be the best method to create a database easily modified through my website (mySQL, php, etc), and also easily referenced easily through Android and the Google Maps API? I need some ideas on the languages I will need to use to create this database and website so I can go buy the necessary books to start reading up. Thanks so much

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  • What are some useful SQL statements that should be known by all developers who may touch the Back en

    - by Jian Lin
    What are some useful SQL statements that should be known by all developers who may touch the Back end side of the project? (Update: just like in algorithm, we know there are sorting problems, shuffling problems, and we know some solutions to them. This question is aiming at the same thing). For example, ones I can think of are: Get a list of Employees and their boss. Or one with the employee's salary greater than the boss. (Self-join) Get a list of the most popular Classes registered by students, from the greatest number to the smallest. (Count, group by, order by) Get a list of Classes that are not registered by any students. (Outer join and check whether the match is NULL, or by Get from Classes table, all ClassIDs which are NOT IN (a subquery to get all ClassIDs from the Registrations table)) Are there some SQL statements that should be under the sleeve of all developers that might touch back end data?

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  • How do you store sets in Cassandra?

    - by Ben W
    I'd like to convert this JSON to a data model in Cassandra, where each of the arrays is a set with no duplicates: var data = { "data1": { "100": [1, 2, 3], "200": [3, 4] }, "data2": { "k1", [1], "k2", [4, 5] } } I'd like to query like this: data["data1"]["100"] to retrieve the sets. Anyone know how you might model this in Cassandra? (The only thing I came up with was columns whose name was a set value and the value of the column was an empty string, but that felt wrong.) It's not OK to serialize the sets as JSON or some other string, which would make this much easier. Also, I should note that it's OK to split data1 and data2 into separate ColumnFamilies, it's not necessary that they're keys in the same one.

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  • Using "CASE" in Where clause to choose various column harm the performance

    - by zivgabo
    I have query which needs to be dynamic on some of the columns, meaning I get a parameter and according its value I decide which column to fetch in my Where clause. I've implemented this request using "CASE" expression: (CASE @isArrivalTime WHEN 1 THEN ArrivalTime ELSE PickedupTime END) >= DATEADD(mi, -@TZOffsetInMins, @sTime) AND (CASE @isArrivalTime WHEN 1 THEN ArrivalTime ELSE PickedupTime END) < DATEADD(mi, -@TZOffsetInMins, @fTime) If @isArrivalTime = 1 then chose ArrivalTime column else chose PickedupTime column. I have a clustered index on ArrivalTime and nonclustered index on PickedupTime. I've noticed that when I'm using this query (with @isArrivalTime = 1), my performance is a lot worse comparing to only using ArrivalTime. Maybe the query optimizer can't use\choose the index properly in this way? I compared the execution plans an noticed that when I'm using the CASE 32% of the time is being wasted on the index scan, but when I didn't use the CASE(just usedArrivalTime`) only 3% were wasted on this index scan. Anyone know the reason for this?

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  • How to use Unique Composite Key

    - by LifeH2O
    I have a table Item(ItemName*, ItemSize*, Price, Notes) I was making composite key of (ItemName,ItemSize) to uniquely identify item. And now after reading some answers on stackoverflow suggesting the use of UNIQUE i revised it as Item(ItemID*, ItemName, ItemSize, Price, Notes) But How to apply UNIQUE constraint on ItemName and ItemSize please correct if there is something wrong in question

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