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  • Data Source Security Part 4

    - by Steve Felts
    So far, I have covered Client Identity and Oracle Proxy Session features, with WLS or database credentials.  This article will cover one more feature, Identify-based pooling.  Then, there is one more topic to cover - how these options play with transactions.Identity-based Connection Pooling An identity based pool creates a heterogeneous pool of connections.  This allows applications to use a JDBC connection with a specific DBMS credential by pooling physical connections with different DBMS credentials.  The DBMS credential is based on either the WebLogic user mapped to a database user or the database user directly, based on the “use database credentials” setting as described earlier. Using this feature enabled with “use database credentials” enabled seems to be what is proposed in the JDBC standard, basically a heterogeneous pool with users specified by getConnection(user, password). The allocation of connections is more complex if Enable Identity Based Connection Pooling attribute is enabled on the data source.  When an application requests a database connection, the WebLogic Server instance selects an existing physical connection or creates a new physical connection with requested DBMS identity. The following section provides information on how heterogeneous connections are created:1. At connection pool initialization, the physical JDBC connections based on the configured or default “initial capacity” are created with the configured default DBMS credential of the data source.2. An application tries to get a connection from a data source.3a. If “use database credentials” is not enabled, the user specified in getConnection is mapped to a DBMS credential, as described earlier.  If the credential map doesn’t have a matching user, the default DBMS credential is used from the datasource descriptor.3b. If “use database credentials” is enabled, the user and password specified in getConnection are used directly.4. The connection pool is searched for a connection with a matching DBMS credential.5. If a match is found, the connection is reserved and returned to the application.6. If no match is found, a connection is created or reused based on the maximum capacity of the pool: - If the maximum capacity has not been reached, a new connection is created with the DBMS credential, reserved, and returned to the application.- If the pool has reached maximum capacity, based on the least recently used (LRU) algorithm, a physical connection is selected from the pool and destroyed. A new connection is created with the DBMS credential, reserved, and returned to the application. It should be clear that finding a matching connection is more expensive than a homogeneous pool.  Destroying a connection and getting a new one is very expensive.  If you can use a normal homogeneous pool or one of the light-weight options (client identity or an Oracle proxy connection), those should be used instead of identity based pooling. Regardless of how physical connections are created, each physical connection in the pool has its own DBMS credential information maintained by the pool. Once a physical connection is reserved by the pool, it does not change its DBMS credential even if the current thread changes its WebLogic user credential and continues to use the same connection. To configure this feature, select Enable Identity Based Connection Pooling.  See http://docs.oracle.com/cd/E24329_01/apirefs.1211/e24401/taskhelp/jdbc/jdbc_datasources/EnableIdentityBasedConnectionPooling.html  "Enable identity-based connection pooling for a JDBC data source" in Oracle WebLogic Server Administration Console Help. You must make the following changes to use Logging Last Resource (LLR) transaction optimization with Identity-based Pooling to get around the problem that multiple users will be accessing the associated transaction table.- You must configure a custom schema for LLR using a fully qualified LLR table name. All LLR connections will then use the named schema rather than the default schema when accessing the LLR transaction table.  - Use database specific administration tools to grant permission to access the named LLR table to all users that could access this table via a global transaction. By default, the LLR table is created during boot by the user configured for the connection in the data source. In most cases, the database will only allow access to this user and not allow access to mapped users. Connections within Transactions Now that we have covered the behavior of all of these various options, it’s time to discuss the exception to all of the rules.  When you get a connection within a transaction, it is associated with the transaction context on a particular WLS instance. When getting a connection with a data source configured with non-XA LLR or 1PC (using the JTS driver) with global transactions, the first connection obtained within the transaction is returned on subsequent connection requests regardless of the values of username/password specified and independent of the associated proxy user session, if any. The connection must be shared among all users of the connection when using LLR or 1PC. For XA data sources, the first connection obtained within the global transaction is returned on subsequent connection requests within the application server, regardless of the values of username/password specified and independent of the associated proxy user session, if any.  The connection must be shared among all users of the connection within a global transaction within the application server/JVM.

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  • how to evaluate query by DMBS?

    - by Kevinniceguy
    How do we evaluate the below database query by DBMS? the query is something like : 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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  • Cassandra or MySQL/PostgreSQL?

    - by Ivri
    Hi! I have huge database (kinda wordnet). And want to know if it's easier to use Cassandra instead of MySQL|PostrgreSQL All my life I was using MySQL and PostrgreSQL and I could easily think in terms of relational algebra, but several weeks ago I learned about cassandra and that it's used in facebook and twitter. Is it more convenient? What DBMS are usually used nowadays to store social net's data, relationships between objects, wordnet?

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  • Oracle & Active Directory : A love/hate relationship

    - by Frank
    Hi SO'ers, I'm currently trying to access Active Directory via the dbms_ldap API in Pl/Sql (Oracle). The trouble is that I'm not able to connect with my own username and password or anynoymously. However, in C# I can connect anonymously with this code : DirectoryEntry ldap = new DirectoryEntry("LDAP://Hostname"); DirectorySearcher searcher = new DirectorySearcher(ldap); searcher.Filter = "(SAMAccountName=username)"; SearchResult result = searcher.FindOne(); If I try to connect anonymously in Oracle, I only get the error(ORA-31202 : LDAP client/server error) when I try to search (and the result code for the bind is SUCCESS)... my_session := dbms_ldap.init('HOST','389'); retval := dbms_ldap.simple_bind_s(my_session, '', ''); retval := dbms_ldap.search_s(my_session, ldap_base, dbms_ldap.scope_subtree, 'objectclass=*', my_attrs, 0, my_message); Why is the anonymous connection is C# works but doesn't work in Pl/Sql? Do you have any other idea to connect to Active Directory via Oracle? Help me reunite them together. Thanks. Edit When I bind with anonymous credentials I get : ORA-31202: DBMS_LDAP: LDAP client/server error 00000000: LdapErr: DSID-0C090627, comment: In order to perform this operation a successful bind must be completed on the connection And if I try to connect with my credentials, which are supposed to be valid since I'm connected to the domain with it... I get : ORA-31202: DBMS_LDAP: LDAP client/server error Invalid credentials 80090308: LdapErr: DSID-0C090334, comment: AcceptSecurityContext error

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  • Oracle performance problems with large batch of XSL operations

    - by FrustratedWithFormsDesigner
    I have a system that is performing many XSL transformations on XMLType objects. The problem is that the system gradually slows down over time, and sometimes crashes when it runs out of memory. It seems that the slow down (and possibly memory crash) is around the dbms_xslprocessor.processXSL function call, which gradually takes longer and longer to complete. The code looks like this: v_doc dbms_xmldom.DOMDocument; v_transformer dbms_xmldom.DOMDocument; v_XSLprocessor dbms_xslprocessor.Processor; v_stylesheet dbms_xslprocessor.Stylesheet; v_clob clob; ... transformer := PKG_STUFF.getXSL(); v_transformer := dbms_xmldom.newDOMDocument(transformer); v_XSLprocessor := Dbms_Xslprocessor.newProcessor; v_stylesheet := dbms_xslprocessor.newStylesheet(v_transformer, ''); ... for source_data in (select id in source_tbl) loop begin v_doc := PKG_CONVERT.convert(in_id => source_data.id); --start time of operation v_begin_op_time := dbms_utility.get_time; --reset the CLOB v_clob := ' '; --Apply XSL Transform dbms_xslprocessor.processXSL(p => v_XSLprocessor, ss => v_stylesheet, xmldoc => v_Doc, cl => v_clob); v_doc := dbms_xmldom.newDOMDocument(XMLType(v_clob)); --end time v_end_op_time := dbms_utility.get_time; --calculate duration v_time_taken := (((v_end_op_time - v_begin_op_time))); --log the duration PKG_LOG.log_message('Time taken to transform XML: '||v_time_taken); ... ... DBMS_XMLDOM.freeDocument(v_Doc); DBMS_LOB.freetemporary(lob_loc => v_clob); end loop; The time taken to transform the XML is slowly creeping up (I suppose it might also be the call to dbms_xmldom.newDOMDocument, but I had thought that to be fairly straightforward). I have no idea why.... :( (Oracle 10g)

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  • Is Oracle AQ/Streams of any use in my situation?

    - by RenderIn
    I'm writing a workflow system that is driven entirely at each step by explicit human interaction. That is, a task is assigned to a person, that person selects from a few limited options {approve, reject, forward}, and then it is either sent along to the next person or terminated. Just curious of Oracle Streams/AQ has anything to offer over flat tables managed by regular web application code. The amount of processing after each action is fairly limited and the volume is not terribly high, so there's not really a need to throttle things by throwing them into a queue. What are some of the benefits of introducing a queue structure, or is it overkill for my situation?

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  • Why are there so many Database Management Systems?

    - by mr.bio
    Why are there so many Database management systems? I am not an DB expert and I've never thought about using another Database other than mySQL. Programming languages offer different paradigms, so it makes sense to choose a specific language for your purpose. Question What are the factors in choosing a specific Database management system ?

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  • Is there a declarative language for data definitions?

    - by Jekke
    Reading about WPF and thinking about my application's data store at the same time led me to wonder if there are any languages or tools that allow you to define relational data in a declarative way? A shallow Google search suggests no such thing exists. Yet it seems so obviously useful. The kind of tool I have in mind would declaratively describe (at least) entities, relationships and views is a platform-agnostic way that would act as an abstraction layer between data-driven applications and their datastores. Does any such tool exist?

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  • Scalability comparison between different DBMSs

    - by Björn Lindfors
    By what factor does the performance (read queries/sec) increase when a machine is added to a cluster of machines running either: a Bigtable-like database MySQL? Google's research paper on Bigtable suggests that "near-linear" scaling is achieved can be achieved with Bigtable. This page here featuring MySQL's marketing jargon suggests that MySQL is capable of scaling linearly. Where is the truth?

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  • Would this method work to scale out SQL queries?

    - by David
    I have a database containing a single huge table. At the moment a query can take anything from 10 to 20 minutes and I need that to go down to 10 seconds. I have spent months trying different products like GridSQL. GridSQL works fine, but is using its own parser which does not have all the needed features. I have also optimized my database in various ways without getting the speedup I need. I have a theory on how one could scale out queries, meaning that I utilize several nodes to run a single query in parallel. The idea is to take an incoming SQL query and simply run it exactly like it is on all the nodes. When the results are returned to a coordinator node, the same query is run on the union of the resultsets. I realize that an aggregate function like average need to be rewritten into a count and sum to the nodes and that the coordinator divides the sum of the sums with the sum of the counts to get the average. What kinds of problems could not easily be solved using this model. I believe one issue would be the count distinct function. Edit: I am getting so many nice suggestions, but none have addressed the method.

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  • In SQL, in what situation do we want to Index a field in a table, or 2 fields in a table at the same

    - by Jian Lin
    In SQL, it is obvious that whenever we want to do a search on millions of record, say CustomerID in a Transactios table, then we want to add an index for CustomerID. Is another situation we want to add an index to a field when we need to do inner join or outer join using that field as a criteria? Such as Inner join on t1.custumerID = t2.customerID. Then if we don't have an index on customerID on both tables, we are looking at O(n^2) because we need to loop through the 2 tables sequentially. If we have index on customerID on both tables, then it becomes O( (log n) ^ 2 ) and it is much faster. Any other situation where we want to add an index to a field in a table? What about adding index for 2 fields combined in a table. That is, one index, for 2 fields together?

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  • dbms_xmlschema fail to validate with complexType

    - by Andrew
    Preface: This works on one Oracle 11gR1 (Solaris 64) database and not on a second and we can't figure out the difference between the two databases. Somehow the complexType causes the validation to fail with this error: ORA-31154: invalid XML document ORA-19202: Error occurred in XML processing LSX-00200: element "shiporder" not empty ORA-06512: at "SYS.XMLTYPE", line 354 ORA-06512: at line 13 But the schema is valid (passes this online test: http://www.xmlme.com/Validator.aspx) -- Cleanup any existing schema begin dbms_xmlschema.deleteschema('shiporder.xsd',dbms_xmlschema.DELETE_CASCADE); end; -- Define the problem schema (adapted from http://www.w3schools.com/schema/schema_example.asp) begin dbms_xmlschema.registerSchema('shiporder.xsd','<?xml version="1.0" encoding="ISO-8859-1" ?> <xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"> <xs:element name="shiporder"> <xs:complexType> <xs:sequence> <xs:element name="orderperson" type="xs:string"/> </xs:sequence> </xs:complexType> </xs:element> </xs:schema>',owner=>'SCOTT'); end; -- Attempt to validate declare bbb xmltype; begin bbb := XMLType('<?xml version="1.0" encoding="ISO-8859-1"?> <shiporder xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="shiporder.xsd"> <orderperson>John Smith</orderperson> </shiporder>'); XMLType.schemaValidate(bbb); end; Now if I gut the schema definition and leave only a string in the XML then the validation passes: begin dbms_xmlschema.deleteschema('shiporder.xsd',dbms_xmlschema.DELETE_CASCADE); end; begin dbms_xmlschema.registerSchema('shiporder.xsd','<?xml version="1.0" encoding="ISO-8859-1" ?> <xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"> <xs:element name="shiporder" type="xs:string"/> </xs:schema>',owner=>'SCOTT'); end; DECLARE xml XMLTYPE; BEGIN xml := XMLTYPE('<?xml version="1.0" encoding="ISO-8859-1"?> <shiporder xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="shiporder.xsd"> John Smith </shiporder>'); XMLTYPE.schemaValidate(xml); END;

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  • Finding the right terminology for a dictionary table

    - by Karl Forner
    My concern is about what I currently call "dictionary tables", that are database tables containing a list of controlled vocabulary. Let's use an example: Suppose you have a table User containing fields: user_id : primary key first_name last_name user_type_id : foreign key to the UserType table and another table UserType with just two fields: user_type_id : primary key name : the name/value of a particular type of user. For instance, the UserType table may contain (1, Administrator), (2, PowerUser), (3, Normal)... My question is: what is the canonical term for a table like UserType, that only contains a list of (dictinct) words. I want to publish some code that help managing this kind of tables, but first I have to name them ! Thanks for your help. Current state of thought: For now I feel Lookup Tables is a good term. It is also used with the same meaning in these posts: http://dbix-class.35028.n2.nabble.com/RFC-Component-for-Lookup-tables-td3504085.html http://tonyandrews.blogspot.de/2004/10/otlt-and-eav-two-big-design-mistakes.html Lookup Tables Best Practices: DB Tables... or Enumerations The only problem is that lookup table is also sometimes used to name a junction table.

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  • what is the question for the query?

    - 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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  • Why are there so many DB management Systems ?

    - by mr.bio
    Hi there , i always asked myself. Why are there so many DB management systems? I am not an DB expert and i never thought about using another DB than mysql. Programming languages offer different paradigms, so there it makes sense to choose a specific language for your purpose. What are factors to choose a specific DB management system ?

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  • Explain this SQL query in plain English.

    - by Kevinniceguy
    Please explain, in plain English, what question this SQL query answers: 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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  • Do we need Record Level Locking when we already have Transaction for online ordering? (of concert ti

    - by Jian Lin
    For online ordering of concert seat or airline ticket, do we need Record Level Locking or is Transaction good enough? For concert ticket (say, seat Number 20B), or airline ticket (even with overbooking, the limit is 210, for example), I think the website cannot lock any record or begin transaction when showing the ticket purchase screen. But after the user clicks "Confirm Purchase", then the server should Begin a Transaction, Purchase Seat Number 20B, and try to Commit. If another user already bought Seat 20B in a previous transaction, then it is the "Commit" part that the current transaction will fail? So... we don't need Record Level Locking? Do Transactions always go serialized (one after another), so that's why we can know for sure there is no "race condition"? In what situation is Record Level Locking needed then?

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  • SQLServer using too much memory

    - by Israel Pereira Valverde
    I have installed on my desktop machine (with windows 7) SQLServer 2008 R2 Express. I have only one local server running (./SQLEXPRESS) but the sqlserver process is taking ALL the RAM possible. With an machine with 3GB of RAM the things starts to get slow, so I limited the maximun amount of RAM in the server, and now, constantly the SQLServer give some error messages that the memory is not enought. It's using 1GB of RAM with only one LOCAL server with 2 databases completely empty, how 1GB of RAM isn't enought ? When the process start it's using an really acceptable amount of memory (around 80MB) but it's keep increasing until it reaches the maximun defined and start to complain about having not enought memory available. In that point I have to restart the server to use it again. I have read about an hotfix to solve one of the errors I got from sqlserver: There is insufficient system memory in resource pool 'internal' to run this query But it's already installed on my sqlserver. Why it's using so much memory?

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  • Password hashing, salt and storage of hashed values

    - by Jonathan Leffler
    Suppose you were at liberty to decide how hashed passwords were to be stored in a DBMS. Are there obvious weaknesses in a scheme like this one? To create the hash value stored in the DBMS, take: A value that is unique to the DBMS server instance as part of the salt, And the username as a second part of the salt, And create the concatenation of the salt with the actual password, And hash the whole string using the SHA-256 algorithm, And store the result in the DBMS. This would mean that anyone wanting to come up with a collision should have to do the work separately for each user name and each DBMS server instance separately. I'd plan to keep the actual hash mechanism somewhat flexible to allow for the use of the new NIST standard hash algorithm (SHA-3) that is still being worked on. The 'value that is unique to the DBMS server instance' need not be secret - though it wouldn't be divulged casually. The intention is to ensure that if someone uses the same password in different DBMS server instances, the recorded hashes would be different. Likewise, the user name would not be secret - just the password proper. Would there be any advantage to having the password first and the user name and 'unique value' second, or any other permutation of the three sources of data? Or what about interleaving the strings? Do I need to add (and record) a random salt value (per password) as well as the information above? (Advantage: the user can re-use a password and still, probably, get a different hash recorded in the database. Disadvantage: the salt has to be recorded. I suspect the advantage considerably outweighs the disadvantage.) There are quite a lot of related SO questions - this list is unlikely to be comprehensive: Encrypting/Hashing plain text passwords in database Secure hash and salt for PHP passwords The necessity of hiding the salt for a hash Clients-side MD5 hash with time salt Simple password encryption Salt generation and Open Source software I think that the answers to these questions support my algorithm (though if you simply use a random salt, then the 'unique value per server' and username components are less important).

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  • How to use SQLAlchemy to dump an SQL file from query expressions to bulk-insert into a DBMS?

    - by Mahmoud Abdelkader
    Please bear with me as I explain the problem, how I tried to solve it, and my question on how to improve it is at the end. I have a 100,000 line csv file from an offline batch job and I needed to insert it into the database as its proper models. Ordinarily, if this is a fairly straight-forward load, this can be trivially loaded by just munging the CSV file to fit a schema, but I had to do some external processing that requires querying and it's just much more convenient to use SQLAlchemy to generate the data I want. The data I want here is 3 models that represent 3 pre-exiting tables in the database and each subsequent model depends on the previous model. For example: Model C --> Foreign Key --> Model B --> Foreign Key --> Model A So, the models must be inserted in the order A, B, and C. I came up with a producer/consumer approach: - instantiate a multiprocessing.Process which contains a threadpool of 50 persister threads that have a threadlocal connection to a database - read a line from the file using the csv DictReader - enqueue the dictionary to the process, where each thread creates the appropriate models by querying the right values and each thread persists the models in the appropriate order This was faster than a non-threaded read/persist but it is way slower than bulk-loading a file into the database. The job finished persisting after about 45 minutes. For fun, I decided to write it in SQL statements, it took 5 minutes. Writing the SQL statements took me a couple of hours, though. So my question is, could I have used a faster method to insert rows using SQLAlchemy? As I understand it, SQLAlchemy is not designed for bulk insert operations, so this is less than ideal. This follows to my question, is there a way to generate the SQL statements using SQLAlchemy, throw them in a file, and then just use a bulk-load into the database? I know about str(model_object) but it does not show the interpolated values. I would appreciate any guidance for how to do this faster. Thanks!

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  • How to create select SQL statement that would produce "merged" dataset from two tables(Oracle DBMS)?

    - by Roman Kagan
    Here's my original question: merging two data sets Unfortunately I omitted some intircacies, that I'd like to elaborate here. So I have two tables events_source_1 and events_source_2 tables. I have to produce the data set from those tables into resultant dataset (that I'd be able to insert into third table, but that's irrelevant). events_source_1 contain historic event data and I have to do get the most recent event (for such I'm doing the following: select event_type,b,c,max(event_date),null next_event_date from events_source_1 group by event_type,b,c,event_date,null events_source_2 contain the future event data and I have to do the following: select event_type,b,c,null event_date, next_event_date from events_source_2 where b>sysdate; How to put outer join statement to fill the void (i.e. when same event_type,b,c found from event_source_2 then next_event_date will be filled with the first date found GREATLY APPRECIATE FOR YOUR HELP IN ADVANCE.

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