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  • Is there a "rigorous" method for choosing a database?

    - by Andrew Martin
    I'm not experienced with NoSQL, but one person on my team is calling for its use. I believe our data and its usage isn't optimal for a NoSQL implementation. However, my understanding is based off reading various threads on various websties. I'd like to get some stronger evidence as to who's correct. My question is therefore, "Is there a technique for estimating the performance and requirements of a certain database, that I could use to confirm or modify my intuitions?". Is there, for example, a good book for calculating the performance of equivalent MongoDB/MySQL schema? Is the only really reliable option to build the whole thing and take metrics?

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  • Which databases support parallel processing across multiple servers?

    - by David
    I need a database engine that can utilize multiple servers for processing a single SQL query in parallel. So far I know that this is possible with the some engines, though none of them are feasible for me either because of pricing or missing features. The engines currently known to me are: MS SQL (enterprise) DB2 (enterprise) Oracle (enterprise) GridSQL Greenplum Which other engines have this feature? Do you have any experience with using this feature? Edit: I have now proposed a method for creating one myself. Any input is welcome. Edit: I have found another one: Informix Extended Parallel Server

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  • Was Joel right about XML being slow?

    - by Will
    A long time ago Joel explained how various every-day coding things were slow, and this led to XML as a data store being slow: http://www.joelonsoftware.com/articles/fog0000000319.html Are those every-day coding things - strcat and malloc - still slow in a std::string and dlmalloc world? What else has changed in modern processors and mainstream frameworks? And is XML still slow? You can't find an RDBMS that doesn't claim some kind of native XML support these days; haven't they got it faster - a single pass to index it for example - yet?

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  • free public databases with non-trivial table structures?

    - by Caffeine Coma
    I'm looking for some sample database data that I can use for testing and demonstrating a DB tool I am working on. I need a DB that has (preferably) many tables, and many foreign key relationships between the tables. Ideally the data would be in SQL dump format, or at least in something that maintains the foreign key references, and could be easily import into an RDBMS (MySQL or H2). The dataset itself doesn't have to be huge (in fact, best if it's not). I thought about using the Stackoverflow Data Dump, but it's only about 5 tables.

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  • What is a good DBMS for archiving?

    - by Thomas.Winsnes
    I've been stuck in a MsSql/MySql world now for a few years, and I've decided to spread my wings a little further. At the moment I'm researching which DBMS is good at things needed when archiving data. Eg. lots of writes and low reads. I've seen the NoSQL crusade, but I have a very RDBMS mindset, so I'm a bit skeptical. Anyone have any suggestions? Or even any pointers to where there are some benchmarks etc for this kind of stuff. Thank you :) Thomas

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  • Reasons for & against a Database

    - by dbemerlin
    Hi, i had a discussion with a coworker about the architecture of a program i'm writing and i'd like some more opinions. The Situation: The Program should update at near-realtime (+/- 1 Minute). It involves the movement of objects on a coordinate system. There are some events that occur at regular intervals (i.e. creation of the objects). Movements can change at any time through user input. My solution was: Build a server that runs continously and stores the data internally. The server dumps a state-of-the-program at regular intervals to protect against powerfailures and/or crashes. He argued that the program requires a Database and i should use cronjobs to update the data. I can store movement information by storing startpoint, endpoint and speed and update the position in the cronjob (and calculate collisions with other objects there) by calculating direction and speed. His reasons: Requires more CPU & Memory because it runs constantly. Powerfailures/Crashes might destroy data. Databases are faster. My reasons against this are mostly: Not very precise as events can only occur at full minutes (wouldn't be that bad though). Requires (possibly costly) transformation of data on every run from relational data to objects. RDBMS are a general solution for a specialized problem so a specialized solution should be more efficient. Powerfailures (or other crashes) can leave the Data in an undefined state with only partially updated data unless (possibly costly) precautions (like transactions) are taken. What are your opinions about that? Which arguments can you add for any side?

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  • Configure PERL DBI and DBD in Linux

    - by Balualways
    I am new to Perl and I work in a Linux OEL 5x server. I am trying to configure the Perl DB modules for Oracle connectivity (DBD and DBI modules). Can anyone help me out in the installation procedure? I had tried CPAN didn't really worked out. Any help would be appreciated. I am not quite sure I need to initialize any variables other than $LD_LIBRARY_PATH and $ORACLE_HOME These are my observations: ISSUE:: I am getting the following issue while using the DBI module to connect to Oracle: install_driver(Oracle) failed: Can't locate loadable object for module DBD::Oracle in @INC (@INC contains: /usr/lib64/perl5/site_perl/5.8.8/x86_64-linux-thread-multi /usr/lib/perl5/site_perl/5.8.8 /usr/lib/perl5/site_perl /usr/lib64/perl5/vendor_perl/5.8.8/x86_64-linux-thread-multi /usr/lib/perl5/vendor_perl/5.8.8 /usr/lib/perl5/vendor_perl /usr/lib64/perl5/5.8.8/x86_64-linux-thread-multi /usr/lib/perl5/5.8.8 .) at (eval 3) line 3 Compilation failed in require at (eval 3) line 3. Perhaps a module that DBD::Oracle requires hasn't been fully installed at connectdb.pl line 57 I had installed the DBD for oracle from /usr/lib64/perl5/5.8.8/x86_64-linux-thread-multi/DBD/DBD-Oracle-1.50 Could you please take a look into the steps and correct me if I am wrong: Observations: $ echo $LD_LIBRARY_PATH /opt/CA/UnicenterAutoSysJM/autosys/lib:/opt/CA/SharedComponents/Csam/SockAdapter/lib:/opt/CA/SharedComponents/ETPKI/lib:/opt/CA/CAlib $ echo $ORACLE_HOME /usr/local/oracle/ORA This is how I tried to install the DBD module: Download the file DBD 1.50 for Oracle Copy to /usr/lib64/perl5/5.8.8/x86_64-linux-thread-multi/DBD Untar and Makefile.PL . Message: Using DBI 1.52 (for perl 5.008008 on x86_64-linux-thread-multi) installed in /usr/lib64/perl5/vendor_perl/5.8.8/x86_64-linux-thread-multi/auto/DBI/ Configuring DBD::Oracle for perl 5.008008 on linux (x86_64-linux-thread-multi) Remember to actually *READ* the README file! Especially if you have any problems. Installing on a linux, Ver#2.6 Using Oracle in /opt/oracle/product/10.2 DEFINE _SQLPLUS_RELEASE = "1002000400" (CHAR) Oracle version 10.2.0.4 (10.2) Found /opt/oracle/product/10.2/rdbms/demo/demo_rdbms.mk Found /opt/oracle/product/10.2/rdbms/demo/demo_rdbms64.mk Found /opt/oracle/product/10.2/rdbms/lib/ins_rdbms.mk Using /opt/oracle/product/10.2/rdbms/demo/demo_rdbms.mk Your LD_LIBRARY_PATH env var is set to '/usr/local/oracle/ORA/lib:/usr/dt/lib:/usr/openwin/lib:/usr/local/oracle/ORA/ows/cartx/wodbc/1.0/util/lib:/usr/local/oracle/ORA/lib:/usr/local/sybase/OCS-12_0/lib:/usr/local/sybase/lib:/home/oracle/jdbc/jdbcoci73/lib:./' WARNING: Your LD_LIBRARY_PATH env var doesn't include '/opt/oracle/product/10.2/lib' but probably needs to. Reading /opt/oracle/product/10.2/rdbms/demo/demo_rdbms.mk Reading /usr/local/oracle/ORA/rdbms/lib/env_rdbms.mk Attempting to discover Oracle OCI build rules sh: make: command not found by executing: [make -f /opt/oracle/product/10.2/rdbms/demo/demo_rdbms.mk build ECHODO=echo ECHO=echo GENCLNTSH='echo genclntsh' CC=true OPTIMIZE= CCFLAGS= EXE=DBD_ORA_EXE OBJS=DBD_ORA_OBJ.o] WARNING: Oracle build rule discovery failed (32512) Add path to make command into your PATH environment variable. Oracle oci build prolog: [sh: make: command not found] Oracle oci build command: [] WARNING: Unable to interpret Oracle build commands from /opt/oracle/product/10.2/rdbms/demo/demo_rdbms.mk. (Will continue by using fallback approach.) Please report this to [email protected]. See README for what to include. Found header files in /opt/oracle/product/10.2/rdbms/public. client_version=10.2 DEFINE= -Wall -Wno-comment -DUTF8_SUPPORT -DORA_OCI_VERSION=\"10.2.0.4\" -DORA_OCI_102 Checking for functioning wait.ph System: perl5.008008 linux ca-build9.us.oracle.com 2.6.20-1.3002.fc6xen #1 smp thu apr 30 18:08:39 pdt 2009 x86_64 x86_64 x86_64 gnulinux Compiler: gcc -O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector --param=ssp-buffer-size=4 -m64 -mtune=generic -D_REENTRANT -D_GNU_SOURCE -fno-strict-aliasing -pipe -Wdeclaration-after-statement -I/usr/local/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64 -I/usr/include/gdbm Linker: not found Sysliblist: -ldl -lm -lpthread -lnsl -lirc Oracle makefiles would have used these definitions but we override them: CC: cc CFLAGS: $(GFLAG) $(OPTIMIZE) $(CDEBUG) $(CCFLAGS) $(PFLAGS)\ $(SHARED_CFLAG) $(USRFLAGS) [$(GFLAG) -O3 $(CDEBUG) -m32 $(TRIGRAPHS_CCFLAGS) -fPIC -I/usr/local/oracle/ORA/rdbms/demo -I/usr/local/oracle/ORA/rdbms/public -I/usr/local/oracle/ORA/plsql/public -I/usr/local/oracle/ORA/network/public -DLINUX -D_GNU_SOURCE -D_LARGEFILE64_SOURCE=1 -D_LARGEFILE_SOURCE=1 -DSLTS_ENABLE -DSLMXMX_ENABLE -D_REENTRANT -DNS_THREADS -fno-strict-aliasing $(LPFLAGS) $(USRFLAGS)] build: $(CC) $(ORALIBPATH) -o $(EXE) $(OBJS) $(OCISHAREDLIBS) [ cc -L$(LIBHOME) -L/usr/local/oracle/ORA/rdbms/lib/ -o $(EXE) $(OBJS) -lclntsh $(EXPDLIBS) $(EXOSLIBS) -ldl -lm -lpthread -lnsl -lirc -ldl -lm $(USRLIBS) -lpthread] LDFLAGS: $(LDFLAGS32) [-m32 -o $@ -L/usr/local/oracle/ORA/rdbms//lib32/ -L/usr/local/oracle/ORA/lib32/ -L/usr/local/oracle/ORA/lib32/stubs/] Linking with /usr/local/oracle/ORA/rdbms/lib/defopt.o -lclntsh -ldl -lm -lpthread -lnsl -lirc -ldl -lm -lpthread [from $(DEF_OPT) $(OCISHAREDLIBS)] Checking if your kit is complete... Looks good LD_RUN_PATH=/usr/local/oracle/ORA/lib Using DBD::Oracle 1.50. Using DBD::Oracle 1.50. Using DBI 1.52 (for perl 5.008008 on x86_64-linux-thread-multi) installed in /usr/lib64/perl5/vendor_perl/5.8.8/x86_64-linux-thread-multi/auto/DBI/ Writing Makefile for DBD::Oracle Writing MYMETA.yml and MYMETA.json *** If you have problems... read all the log printed above, and the README and README.help.txt files. (Of course, you have read README by now anyway, haven't you?)

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  • When NOT to use Cassandra?

    - by JimJim
    There has been a lot of talk related to Cassandra lately. Twitter, Digg, Facebook, etc all use it. When does it make sense to: use Cassandra, not use Cassandra, and use a RDMS instead of Cassandra.

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  • Accessing the Custom Object Return type from ojdbc6 JDBC Thin Drivers

    - by Andrew Harmel-Law
    I'm writing some JDBC code which calls a Oracle 11g PL/SQL procdedure which has a Custom Object return type. I can get the code to call the procedure, but how do I access the returned Custom Object to obtain it's contained values?. An example of my code calling the procedure is below: PLSQL Code: Procedure GetDataSummary (p_my_key IN KEYS.MY_KEY%TYPE, p_recordset OUT data_summary_tab, p_status OUT VARCHAR2); Java Code: String query = "begin manageroleviewdata.getdatasummary(?, ?, ?); end;"); CallableStatement stmt = conn.prepareCall(query); stmt.setInt(1, 83); stmt.registerOutParameter(2, OracleTypes.ARRAY, "DATA_SUMMARY_TAB"); stmt.registerOutParameter(3, OracleTypes.VARCHAR); stmt.execute(stmt); How do I get the result back fron this?

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  • Why use NoSQL over Materialized Views?

    - by JustinT
    There has been a lot of talk recently about NoSQL. The #1 reason why I hear people use NoSQL is because they start to de-normalize their DBMS data so much so, to increase performance, that they end up with just one table with all of their data within that single table. With Materialized Views however, you can keep your data normalized, yet have it stored as a single table view for the same reasons why you'd use NoSQL. As such, why would someone use NoSQL over Materialized Views?

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  • Calling an Oracle PL/SQL procedure with Custom Object return types from 0jdbc6 JDBCthin drivers

    - by Andrew Harmel-Law
    I'm writing some JDBC code which calls a Oracle 11g PL/SQL procdedure which has a Custom Object return type. Whenever I try an register my return types, I get either ORA-03115 or PLS-00306 as an error when the statement is executed depending on the type I set. An example is below: PLSQL Code: Procedure GetDataSummary (p_my_key IN KEYS.MY_KEY%TYPE, p_recordset OUT data_summary_tab, p_status OUT VARCHAR2); Java Code: String query = "beginmanageroleviewdata.getdatasummary(?, ?, ?); end;"); CallableStatement stmt = conn.prepareCall(query); stmt.setInt(1, 83); stmt.registerOutParameter(2, OracleTypes.CURSOR); // Causes error: PLS-00306 stmt.registerOutParameter(3, OracleTypes.VARCHAR); stmt.execute(stmt); // Error mentioned above thrown here. Can anyone provide me with an example showing how I can do this? I guess it's possible. However I can't see a rowset OracleType. CURSOR, REF, DATALINK, and more fail. Apologies if this is a dumb question. I'm not a PL/SQL expert and may have used the wrong terminology in some areas of my question. (If so, please edit me). Thanks in advance. Regs, Andrew

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  • MySQL nested set hierarchy with foreign table

    - by Björn
    Hi! I'm using a nested set in a MySQL table to describe a hierarchy of categories, and an additional table describing products. Category table; id name left right Products table; id categoryId name How can I retrieve the full path, containing all parent categories, of a product? I.e.: RootCategory > SubCategory 1 > SubCategory 2 > ... > SubCategory n > Product Say for example that I want to list all products from SubCategory1 and it's sub categories, and with each given Product I want the full tree path to that product - is this possible? This is as far as I've got - but the structure is not quite right... select parent.`name` as name, parent.`id` as id, group_concat(parent.`name` separator '/') as path from categories as node, categories as parent, (select inode.`id` as id, inode.`name` as name from categories as inode, categories as iparent where inode.`lft` between iparent.`lft` and iparent.`rgt` and iparent.`id`=4 /* The category from which to list products */ order by inode.`lft`) as sub where node.`lft` between parent.`lft` and parent.`rgt` and node.`id`=sub.`id` group by sub.`id` order by node.`lft`

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  • SQLite long to wide formats?

    - by Stephen
    Hi, I wonder if there is a canonical way to convert data from long to wide format in SQLite (is that operation usually in the domain of relational databases?). I tried to follow this example for MySQL but I guess SQLite does not have the same IF construct... Thanks!

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  • NoSQL: How to retrieve a 'house' based on lat & long?

    - by Tedk
    I have a NoSQL system for storing real estate houses. One piece of information I have in my key-value store for each house is the longitude and latitude. If I wanted to retrieve all houses within a geo-lat/long box, like the SQL below: SELECT * from houses WHERE latitude IS BETWEEN xxx AND yyy AND longitude IS BETWEEN www AND zzz Question: How would I do this type of retrival with NoSQL ... using just a key-value store system? Even if I could do this with NoSQL, would it even be efficient or would simply going back to using a tradition database retrieve this type of information faster?

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  • Database for Python Twisted

    - by Will
    There's an API for Twisted apps to talk to a database in a scalable way: twisted.enterprise.dbapi The confusing thing is, which database to pick? The database will have a Twisted app that is mostly making inserts and updates and relatively few selects, and then other strictly-read-only clients that are accessing the database directly making selects. (The read-only users are not necessarily selecting the data that the Twisted app is inserting; its not as though the database is being used as a message-queue) My understanding - which I'd like corrected/adviced - is that: Postgres is a great DB, but all the Python bindings - and there is a confusing maze of them - are abandonware There is psycopg2, but that makes a lot of noise about doing its own connection-pooling and things; does this co-exist gracefully/usefully/transparently with the Twisted async database connection pooling and such? SQLLite is a great database for little things but if used in a multi-user way it does whole-database locking, so performance would suck in the usage pattern I envisage MySQL - after the Oracle takeover, who'd want to adopt it now or adopt a fork? Is there anything else out there?

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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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  • Hibernate updating records and implementing listeners : getting only required attribute values for event.getOldState()

    - by Narendra
    Hi All, I am using Hibernate 3 as my persistence framework. Below is the sample hbm file I am using. <?xml version="1.0"?> <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd"> <hibernate-mapping> <class name="com.test.User" table="user"> <meta attribute="implements">com.test.dao.interfaces.IEntity</meta> <id name="key" type="long" column="user_key"> <generator class="increment" /> </id> <property name="userName" column="user_name" not-null="true" type="string" /> <property name="password" column="password" not-null="true" type="string" /> <property name="firstName" column="first_name" not-null="true" type="string" /> <property name="lastName" column="last_name" not-null="true" type="string" /> <property name="createdDate" column="created_date" not-null="true" type="timestamp" insert="false" update="false" /> <property name="createdBy" column="created_by" not-null="true" type="string" update="false" /> </class> </hibernate-mapping> I am added a post-update listener. What it will do is if there any updations perfomed on User then it will be invoked and cahnges will be inserted to audit table. Below is the sample implementation for postupdate event. public void onPostUpdate(PostUpdateEvent event) { LogHelper.info(logger, "Begin - onPostUpdate " + event.getEntity().getClass().getSimpleName()); if (!this.checkForAudit(event.getEntity().getClass().getSimpleName())) { // check do we need to audit it. } // Get Attribute Names String[] attrNames = event.getPersister().getEntityMetamodel() .getPropertyNames(); Object[] oldobjectValue = c Object[] newObjectValue = event.getState(); this.auditDetailsEvent(attrNames, oldobjectValue, newObjectValue); LogHelper.info(logger, "End - onPostUpdate"); // return false; } Here is my requirement. event.getPersister().getEntityMetamodel() .getPropertyNames(); or event.getOldState(); or event.getState(); must return attribute names or value which i can update or insert. Is there any way to control the return values of above one's. Pleas help me on this regard. Thanks, Narendra

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  • Oracle Unique Indexes

    - by Melvin
    I was creating a new table today in 10g when I noticed an interesting behavior. Here is an example of what I did: CREATE TABLE test_table ( field_1 INTEGER PRIMARY KEY ); Oracle will by default, create a non-null unique index for the primary key. I double checked this. After a quick check, I find a unique index name SYS_C0065645. Everything is working as expected so far. Now I did this: CREATE TABLE test_table ( field_1 INTEGER, CONSTRAINT pk_test_table PRIMARY KEY (field_1) USING INDEX (CREATE INDEX idx_test_table_00 ON test_table (field_1))); After describing my newly created index idx_test_table_00, I see that it is non-unique. I tried to insert duplicate data into the table and was stopped by the primary key constraint, proving that the functionality has not been affected. It seems strange to me that Oracle would allow a non-unique index to be used for a primary key constraint. Why is this allowed?

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  • Are there any issues with MySQL's i18n(indic language) support ?

    - by anjanb
    Hi All, We're evaluating MySQL and PostgreSQL for building our indic language web application which will use MySQL or PostgreSQL. One of my colleagues mentioned that MySQL had issues with i18n. I mostly come from the Oracle world and although I've played a lil with MySQL, I don't know enough to know that there are issues with its i18n support. Does anyone know issues with MySQL's i18n support and if PostgreSQL would be better placed for building an application with indic language support(kannada, telugu, tamil, etc) ? Just so you know, we're going to be using J2EE to build this application and we will be using JDBC drivers to access the DB. P.S : Will anything change if we were to use Rails to build the app instead of J2EE ? Thank you,

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  • What alternatives do I have if I want a distributed multi-master database?

    - by Jonas
    I will build a system where I want to reduce single-point-of-failures, and I need a database. Is there any (free) relational database systems that can handle multi-master setups good (i.e where it is easy to add and remove nodes) or is it better to go with a NoSQL-database? As what I have understood, a key-value store will handle this better. What database system do you recommend for a multi-master (cluster) setup?

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  • Revisions: algorithm and data structure

    - by SODA
    Hi, I need ideas for structuring and processing data with revisions. For example, I have a database of objects (e.g. cars). Each object has a number of properties, which can be arbitrary, so there's no a set schema to describe these objects. These objects are probably saved as key-value pairs. Now I need to change property of an object. I don't want to completely rewrite it - I want to be able to go back and see history of changes to these properties, that's why I want to add new property and keep the old one (so I guess a timestamp would do the job of telling which property is the latest). At the same time I want to be able to get info about any object in a snap, with only latest versions of each of the properties. Any ideas what would be the best approach? At least please point me in the right direction. Thanks!

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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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  • MS Access questions - Scalability / indexing / transactions

    - by oo
    A few questions on MS Access databases - Size: Are there limits to the size of an access database? The reason i ask is that we have an access database that has a few simple tables. The size of the db is about 1GB. When I do a query on it, i see it taking over 10 minutes to run. With proper indexing, should MS Access be able to handle this or are there fundamental limitations to the technology. This is MS Access XP. Also, does MS Access support db transactions, commit and rollback?

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