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  • How to approach performance issues?

    - by jess
    Hi, We are developing a client-server desktop application(winforms with sql server 2008, using LINQ-SQL).We are now finding many issues related to performance.These relate to querying too much data with LINQ , bad database design,not much caching etc.What do you suggest,we should do - how to go about solving these performance issues? One thing,I am doing is doing sql profiling,and trying to fix some queries.As far caching is concerned,we have static lists.But,how to keep them updated,we don't have any server side implementation.So,these lists can be stale,if someone changes data. regards

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  • How do I get results from a link query in the order of IDs that I provide?

    - by Keltex
    I'm looking to get query results back from Linq in the order that I pass IDs to the query. So it would look something like this: var IDs = new int [] { 5, 20, 10 } var items = from mytable in db.MyTable where IDs.Contains(mytable.mytableID) orderby // not sure what to do here select mytable; I'm hoping to get items in the order of IDs (5, 20, 10). (Note this is similar to this question, but I would like to do it in Linq instead of SQL)

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  • c#: Design advice. Using DataTable or List<MyObject> for a generic rule checker

    - by Andrew White
    Hi, I have about 100,000 lines of generic data. Columns/Properties of this data are user definable and are of the usual data types (string, int, double, date). There will be about 50 columns/properties. I have 2 needs: To be able to calculate new columns/properties using an expression e.g. Column3 = Column1 * Column2. Ultimately I would like to be able to use external data using a callback, e.g. Column3 = Column1 * GetTemperature The expression is relatively simple, maths operations, sum, count & IF are the only necessary functions. To be able to filter/group the data and perform aggregations e.g. Sum(Data.Column1) Where(Data.Column2 == "blah") As far as I can see I have two options: 1. Using a DataTable. = Point 1 above is achieved by using DataColumn.Expression = Point 2 above is acheived by using DataTable.DefaultView.RowFilter & C# code 2. Using a List of generic Objects each with a Dictionary< string, object to store the values. = Point 1 could be achieved by something like NCalc = Point 2 is achieved using LINQ DataTable: Pros: DataColumn.Expression is inbuilt Cons: RowFilter & coding c# is not as "nice" as LINQ, DataColumn.Expression does not support callbacks(?) = workaround could be to get & replace external value when creating the calculated column GenericList: Pros: LINQ syntax, NCalc supports callbacks Cons: Implementing NCalc/generic calc engine Based on the above I would think a GenericList approach would win, but something I have not factored in is the performance which for some reason I think would be better with a datatable. Does anyone have a gut feeling / experience with LINQ vs. DataTable performance? How about NCalc? As I said there are about 100,000 rows of data, with 50 columns, of which maybe 20 are calculated. In total about 50 rules will be run against the data, so in total there will be 5 million row/object scans. Would really appreciate any insights. Thx. ps. Of course using a database + SQL & Views etc. would be the easiest solution, but for various reasons can't be implemented.

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  • Rewrite SQL Fulltext Function to return Table only

    - by Alex
    I have a MS SQL Fulltext Function like this: (...) RETURNS TABLE AS RETURN SELECT * FROM fishes INNER JOIN CONTAINSTABLE(fishes, *, @keywords, @limit) AS KEY_TBL ON fishes.id = KEY_TBL.[KEY] When I use this function in LINQ, it generates a special return type which includes all fields of my "fishes" table, plus Key and Rank. How could I rewrite above query, or change something in LINQ, to omit Key and Rank and just return my "fishes" results (and to have the fulltext search result objects be of type Fish, which is what I really care about, so I don't have to cast)?

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  • How to get an object from a list based upon IEqualityComparer<T>

    - by Greg
    The Compare method in Linq lets you find by an IEqualityComparer, but I can't find a counterpart method that allows you retrieve an item by the same comparer. Is this really the best way to do it? MyItem myFinderItem = new MyItem(keyField1, keyField2); if (myList.Contains(myFinderItem, new MyEqualityComparer())) { MyItem myRealItem = myList.Single(item => new MyEqualityComparer().Equals(item , myFinderItem)); } (I'm sharing the usage of the IEqualityComaprer with a call to the Except Linq method and I'd like to maintain a single source for equality comparisons)

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  • Is opening too many datacontexts bad?

    - by ryudice
    I've been checking my application with linq 2 sql profiler, and I noticed that it opens a lot of datacontexts, most of them are opened by the linq datasource I used, since my repositories use only the instance stored in Request.Items, is it bad to open too many datacontext? and how can I make my linqdatasource to use the datacontext that I store in Request.Items for the duration of the request? thanks for any help!

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  • Helping linqtosql datacontext use implicit conversion between varchar column in the database and tab

    - by user213256
    I am creating an mssql database table, "Orders", that will contain a varchar(50) field, "Value" containing a string that represents a slightly complex data type, "OrderValue". I am using a linqtosql datacontext class, which automatically types the "Value" column as a string. I gave the "OrderValue" class implicit conversion operators to and from a string, so I can easily use implicit conversion with the linqtosql classes like this: // get an order from the orders table MyDataContext db = new MyDataContext(); Order order = db.Orders(o => o.id == 1); // use implicit converstion to turn the string representation of the order // value into the complex data type. OrderValue value = order.Value; // adjust one of the fields in the complex data type value.Shipping += 10; // use implicit conversion to store the string representation of the complex // data type back in the linqtosql order object order.Value = value; // save changes db.SubmitChanges(); However, I would really like to be able to tell the linqtosql class to type this field as "OrderValue" rather than as "string". Then I would be able to avoid complex code and re-write the above as: // get an order from the orders table MyDataContext db = new MyDataContext(); Order order = db.Orders(o => o.id == 1); // The Value field is already typed as the "OrderValue" type rather than as string. // When a string value was read from the database table, it was implicity converted // to "OrderValue" type. order.Value.Shipping += 10; // save changes db.SubmitChanges(); In order to achieve this desired goal, I looked at the datacontext designer and selected the "Value" field of the "Order" table. Then, in properties, I changed "Type" to "global::MyApplication.OrderValue". The "Server Data Type" property was left as "VarChar(50) NOT NULL" The project built without errors. However, when reading from the database table, I was presented with the following error message: Could not convert from type 'System.String' to type 'MyApplication.OrderValue'. at System.Data.Linq.DBConvert.ChangeType(Object value, Type type) at Read_Order(ObjectMaterializer1 ) at System.Data.Linq.SqlClient.ObjectReaderCompiler.ObjectReader2.MoveNext() at System.Linq.Buffer1..ctor(IEnumerable1 source) at System.Linq.Enumerable.ToArray[TSource](IEnumerable`1 source) at Example.OrdersProvider.GetOrders() at ... etc From the stack trace, I believe this error is happening while reading the data from the table. When presented with converting a string to my custom data type, even though the implicit conversion operators are present, the DBConvert class gets confused and throws an error. Is there anything I can do to help it not get confused and do the implicit conversion? Thanks in advance, and apologies if I have posted in the wrong forum. cheers / Ben

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  • MySQL.. search using Fulltext or using Like? What is better?

    - by user156814
    I'm working on a search feature for my application, I want to search all articles in the database. As of now, I'm using a LIKE in my queries, but I want to add a "Related Articles" feature, sort of like what SO has in the sidebar (which I see as a problem if I use Like). What's better to use for MySQL searching, Fulltext or Like... or anything else I might not know about? Also, I'm using the Kohana Framework, so If anybody knows an easy way to do fulltext matching using the query builder, I'd appreciate that. Thanks.

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  • Filter to values in collection in one query

    - by dotnetdev
    Hi, I have the following LINQ query: List<string> Types = (List<string>) Directory.GetFiles(@"C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727") Where(x => System.IO.Path.GetFileNameWithoutExtension(x).Contains("Microsoft")) .ToList<string>(); How could I modify this so it can only get the values stored in a collection, without writing another LINQ query (which I assume will impact performance?)? Thanks

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  • Intersection() and Except() is too slow with large collections of custom objects

    - by Theo
    I am importing data from another database. My process is importing data from a remote DB into a List<DataModel> named remoteData and also importing data from the local DB into a List<DataModel> named localData. I am then using LINQ to create a list of records that are different so that I can update the local DB to match the data pulled from remote DB. Like this: var outdatedData = this.localData.Intersect(this.remoteData, new OutdatedDataComparer()).ToList(); I am then using LINQ to create a list of records that no longer exist in remoteData, but do exist in localData, so that I delete them from local database. Like this: var oldData = this.localData.Except(this.remoteData, new MatchingDataComparer()).ToList(); I am then using LINQ to do the opposite of the above to add the new data to the local database. Like this: var newData = this.remoteData.Except(this.localData, new MatchingDataComparer()).ToList(); Each collection imports about 70k records, and each of the 3 LINQ operation take between 5 - 10 minutes to complete. How can I make this faster? Here is the object the collections are using: internal class DataModel { public string Key1{ get; set; } public string Key2{ get; set; } public string Value1{ get; set; } public string Value2{ get; set; } public byte? Value3{ get; set; } } The comparer used to check for outdated records: class OutdatedDataComparer : IEqualityComparer<DataModel> { public bool Equals(DataModel x, DataModel y) { var e = string.Equals(x.Key1, y.Key1) && string.Equals(x.Key2, y.Key2) && ( !string.Equals(x.Value1, y.Value1) || !string.Equals(x.Value2, y.Value2) || x.Value3 != y.Value3 ); return e; } public int GetHashCode(DataModel obj) { return 0; } } The comparer used to find old and new records: internal class MatchingDataComparer : IEqualityComparer<DataModel> { public bool Equals(DataModel x, DataModel y) { return string.Equals(x.Key1, y.Key1) && string.Equals(x.Key2, y.Key2); } public int GetHashCode(DataModel obj) { return 0; } }

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  • Cannot login with PhpMyAdmin on Mac os x 10.6. Does anyone know a fix to this error message?

    - by Jannis
    Hi, I just reinstalled Mac Os X 10.6.2 and had to reinstall/update my MySQL server. I run phpMyAdmin inside my localhost and I used to be able to login without a hitch. Since the updated (latest version MySQL 5.1.45 & PMA 3.3.1) versions I only get the following error when trying to login with phpMyAdmin: phpMyAdmin - Error Cannot start session without errors, please check errors given in your PHP and/or webserver log file and configure your PHP installation properly. The only thing I noticed is that mcrypt cannot be loaded (this has always been the case, no idea what to do to install this..) but this has never been a problem before. If anyone know what to do here that would be really appreciated. Thanks for reading, Jannis PS: The MySQL server itself is running and I am able to login with as root user via the MySQL Administrator.app

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  • Overflow exception while performing parallel factorization using the .NET Task Parallel Library (TPL

    - by Aviad P.
    Hello, I'm trying to write a not so smart factorization program and trying to do it in parallel using TPL. However, after about 15 minutes of running on a core 2 duo machine, I am getting an aggregate exception with an overflow exception inside it. All the entries in the stack trace are part of the .NET framework, the overflow does not come from my code. Any help would be appreciated in figuring out why this happens. Here's the commented code, hopefully it's simple enough to understand: class Program { static List<Tuple<BigInteger, int>> factors = new List<Tuple<BigInteger, int>>(); static void Main(string[] args) { BigInteger theNumber = BigInteger.Parse( "653872562986528347561038675107510176501827650178351386656875178" + "568165317809518359617865178659815012571026531984659218451608845" + "719856107834513527"); Stopwatch sw = new Stopwatch(); bool isComposite = false; sw.Start(); do { /* Print out the number we are currently working on. */ Console.WriteLine(theNumber); /* Find a factor, stop when at least one is found (using the Any operator). */ isComposite = Range(theNumber) .AsParallel() .Any(x => CheckAndStoreFactor(theNumber, x)); /* Of the factors found, take the one with the lowest base. */ var factor = factors.OrderBy(x => x.Item1).First(); Console.WriteLine(factor); /* Divide the number by the factor. */ theNumber = BigInteger.Divide( theNumber, BigInteger.Pow(factor.Item1, factor.Item2)); /* Clear the discovered factors cache, and keep looking. */ factors.Clear(); } while (isComposite); sw.Stop(); Console.WriteLine(isComposite + " " + sw.Elapsed); } static IEnumerable<BigInteger> Range(BigInteger squareOfTarget) { BigInteger two = BigInteger.Parse("2"); BigInteger element = BigInteger.Parse("3"); while (element * element < squareOfTarget) { yield return element; element = BigInteger.Add(element, two); } } static bool CheckAndStoreFactor(BigInteger candidate, BigInteger factor) { BigInteger remainder, dividend = candidate; int exponent = 0; do { dividend = BigInteger.DivRem(dividend, factor, out remainder); if (remainder.IsZero) { exponent++; } } while (remainder.IsZero); if (exponent > 0) { lock (factors) { factors.Add(Tuple.Create(factor, exponent)); } } return exponent > 0; } } Here's the exception thrown: Unhandled Exception: System.AggregateException: One or more errors occurred. --- > System.OverflowException: Arithmetic operation resulted in an overflow. at System.Linq.Parallel.PartitionedDataSource`1.ContiguousChunkLazyEnumerator.MoveNext(T& currentElement, Int32& currentKey) at System.Linq.Parallel.AnyAllSearchOperator`1.AnyAllSearchOperatorEnumerator`1.MoveNext(Boolean& currentElement, Int32& currentKey) at System.Linq.Parallel.StopAndGoSpoolingTask`2.SpoolingWork() at System.Linq.Parallel.SpoolingTaskBase.Work() at System.Linq.Parallel.QueryTask.BaseWork(Object unused) at System.Linq.Parallel.QueryTask.<.cctor>b__0(Object o) at System.Threading.Tasks.Task.InnerInvoke() at System.Threading.Tasks.Task.Execute() --- End of inner exception stack trace --- at System.Linq.Parallel.QueryTaskGroupState.QueryEnd(Boolean userInitiatedDispose) at System.Linq.Parallel.SpoolingTask.SpoolStopAndGo[TInputOutput,TIgnoreKey](QueryTaskGroupState groupState, PartitionedStream`2 partitions, SynchronousChannel`1[] channels, TaskScheduler taskScheduler) at System.Linq.Parallel.DefaultMergeHelper`2.System.Linq.Parallel.IMergeHelper<TInputOutput>.Execute() at System.Linq.Parallel.MergeExecutor`1.Execute[TKey](PartitionedStream`2 partitions, Boolean ignoreOutput, ParallelMergeOptions options, TaskScheduler taskScheduler, Boolean isOrdered, CancellationState cancellationState, Int32 queryId) at System.Linq.Parallel.PartitionedStreamMerger`1.Receive[TKey](PartitionedStream`2 partitionedStream) at System.Linq.Parallel.AnyAllSearchOperator`1.WrapPartitionedStream[TKey](PartitionedStream`2 inputStream, IPartitionedStreamRecipient`1 recipient, BooleanpreferStriping, QuerySettings settings) at System.Linq.Parallel.UnaryQueryOperator`2.UnaryQueryOperatorResults.ChildResultsRecipient.Receive[TKey](PartitionedStream`2 inputStream) at System.Linq.Parallel.ScanQueryOperator`1.ScanEnumerableQueryOperatorResults.GivePartitionedStream(IPartitionedStreamRecipient`1 recipient) at System.Linq.Parallel.UnaryQueryOperator`2.UnaryQueryOperatorResults.GivePartitionedStream(IPartitionedStreamRecipient`1 recipient) at System.Linq.Parallel.QueryOperator`1.GetOpenedEnumerator(Nullable`1 mergeOptions, Boolean suppressOrder, Boolean forEffect, QuerySettings querySettings) at System.Linq.Parallel.QueryOpeningEnumerator`1.OpenQuery() at System.Linq.Parallel.QueryOpeningEnumerator`1.MoveNext() at System.Linq.Parallel.AnyAllSearchOperator`1.Aggregate() at System.Linq.ParallelEnumerable.Any[TSource](ParallelQuery`1 source, Func`2 predicate) at PFact.Program.Main(String[] args) in d:\myprojects\PFact\PFact\Program.cs:line 34 Any help would be appreciated. Thanks!

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  • Innodb setting in xampp doesn't seem locate my.cnf file....

    - by bala3569
    I created a new mysql database and i want to use foreign keys with it... I googled and found out this... InnoDB is one of MySQL storage engines, it supports transactions, row-level locking, and foreign-keys. However, by default, InnoDB is not enabled by XAMPP. To enable it, locate the my.cnf configuration file (normally in C:/xampp/mysql/bin directory) and search for the following lines: # Comment the following if you are using InnoDB tables But the path C:/xampp/mysql/bin directory in my system doesn't seem to have such a file... Look at this image http://img691.imageshack.us/img691/524/mysqln.jpg Where is my.cnf file? Any suggestion...

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  • MySQLdb within python2.5 virtualenv

    - by wizard
    I have a Fedora 11 box with MySQL server. Fedora 11 uses python 2.6 internally and python 2.6 is automatically installed on the box. I have created a python virtual-env for version 2.5.5, so that I can run turbogears 1.x application. I have MySQLdb rpm installed on the box (and it works fine with python 2.6). When I import MySQLdb from within python version 2.6 it imports is successfully. When I import MySQLdb from within the python 2.5.5 virtual-env the import fails (because I have installed virtual-env with --no-site-packages). So, I have to install MySQLdb python as a local package (local to virtual-env). 'easy_install MySQL-python' within the virtual env fails. It downloads the MySQL-python-1.2.3.c1.tar.gz/download, but the 'python setup.py build' fails with error. The same problem occurs when building the MySQL outside of virtual-env. Is the 'python setup.py build' for MySQL-python trying to link to a library (and am I missing some library)? Or is the downloaded code missing some header files (unlikely)? Thanks.

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  • Warning: mysql_real_escape_string()?

    - by Tom
    Hi, I am getting the error; Warning: mysql_real_escape_string() [function.mysql-real-escape-string]: Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2) Why do I get this error? The mysql_real_escape_string() works on all of my pages apart from one? Is it something to do with MySQL being on a different server to the PHP server - if so, how do I fix it? Thanks Tom

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  • MySQLNonTransientConnectionException in jdbc program at run time

    - by Sunil Kumar Sahoo
    Hi I have created jdbc mysql connection. my program works fine for simple execution of query. But if i run the same program for more than 10 hour and execute query then i receives the following mysql exception. I have not used close() method anywhere. i created database connection and opened it forever and always execute query. there is no where that i explicitly mentioned timeout for connection. i am unable to identify the problem com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Connection.close() has already been called. Invalid operation in this state. at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: No operations allowed after statement closed. at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) sample code for database connection: String driver = PropertyReader.getDriver(); String url = dbURLPath; Class.forName(driver); connectToServerDB = DriverManager.getConnection(url); connectToServerDB.setAutoCommit(false);

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  • How do I show todays top search list??

    - by mathew
    I owns a website which is doing lots of searches per day. these search results are stored in my MySQL databse. what I want is I want retrieve today's top searches from MySQL limit to 20 and display in my website. how do I do this with PHP & MySQL?? Thanks Mathew

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  • Wordpress databse insert() and update() - using NULL values

    - by pygorex1
    Wordpress ships with the wpdb class which handles CRUD operations. The two methods of this class that I'm interested in are the insert() (the C in CRUD) and update() (the U in CRUD). A problem arises when I want to insert a NULL into a mysql database column - the wpdb class escapes PHP null variables to empty strings. How can I tell Wordpress to use an actual MySQL NULL instead of a MySQL string?

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  • Getting content from PHP: Trouble with POST and query.

    - by vgm64
    Apologies for my longest question on SO ever. I'm trying to interface with a php frontend for a mysql database in ROOT (a CERN framework in C++ for high energy physics analysis). To start off with, I tried to get this php interface to play nice with wget and curl first because I'm more familiar with them. The following command works: wget --post-data "hostname=localhost:3306&un=joeuser&pw=psswd&myquery=show_spazio_databases;" http://some.host.edu/log/log_query_matlab.php The results are: database1 database2 That's good. If I leave out the --post-data then I get the result: Warning: mysql_connect() [function.mysql-connect]: Access denied for user 'admin'@'localhost' (using password: NO) in /log/log_query_matlab.php on line 6 i'm dead! Access denied for user 'admin'@'localhost' (using password: NO) Warning: mysql_query() [function.mysql-query]: Access denied for user 'admin'@'localhost' (using password: NO) in /log/log_query_matlab.php on line 29 Warning: mysql_query() [function.mysql-query]: A link to the server could not be established in /log/log_query_matlab.php on line 29 I have access to the php script (read only), but the error itself isn't too important. What matters it that using ROOT, I use a function called as socket.SendRaw(message, message.Length()) (socket is a TSocket) and this gives me the same "error" as wget without the post data switch if my "message" is "POST http://some.host.edu/log/log_query_matlab.php?hostname=localhost:3306&un=joeuser&pw=psswd&myquery=show_spazio_databases" This may be in vain, but does someone knows a way I should format the "message" that includes something that is equivalent to the --post-data switch. Or, is there a standard way to format POST requests in a single line (I've seen multi-line stuff. Is that right?) Sorry I'm clueless! PS. The mysql query is show databases but the space has been replaced with _spazio_, Italian for space. The author of the db and php interface requires it (and various replacements for symbols), but has anyone seen this before? Trying to troubleshoot that was terrible!

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  • MongoDB - proper use of collections?

    - by zmg
    In Mongo my understanding is that you can have databases and collections. I'm working on a social-type app that will have blogs and comments (among other things) and had previously be using MySQL and pretty heavy partitioning in an attempt to limit possible concurrency issues. With MySQL I've stuffed all my user data into a _user database with several tables to further partition the data (blogs, pages, etc). My immediate reaction with Mongo would be to create a 'users' database with one collection per user. In this way user 'zach' blog entries would go into the 'zach' collection with associated comments and such becoming sub-objects in the same collection. Basically like dynamically creating one table per user in MySQL, but apparently without the complexity and limitations that might impose. Of course since I haven't really used Mongo before I'm having trouble gauging the (ahem..) quality of this idea and the potential problems it might cause down the road. I'd like user data to be treated a lot like a users directory in a *nix environment where user created/non-shared (mostly) gets put into one place (currently with MySQL that would be the appname_users as mentioned above). Most of the users data will be specific to the users page(s). Some of the user data which is queried across all site users (searchable user profiles) is currently kept in a separate database/table and I expect things like this could be put into a appname_system database and be broken up into collections and/or application specific databases (appname_profiles). Anyway, since the available documentation on this is currently a little thin and my experience is extremely limited I thought I might find a little guidance from someone with a better working understanding of the system. On the plus side I'd really already been attempting to treat MySQL as a schema-less document-store and doing this with Mongo seems much more intuitive/sane/rational so I'm really looking forward to getting started. Thanks, Zach

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