I have inherited a custom built tool that is poorly designed and unstable, and I have a great opportunity to rebuild it from scratch. This is an internal tool only that works almost entirely in Access, and its purpose is to provide higher detail on parts that cost the company over a certain dollar amount.
How it works:
1) The raw data (new part numbers) gets pulled nightly from the EDW via macros in Access.
2) The same macros then join two tables (part numbers from one, names from another). Any part under a certain dollar amount is removed, and the new data is appended to the existing Access database.
3) During the day employees can then open a custom Access form to add more details about the part. Different questions are asked depending on the part category.
4) The completed form is forwarded to management, and the information entered is retained in the Access database – it does not write back to the EDW.
5) Managers can also pull some basic reports from the database, based on overall costs.
The problems:
1) Currently everyone has to have Access installed on their work stations, and whenever there is an update the new database gets pushed to their stations. This is not considered an ideal situation by management or IT.
2) If anyone has left the tool open accidentally at the end of the day the database is locked out, therefore the macros cannot run and the tool cannot be updated with new part numbers.
3) If the tool cannot update for a few days in a row the database can become corrupted. We can restore from the last good backup, in the past this has resulted in the loss of multiple days of work.
Ideally we want to take the tool completely out of Access. I am building a SharePoint site that can host the tool, which (if I can get it right) will eliminate the need of Access on end-user stations with a database push. However the SharePoint form would need read/write ability.
The big question is: How do I build this?
I have a completely open path of possibilities – I can design it work any way I want, using any tools or platform I want, as long as it works. It does not have to update automatically, as I already run a number of SQL scripts at the start of my day and adding one more is inconsequential.
The resources I have at my immediate disposal are: SharePoint (with designer), Access, Toad, and SQL Server. The database can be hosted on a shared network drive.
I am a recent college graduate with basic SQL knowledge. I have about a year to produce a final product, but would like to get it up and running far sooner if possible.
Any advice on what direction to pursue would be very helpful, thank you.
Caveat: I've never worked with SQL Server, so I don't know all of it's capabilities (I'm an Oracle developer).
What I'd do in your situation is something like the following (although not necessarily in this exact order):
Get a SQL Server database set up to host your tables.
Create the tables etc
Migrate test data across (I'm assuming you have a dev/uat/test environment for your current system! If you haven't, make sure you set up at least a separate test environment to prod for your new db!)
Write stored procs to do the work for adding new parts, updating existing data, etc etc
Set up an automated job on the db (I'm assuming SQL Server can do this!) to do the overnight processing.
Create a separate db user with the necessary permissions to call the stored procedures
Get your frontend to call the stored procs with the relevant parameters using the db user you created in step 6 to connect to the db.
You'd also have to think about transaction control to try and mitigate the case where users go home at the end of the day without committing their work - Does the db handle the commits/rollbacks or does Sharepoint?
Once you've worked out everything in your test environment, it's then a case of creating the prod db, users and objects, and then working out the best way of migrating the prod data across.
Good luck.
Don't forget to get backups for the new db set up as well.
Related
I've been using Access to rapid-prototype a DB. Now I'd like to do a small group online test so I split the DB and placed the back-end on Azure SQL Server, then re-linked. It's incredibly slow and I've been researching solutions for days without positive results. My local environment is Win10, Office2016 64bit and internet connection is fast and stable.
I have tried different ODBC drivers, including the SQL Native Client v11.
I've disabled auto-tuning level on the NIC.
I've recreated all queries from access on the server.
I've made sure that Tracing in ODBC is off.
But I enabled tracing temporarily to see what was happening. If I opened the front-end, logged in (Small user table), and did something on the first form (Add 1 record with 3 sub-records...and really...nothing fancy or heavy at all and this only takes 1 minute) then closed the DB, I see that the Tracing log file is 1.5MB.
So I created an empty Access file and an ODBC link to only the User table (12 columns, 20 records), and then monitored the tracing log file again. Opening access doesn't add anything to the log file, but opening this one, linked table made the log file grow to 255kb. Opening this table in access took 5 seconds.
Access sent about 800 requests to the server for opening just this one small table. If I paste all the User table data into a text file, it's only 2kb. SO why is it so slow?
Any ideas on this, and specifically other suggestions to get this working faster?
Kind regards,
Well, the reason why using Azure is slower than running Access connected to a local instance of SQL server is because, well slow is slow!
I mean, if you going to travel 30 miles, you have a choice to walk, or to take a car.
So here is the question you need to know:
Why is walking slower than driving a car?
Answer: Because you are travelling at a slower speed!
So why is using Azure slower the using an instance of SQL server running on your local computer or local network?
Answer:
Because the connection speed to Azure is about 100 times slower!
The idea here that you not going to take into account the DIFFERENCE in connection speed is the issue here. It is a disservice to the reading public that may conclude that such a setup (Access front end on a pc to Azure instance of SQL server) is not a viable setup.
So the first issue here is to make a note of your connection speed to the back end database.
A typical office local area network has a speed of 100mbits, or today most are 1gig – even the el-cheapo routers you purchase at Best Buy are now rated at 1gig (1000 mbits).
However, your typical high speed internet is rated at about 5, or 10 mbits. So that is 100 times slower. (Actually 1000/5 = 200 times slower!!!).
That means if something NOW takes 3 seconds on your office network with Access and SQL server? Well then a WAN (over the internet), then you need to multiple the time by the change in your connection speed (this is so simple – yet it seems to escape all!). So, if you lucky, you might have a 5 mbits speed rating for your internet. That means you go
1000 / 5 = 200
You now take the 200 and multiple the existing delay you have of say 3 seconds and you get 600 seconds (that is 10 minutes if you are wondering!). So you going from 3 seconds to 10 minutes!
This kind of comparison in speed would be like walking into a sports shop to purchase a rubber boat to cross the Atlantic. So not taking into account the change in internet speed and wondering why things are slow is the issue here.
You can most certainly use Access to Azure, but you have to realize two simple concepts.
a connection and test with a connection that is 50-200 times slower than your LAN is a test that going to run 50 to 200 times slower! The failure to mention and take into considering the MASSIVE DIFFERENCE in your speed connection of your LAN compared to a WAN is the simple issue here.
opening a form bound to a large table of data is going to case performance issues.
I was sitting at the bus stop talking to a 90 year old granny lady. I asked her the following:
Have you ever used an instant teller?
She said, why yes, I use them all the time.
I then asked here don’t you think it would be bad to have the teller machine download all the peoples accounts while you wait and THEN ask you for your account number?
The old lady stated, of course, that would be silly. I type in my account pin and the machine ONLY downloads my account information – this is practical and obvious.
In other words that old lady realised that downloading a bunch of data BEFORE you the user even types in or does anything is a waste of bandwidth.
So you never want to launch a form bound to a table and THEN ask the user what record to work on. Why have Access download large numbers of records into a form and THEN ask the user or allow the user to navigate to the required record?
Even when using Google, it does not download the whole internet into your web browser page and you then go ctrl+f to search the contents of that web page.
The same concepts should be applied to Access applications. A design that asks for what to work on and then launches a form bound to a table with a "where" clause will thus fix this issue.
So if you have a form (and even a sub form) that displays a customer invoice, you would FIRST ASK FOR the invoice number, and then simply launch that form using a where clause that restricts the form to the ONE invoice!
Keep in mind that you can STILL use that invoice form bound to a table of 1 million rows and ONLY THE ONE record will be pulled down the network connection *if one used the where clause.
So a typical internet connection has adequate speed to run a browser, and also has MORE than adequate bandwidth speed to pull down a few records. Access often gets a bad rap for poor performance, but that is ONLY DUE to Access developers IGNORING the obvious advice that downloading tons of things that you don’t yet need into a form will run slow.
So web based applications, or even desktop applications written in vb.net perform well with SQL Azure running in the cloud over that MUCH slower internet connection because those applications don’t launch forms bound to large datasets WITHOUT FIRST simply allowing the user to request what they need to see and view.
As for Access and using SharePoint? That setup can be VERY fast, and in fact MUCH faster than SQL Azure, MySQL or any traditional database system because when you using SharePoint tables and Access, then Access automatic syncs a copy of the data local. This setup means your application will continue to run WITHOUT ANY internet connection. The instant the connection is restored, then the data sync can resume.
This means that if you have a table with 15,000 rows and run a report on that data the report can run and launch in an instant with SharePoint back end since a local copy of the data exists in the front end at ALL TIMES! So this setup is VERY well suited an off line mode or in cases that you have a poor and slow internet connections since you as noted always have local copy of the data – only when a record is changed does a sync occur, and that sync can occur independent of Access. So you change one record – and it starts syncing with SharePoint.
However for larger data sets that have to be updated, then SQL server is far better since you can execute a sql update on 10,000 rows and ZERO network traffic and transfer of data need occur to update those 10,000 rows when using SQL server (a pass through query) and when using SharePoint, the 10,000 rows WILL transfer over the network since the local copy requires the rows to be updated. So that massive advantage of using SharePoint for the database backend does not exist for applications that have to update lots of rows or do lots of row update types of data processing.
So the key concepts and take away here:
The high speed internet connection you have is often 10-200 times slower than your typical cheap office (local) network. So that means a 2 second operation will now take 10-200 times longer.
The Access application needs to be optimized to avoid things like loading too many records into a form. So building search forms etc. That FIRST ASK the user what they need to work on is a basic and simple requirement for all good developers and that includes Access developers.
Access and SharePoint can be the BEST option, and such a setup allows the application to run EVEN WHEN there is no internet connection at all. If table sizes are below say 10,000 rows, then this setup can often be ideal. However for applications that have to update lots of rows and for data processing heavy applications this setup is poor since updates to any rows will case data syncing to occur over the network. This setup is also the cheapest, since a single office 365 account with SharePoint support for Access can be had for $6 per month, and that $6 account allows up to 500 free users and those 500 users can even use their Gmail or non-Microsoft account for this setup. And such access applications that do fit within the bounds of SharePoint tables tend to need far less changes and optimizing then using SQL server over the internet.
With SQL server, use of views, pass-tough query and in some cases writing store procedures allows updates and code to run WITHOUT using ANY bandwidth. So one can send a single update query to the server that updates 10,000 rows of data – the only network cost will be the “tiny” amount of bandwidth to send that sql statement.
So while bound forms can be used with SQL Azure running in the cloud, one needs to build software like those do for the web, or vb.net in which they FIRST ask the user what account or customer to work on and THEN launch the UI to display that given data.
So in access, you build a search form say like this:
So at the end of the day, it is important to ignore posts here that suggests Access to SQL in the cloud is not viable. Access with proper designs will work rather well over typical internet connections to SQL server running on Azure.
In fact I seen people use Access to SQL over a 56k modem!
One has to adopt sensible designs in which the data pulled for a given task is restricted – this is a hall mark of all developers – the only issue is Access does NOT enforce this approach while most other developer tools don’t let you hang yourself with things like bound forms to large tables! It not that Access is slow, but Access is slow when you make poor design decisions.
Access to SharePoint can be a real winner – especially for poor bandwidth, spotty bandwidth and even when the connection is lost, the application will continue to run and run faster than 99% of the cases if you were running the same application with a SQL back end. There is a BIG caveat here since only certain types of applications will work well with SharePoint tables. For me to explain the why, how, and when such applications are better is beyond a simple post here, but one simply needs to be aware that SharePoint can be incredible solution, but not for all applications and SQL server can and will be better choice. This SharePoint “better” choice can only be determined on a case by case evaluation of the given type of application in question.
The problem is simply that Azure SQL Database is not very fast running with small DTUs (Database Transaction Units) compared to, say, an in-house instance of SQL Server hosted on even a moderate modern server.
I've checked it out too, and it requires extremely careful design of queries and filtering - far from what you normally can get away with - to obtain acceptable overall speed. On the other hand, this is a giving experience that will bring focus to potential bottlenecks you otherwise wouldn't encounter before it might be too late.
OK, so after almost a week of trying to get this to work (Access front-end to SQL Server back-end on Azure), I've come to the conclusion that it's not a viable solution.
I've tried SQL Server, and setup a Sharepoint 2016 server on Azure, which also failed.
What has worked is using a product from Bullzipp called MS Access to MySQL to convert the access tables, then adding a MySQL DB on the server and importing the file generated by Bullzip. The only thing to note here is that Bullzip doesn't like the newer access formats (it wants an MDB file) so go to Access, create a new, empty file, but make sure you set its file type to MDB. then import your tables across and run Bullzip.
It's now working a hell of a lot faster than the SQL Server, but I am getting some write conflicts in Access, so I just need to go through the code and do whatever I need to so I can avoid those messages.
Using Access as a front to Azure SQL tables is the worst solution. But, sometimes you have to do it. I have a client who is adamant that she wants to keep her Access database. When she hired her very first employee, it became clear she needed to SQL tables behind the screens.
This was a bit of a nightmare. However, after redesigning some terrible table structures, creating views and many procs, I've been able to do it. I use local tables in some cases, and refill by pulling from a stored proc and inserting into the local table. I use linked tables for basic data edits, and do explicit save records almost constantly.
I also have a first-load module that opens all forms, goes to the last record, back to the first record, and then hides the form until needed. The load limps along for about 3
My only remaining issue is now that Azure will close connections after idle time of (I think) 30 or more minutes -- or maybe it's when the laptop sleeps? That kills the app and it has to be closed and re-opened.
In all the years of my experience, I always connected to a database by creating a new connection using IP address, username and password.
I recently joined a company where they use a desktop application written in VB6 that has an SQL server backend. Here, the practice is, get a backup of the latest version of SQL server and name it as a different DB, use it for testing purposes.
We now have a issue where we have loads of these databases created by users and it needs cleanup.
My question: Is it possible to have a centralised database which exists remotely to which everyone connects and gets the data? what are the things that we need to keep in mind to achieve this goal, so everyone can have one single database to access to, where they can make the changes.
We've been using a single centralized dev/test environment for over a decade now, with up to 50 full time developers using it -- and I'd say it works quite fine. Most of the changes are new columns into tables and not that many developers are working with the same tables / modules at the same time, so it doesn't cause that much issues.
All our stored procedures / functions are renamed for each release separately (by adding a release number in the end), and installed automatically with compilation process, even for developers. For developers compilation, the version numbers also include the developers userid. This way changing stored procedures in development won't break the test environment, or the procedures other developers are using.
The biggest advantage of this is that we can use similarly sized databases for testing and production.
Your ability to do that is really a functional and/or procedural issue. There's nothing technical that prevents you from having a single, shared database for dev/test. The challenge is, dev/test environments tend to be destructive and/or disruptive.
If you have a single DB used for all development and testing requirements, you'll probably get little to no work done. One dev modifying an object (SP, FN, table, view, etc...) can potentially break everyone else (or no one). A tester running stress tests will have everyone else getting mad about slow responses, timeouts, etc... Someone decides to test Always Encrypted or even sometime simpler like TDE can end up breaking everybody.
Dev environments almost always need their own sandbox before check-in. Checked in code/schema then get tested in a central environment that mimics prod before going to pre-prod that is (ideally) identical to prod. This is pretty basic though each team/company will have its variations.
One thing you could do right away is to automate taking a copy backup of the prod database so you drop a fresh .bak to a common location where everyone can grab from and restore to their own instance. This reduces the impact on your production system and reduces storage consumption. Another benefit is you remove all non-essential access to your production database - this is really, really important. Finally, once this is standard op, you can implement further controls or tasks in the future easily (e.g. restore to a secure instance, obfuscate/mask sensitive data, take new backup for dev/test use).
It is possible but it's usually not a good idea. It would be ok (and no more than ok) if all database access was inquiry only, but imagine the confusion that could arise if developer a fires in some updates to a table that developer be is writing a report for or if the DB was recovered in an uncontrolled manner. Development and test need a lot of managing and how many databases you need and where will depend on an analysis of your dev and test requrements.
Thanks for all the answers. We all had a discussion in our team and came up with a process that suits to our team:
There is a master database backed up and restored from the most recent and stable source
Only QA team has got write access to this database
Developers make their own test database using the Master backup
If new data is required, write SQL scripts to add it
Run unit & E2E tests on their copy
Give the new tests and scripts to add new data (if any) to QA
QA runs the tests and data scripts on the Master
When the tests are passed, if there is a SQL update script, then QA restores the Master Database from the backup (to remove data changes made by running the tests), runs the SQL scripts to update the data then backs it up as the new Master
Scripts are added to source control so we have a history
Note: As an extra safeguard we can keep a copy of the very first ever Master database somewhere else. So if anybody ever does something dumb and corrupts it, we can retrieve it and run all the SQL scripts to bring it up to date.
In SQL 2008, is there a way to specify a service_broker_guid instead of simply taking whatever GUID is given to you by:
ALTER DATABASE MyDB SET NEW_BROKER
Our current (broken, in my opinion) release methodology is to restore two databases which have a codependent relationship. One is a "source" database, and one is a star-schema BI database. Part of the regression test plan is to restore backups of both databases in a "gold" state across different servers and even on the same server.
We generally do not include BROKER_INSTANCE variables on our routes because most places, we do not need them (i.e. the combination of SERVICE_NAME and ADDRESS is enough to guarantee delivery). However, when we have 2 databases running on the same instance both with broker enabled, one of these will need a new BROKER_ID. In addition, all routes to these databases will now require a BROKER_INSTANCE qualifier, since there are 2 SERVICE_NAME's on the same ADDRESS.
We use Visual Studio Database Professional to generate our build output scripts, and there's simply no simple way to include a BROKER_INSTANCE as part of it's SQLCMD variable replacement technique, unless you know it before hand.
No. NEW_BROKER would generate a new guid.
There is no way to use a specific guid and that is very much intentional. If you explain what is the underlying problem that is making you ask this question, perhaps we can work toward a solution to that problem.
After your edit.
The broker_instance, as well as routing information, is considered runtime, deployment specific information. As such, it was not designed to accept fixed, predetermined values, which is what a VS GDR project or a set of SQLCMD scripts would like to use. Besides, the broker_instance_id is really meant to be a unique, database instance specific value, and allowing users to specify their own would quickly result in duplicates, which would confuse the heck out of conversation endpoints trying to exchange messages.
The problem you're facing though is a legitimate one. How to automate deployment of routing information (and it's associate problems of automating the deployment and exchange of certificates, configuring users w/o login and granting appropiate permissions, configuration of remote service bindings and service broker transport endpoints). There simply is no Wizard to do this. Quest has a set of tools that handle this actually.
Once upon a time I made a tool, called ssbslm.exe, that automated this entire process and was designed to be usable from scripts. This tool did everything to set up the routes, certificates and endpoints between two arbitrary services. While this tool is no longer available (long and boring story why that is the case), the gist of this story is that is not that hard to write one. Took me few days back in the day.
Just a question about best-practices when upgrading an existing database. Assuming there will be all kinds of modifications to the data itself, the structure, the relations, additional columns, disappearing columns and whatever more.
My problem is a simple one. I'm working on a project that will use SQL Server. No problem there, since I'm enough of an expert to handle this. But this project will be upgraded later on and I need to specify a protocol that needs to be followed by the upgrade mechanism. Basically, this protocol needs to be followed when creating upgrade scripts...
Right now, I have these simple steps:
Add the new columns to the tables.
Add constraints to the new columns.
Add new tables.
Drop constraints where needed.
Drop columns that need to be removed.
Drop tables that need to be removed.
Somehow, this list feels incomplete. Is there a more extended list somewhere describing the proper steps which needs to be followed during an upgrade?
Also, is it always possible to do a complete upgrade within a single database transaction (with SQL Server) or are there breakpoints that need to be included within the protocol where one transaction should end and another one starts?While automated tools will provide a nice, automated solution, I still can't really use them. The development team working on this system has 4 developers, each with their own database on their local system. Every developer keeps track of their own updates to the structure and keeps track of them by generating both an Upgrade and Downgrade script for his own modifications, both for structural changes and data changes. These scripts can then be used by the other developers to keep their own system up-to-date. Whenever the system is going to be released, those scripts are all merged into one big script.
The system does not include any stored procedures or other "special" features. The database is just that: a data storage with just tables and relations between them. No roles, no users, no stored procedures, no triggers, no complex datatypes...The DB is used by an application where users work from 9-to-5 so shutting down can be done easily, including upgrades for the clients. We also add a version number to the database and applications will check if they're linked to the correct database version.
During development, all developers use their own database instance, which they can fully control. Since we're not the ones who use the application, we tend to develop for the Express edition, not any more expensive one. To be honest, we don't develop our application to support a lot of users, but we'll inform our users that since it uses SQL Server, they could install the system on a bigger SQL Server platform, according to their own needs. They will need their own DBA for this, though. We do have a bigger SQL Server available for ourselves, which we also use for our own web interface, but this server is located in a special dataserver where it is being maintained for us, not by us.
The project previously used MS Access for it's data storage and was intended for single-user development, but as it turned out, many users still decided to share their databases and this had shown that the datamodel itself is reliable enough for multi-user environments. So we migrated to SQL Server to support smaller offices with 3 or more users and some big organisation who will have 500 or more users at the same time.
Since we need to keep the cost of the software low, we don't have a big budget to spend on expensive tools or a more expensive server.
Check out Red-Gate's SQL Compare (structure comparison), SQL Data Compare (data comparison), and SQL Packager (for packaging up updates scripts into a C# project or a .NET executable).
They provide a nice, clean, fully functional and easy-to-use solution for all your database upgrade needs. They're well worth their license fees - that pays for itself in a few weeks or months.
Highly recommended!
In my opinion, it's an absolute bear doing these manually. For Microsoft SQL Server, I'd recommend using the Database editiion of Team System, since it includes complete source control capabilities for your database, and can automatically build your scripts for upgrading/downgrading versions.
Another option is SQLCompare with Redgate, which can also handle these kinds of upgrades/downgrades, and will result in a very nice SQL script. I've used both, and keeping the historic scripts has helped us troubleshoot issues and resolve many a mystery.
If you are working with a manual script as above, don't forget to also account for SP changes in your scripts. Also, any hand-edited script should be able to be executed multiple times on a database - i.e. if your script includes a table creation or drop, be sure to check for existance first, otherwise your script will fail if executed back to back.
Again, while it's possible to build a manual protocol I'd still fall back on using one of the purpose-built tools out there, and both Team System and SQL Compare will be able to output scripts that you could include as part of an installation/upgrade package.
With database updates I always believe it should be all or nothing. If any of the DB updates fail your application will be left in an unknown state that could be harmful to the data so I think it is best practice to either apply them all or none (1 transaction around them all).
I also like to backup the database before applying updates so that if anything does go wrong the database can be rolled back (this has saved me numerous times when working with live data).
Hope this helps.
Best practices for upgrading a production database schema actually look pretty bad on the surface. Unless you can completely shut down your system for the upgrade, which is often not possible, your changes all need to be backwards compatible. If you have many clients accessing the database, you can't update them all simultaneously, so any schema changes you make need to allow old code to run.
That means never renaming a column, and making all new columns nullable. This doesn't mean you leave it like that forever. You write two scripts, one for the initial change, which is backwards compatible, then another to clean things up after all clients have been updated.
Automated tools are great for validation of schemas, but they are not so good when it comes to actually modifying a complex system. You should break your changes up into many small, discrete change scripts so each can be run manually. If there's a failure, it's easier to pinpoint the cause and fix it. Basically, each feature gets its own script. Give each a unique name and then store that name in the database itself when you run the script so you can query the database to find out what's been run and what hasn't. This is invaluable when you have instances on developer's machines, test servers, production, etc.
I'm writing a system at the moment that needs to copy data from a clients locally hosted SQL database to a hosted server database. Most of the data in the local database is copied to the live one, though optimisations are made to reduce the amount of actual data required to be sent.
What is the best way of sending this data from one database to the other? At the moment I can see a few possibly options, none of them yet stand out as being the prime candidate.
Replication, though this is not ideal, and we cannot expect it to be supported in the version of SQL we use on the hosted environment.
Linked server, copying data direct - a slow and somewhat insecure method
Webservices to transmit the data
Exporting the data we require as XML and transferring to the server to be imported in bulk.
The data copied goes into copies of the tables, without identity fields, so data can be inserted/updated without any violations in that respect. This data transfer does not have to be done at the database level, it can be done from .net or other facilities.
More information
The frequency of the updates will vary completely on how often records are updated. But the basic idea is that if a record is changed then the user can publish it to the live database. Alternatively we'll record the changes and send them across in a batch on a configurable frequency.
The amount of records we're talking are around 4000 rows per table for the core tables (product catalog) at the moment, but this is completely variable dependent on the client we deploy this to as each would have their own product catalog, ranging from 100's to 1000's of products. To clarify, each client is on a separate local/hosted database combination, they are not combined into one system.
As well as the individual publishing of items, we would also require a complete re-sync of data to be done on demand.
Another aspect of the system is that some of the data being copied from the local server is stored in a secondary database, so we're effectively merging the data from two databases into the one live database.
Well, I'm biased. I have to admit. I'd like to hypnotize you into shelling out for SQL Compare to do this. I've been faced with exactly this sort of problem in all its open-ended frightfulness. I got a copy of SQL Compare and never looked back. SQL Compare is actually a silly name for a piece of software that synchronizes databases It will also do it from the command line once you have got a working project together with all the right knobs and buttons. Of course, you can only do this for reasonably small databases, but it really is a tool I wouldn't want to be seen in public without.
My only concern with your requirements is where you are collecting product catalogs from a number of clients. If they are all in separate tables, then all is fine, whereas if they are all in the same table, then this would make things more complicated.
How much data are you talking about? how many 'client' dbs are there? and how often does it need to happen? The answers to those questions will make a big difference on the path you should take.
There is an almost infinite number of solutions for this problem. In order to narrow it down, you'd have to tell us a bit about your requirements and priorities.
Bulk operations would probably cover a wide range of scenarios, and you should add that to the top of your list.
I would recommend using Data Transformation Services (DTS) for this. You could create a DTS package for appending and one for re-creating the data.
It is possible to invoke DTS package operations from your code so you may want to create a wrapper to control the packages that you can call from your application.
In the end I opted for a set of triggers to capture data modifications to a change log table. There is then an application that polls this table and generates XML files for submission to a webservice running at the remote location.