I do not want to pay any more money - so, this is not a duplicate.
A request has come down to restart using numbers after 30 days.
I am using AZURE SQL Server.
I have an integer field that is populated when a new record is created. This number, from the previous usage was an autoincrement integer, but, from the manager, this is getting confusing to the users to a see a number that keeps getting larger as they use the system.
So, the manager wants to see the number restart at one on the first of the month, and then increment from there, until the 1st of the month, then the number should start over at 1.
This resetting number is used as part of a concatenated string to generate a unique value, so i am not too worried about the repeating effect of using the same number.
My question is this -
how in the world would this resetting be done? Azure does not really have a event scheduler 'thing' like a locally installed SQL Server does, and I only need it to run one time, where if two records are entered at 12:02AM only the first record would reset the number, the second would build from there.
My first guess was to use an insert trigger on the table, but this would require a large effort. my second thought was to have a next number table, but since it is a reactive type scenario, the number cannot be reset until AFTER midnight and on the first request.
any ideas would be greatly appreciated.
Just done a lift and shift to Azure (mainly App Services & Azure SQL) where there were more than 30 SQL Agent and SSIS Jobs
Solution was to use Azure Functions with Schedule triggers and a set of helpers (there is a small set of common operations that covers most of what was done like sending an email, generating a CSV, saving content to blob storage).
Related
In an on-premises SQL Server database, I have a number of tables in to which various sales data for a chain of stores is inserted during the day. I would like to "harvest" these data to Azure every, say 15, minutes via Data Factory and an on-premises data management gateway. Clearly, I am not interested in copying all table data every 15 minutes, but only in copying the rows that have been inserted since last fetch.
As far as I can see, the documentation suggests using data "slices" for this purpose. However, as far as I can see, these slices require a timestamp (e.g. a datetime) column to exist on the tables where data is fetched from.
Can I perform a "delta" fetch (i.e. only fetch the rows inserted since last fetch) without having such a timestamp column? Could I use a sequential integer column instead? Or even have no incrementally increasing column at all?
Assume that the last slice fetched had a window from 08:15 to 08:30. Now, if the clock on the database server is a bit behind the Azure clock, it might add some rows with the timestamp being set to 08:29 after that slice was fetched, and these rows will not be included when the next slice (08:30 to 08:45) is fetched. Is there a smart way to avoid this problem? Shifting the slice window a few minutes into the past could minimize the risk, but not totally eliminate it.
Take Azure Data Factory out of the equation. How do you arrange for transfer of deltas to a target system? I think you have a few options:
add date created / changed columns to the source tables. Write parameterised queries to pick up only new or modified values. ADF supports this scenario with time slices and system variables. Re identity column, you could do that with a stored procedure (as per here) and a table tracking the last ID sent.
Engage Change Data Capture (CDC) on the source system. This will allow you to access deltas via the CDC functions. Wrap them in a proc and call with the system variables, similar to the above example.
Always transfer all data, eg to staging tables on the target. Use delta code EXCEPT and MERGE to work out what records have change; obviously not ideal for large volumes, this would work for small volumes.
HTH
We are planning to add this capability into ADF. It may start from sequential integer column instead of timestamp. Could you please let me know if the sequential integer column will help?
By enabling "Change Tracking" on SQL Server, you can leverage on the "SYS_CHANGE_VERSION " to incrementally load data from On-premise SQL Server or Azure SQL Database via Azure Data Factory.
https://learn.microsoft.com/en-us/azure/data-factory/tutorial-incremental-copy-change-tracking-feature-portal
If using SQL Server 2016, see https://msdn.microsoft.com/en-us/library/mt631669.aspx#Enabling-system-versioning-on-a-new-table-for-data-audit. Otherwise, you can implement the same using triggers.
And use NTP to synchronize your server time.
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.
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.
I'm using an application written in LabVIEW (an engineering software framework/programming language) to run about twenty thousand simulations. Each simulation takes about 5 mins to complete, and results will be dumped into a database hosted in a laptop in my local network. I'm using SQL Express as my database.
Each simulation job has a set of starting parameters that will be passed to the application. This could be as simple as a string of characters that the application would parse into valid simulation characteristics, but I'm not sure exactly how to structure this.
Because the simulations would take about 3 months to run on one computer, I want to add in the capability for the database computer to be able to "schedule" jobs. That way, I can run the application on any computer in my local network (I have 5 available) for a few simulations, and stop simulations when I need to use it for other things. The database computer will hand out these jobs as they get requested by the application, as well as continuously run jobs itself.
How would I go about setting up this queue from an SQL point of view? The framework I currently have in mind would work something like this: Database has 3 tables in addition to tables used to store simulation data. The tables contain CompletedJobs,RunningJobs, and JobsToRun. The application would request a job from JobsToRun, and place that job's ID into the RunningJobs table. It would then parse the job's ID for relevant information, run the simulation, and if it exits without errors, move the job ID to the CompletedJobs table.
Would this work?
I don't see the need for three tables - why not have one table, Jobs, with a JobStatus field that can take values (e.g.) ToRun, Running, Completed, and perhaps Failed - you can probably think of others. When a simulation starts a new job, it changes the status to Running, when it completes the job it changes it again to Completed or Failed.
You might want fields for StartTime and EndTime, perhaps ErrorCode if your simulation might fail with different types of error? What does the output of the simulation consist of - should you store a filename of the output file, or even upload the output data itself as a BLOB? Let the database take care of assigning each job a unique ID, which would be the primary key for the database table.
What sort of data actually are the starting parameters? If you can store them in database fields, do that. You could put those in a second table if you wanted, and have your Jobs table refer to the parameter set's ID in the job parameters table.
I'm current on POS project. User require this application can work both online and offline which mean they need local database. I decide to use SQL Server replication between each shop and head office. Each shop need to install SQL Server Express and head office already has SQL Server Enterprise Edition. Replication will run every 30 minutes as schedule and I choose Merge Replication because data can change at both shop and head office.
When I'm doing POC, I found this solution not work properly, sometime job is error and I need to re-initialize its. This solution also take a very long time, which obviously unacceptable to user.
I want to know, are there any solutions better than one that I'm doing now?
Update 1:
Constraints of the system are
Almost of transactions can occur at
both shop and head office.
Some transaction need to work in real-time mode, that being said,
after user save data to their local shop that data should go to update at head office too. (If they're currently online)
User can working even their shop has disconnected from head office database.
Our estimation about amount of data is at-most 2,000 rows in each day.
Windows 2003 is OS of Server at head office and Windows XP is OS of all clients.
Update 2:
Currently they're about 15 clients, but this number will growing in fairly slow rate.
Data's size is about 100 to 200 rows per replication, I think it may not more than 5 MB.
Client connect to server by lease-line connection; 128 kbps.
I'm in situation that replication take a very long time (about 55 minutes while we've only 5 minutes or so) and almost of times I need to re-initialize job to start replicate again, if I don't re-initialize job, it can't replicate at all. In my POC, I find that it always take very long time to replicate after re-initialize, amount of time doesn't depend on amount of data. By the way, re-initialize is only solution I find it work for my problem.
As above, I conclude that, replication may not suitable for my problem and I think it may has another better solution that can serve what I need in Update 1:
Sounds like you may need to roll your own bi-directional replication engine.
Part of the reason things take so long is that over such a narrow link (128kbps), the two databases have to be consistent (so they need to check all rows) before replication can start. As you can imagine, this can (and does) take a long time. Even 5Mb would take around a minute to transfer over this link.
When writing your own engine, decide what needs to be replicated (using timestamps for when items changed), figure out conflict resolution (what happens if the same record changed in both places between replication periods) and more. This is not easy.
My suggestion is to use MS access locally and keep updating data to the server after a certain interval. Add a updated column to every table. When a record is added or updated, set the updated coloumn. For deletion you need to have a seprate table where you can put primary key value and table name. When synchronizing fetch all local records whose updated field not set and update (modify or insert) it to central server. Delete all records using local deleted table and you are done!
I assume that your central server is only for collecting data.
I currently do exactly what you describe using SQL Server Merge Replication configured for Web Synchronization. I have my agents run on a 1-minute schedule and have had success.
What kind of error messages are you seeing?