Context
I have an Azure Function which executes daily, it is change tracking a pricing feed with the results stored in a Cosmos DB. Each time it runs it compares the latest price from the feed, against the most recent values in the DB collection and writes a new item if there is a difference. It is scheduled to run at 23:55 each day. The overall setup is tiny, with 10 items in the DB, and changes seen usually once a week. My consumption is 3.84 RUs for the daily execution when the price hasn't changed.
Question
In addition to the expected activity at 23:55 each day, there is additional activity appearing almost every 3 hrs 45 mins. This unexpected activity consumes 4 RUs each time (around 24 RUs per day). How can I identify the source of the additional activity?
Other info
I noticed that the backups were scheduled to 4 hours, so I changed that to daily. That didn't help.
Since noticing the additional usage I have added diagnostic settings to save all logs into a Log Analytics workspace. I can see that the RUs are Read operations, Type = AzureDiagnostics, requestResourceType = Collection, Source IP = 51.11.40.180, 1 of the 4 is a read against the __Cosmos/colls/__Query collection. This suggests to me that it's the diagnostics causing the cost. I disabled the diagnostic settings to see if that reduced my RU consumption, but it does not.
Is it just a case that diagnostics are run by Microsoft and that is simply part of having a cosmos db?
And that usually it's a smaller proportion of the overall cost, therefore not an issue?
Related
I’m struggling to understand how the pricing mechanism for RU/s works. Specifically my confusion comes in when the word “first” is used.
I’ve done my research here:https://devblogs.microsoft.com/cosmosdb/build-apps-for-free-with-azure-cosmos-db-free-tier/?WT.mc_id=aaronpowell-blog-aapowell
In the second paragraph it’s mentioned:
“With Azure Cosmos DB Free Tier enabled, you’ll get the first 400 RU/s throughput and 5 GB storage in your account for free each month, for the lifetime of the account.”
So hypothetically speaking if I have an app that does one query and that 1 query evaluates to 1RU. Can I safely assume that
400 users can execute the query once per second for free?
500 users can execute the query once per second and I will only be charged for 100RU
If the RU is consistently less than 401 per second, there will be no charge
Please do make mention if there’s any other costing I should be aware of. Ie. Any cosmosDb dependencies, or app service costing
You're not really thinking about RU/sec correctly.
If you have, say, 400 RU/sec, then that is your allocated # of RU within a one-second window. It has nothing to do with # of users (as I doubt you're giving end-users direct access to your Cosmos DB instance).
in the case of operations only costing 1 RU, then yes, you should be able to execute 400 operations within a 1-second window, without issue (although there is only one type of operation costing 1 RU, and that's a point-read).
in the case you run some type of operation that puts you over the 400RU quota for that 1-second period, that operation completes, but now you're "in debt" so to speak: you will be throttled until the end of the 1-second period, and likely a bit of time into the next period (or, depending on how deep in RU-debt you went, maybe a few seconds).
when you exceed your RU/sec allocation, you do not get charged. In your example, you asked what happens if you try to consume 500 RU in a 1-second window, and asserted you'd be charged for 100 RU. Nope. You'll just be throttled after exhausting the 400 RU allocation.
The only way you'll end up being charged for more RU/sec, is if you increase your RU/sec allocation.
There is some more reading out there you can do:
azure cosmos db free tier
pricing examples
I'm thinking of using Data Factory in order to copy data from a Blob Storage container to an SQL table but I'm not quite sure I understand how the pricing works, specifically how the activities are counted.
So if I have a pipeline with 3 activities that copies the data from a CSV with 1000 lines will the total activity count be 3*1 or 3*1000? In other words, will I be charged based on the number o files it processes or the total number of lines it copies?
That's 3 activity runs. Activity runs are measured by the thousand, at $1 per. Since these are Copy activities, they consume Data Integration Units (DIU) at $.25 per hour. Pipeline execution time is billed at $.005 per hour. If you add all this up for 1 pipeline with 3 Copy activities that runs for 1 hour, your total bill is like 27 cents.
We run THOUSANDS of pipelines a month, all with many activities including quite a few Copy activities. Our Data Factory billing is still so low that it looks like a rounding error in our total Azure spend.
The exception to this is Data Flow. Data Flow is a Spark wrapper, so you have to pay for Cluster time, which can get expensive quickly if you aren't careful.
Actually, you have to pay for 2 important metrics: Orchestration and Execution. Please refer to more details from this document.
1.Orchestration, $1 per 1,000 runs. You have 3 activities, then it should be $ 3/1000.
2.Execution, it depends on the DIU you configured,which means the performance of your transmission.
At the moment most of the data retained for 90 days by default. I was wondering if there way to change this setting to 30-40 days. I know that I can export them to keep the data longer but what I'm looking for is mainly keep the data for shorter duration for the upcoming regulations.
Update
The default retention for Application Insights resources is 90 days. Different retention periods can be selected for each Application Insights resource. The full set of available retention periods is 30, 60, 90, 120, 180, 270, 365, 550 or 730 days.
Note: If you need to keep data longer than 730 days, you can use Continuous Export to copy it to a storage account during data ingestion.
To change the retention, from your Application Insights resource, go to the Usage and Estimated Costs page and select the Data Retention option:
Reference
Sometimes the only answer is a no. In this case, you can't. From the docs:
Raw data points (that is, items that you can query in Analytics and inspect in Search) are kept for up to 90 days. If you need to keep data longer than that, you can use continuous export to copy it to a storage account.
Aggregated data (that is, counts, averages and other statistical data that you see in Metric Explorer) are retained at a grain of 1 minute for 90 days.
I remember that a long time ago the pricing tier dictated the maximum retention period but it is now fixed to 90 days for all plans.
You can try give your feedback / ask for this feature here.
It is now available as an option in the Azure portal. If not, you need to get in touch with Azure support to get it activated.
Note
This is getting quite long so I will try and re-edit parts through the day.
These databases are no long active, which means I can play with them to work out what is going wrong.
The only thing left to answer: Given two databases running on Azure Databases at S3 (100 DTU). Should any secondary ever get significantly behind the primary database? Even while the DTU is hammered to 100% for over half the day. The reason for the DTU being hammered being IO writes mostly.
The Start: a few problems.
DTU limits were hit on Monday, Tuesday and to some extent on Wednesday for a significant amount of time. 3PM UTC - 6AM UTC.
Problem 1 (lag in data on the secondary): This had appeared to have caused a lag of data in the secondary of about 9 1/2 hours. The servers were effectively being spammed with updates causing a lot of IO updates. 6-8 million records on one table for the 24 hour period for example. This problem drove the reason for the post:
Shouldn't these be much more in sync?
The data became out of sync on Monday morning and continued out of sync until Friday. On Thursday some new databases were started up to replace these standard SQL databases and so they were left to rot. Well, for me to experiment with at least.
The application causing the redundant queries couldn't be fixed for a few days (I'm doubting they will ever fix it now) so that leaves changing the instance type. That action was attempted on the current instance but, the instance must disconnect with all standard replicas to increase to the performance tier. This led to the second problem (see below). The replica taking its time to be removed. Began on Wednesday morning and did not complete until Friday.
Problem 2 (can't remove the replica):
(Solved itself after two days)
Disconnecting the secondary database process began ~ Wed 8UTC (when the primary was at about 80GBs). The secondary being about 11GB behind in size at this point.
Setup
The databases (primary and secondary) are S3 that is geo-replicated (North + West Europe).
It has an audit log table(which I read from the secondary - normally with an SQL query), but this is currently 9 1/2 hours behind the last entry for the primary database. Running the query again on the secondary a few seconds later it is slowly catching up, but appears to be relative to the refresh rather than playing catch-up.
Both primary and secondary (read-only) databases are S3 (about to be bumped to P2).
the azure documentation states:
Active Geo-Replication (readable secondaries) is now available for all databases in all service tiers. In April 2017, the non-readable secondary type will be retired and existing non-readable databases will automatically be upgraded to readable secondaries.
How has the secondary has got so far behind? seconds to minutes would be acceptable. Hours not so much. The link above describes it as slightly:
While at any given point, the secondary database might be slightly behind the primary database, the secondary data is guaranteed to always be transactionally consistent with changes committed to the primary database.
Given the secondary is about to be destroyed and replaced by a higher level (need to remove replicas when upgrading from standard -> premium). I'm curious to know if it will happen again as well as what the definition of slight might be in this instance?
Notes: The primary did reach maximum DTU for a few hours but didn't harm the performance significantly, which is where the 9-hour difference was noticed.
Stats
Update for TheGameiswar:
I can't query it right now as it started removing itself as a replica (to be able to move the primary up to the P2 level, but that began hours ago at ~8.30UTC and 5 hours later it is still going). I think it's quite broken now.
Query - nothing special:
SELECT TOP 1000 [ID]
,[DateCreated]
,[SrcID]
,[HardwareID]
,[IP_Port]
,[Action]
,[ResponseTime]
,[ErrorCode]
,[ExtraInfo]
FROM [dbo].[Audit]
order by datecreated desc
I can't compare the tables anymore as it's quite stuck and refusing connections.
The 586 hours (10-14GB) are inserts into the primary database audit table. It was similar yesterday when noticing the 9 1/2 hour difference in data.
When the attempt to remove the replica (another person stated the process) it had about 10GB difference in size.
Cant compare data but can show DB-size at equivalent time
Primary DB Size (last 24 hours):
Secondary DB Size (last 24 hours):
Primary database size - week view
Secondary database size - week view
As mentioned ... it is being removed as a replica... but is still playing catch up with the DB size if you observe the charts above.
Stop replication errored for serverName: ---------, databaseName: Cloud4
ErrorCode: 400
ErrorMessage: A terminate operation is already in progress for database 'Cloud4'.
Update 2 - Replication - dm_continuous_copy_status
Replication is still removing ... moving on...
select * from sys.dm_continuous_copy_status
sys.dm_exec_requests
Querying from Thursday
Appears to be quite empty. The only record being
Replica removed itself at last.
The replica has removed itself after 2 days. At the 80GB mark that I predicted. It waited to replay the data in the transactions (till the point it was removed as a replica) before it would remove the replica.
A Week after on the P2 databases
DTU is holding between 20-40% at busy periods and currently performing ~12 million data entries every 24 hours (a similar amount for reads, but writing is much worse on the indexes and the table). 70-100% inserts extra in a week. This time, the replica is not struggling to keep up, which is good but that is likely due to it not reaching 100% DTU.
Conclusion
The replicas are useful but not in this case. This one caused degraded performance for several days that could have been averted. A simple increase to the performance tier until the cause of the problem could be fixed. IF the replica looks like it is dragging behind and you are on the border of Basic -> Standard or Standard -> Performance it would be safe to remove the replica as soon as possible and increase to a different tier.
Now we are on P2. The database is increasing at 20GB a day... and they say they have fixed the problem that sends 15 thousand redundant updates per minute. Thanks to the query performance insight for highlight that as querying the table is extremely painful on the DTU (even querying the last minute of data in that table is bad on the DTU. ~15 thousand new records every minute).
62617: insert ...
62618: select ...
62619: select ...
A positive from the above is that it's moved from 586 hours combined time for the insert statements (7.5 million entry rows per day) on S3 to 3 hours on P2 (12.4 million row rows per day). An extremely significant decrease in processing time. It did start with an empty table on Thursday but that has surpassed the previous size in a week whereas the previous one took a few months to get there.
It's doing well on the new tier. It should be ~5% if the applications were using the database responsibly and the secondary is up to date.
Spoke too soon. Now on P2
Someone thought it was a good idea to run an SQL query that repeats itself that deletes a thousand rows at a time. 12 million new rows a day.
10AM - 12AM it's managed to remove about 5.2 million rows. Now the database is showing signs of being in the same state as last week. Im curious if that is what happened now.
The facts:
1 Azure SQL S0 instance
a few tables one of them containing ~ 8.6 Million Rows and 1 PK
Running a Count-query on this table takes nearly 30 minutes (!) to complete.
Upscaling the instance from S0 to S1 reduces the query time to 13 minutes:
Looking into Azure Portal (new version) the resource-usage-monitor shows the following:
Questions:
Does anyone else consider even 13 minutes as rediculos for a simple COUNT()?
Does the second screenshot meen that during the 100%-period my instance isn't responding to other requests?
Why are my metrics limited to 100% in both S0 and S1? (see look under "Which Service Tier is Right for My Database?" stating " These values can be above 100% (a big improvement over the values in the preview that were limited to a maximum of 100).") I'd expect the S0 to bee like on 150% or so if the quoted statement is true.
I'm interested in experiences regarding usage of databases with more than 1.000 records or so from other people. I don't see how a S*-scaled Azure SQL for 22 - 55 € per month could help me in upscaling-strategies at the moment.
Azure SQL Database editions provide increasing levels of DTUs from Basic -> Standard -> Premium levels (CPU,IO,Memory and other resources - see https://msdn.microsoft.com/en-us/library/azure/dn741336.aspx). Once your query reaches its limits of DTU (100%) in any of these resource dimensions, it will continue to receive these resources at that level (but not more) and that may increase the latency in completing the request. It looks like in your scenario above, the query is hitting its DTU limit (10 DTUs for S0 and 20 for S1). You can see the individual resource usage percentages (CPU, Data IO or Log IO) by adding these metrics to the same graph, or by querying the DMV sys.dm_db_resource_stats.
Here is a blog that provides more information on appropriately sizing your database performance levels. http://azure.microsoft.com/blog/2014/09/11/azure-sql-database-introduces-new-near-real-time-performance-metrics/
To your specific questions
1) As you have 8.6 million rows, database needs to scan the index entries to get the count back. So, it may be hitting the IO limit for the edition here.
2) If you have multiple concurrent queries running against your DB, they will be scheduled appropriately to not starve one request or the other. But latencies may increase further for all queries since you will be hitting the available resource limits.
3) For older Web/Business editions, you may be able to see the metric values going beyond 100% (they are normalized to the limits of an S2 level), as they don't have any specific limits and run in a resource-shared environment with other customer loads. For the new editions, metrics will never exceed 100%, because system guarantees you resources upto 100% of that edition's limits, but no more. This provides predictable, guaranteed amount of resources for your DB unlike Web/Business editions, where you may get very little or lot more resources at different times depending on other competing customer DB workloads running on the same machine.
Hope this helps.
-- Srini