Hello everyone I have prometheus as a label returns the amount. The metric value is the number of payments. How do I withdraw the total amount a day to the dashboard? i.e. value_metric*sum
As far as I know, there is no way to do that because labels aren't meant to be used in calculations. Labels and their values are essentially the index of Prometheus' NoSQL TSDB, they're used to create relations and join pieces of data together. You wouldn't store values and do math with column names of a relational database, would you?
Another problem is that labels with high cardinality greatly increase database size. Here is an extraction from Prometheus best practices:
CAUTION: Remember that every unique combination of key-value label pairs represents a new time series, which can dramatically increase the amount of data stored. Do not use labels to store dimensions with high cardinality (many different label values), such as user IDs, email addresses, or other unbounded sets of values.
Though I see that you use somewhat fixed values in labels, maybe a histogram would fit your needs.
Related
Please help me understand the best way storing information in HBase.
Basically, I have a rowkey like hashed_uid+date+session_id with metrics like duration, date, time, location, depth and so on.
I have read a lot of materials where I am bit confused. People have suggested less column family for better performance, so I am facing three options to choose:
Have each metrics sits in one row like rowkey_key cf1->alias1:value
Have many columns like rowkey cf1->key1:val1, cf1->key2:val2 ...
Have all the key-value pairs coded into one big string like rowkey cf1->"k1:v1,k2:v2,k3:v3..."
Thank you in advance. I don't know which to choose. The goal of my HBase design is to prepare for incremental windowing functions of a user profiling output, like percentiles, engagement and stat summary for last 60 days. Most likely, I will use hive for that.
Possibly you are confused by the similarity of naming of column family and column. These concepts are different things in HBase. Column family consist of several columns. This design is to improve the speed of access to data when you need to read only some type of columns. E.g., you have raw data and processed data. Reading processed data will not involve raw data if they are stored in separated column families. You can partially to have any numbers of columns per row key; it should be stored in one region, no more than 10GB. The design depends on what you what:
The first variant has no alternatives when you need to store a lot of
data per one-row key, that can't be stored in on a region. More than
10GB.
Second is good when you need to get only a few metrics per
single read per row key.
The last variant is suitable when you
always get all metrics per single read per row key.
I'm trying to model a database of users. These users have various vital statistics: age, sex, height, weight, hair color, etc.
I want to be able to write queries like these:
get all users 5'1" to 6'0" tall with red hair who weigh more than 100 pounds
or
get all users who are men who are 6'0" are ages 31-37 and have black hair
How can I model my data in order to make these queries? Let's assume this database will hold billions of users. I can't think of an approach that wouldn't require me to make MANY requests or cluster the data on VERY few nodes.
EDIT:
Just a little more background, let's assume this thought problem is to build a dating website. The site should allow users to filter people based on the aforementioned criteria (age, sex, height, weight, hair, etc.). These filters are optional, and you can have as many as you want. This site has 2 billion users. Is that something that can be achieved through data modeling alone?
IF I UNDERSTAND THINGS CORRECTLY
If I have 2 billion users and I create both of the tables mentioned in the first answer (assuming options of male and female for sex, and blonde, brown, red for hair color), I will, for the first table, be putting at most 2 billion records on one node if everyone has blonde hair. Best case scenario, 2/3 billion records on three nodes. In the second case, I will be putting 2/5 billion records on each node in the best case with the same worst case. Am I wrong? Shouldn't the partition keys be more unique than that?
So if you are trying to model you data inside Cassandra then the general rule is that you need to make a table per query. There are also significant restrictions on what you can filter your query by. If you want to understand some of the restrictions I suggest you take a look at this post:
http://www.datastax.com/dev/blog/a-deep-look-to-the-cql-where-clause
or my long answer here:
cassandra - how to perform table query?
All of the above only applies if you are running fixed queries that are known ahead of time. If instead you are looking to perform some sort of analytical analysis on your data (it sounds like you might be) than I would look at using Spark in conjunction with Cassandra. This will provide you a fast tool to do in-memory processing of your data. If you look at using Datastax (Community or Enterprise) then Spark also has a connector that makes reading and writing data to and from Cassandra easy.
Edited with Additional Information
Based on the query "get all users 5'1" to 6'0" tall with red hair who weigh more than 100 pounds" you would need to build a table with following:
CREATE TABLE user_by_haircolor_weight_height (
haircolor text,
weight float,
height_in int,
user varchar,
PRIMARY KEY ((haircolor), weight, height_in)
);
You could then query this by:
SELECT * from user_by_haircolor_weight_height where haircolor='red' and weight>100 and height_in>61 and height_in<73;
For the query "get all users who are men who are 6'0" are ages 31-37 and have black hair" you would need to build a similar table with a
PRIMARY KEY ((haircolor, sex), height_in, age)
In the end if what you are trying to do is perform either ad-hoc or a set number analytics (i.e. can have a bit more latency than a straight CQL query) on the data stored in you cassandra table than I suggest you look at using Spark. If you need something a bit more real-time to handle ad-hoc queries you can look at using Solr to perform Lucene powered searches on your table.
my recommendation is :
1) keep main table with proper partition key, so that million records being spread across cluster, don't here use any cluster column which will cross row key limitation of 2gb etc.,
2) depending on query pattern you may better create additional tables(like index) as much as possible to keep inverted index data in it. coz write is cheap.
3) use multiple query to get what you need.
4) last option is, use DSE solr search capability.
Just to reiterate the end of the conversation:
"Your understanding is correct and you are correct in stating that partition keys should be more unique than that. Each partition had a maximum size of 2GB but a practical limit is lower. In practice you would want your data partitioned into far smaller chunks that the table above. Given the ad-hoc nature of your queries in your example I do not think you would be able to practically do this by data modelling alone. I would suggest looking at using a Solr index on a table. This would allow you a robust search capability. If you use Datastax you are even able to query this via CQL"
Cassandra alone is not a good candidate for this sort of complex filtering across a very large data set.
I am in the process of merging two data sets together in Stata and came up with a potential concern.
I am planning on sorting each data set in exactly the same manner on several categorical variables that are common to both sets of data. HOWEVER, several of the categorical variables have more categories present in one data set over the other. I have been careful enough to ensure that the coding matches up in both data sets (e.g. Red is coded as 1 in both data set A and B, but data set A has only Red, Green and Blue whereas data set B has Red, Green, Blue, and Yellow).
If I were to sort each data set the same way and generate an id variable (gen id = _n) and merge on that, would I run into any problems?
There is no statistical question here, as this is purely about data management in Stata, so I too shall shortly vote for this to be migrated to Stack Overflow, where I would be one of those who might try to answer it, so I will do that now.
What you describe to generate identifiers is not how to think of merging data sets, regardless of any of the other details in your question.
Imagine any two data sets, and then in each data set, generate an identifier that is based on the observation numbers, as you propose. Generating such similar identifiers does not create a genuine merge key. You might as well say that four values "Alan" "Bill" "Christopher" "David" in one data set can be merged with "William" "Xavier" "Yulia" "Zach" in another data set because both can be labelled with observation numbers 1 to 4.
My advice is threefold:
Try what you are proposing with your data and try to understand the results.
Consider whether you have something else altogether, namely an append problem. It is quite common to confuse the two.
If both of those fail, come back with a real problem and real code and real results for a small sample, rather than abstract worries.
I think I may have solved my problem - I figured I would post an answer specifically relating to the problem in case anybody has the same issue.
~~
I have two data sets: One containing information about the amount of time IT help spent at a customer and another data set with how much product a customer purchased. Both data sets contain unique ID numbers for each company and the fiscal quarter and year that link the sets together (e.g. ID# 1001 corresponds to the same company in both data sets). Additionally, the IT data set contains unique ID numbers for each IT person and the customer purchases data set contains a unique ID number for each purchase made. I am not interested in analysis at the individual employee level, so I collapsed the IT time data set to the total sum of time spent at a given company regardless of who was there.
I was interested in merging both data sets so that I could perform analysis to estimate some sort of "responsiveness" (or elasticity) function linking together IT time spent and products purchased.
I am certain this is a case of "merging" data because I want to add more VARIABLES not OBSERVATIONS - that is, I wish to horizontally elongate not vertically elongate my final data set.
Stata 12 has many options for merging - one to one, many to one, and one to many. Supposing that I treat my IT time data set as my master and my purchases data set as my merging set, I would perform a "m:1" or many to one merge. This is because I have MANY purchases corresponding to one observation per quarter per company.
I have a timeseries of values (e.g., a random walk of stock market prices) stored in a PostgreSQL database. It's a very large table and I'd like to be able to handle queries for arbitrary time spans similarly fast. I have this chart in the back of my mind, and I wonder how they did this.
A simple Example:
WITH t(ts, val) AS ( VALUES
('2012-10-04 00:00:00'::timestamp, 1.11::numeric),
('2012-10-04 00:00:01', 1.21),
('2012-10-04 00:00:02', 1.25),
('2012-10-04 00:00:03', 1.41),
('2012-10-04 00:00:04', 1.31),
('2012-10-04 00:00:05', 1.25),
('2012-10-04 00:00:06', 1.33))
(Assume there's an index on the timestamp column.) The table is large, and it takes a long time to retrieve all values of a time span of, e.g., a quarter of a year. However, as all I want to do with that data is to make a plot to visualize the global trend, I do not really need to get the entire data set from that period, but a representative subset would be fine.
Things that came to my mind:
generate a list of sub-statements, each of which retrieves one arbitrary value for a short sub-time-interval (e.g. one value per hour interval).
aggregate values, e.g. AVG() and group by date_trunc('hour', ts) or similar (but would this be any faster on its own? Probably make another table that holds pre-aggregated values?)
Is there a way-to-go to achieve this?
My first impulse would be to create a materialized view with aggregated data. This should be very fast (not counting the one-time operation to create it.)
Barring that, if you don't want to create more objects in your database, (truly) random selection combined with an index might be fast and valid enough.
Depending on the specifics and the actual size of your table and the requirements as to how exact your result has to be, you might be able to pull something off along these lines, which could be comparatively fast.
This is applicable to Google App Engine, but not necessarily constrained for it.
On Google App Engine, the database isn't relational, so no aggregate functions (such as sum, average etc) can be implemented. Each row is independent of each other. To calculate sum and average, the app simply has to amortize its calculation by recalculating for each individual new write to the database so that it's always up to date.
How would one go about calculating percentile and frequency distribution (i.e. density)? I'd like to make a graph of the density of a field of values, and this set of values is probably on the order of millions. It may be feasible to loop through the whole dataset (the limit for each query is 1000 rows returned), and calculate based on that, but I'd rather do some smart approach.
Is there some algorithm to calculate or approximate density/frequency/percentile distribution that can be calculated over a period of time?
By the way, the data is indeterminate in that the maximum and minimum may be all over the place. So the distribution would have to take approximately 95% of the data and only do a density based on that.
Getting the whole row (with that limit of 1000 at a time...) over and over again in order to get a single number per row is sure unappealing. So denormalize the data by recording that single number in a separate entity that holds a list of numbers (to a limit of I believe 1 MB per query, so with 4-byte numbers no more than 250,000 numbers per list).
So when adding a number also fetch the latest "added data values list" entity, if full make a new one instead, append the new number, save it. Probably no need to be transactional if a tiny error in the statistics is no killer, as you appear to imply.
If the data for an item can be changed have separate entities of the same kind recording the "deleted" data values; to change one item's value from 23 to 45, add 23 to the latest "deleted values" list, and 45 to the latest "added values" one -- this covers item deletion as well.
It may be feasible to loop through the whole dataset (the limit for each query is 1000 rows returned), and calculate based on that, but I'd rather do some smart approach.
This is the most obvious approach to me, why are you are you trying to avoid it?