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The Rise and Fall of the OLAP Cube

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Re: The Rise and Fall of the OLAP Cube

#21
post #7

How does something like Tableau fit in? I know of people using Tableau with a Postgres connector, but I am not sure if that allows you the same kind of performance as you'd get with OLAP or even a columnar DB.

Tableau (the general visualization engine) just runs queries against whatever database (relational, cube, columnar, web service, file).

Tableau has a proprietary extract engine called Hyper that uses a sort of columnar storage. Then you can use the extract in dashboards.

Re: The Rise and Fall of the OLAP Cube

#22
Sorry, could someone ELI5 what is OLAP? And while you are there, what is Tabular Model? As background,I have worked with SQL and relational databases, and occasionally keep on hearing these, but nobody ever explained to me what these are and why I should be interested. So far I have just shrugged and thought that I guess my workloads/datamodels/whatnot just do not need these fancy things, but always I see them, there is someone nagging at the back of my head that maybe you should have a look...

Re: The Rise and Fall of the OLAP Cube

#23

I'm conflicted; its a nice write-up, and probably generally true right now, for most stuff. However, I still live with databases big enough to still need cubes, although these cubes can afford to be less refined these days. Saying 'bigtable can do a regex on 30M rows per second' isn't saying it can't be done cheaper and quicker without paying google etc, if you just have some cubes. And I think its going to track the…

Thanks for your comment, I'm not familiar with presto at all - but I did do a bit of reading of an older article: https://www.slideshare.net/frsyuki/prestogres-internals

Would you view presto in its current state as a replacement for vanilla Postgres with FDW for standard data analysis queries? I don't fully understand the Postgres/Presto relationship.

Re: The Rise and Fall of the OLAP Cube

#24

Sorry, could someone ELI5 what is OLAP? And while you are there, what is Tabular Model? As background,I have worked with SQL and relational databases, and occasionally keep on hearing these, but nobody ever explained to me what these are and why I should be interested. So far I have just shrugged and thought that I guess my workloads/datamodels/whatnot just do not need these fancy things, but always I see them, there…

OLAP: Online Analytical Processing. Cranking through large amounts of data with a focus on aggregations like sums, averages, medians, etc. Measures (numbers) are defined by dimensions (attributes with usually discrete domains). Aggregations are frequently precomputed on many (or all) dimension axes so that they are immediately available. Models can be built from something as simple as a wide CSV file or as complicated as a snowflake schema.

The kind of relational database you're familiar with is probably OLTP (Online Transactional Processing).

Re: The Rise and Fall of the OLAP Cube

#25
post #17

well, I would like to say the OLAP Cube is just re-rising now. There are 1000+ companies deployed Apache Kylin (OLAP Engine for Big Data) in the past 5 years, for 100+B rows, for 100+ concurrent users...many different use cases are based that technology...it works very well with BI tools and so friendly to analysts who are using such "old fashion" every day over the decade (how hard for them to be Data Scientists?) c…

+1 for Apache Kylin, it's a great project and awesome open source community. If anyone is curious about what modern OLAP is capable of, check it out.

If you want an alternative take on where OLAP is today and what it is capable of, I usually recommend this article: https://kyligence.io/blog/olap-analytics-is-dead-really/

Re: The Rise and Fall of the OLAP Cube

#26

This piece reiterates a bunch of the usual misunderstandings of OLAP. Likely because it’s following the DBMS community’s redefinition of OLAP towards cross-tab group-by, and away from the higher end of the OLAP market. The “cube” is just as much a logical construct as a SQL table is, and just because row stores were bad at certain analytics didn’t mean that SQL was. Compressed column-stores hurt OLAP, because update…

> Compressed column-stores hurt OLAP, because update throughput (the “on-line” in OLAP) is relatively bad. Uncompressed / array stores are quite good.

But why do you want high update throughout when you're doing mostly reads? Every definition I read about OLAP says this is one of the fundamental differences, or am I misunderstanding something?

Re: The Rise and Fall of the OLAP Cube

#27
post #24

Sorry, could someone ELI5 what is OLAP? And while you are there, what is Tabular Model? As background,I have worked with SQL and relational databases, and occasionally keep on hearing these, but nobody ever explained to me what these are and why I should be interested. So far I have just shrugged and thought that I guess my workloads/datamodels/whatnot just do not need these fancy things, but always I see them, there…

OLAP: Online Analytical Processing. Cranking through large amounts of data with a focus on aggregations like sums, averages, medians, etc. Measures (numbers) are defined by dimensions (attributes with usually discrete domains). Aggregations are frequently precomputed on many (or all) dimension axes so that they are immediately available. Models can be built from something as simple as a wide CSV file or as complicate…

What are typical data sizes for this?

I think the OLAP term has been around a long time, some OLAP tasks of the past are probably not so huge today, I wonder if the shrunked-by-time tasks are still called OLAP or if the smaller ones are implemented differently.

Re: The Rise and Fall of the OLAP Cube

#28
post #26

This piece reiterates a bunch of the usual misunderstandings of OLAP. Likely because it’s following the DBMS community’s redefinition of OLAP towards cross-tab group-by, and away from the higher end of the OLAP market. The “cube” is just as much a logical construct as a SQL table is, and just because row stores were bad at certain analytics didn’t mean that SQL was. Compressed column-stores hurt OLAP, because update…

> Compressed column-stores hurt OLAP, because update throughput (the “on-line” in OLAP) is relatively bad. Uncompressed / array stores are quite good. But why do you want high update throughout when you're doing mostly reads? Every definition I read about OLAP says this is one of the fundamental differences, or am I misunderstanding something?

Your users want their dashboards and reports to contain data that's as up-to-date as possible. No one is happy about waiting 24 hours or more for a batch update to run if there are decisions they need to make right now. The difference vs. OLTP is that it might be acceptable for events to take minutes or even hours to be reflected in the database, vs. ~seconds or less for a transaction where the user is interacting and waiting for a confirmation.

Re: The Rise and Fall of the OLAP Cube

#29
post #23

I'm conflicted; its a nice write-up, and probably generally true right now, for most stuff. However, I still live with databases big enough to still need cubes, although these cubes can afford to be less refined these days. Saying 'bigtable can do a regex on 30M rows per second' isn't saying it can't be done cheaper and quicker without paying google etc, if you just have some cubes. And I think its going to track the…

Thanks for your comment, I'm not familiar with presto at all - but I did do a bit of reading of an older article: https://www.slideshare.net/frsyuki/prestogres-internals Would you view presto in its current state as a replacement for vanilla Postgres with FDW for standard data analysis queries? I don't fully understand the Postgres/Presto relationship.

Hmm, presto is not Postgres.

In a way, presto is like a bunch of FDWs on steroids, and a query planner that has above average cost model for hive etc.

There are plenty of things that presto isn’t, such as a good replacement for Postgres in classic oltp workloads.

Re: The Rise and Fall of the OLAP Cube

#30

Sorry, could someone ELI5 what is OLAP? And while you are there, what is Tabular Model? As background,I have worked with SQL and relational databases, and occasionally keep on hearing these, but nobody ever explained to me what these are and why I should be interested. So far I have just shrugged and thought that I guess my workloads/datamodels/whatnot just do not need these fancy things, but always I see them, there…

OLAP is a way of constructing queries and persisting/refreshing their results. Some OLAP based systems have a query designer where you can drag and drop columns, set values for certain columns to reduce the data, aggregate certain columns or pivot certain columns. They also have special handlers for pivoting such as pivoting datetime columns by a given granularity.

All these reports can be kept up to date in a live fashion by the OLAP service as new relevant data comes in, much like a materialized view.

Many accounting systems support OLAP based queries in order for the accounting department to design reports and export them to excel.

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