Questions tagged [columnstore]

For questions about column-oriented storage and access mechanisms in databases. Although the term "columnstore" itself is used by Microsoft and MariaDB for their respective implementations, you should use this tag for questions about other vendors' technologies (e.g. IBM Db2 column-organized tables) and for questions about the technology in general, not specific to a particular vendor.

Filter by
Sorted by
Tagged with
21
votes
1answer
2k views

What's the anatomy of a columnstore index?

One of the new features in SQL Server 2012 codenamed Denali is the Columnstore index. I know a good bit about regular old row-store indexes, like the b-tree structure, differences in storage between ...
14
votes
4answers
3k views

Does the order of columns in a columnstore index matter?

I have a table with ~200 million rows and ~15 columns in it. I am planning to create a COLUMNSTORE index on my table. Will there be any change in performance based on the order of columns that I use ...
23
votes
1answer
5k views

What exactly can SQL Server 2014 execute in batch mode?

When a columnstore index is being used in a query SQL Server is able to use batch mode. Documentation is thin on what can run in batch mode and what can't. Please look at the following (motivating) ...
7
votes
2answers
3k views

Database for building a realtime analytics system

I want to build a system similar to Google Analytics (only used for internal use, less traffic and less feature), and mainly focus on Real time counting of unique URI visit/PV by different dimensions ...
19
votes
1answer
1k views

Nonclustered index storage on clustered columnstore

In SQL Server, a non-unique nonclustered index on a rowstore table incorporates the base object's bookmark (RID or clustering key) at all levels of the nonclustered index structure. The bookmark is ...
10
votes
3answers
27k views

Create failed for Index 'ClusteredColumnStoreIndex'. Timeout expired

I am creating Clustered Column Store Index in SQL Server 2014. I am getting error as "Timeout expired. The timeout period elapsed prior to completion of the operation or the server is not ...
20
votes
3answers
662 views

Why can it take up to 30 seconds to create a simple CCI rowgroup?

I was working on a demo involving CCIs when I noticed that some of my inserts were taking longer than expected. Table definitions to reproduce: DROP TABLE IF EXISTS dbo.STG_1048576; CREATE TABLE dbo....
6
votes
1answer
410 views

Columnstore Aggregate Pushdown doesn't work for float/real data types

I am having an issue with Aggregate Pushdown for float/real data types. According to the documentation, Aggregate Pushdown is supported for "Any datatype <= 64 bits" or 8 bytes (): ...
5
votes
1answer
794 views

Column Store Index over an clustered index (created when primary key is declared) - SQL Server

When a clustered index is created, the table itself becomes the index structure sorted by the index key. Imagine now that we have 5 columns in a table XPTO (a,b,c,d,e) and "a" is the primary key and ...
6
votes
1answer
1k views

Clustered columnstore index space usage

I have a simple table with a clustered columnstore index: ID INT NOT NULL, Hash BINARY(20) NOT NULL This table has some billion rows and according to sp_spaceused, sys.allocation_units and SSMS ...
5
votes
1answer
168 views

Can adding a columnstore index to a table affect read performance of a query that uses a rowstore index on the same table?

I'm doing some testing of columnstore indexing on a single table that has about 500 million rows. The performance gains on aggregate queries have been awesome (a query that previously took about 2 ...
2
votes
3answers
453 views

Database solution for a large matrix/very wide table

Suppose I have these two data frames (simplified for my question): users +---------+ | user_id | +---------+ | 1 | | 2 | | ... | +---------+ articles +------------+------------+ | ...
1
vote
1answer
826 views

Data structure design for supporting arbitrary number of columns in table or database [closed]

I am currently working on a sort-of a meta-modeler to build a free web service so that people can input data and run several models on that data. The task I am currently struggling is: user needs to ...
0
votes
1answer
388 views

Performance Metrics: Columnstore Indexes vs SSAS Cubes [closed]

What has faster performance speed: Columnstore Indexes or SSAS Cubes? Are Columnstore indexes proven to be faster than SSAS cubes (SQL Analysis Services)? Have their been any performance studies ...