Questions tagged [columnstore]

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5
votes
1answer
216 views

Does it make sense to add indexes to a clustered columnstore index table?

Question is similar to this one, but the answer doesn't seem to answer this question. My understanding of a clustered columnstore table (and please correct me if I am wrong) is that each column is ...
1
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1answer
37 views

Azure tempdb filling up while trying to convert a large table to columnstore… how to mitigate?

I have a large reporting table (approx 6B rows) taking up roughly 400GB of storage on an azure sql db. I've been trying to convert it to a columnstore table using the following commands: insert Logs(...
4
votes
1answer
118 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 ...
0
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1answer
64 views

Recommendations about deleting large set of rows in MSSQL [closed]

I need to delete about 75+ million rows from a table everyday that contains around 3.5 billions of record. Database recovery mode is simple, I have writen a code that deletes 15.000 rows in a while ...
1
vote
1answer
56 views

If a rowstore index is stored in a b-tree data structure, what kind of data structure is used for a columnstore index? [duplicate]

My understanding of how regular rowstore indexes are stored is in a type of b-tree data structure, but I was wondering because of the different nature of columnstore indexes, what type of underlying ...
2
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1answer
46 views

How to control Segmentation min/max data_id on a non-clustered ColumnStore index

Given a simple row-based table without a PK but with a row-based clustered index like so: create clustered index [CX_PropertyValue] ON [dbo].[PropertyValue] ([PropertyId], [Value]) Then I wish to ...
1
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1answer
32 views

Do I still need OLAP cubes after a SQL Server Upgrade

After our DBA got sacked for poor performance, I am now our accidental DBA. I have been pushing to upgrade our SQL Server instance from 2012 to 2017 so I can use the clustered column store indices in ...
2
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1answer
97 views

Adding COMPRESSION_DELAY to an existing COLUMNSTORE INDEX

When I create an COLUMNSTORE index I can specify COMPRESSION_DELAY = x [minutes] in the CREATE-Statement. It delays the movement of the rows in an closed segment from the delta store to the compressed ...
0
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0answers
23 views

Reorganizing columnstore index on uncomitted rows

I want to add a non-clustered columnstore index to the table table_with_csi. The following code runs every day and inserts big amounts of data into the table. Where should I add the reorganize ...
21
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3answers
763 views

Why would a table with a Clustered Columnstore Index have many open rowgroups?

I was experiencing some performance issues with a query yesterday and upon further investigation, I noticed what I believe is odd behavior with a clustered columnstore index that I'm trying to get to ...
0
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1answer
817 views

Columnstore Index maintenance and finding fragmentation

We are using clustered columnstore indexes and partitions in SQL Server 2014. Some tables have a lot of updates and we find ourselves with a lot of deleted rows for some partitions. In our tests, a ...
0
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1answer
11 views

Redshift: Performance wise Is storing delimited values in a single column ever preferable to normalizing them out to another table?

I have been looking at increasing the performance of some tables that have been uploaded to a redshift database. One of the columns in a table has many delimited values which need to be split out and ...
0
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1answer
243 views

Do I still need to disable or drop column store index before insert and/or update on big tables?

As the title says, I thought that from MSSQL 2016 I don't really have to drop or disable ColumnStore indexes before ETL and rebuild it after. Any consensus?
0
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1answer
115 views

Table with Clustered Columnstore Index bigger than a Clustered Rowstore Index

We have a query that is doing an index scan on a 36 million row table that has a Clustered Columnstore Index. All the cost of the plan is pretty much on the index scan of this Clustered Columnstore ...
8
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2answers
285 views

Lob Logical Read and lob read-ahead reads in NCCI [duplicate]

I have a test table with following structure. CREATE TABLE [dbo].[DW_test]( [ID] [bigint] IDENTITY(1,1) NOT NULL, [CourtCaseID] [int] NOT NULL, [ActionID] [int] NOT NULL, PRIMARY KEY CLUSTERED([ID] ...
4
votes
1answer
139 views

MSSQL - How to support aggregate pushdown on indexed view with SUM(decimal)

I have an indexed view with non-clustered columnstore index, e.g. CREATE VIEW [dbo].[SalesAggregated] with schemabinding AS SELECT BusinessDate, ItemId ,...
10
votes
2answers
616 views

How to Prevent Partitioned Columnstore Deadlocks on SELECT

I have three Clustered Columnstore Index (CCI) tables in SQL Server 2016. All of these CCIs are in the same partitioning scheme, based on Tenant ID. Lately, and inconsistently, I am getting deadlocks ...
6
votes
1answer
360 views

Slide Partition from Rowstore to Columnstore

I have a rowstore table which contains ~10 billion records. The table is partitioned on an INT field and has about 1,400 active partitions. I also have a clustered columnstore table built on the same ...
2
votes
1answer
180 views

Storing Social Security Number as DECIMAL(10,9) for Columnstore

I am working on a VERY large database (10B + rows) that performs matching on SSN and BirthDate to try and find duplicate records. The table is using columnstore compression (SQL SERVER 2016) and it ...
2
votes
3answers
324 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 +------------+------------+ | ...
0
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1answer
300 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 ...
10
votes
3answers
481 views

Filter condition not correctly applied to Clustered Columnstore index

Using the below example, the predicates are the same, however the top statement (correctly) returns 0 rows, the bottom statement returns 1 - even though the predicates do NOT match: declare @barcode ...
0
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0answers
44 views

MS SQL 2017: Generate estimate execution plan take more than 3 min

Sometimes generate Execution Plan (estimated) for simple query take ~3min Query: SELECT MAX(field) FROM table_name WHERE Org = x and PartKey = y The table is columnstore cluster index SQL Server ...
2
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1answer
82 views

Does Batch Mode only apply to Agg Functions on ColumnStore Index

Azure SQL Database - Standard Edition (S3 Service Tier) Why does Batch Mode only come into effect when using Aggregate Functions? DROP TABLE IF EXISTS dbo.TransCS CREATE TABLE dbo.TransCS ( ...
5
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1answer
537 views

Columnstore index for Key/Value Pair table on SQL Server

I need to build a database for storing assessments. Each assessment can have an indefinite number of questions, and an indefinite number of responses. Responses for each assessment can grow up to ...
-1
votes
1answer
121 views

Should I place Kimball Data Warehouse in Microsoft Columnstore Index on Premise?

Are Columnstore tables now the vendor default method for Kimball Data warehouse tables with Dim and Facts for On Premise? I know in the cloud, Microsoft automaticaly recommends Azure Data warehouses ...
0
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1answer
44 views

MariaDB Columnstore unexplained behaviour using CASE

We were updating column value based on col 'string_hash_id' value, but we couldn't get through: Error Code: 1815. Internal error: CAL0002: Update Failed: TreeNode::getDecimalVal: non-support ...
2
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1answer
73 views

Microsoft Column Store Database?

Using Microsoft technologies/products is it possible to create a column store database with column family sets? That is each row being able to have a different number and type of columns. Colmun ...
3
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1answer
422 views

SELECT from Clustered Columnstore results in LOB Reads

I am performing a SELECT from the following Clustered Columnstore Index which contains 5.2 Billion Records. When I review the output of STATISTICS IO, I am seeing LOB Logical reads. My question is ...
7
votes
2answers
503 views

How many partitions should I make for my clustered columnstore index tables? Should I partition the rowstore tables also?

I have a data warehouse comprised of four clustered columnstore index tables (CCI) and nine rowstore tables. These tables are used only for analytics and the CCI data is inserted from staging tables ...
-2
votes
1answer
394 views

Is there any Performance Issue joining Row based Table to Clustered Columnstore Index Table [closed]

Is there any Performance Degradation joining Row based Table to Clustered Columnstore Index Table? Does SQL Server have any guidance for or against this? We have a table that is 2 million rows, and ...
1
vote
1answer
1k views

How Large Table before Using Clustered Columnstore Index

At what size should we consider applying Columnstore Index on a table? Is there a SQL Server storage or design guidance? Our Data Warehouse is 5TB total. Additionally, we have tables which are 100GB ...
2
votes
1answer
367 views

Difference between Clustered Columnstore Index Table in Azure SQL and Table in Azure Data Warehouse

What is the essential difference between a Clustered Columnstore Index table in Regular Azure SQL, and a table in Azure Data Warehouse? They both have columnar storage, no foreign keys, no primary ...
1
vote
2answers
2k views

Can a table have Both a Clustered Columnstore Index and Nonclustered Columnstore Index?

Can I a table have both Clustered Columnstore Index and Nonclustered Columnstore Index? I am seeing example strategies to use Clustered Columnstore Indexes with only Nonclustered Binary row indexes. ...
12
votes
1answer
228 views

Why does batch mode window aggregate yield arithmetic overflow?

The following query performs a windowed SUM over a columnstore table with 1500 total rows, each of which has the value 0 or 1, and it overflows the INT data type. Why is this happening? SELECT a, p, ...
2
votes
2answers
268 views

Performance Implications of encrypted data in a Clustered Columnstore Index

I am using SQL Server 2016 and expecting some details on below points regarding performance point of view: Is there any performance gain or additional benefit on creating a primary key - unique ...
4
votes
1answer
379 views

How to drop an in-memory temporal columnstore

Consider the following: CREATE DATABASE [Foo] ALTER DATABASE [Foo] ADD FILEGROUP XTP CONTAINS MEMORY_OPTIMIZED_DATA ALTER DATABASE [Foo] ADD FILE (NAME=XTP,FILENAME='C:\Program Files\Microsoft SQL ...
3
votes
1answer
742 views

How Ola Hallengrens Index maintenance scripts handles columnstore indexes?

I'd like to know how Ola's script handles columnstore indexes. Couln't find any information about that, only in the version history it was mentioned that script does have a support. My experience is ...
1
vote
2answers
67 views

Will table partitions help me?

I have 10 tables. dbo.Table2008 dbo.Table2009 ... dbo.Table2018 Each table holds approximately 500,000,000 records which are 20 columns wide (if that matters). And each table has a clustered ...
6
votes
1answer
862 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 ...
1
vote
2answers
113 views

Why are column store databases the new thing now? [closed]

Column store databases have several advantages over traditional databases - most notably compression and faster seek. Column store seem to be the new fad for databases in the past few years, with HANA ...
15
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2answers
358 views

Columnstore Index in read_only filegroup prevents CheckDB

It appears setting a filegroup to read_only prevents dbcc checkdb for the entire database if the filegroup contains a columnstore index. When attempting to run checkdb or checkfilegroup (for any ...
1
vote
1answer
46 views

select runs in batch mode, but CTAS runs in row mode

I have the same query that shows as running in batch mode when run as a select statement, but row mode when the same query is the select part of a CTAS operation. Both tables (plus the resulting table)...
3
votes
2answers
129 views

Can I artificially limit the Columnstore cache size in SQL Server?

I am trying to evaluate the potential performance of a data science workload on a large-ish dataset (~200GB). We have had excellent results using columnstore indexes in SQL Server 2017. However, the ...
0
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0answers
411 views

Using clustered columnstore indexes in conjunction with non-clustered columnstore indexes

Table A has approximately 500 million records in it and is of the form similar to the following | ID | FirstName | LastName | MiddleName | ------------------------------------------ | 1 | John |...
4
votes
1answer
757 views

When are dimension tables still needed using clustered columnstore indexing?

I am using MS SQL Server 2016 Clustered Columnstore Indexing (let's call it CCI) in my reporting database. In initial designs I was thinking star schema but then I started playing with CCI. Now I ...
1
vote
2answers
497 views

How to install columnstore in MariaDB on Mac OS X with Homebrew

I would analyse time-series data using MariaDB ColumnStore but error encountered MariaDB [(none)]> CREATE DATABASE forex; Query OK, 1 row affected (0.00 sec) MariaDB [(none)]> USE forex; ...
2
votes
2answers
4k views

Creating non-clustered index on large table fills transaction logs

Using SQL Server 2016, I'm trying to create a non-clustered covering index on a table in my database that is of the structure int, bigint, int, varchar(20), varchar(4000). The size is ~13,241,928 rows....
1
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0answers
60 views

What does column family-oriented datastore mean in practice

I was reading this article about HBase. Within it, the storage format of HBase is described: HBase is referred to as a column family-oriented data store. It’s also row-oriented: each row is indexed ...
2
votes
3answers
2k views

What to do when you need a cursor and you have a columnstore clustered index

I have a very large SQL Server table with a ColumnStore clustered index. The table is very fast to query, so this is good. However I need to do some updates to a large portion of records in the ...