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1
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1answer
55 views

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

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 ...
5
votes
0answers
56 views

Restored DB has data, DBCC CHECKDB is clean, but SELECT TOP 1 returns zero rows

Having restored a client's SQL 2014 EE DB onto our Developer Edition instance, without issue, then running a DBCC CHECKDB that found zero errors, and a clustered columnstore index alleging over 1Bn ...
2
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0answers
32 views

Is there impact on query execution as more partitions are added to a table?

We are looking to heavily use partitioned tables in our data warehouse environment. We are looking to take advantage of fast partition switching as well as partition elimination during analytical ...
1
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3answers
5k 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 ...
11
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1answer
140 views

How to make use of Batch Mode with an UNPIVOT (a loop join)?

I have a query of the following form: SELECT ... FROM ColumnstoreTable cs CROSS APPLY ( SELECT * FROM (VALUES ('A', cs.DataA) , ('B', cs.DataB) , ('C', cs.DataC) ) ...
23
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1answer
284 views

Is the eager spool operator useful for this delete from a clustered columnstore?

I'm testing deleting data from a clustered columnstore index. I noticed that there is a large eager spool operator in the execution plan: This completes with the following characteristics: 60 ...
1
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0answers
23 views

Storage solution for realtime time series analytics

I'm designing a system which allows user to analyze their data over time. It is like a IoT database which stores a lot of information from different devices from the user. I don't think that a normal ...
0
votes
1answer
21 views

Columnar & Row Oriented DB

In a previous question, I discussed some challenges with a row-oriented table. I have two tables in this application. The first table is well-suited for row-oriented operation; the second is ...
0
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3answers
338 views

How can we get the table and the column name of known data value?

I have a value (like 'IT department'), based on this I want to get the table and column name in which this value exists/present.
15
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1answer
928 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) ...
6
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1answer
202 views

Clustered columnstore index performance SQL Server 2014

I'm setting up an OLAP database using SQL Server 2014. The core fact table has about 40,000,000 rows, 225 columns with an average row size of 181 bytes. I've been toying around with the clustered ...
8
votes
2answers
178 views

Identity column in columnstore index

I have an extremely large table IMO (~137 million rows) with lots of repeated data, lots of NULL columns, and such. I am considering exploring this using a table with a COLUMNSTORE INDEX and I have ...
0
votes
1answer
29 views

Record scan speed, column orientated databases and SSDs

I'm learning about column orientated databases. I have just watched a YouTube video on column orientated databases by Arnaldo from MIT, who suggests an interesting motivation for column orientated ...
2
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0answers
49 views

Column Store Indices versus Dimensional Tables

I have a Data Warehouse and want to think ahead one year when I may get a database update allowing me to use column store indices. My dimensional tables are mostly junk dimensions containing columns ...
3
votes
1answer
92 views

Why does the Tuple Mover in C-Store consider only rows older than LWM?

In the Tuple Mover section of the C-Store paper by Michael Stonebraker (link: http://db.csail.mit.edu/projects/cstore/vldb.pdf) the following is described: MOP (merge out process) will find all ...
2
votes
1answer
50 views

Building a ColumnStore index hogs system resources

I am experimenting with the columnstore and I am finding that while it is building the process hogs all the system resources. I have a table with 2.3 billion rows and while I build the columnstore on ...
4
votes
1answer
162 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 ...
1
vote
1answer
133 views

Column store index on a large fact table

I have seen column store index and also tested it. I have no doubt admiring that it is lightning fast. But every tutorial and blogs I have considered, says about its limitation "table will become read ...
0
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0answers
60 views

Columnstore Index Scan Cardinality Estimates

In SQL Server 2012, I am seeing large cardinality estimate discrepancies for a columnstore index scan. It looks like statistics have been generated for the index, but I don't see any details in DBCC ...
0
votes
1answer
38 views

NC Columnstore and delete on batch

hope you can give me some pointers on this behavior I have a NC Columnstore and in the same batch I want to drop this column store and "delete" some information. But I get this error: DELETE ...
0
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0answers
90 views

Oracle In-Memory POPULATE_STATUS does not change to completed

I'm experimenting with the Oracle In-memory options for BI purposes, when I'm trying to populate one table to in-memory in the v$im_segments the POPULATE_STATUS does not change to completed, for other ...
2
votes
1answer
462 views

Any experience with cstore_fdw? [closed]

It looks like there is a (finally) an open source columnar and compression extension for Postgres. I wonder if anyone had any experience with it yet? I've worked with Greenplum for years, but I've ...
13
votes
2answers
1k views

Clustered columnstore indexes and foreign keys

I am performance tuning a data warehouse using indexes. I am fairly new to SQL Server 2014.Microsoft describes the following: "We view the clustered columnstore index as the standard for storing ...
0
votes
1answer
177 views

How to create column group in WiredTiger engine in mongodb 2.8?

MongoDB 2.8 supports WiredTiger strorage engine, and WiredTiger supports column grouping. How we can create a collection in mongodb 2.8 with grouped columns?
5
votes
3answers
420 views

Has the guidance on the setting for 'cost threshold for parallelism' changed with the advent of columnstore indexes?

First off, what I'm not asking. I'm not asking what my setting should be. Many are recommending upping the value past the default, and I certainly understand why that's the case for B-Tree based ...
3
votes
1answer
159 views

sp_estimate_data_compression_savings for column store compressions

Is there a way to get compressions saving for column store and column store column store archival compression? In order to check these compressions saving I have to drop all clustered and non ...
0
votes
1answer
208 views

Msg 823, Level 24, State 2 for Clustered Column Store Index in SQL Server 2014

CREATE CLUSTERED COLUMNSTORE INDEX CCI_TempTable1 ON dbo.TempTable1 ON[PRIMARY] After firing this query I found the error. Msg 823, Level 24, State 2, Line 20 The operating system returned error ...
1
vote
0answers
34 views

Does the order of columns in a non-clustered ColumnStore index matter? [duplicate]

I'm reading about creating a non-clustered ColumnStore index. I noticed that when I modify an already created non-clustered ColumnStore in SQL Server Management Studio I have an option to change the ...
2
votes
2answers
325 views

Are indexes unnecessary for columnar database?

In a columnar database, are indexes unnecessary or useless?
1
vote
1answer
338 views

what is the structure of a Mysql multi-column index? [closed]

For example: CREATE TABLE test( col_1 INT, col_2 INT, col_3 VARCHAR(11), col_4 VARCHAR(11) )ENGINE = INNODB; CREATE INDEX mul ON test(col_2,col_3,col_4); Sorry,my English is not good,I mean ...
0
votes
1answer
285 views

Storing 5TB web server access log vs OLAP DB

We have over 5TB compressed web server log in a HDFS and we often analyse using Hadoop. It is painful to run map reduce on 5TB of data and most importantly, not many developer are familiar with it. ...
2
votes
0answers
343 views

Best Practice to update columnstore indexed tables

I have a table with aprox. 22 Bn rows, for each month I have made one partition that and each partition has two data files. I created the columnstore index on this table and the performance ...
1
vote
1answer
2k views

IBM DB2 - store large files

I want to store large files in a DB2 database and I need more information about which is the best technique to use as I am new in this IBM product (previous experience with T-SQL only). The ...
13
votes
1answer
1k 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 ...
6
votes
2answers
429 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 ...
7
votes
2answers
2k 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 ...