Time Series is the historical representation of data points collected at periodic intervals of time. Statistical tools like R use forecasting models to analyse historical time series data to predict future values with reasonable accuracy. In this post I will be using R time series to forecast the exchange rate of Australian dollar using daily closing rate of the dollar collected over a period of two years.Continue reading
Partitions improve the query response of SSAS cube by narrowing the MDX query to a pre-defined subset of data. Usually cubes are developed with few basic partitions to begin with and new partitions are added over time. Partitions are created using XMLA commands. The rest of this post explains the steps to create partitions using metadata and SSIS package.Continue Reading
SSAS Partitions are primarily geared towards better query performance by narrowing the MDX query to a pre-defined subset of data. Each partition must be in processed state for the cube to be available for browsing. However in a delta ETL run, it is more than likely that only some partitions would be refreshed with data while the rest remain unchanged. For example in a hospital admissions cube partitioned by month, data movements are frequent for admissions made during the current/last month compared to earlier months. This means if the partitions updated by the ETL run can be identified, then we can tailor SSIS package to dynamically process only those partitions that require data refresh while leaving the remaining partitions untouched.Continue Reading
The execution plan of SSAS processing engine triggers a sequence of processing tasks based on the object’s current processed state and its dependencies with other objects. This is what happens when the SSAS cube is processed from SQL Server Management Studio (SSMS). It is possible to replicate this execution plan close enough in an SSIS package so that the cube is always processed and refreshed with latest data.Continue Reading
If your SSRS report is using SSAS MDX datasets, the member uniquename is particularly useful to pass parameter values to drill-through MDX reports or for sorting based on key values. If Fields!Attribute.UniqueName is returning nothing or blank or null value in your report, then most likely you are missing the DIMENSION PROPERTIES clause in your MDX dataset query
In a data warehouse, Periodic Snapshot table is a type of fact table that “freezes” the measure value at recurring reporting periods. This enables reporting of measures AS AT a point in time. Periodic Snapshots are usually created from Transaction Fact tables that support reporting FOR the period. Using MDX it is possible to create snapshot values for measures from transaction fact without creating Periodic Snapshot tables.Continue Reading
Bulk Insert option for SSIS ADO.NET Destination which is available since SQL Server 2008 R2 improves data load speeds significantly. This option is enabled on the ADO.NET Destination component by selecting the “Use Bulk Insert when possible” check-box Continue Reading
Since SQL Server 2014, Tables with Columnstore Index are no longer read only and are updatable. This post is only applicable to SQL Server 2012.
Columnstore Index on fact tables provide significant improvements in response time especially for aggregated queries. One of the first things I did after migrating my databases to SQL Server 2012 was to create Columnstore Index on fact tables. Now I can run aggregated queries that fetch results in reasonable response a time which is great for development, unit testing and helps testers to run their test scripts faster.
One caveat to be aware of is that the table on which a Columnstore Index is defined cannot be inserted, updated or deleted (at the time of writing this post). Continue Reading
Often there is requirement to calculate measures based on two different date dimensions. For e.g. how many orders that were delivered this month was actually ordered last month? How many orders were delivered in the same month as they were ordered? How many orders were carried forward to next month?Continue Reading
An easy way to completely enable/disable SSIS Logging would be to set the LoggingMode property of the package using a Package Variable or Parent Package variable. LoggingMode takes the following enumerated values: