Sort

• Sorts input data in ascending or descending order.

• Multiple sorts can be applied; each sort is identified by a numeral that determines the sort order.

• Positive number denotes ascending order, and a negative number denotes descending order.

• Column with the lowest number is sorted first, second lowest number is sorted next, and so on.

• It can also remove duplicate rows as part of its sort.

• It has one input and one output. It does not support error outputs.

• full blocking

  
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how to sort the output
change the source output, false to true

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Aggregate

• Used to perform following operations on input columns:
  ▶Sum, Average, Count, Count Distinct, Minimum, Maximum
  ▶Group By
  ▶The comparison options of the aggregation

• Handles null values in the same way as the SSMS does.

• IsBig property can be set for handling big or high-precision numbers.

• Performance Can be Improved by:
  ▶Set Keys or KeysScale properties When performing a Group by operation
  ▶Set CountDistinctKeys or CountDistinctScale properties while performing Distinct count operation.
  ▶because the tranformation is able to allocate adequate memory for the data that the transformation caches.

• The Aggregate transformation has one input and one or more outputs. It does not support an error output.

• full blocking

count distinct ask more space from ram???
isbig

Union All

• Combines multiple inputs into one output.
• Inputs are added to the transformation output one after the other; no reordering of rows occurs.
• At least one input must be mapped to each output column.
• Metadata of the columns must match. dayatype must be matched
• Columns that are not mapped, are set to null values in output.
• This transformation has multiple inputs and one output. It does not support an error output.
• semi-blocking

Merge

• Combines two sorted datasets into a single dataset.
• Merging is based on values in their key columns.
• It can be used to perform:
  ▶Merge data from two data sources.
  ▶Create complex datasets by nesting Merge transformations.
  ▶Remerge rows after correcting errors in the data.
• Inputs have matching metadata.
• This transformation has two inputs and one output. It does not support an error output.
• semi blocking

Merge Join

• Combines two sorted datasets into a single dataset by using a FULL, LEFT, or INNER join.
• It can configured as follows:
  ▶Specify the join: FULL, LEFT, or INNER join.
  ▶Specify the columns the join uses.
  ▶Specify whether the transformation handles null values as equal to other nulls.
• Joining columns have matching metadata.
• This transformation has two inputs and one output. It does not support an error output.
• semi blocking
• swap input

sorting in the property, it can improve performance(?)

Conditional Split

• It can route data rows to different outputs depending on the content of the data.

• It evaluates expressions, and based on the results, directs the data row to the specified output.

• It can configured as follows:
  ▶Specify an expression that evaluates to a Boolean for each condition.
  ▶Specify the order in which the conditions are evaluated.
  ▶Specify the default output for the transformation.

• This transformation has one input, one or more outputs and one error output.

• like case statement in sql

• non-blocking

• 注意大小写

eg: [id]>1 && [id]<5

Multicast

• Multicast transformation distributes its input to one or more outputs.
• Multicast transformation directs every row to every output, unlike Conditional Split directs a row to a single output.
• You configure the Multicast transformation by adding outputs.
• This transformation has one input and multiple outputs. It does not support an error output.
• non- blocking
• like copy the dataset

区别： conditional的是符合条件的去，multicast是复制粘贴，不管条件

Row Count

• Count the number of rows, as they pass through a data flow and stores the final count in a variable.
• Variable used Must already exist.
• Variable must be in the scope of Data Flow Task using Row Count.
• Row count value is stored in the variable only after the last row has passed the transformation.
• This transformation has one input and one output. It does not support an error output
• non-blocking
• https://www.c-sharpcorner.com/UploadFile/muralidharan.d/how-to-use-rowcount-in-ssis/

Audit

• Audit transformation enables the data flow in a package to include data about the environment in which the package runs.
• SSIS includes system variables that provide this information.
• It can be configured as:
  ▶Provide the name of a output column.
  ▶Map the system variable to the output column.
• Single system variable can be mapped to multiple columns.
• This transformation has one input and one output. It does not support an error output.
• non blocking

how to show the num