Lookup Component Usage

Lookup component A JOIN clause similar to TSQL,

Select A.* , B.* from dbo.tis aleftjoin  dbo. Tdes b   on A.code=B.code

Analysis of the composition of Lookup component

• Two inputs, one is the input dbo.tis of the upstream data stream, and the other is the data set Dbo.tdes to find;
• Two outputs, one is the output matches the successful data, one is the output matches the unsuccessful data. A row of data from the upstream data stream matches the entire lookup set, and if the match succeeds, the output matches the successful data, otherwise the output matches the unsuccessful data.
• Compare logic, to make a match must be compared, lookup componet is an equivalent comparison, similar to the ON clause of join, the ON clause uses "=" to make conditional judgments.
• To compare columns, Lookup component needs to set the comparison column at both ends of the "=" sign.

1,lookup component has three cache mode,fullcache,partial caches and no caches, and these three cache mode are for the Lookup dataset, Because each row of the upstream traffic is matched to all rows of the lookup dataset, access to the lookup dataset is very frequent, and the lookup dataset must be accessed faster to improve performance. If memory allows, select full cache, and the data from the lookup dataset resides in the cache, with the highest access speed.

The 2,cache Connection Manager is a memory-link receiver, and the data resides in the cache. Enter column manually, and select Type,length,codepage,index position. Index position identifies whether the column is an index column. Index is used to identify the comparison column, columnindex column for 1, for comparison, and 0 to identify that the column is not index column, although it cannot be used for comparison columns, but can be used for replace input columns.

3,cache Connection Manager is just the schema that identifies the memory, but where is the data source? You need to use the cache conversion to import data from the data source into the cache. Codex is preceded by a magnifying glass that identifies the column as a lookup column for comparison.

4,lookup component setting Comparison column mapping

In the Columns tab of the lookup component, set the comparison column Mapping,code and codex to compare, that is, the ON clause comparison condition.

If you need to use a lookup set instead of the upstream data stream input, you can tick available lookup columns's non-lookup column (the column with the index column without a magnifying glass), and then select Replace in the lookup operations. If you want to add the lookup columns to the output stream, select Add as New column in the lookup operations.

The output of the 5,lookup component is two, and the matching is always output, but it needs to be configured to match the unsuccessful output.

Redirect rows to no match output: outputs no matching rows to the matching unsuccessful output stream.

Lookup Component Usage