a.
merge and merge join-- Merge Acts like a union all in T-sql but you can provide only two input
to this transformation which must be pre- sorted and merge join joins the two
datasets like T-SQL joins(inner join , left join, right join )
b.
union and union all---- The union command is used to select related information
from two tables but with union distinct values are selected. The union all
command is equal to the union command, except union all selects all values and
will not get rid of duplicate rows.
c.
merge join and union all--- Merge can only accept two datasets while
Union All can accept more than two datasets for input. The second difference is
that Merge requires both datasets to be sorted while Union All does not require
sorted datasets
d.
row sampling and percentage sampling--- Row sampling is used to randomly
select some rows and move them as output to the required process as and when
required to divide the rows. Percentage Sampling on the other hand, selects
rows randomly by percentage.
e.
dts and ssis---- DTS is a set of objects using an ETS tool to extract,
transform, and load information to or from a database; SSIS is an ETL tool
provided by Microsoft to extract data from different sources.
f.
pivot and unpivot---- Pivot will convert rows to columns and un-pivot will go the other way,
columns to rows
g.
scnhronous transformation and
ascnchronous transformation--- A synchronous transformation processes incoming rows and passes them on
in the data flow one row at a time. Output is synchronous with input, meaning
that it occurs at the same time. The
transformation does not need information about other rows in the data set. The
Rows are grouped into Buffers as they pass from one component to the next.
Meanwhile, in an asynchronous
transformation, you cannot pass each row along in the data flow as it is
processed, but instead must output data asynchronously, or at a different time,
than the input.
h.
look-up and merge join--- The Lookup transformation performs lookups by joining data in input
columns with columns in a reference dataset.
Lookup uses an ole db connection manager. While a merge join combines
two sorted datasets using a FULL, LEFT, or INNER join.
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