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During synchronization, the data comparer makes the contents of
the secondary table equal to the contents of the primary one. There
are three steps:
- Data comparison.
- Synchronization script generation.
- Synchronization script execution.
It is important to understand that data synchronization
based on primary/unique key values. Please be careful when select
custom key. The incorrect custom key
definition is most possible reason of unexpected synchronization
issues.
In this process records absent in the primary table will be
deleted from the secondary one, records that differ will be updated, while records
absent in the secondary
table will be inserted from the primary one.
The user can change this behavior using the following options:
- Delete from secondary - disabling this option will block
deleting a record from the secondary table even if there is no such
record in the primary table.
- Insert by primary - disabling this option will block adding
records from the primary table even if there are no such records in
the secondary table.
- Update secondary - disabling this option will block secondary
rows modifications (updates).
The user can prevent script execution using related option. In this case the script will be
produced without actual database modification.
There are two places for output SQL script location definition:
project level and product level. In the first case different projects will use different
output files. In the second common file
will be used. If necessary we recommend to use $DATE$ and $TIME$
macros in the script file name to generate unique output files.
The program stops at the first error happen during
synchronization script execution. This option can be switched off. Moreover, the program can
rollback changes already made if the error happen. Please be sure
that specified transaction size is enough to cover all changes.
DTM Data Comparer can add optional COMMIT statements to the
synchronization script. Also, the user can specify custom SQL
statement delimiter like 'go' or ';'.
The "Date Conversion Function"
feature is useful when you synchronize date and time values with
different format: different databases, locations, culture, etc.
Note for Microsoft SQL Server users: there two modes for IDENTITY columns. By default the
comparison tool ignores identity column i.e. generates no code to
synchronize. In the second case the program will synchronize these
values as well.
See also: data synchronization settings.
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