StatementData Objects
The StatementData class contains information
about data that has been replicated as an SQL statement, as opposed to
information that is replicated as row-based data.
Processing and filtering statement information relies on editing the original SQL query statement, or the metadata recorded with it in the THL, such as the schema name or character set. Care should be taken when modifying SQL statement data to ensure that you are modifying the right part of the original statement. For example, a search and replace on an SQL statement should be made with care to ensure that embedded data is not altered by the process.
The key methods used for interacting with a
StatementData object are listed below:
| Method | Description |
|---|---|
getQuery()
| Returns the SQL statement |
setQuery()
| Updates the SQL statement |
appendToQuery()
| Appends a string to an existing query |
getDefaultSchema()
| Returns the default schema in which the statement was executed. The schema may be null for explicit or multi-schema queries. |
setDefaultSchema()
| Set the default schema for the SQL statement |
getTimestamp()
| Gets the timestamp of the query. This is required if data must be applied with a relative value by combining the timestamp with the relative value |
Updating the SQL
The primary method of processing statement based data is to load and
identify the original SQL statement (using
getQuery(), update or modify the SQL
statement string, and then update the statement within the THL again
using setQuery(). For example:
sqlOriginal = d.getQuery();
sqlNew = sqlOriginal.replaceAll('NOTEPAD','notepad');
d.setQuery(sqlNew);The above replaces the uppercase 'NOTEPAD' with a lowercase version in the query before updating the stored query in the object.
Changing the Schema Name
Some schema and other information is also provided in this structure. For example, the schema name is provided within the statement data and can be explicitly updated. In the example below, the schema “products” is updated to “nyc_products”:
if (change.getDefaultSchema().compareTo("products") == 0)
{
change.setDefaultSchema("nyc_products");
}
A similar operation should be performed for any row-based changes. A
more complete example can be found in
Section 10.4.8, “dbrename.js Filter”.