Native XML databases - Making Sense of NoSQL - page 120

Figure 5.12 A sample data flow of an operational data store (ODS) for a complex
financial derivatives system using multiple RDBMSs to store the data. The trading
systems each stored data into RDBMSs using complex SQL INSERT statements. SQL
SELECT statements were used to extract data. Each new derivative type required custom
software to be written.
Highlights of the banks conversion process included these:
 Each system had its own method for ingesting the transactions, converting them
to row structures, storing the rows in tables, and reporting on the transactions.
 Custom software was required for each new derivative type so key parameters
could be stored and queried.
 In many instances, a single column stored different types of information based
on other parameters in the transaction.
 After the data was stored, SQL queries were written to extract information for
downstream processing when key events occurred.
 Because different data was shoehorned into the same column based on the
derivative type, reporting was complex and error prone.
 Errors resulted in data quality issues and required extensive auditing of output
results before the data could be used by downstream systems.
This complex conversion process made it difficult for the bank to get consistent and
timely reports and to efficiently manage document workflow. What they needed was a
flexible way to store the derivative documents in a standard format such as XML , and
to be able to report on the details of the data. If all derivatives were stored as full XML
documents, each derivative could contain its unique parameters, without changes to
the database.
As a result of this analysis, the bank converted their operational data store ( ODS )
to a native XML database (MarkLogic) to store their derivative contracts. Figure 5.13
shows how the MarkLogic database was integrated into the financial organization's
workflow.
MarkLogic is a commercial document-oriented NoSQL system that has been
around since before the term NoSQL was popular. Like other document stores, Mark-
Logic excels at storing data with high variability and is compliant with W3C standards
such as XML , XPath, and XQuery.