Query Builder Components
The master index application performs two types of queries. Users perform manual queries from the MIDM and the master index application automatically performs queries before processing matches for an incoming record. Two types of queries, basic queries and blocking queries, are predefined in the Query Builder. By default, basic queries are defined for the MIDM and blocking queries are defined for match processing, though this is not required. You can also use a blocking query for the phonetic searches performed from the MIDM. Both types of queries are configured by query.xml, and custom queries can be created and implemented with the master index application.
You can configure certain query properties. You can configure both basic and blocking queries to search on standardized or phonetic versions of the search criteria, and you can also specify that they search on exact values or a range of values. Basic queries can be configured to allow wildcard characters. For the blocking queries, you define the criteria to include in each block of query criteria.
The following topics provide additional information about the different types of queries:
Basic Queries in a Master Index
By default, searches performed from the MIDM follow the logic defined in the configured basic queries. You can specify which query type to use for each search defined for the MIDM (this is specified in midm.xml). These searches can be weighted, which means that the match engine calculates the likelihood that the search results match the actual search criteria and assigns a matching weight to each returned record. You can specify whether the search is performed on the original or phonetic version of the criteria.
The basic query uses all supplied search criteria to create a single SQL query. For this query, each field in the WHERE clause is joined by an AND operator, meaning that only records that match on all search fields are returned. This query has an option to allow wildcard characters in the search criteria (a percent sign (%) indicates multiple unknown characters). When this option is set to true, the query uses the LIKE operator rather than EQUALS. This option allows you to search by criteria for which you have incomplete data.
The searches performed from the MIDM can be further customized in midm.xml (for more information, see Master Index Data Manager Configuration).
Blocking Queries in a Master Index
When the master index application evaluates possible matches of records sent to the master index application from external systems and from the MIDM, the index performs a set of predefined SQL queries to retrieve a subset of possible matches. These queries are known as blocking queries. The matching algorithm processes the input record against the profiles retrieved from the blocking query (known as the candidate pool) and assigns them matching probability weights.
Blocking Query Block Processing
In query.xml, you define the criteria and conditions for querying the database to retrieve the subset of possible matches to the incoming record, including hints. You can define multiple queries, known as blocks, for each blocking query, and the master index application performs each of these queries in turn until sufficient records are retrieved (called a match pass). Using the default Query Builder, a block is only processed if the search criteria include all of the fields defined for that block. Each field in a block is joined by an AND operator in the WHERE clause, and each block is joined by a UNION operator. This type of search can also be used as a phonetic search in the MIDM.
Blocking Query for Matching
The blocking queries you define here are referenced in master.xml, which specifies which one of the defined blocking queries to use for match processing. They might also be referenced in midm.xml if a blocking query is used for phonetic searches from the MIDM. To enable extensive searching (that is, searching against additional tables, such as an alias table for a person index), you must add the fields from that table to the blocking query.
Certain fields used as criteria in the blocking query might contain known default or invalid values. You can define exclusion lists to filter out unwanted or invalid values from the blocking query. For more information, see SBR, Matching, and Blocking Filter Configuration.
Phonetic Queries in a Master Index
You can configure both basic queries and blocking queries to perform phonetic searches from the MIDM. If you use a basic query, then all entered criteria must match existing records in order to return results from the search. If you use a blocking query, several queries are performed using different combinations of data until enough matching records are returned or until all defined combinations have been tried.
For example, if you use a basic query and enter first and last name, date of birth, gender, and SSN for criteria, the basic query might not return any matches if any one of those fields does not match the criteria. However, if you use a blocking query for the same example, it might search on SSN, then on first name and date of birth, and then on last name and gender. The query returns any matching records from any of the query passes.
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