daff.IndexPair

An index of rows in two tables. We add a list of columns to use as a key. Rows in the two tables that have the same key are treated as matches. Good indexes have distinct keys within a table, and keys that match (ideally just once) across tables.

Type: class

Constructor:

new(flags : CompareFlags)

Methods:

addColumns (ca : Int, cb : Int) : Void

  Add a column in each table to treat as part of a key.
  Fine to call repeatedly.

Parameters:

ca column in first table

cb column in second table

getQuality () : Float

  Get a measure of the quality of this index pair.  Higher values
  are better.

Returns: index quality

getTopFreq () : Int

  Get the highest number of key collisions for any given key
  within an individual table.  High numbers of collisions are
  a bad sign.

Returns: frequency of key collisions

indexTables (a : Table, b : Table, hdr : Int) : Void

  Go ahead and index all the rows in the given tables.
  Make sure to call `addColumns` first.

Parameters:

a the first reference table

a the second table

localKey (row : Int) : String

  Get the key of a row in the first (local) table.

Parameters: row the row to get a key for

Returns: the key

queryByContent (row : Row) : CrossMatch

  Find matches for a given row.

Returns: match information

queryLocal (row : Int) : CrossMatch

  Find matches for a given row in the first (local) table.