ALTERING DATA TYPE OF A COLUMN IN A DATABASE

摘要

Disclosed herein are system, method, and computer program product embodiments for altering the data type of a column in a database. An embodiment operates by converting an original dictionary associated with a column into a new dictionary. The new dictionary stores the values of the original dictionary using a different data type. An index vector containing the keys of the original dictionary is then updated to contain the associated keys of the new dictionary. Because the size of the original dictionary is often substantially smaller than the number of rows in the associated column, this dictionary conversion decreases the computation cost to the database system of altering the data type of the column and reduces or even minimizes database downtime for users.

主权项

1. A computer implemented method for altering a column in a database from a first data type to a second data type, comprising:
identifying, by at least one processor, a first dictionary associated with the column in the database, wherein the first dictionary includes a key having an associated value of the first data type; converting, by the at least one processor, the associated value in the first dictionary from the first data type to a second data type, wherein the second data type is different than the first data type; mapping, by the at least one processor, the key in the first dictionary to a key in a second dictionary based on the converting; and storing, by the at least one processor, the converted associated value in the second dictionary, wherein at least one of the identifying, converting, mapping, and storing are performed by one or more computers.