Structured large object (LOB) data

摘要

Provided are techniques for processing structured content within Large Object (LOB) data that is stored in a column of a database table. Structural metadata describing structures that each define a different format of the structured content is stored. A request for data in the database table is received. The structural metadata is used to create an empty result set with columns defined by at least two of the structures. For each row of data in the database table that includes LOB data, control data is used to identify one of the structures to be applied to the structured content within the LOB data stored in that row of data, and the structured content within the LOB data in that row of data is mapped to the columns in the result set based on the identified one of the structures. The result set is returned.

主权项

1. A method, comprising:
storing, using a processor of a computer, structural metadata describing a first structure and a second structure that each define a different format of structured content, wherein the structured content is a subset of Large Object (LOB) data, wherein the first structure has a first set of columns, and wherein the second structure has a second set of columns; using the structural metadata to create a result set that is empty with the first set of columns and the second set of columns; for each row of data in the database table that includes the LOB data,
in response to control data identifying the LOB data as having the first structure, mapping the structured content within the LOB data in that row of data to the first set of columns in the result set by generating queries using the structural metadata describing the first structure; andin response to the control data identifying the LOB data has having the second structure, mapping the structured content within the LOB data in that row of data to the second set of columns in the result set by generating queries using the structure metadata describing the second structure; and returning the result set.