Efficient migration of binary XML across databases
Techniques are provided for transporting subset of databases containing binary XML data. In one embodiment, a method is provided that allows transporting binary XML data that conforms to schema by also transporting the schema entries that are necessary to derive the binary XML. In another embodiment, a method is provided that allows transporting binary XML data that does not conform to schema by also transporting the token tables that contain the mapping for the binary XML.
1. A computer implemented method for moving XML data from a source database to a target database, comprising:
generating a copy of a particular tablespace that is part of the source database,
wherein the particular tablespace contains first binary XML data;
wherein the first binary XML data is XML data that has been encoded in a binary format,
wherein the copy of the particular tablespace contains second binary XML data;
wherein the second binary XML data is a copy of the first binary XML data;
incorporating the copy of the particular tablespace into the target database,
wherein incorporating the copy of the particular tablespace into the target database causes the second binary XML data to be incorporated in the target database;
determining translation information, that is used for decoding the first binary XML data in the source database, and that is needed to decode the second binary XML data in the target database; and
generating a copy of the translation information from said source database;
incorporating the copy of the translation information into the target database;
after incorporating the copy of the particular tablespace and the copy of the translation information into the target database, using the copy of the translation information to decode the second binary XML data when the second binary XML data is accessed in the target database;
wherein generating the copy of the translation information includes generating a copy of a set of token tables that contain the translation information necessary to decode the second binary XML data;
wherein incorporating the copy of the translation information into the target database includes updating metadata within the target database to indicate that the copy of the set of token tables are associated with said copy of the particular tablespace; and
wherein the steps of generating a copy of the particular tablespace, incorporating the copy of the particular tablespace, generating a copy of the translation information, incorporating the copy of the translation information, and using the copy of the translation information are performed by one or more computing devices.
2. The method of claim 1 , wherein:
the XML data that resides in said particular tablespace includes unknown-schema XML data.
3. The method of claim 1 wherein:
within the source database, the set of token tables is associated with a particular identifier that is also mapped to said copy of said particular tablespace;
the method further includes associating, within the target database, the copy of the set of token tables with said particular identifier; and
the particular identifier is unique relative to both the target database and the source database;
wherein said copy of said particular tablespace includes multiple XML nodes.
4. The method of claim 3 , further comprising:
appending the particular identifier to a name of at least one token table in the copy of the set of token tables to ensure that the name of the at least one token table is unique within said target database.
5. The method of claim 1 , further comprising:
computing a query using the incorporated copy of the translation information.
6. A non-transitory computer-readable storage medium storing one or more sequences of instructions for moving XML data from a source database to a target database which, when executed by one or more processors, causes the one or more processors to perform:
generating a copy of a particular tablespace that is part of the source database,
wherein the particular tablespace contains XML data that has been encoded in a binary format;
incorporating the copy of the particular tablespace into the target database;
determining translation information, that is used for decoding XML data in the source database, and that is needed to decode the XML data in the particular tablespace; and
generating a copy of the translation information from said source database;
incorporating the copy of the translation information into the target database;
after incorporating the copy of the particular tablespace and the copy of the translation information into the target database, using the copy of the translation information to decode the XML data that is encoded in the binary format, that resides in the copy of the particular database;
wherein generating the copy of the translation information includes generating a copy of a set of token tables that contain the translation information necessary to decode the second binary XML data;
wherein incorporating the copy of the translation information into the target database includes updating metadata within the target database to indicate that the copy of the set of token tables are associated with said copy of the particular tablespace.
7. The non-transitory computer-readable storage medium of claim 6 , wherein:
the XML data that resides in said particular tablespace includes unknown-schema XML data.
8. The non-transitory computer-readable storage medium of claim 6 , wherein: within the source database, the set of token tables is associated with a particular identifier that is also mapped to said copy of said particular tablespace;
the one or more sequences of instructions, when executed by the one or more processors, further cause the one or more processors to perform associating, within the target database, the copy of the set of token tables with said particular identifier; and
the particular identifier is unique relative to both the target database and the source database;
wherein said copy of said particular tablespace includes multiple XML nodes.
9. The non-transitory computer-readable storage medium of claim 8 , wherein the one or more sequences of instructions, when executed by the one or more processors, further cause the one or more processors to perform:
appending the particular identifier to a name of at least one token table in the copy of the set of token tables to ensure that the name of the at least one token table is unique within said target database.
10. The non-transitory computer-readable storage medium of claim 6 , wherein the one or more sequences of instructions, when executed by the one or more processors, further cause the one or more processors to perform:
computing a query using the incorporated copy of the translation information.