Database interface agent for a tenant-based upgrade system

A computer-implemented tenant-based upgrade method associated with a system having a shared storage data store containing a first version of entities with original content and a local tenant storage data store to contain information associated with a tenant's application server, comprising:

• entering, by a computer processor of a database interface agent, a copy-on-access mode such that:
• as an application server accesses a sub-set of the first version of entities, the sub-set is migrated from the shared storage data store to the local tenant storage data store, and associated materialization flags are maintained indicating that the sub-set has been migrated,
• as the application server writes customer data into some of the sub-set of the first version of entities, modification flags are maintained indicating that those entities have received customer data;
• initiating, by the computer processor of the database interface agent, an upgrade process to install a second version of entities from the shared storage data store, wherein the first version of the entities is utilized by the application server during the upgrade process;
• entering, by the computer processor of the database interface agent, a copy-on-write mode such that:
• as the application server accesses an additional sub-set of the first version of entities, the addition sub-set is not migrated from the shared storage data store to the local tenant storage data store, and associated materialization flags are not maintained,
• as the application server writes customer data into some of the first version of entities, modification flags are maintained indicating that those entities have received customer data;
• deleting, from the local tenant storage data store by the computer processor of the database interface agent, entities having flags that indicate the entity was migrated but did not receive customer data;
• updating, by the computer processor of the database interface agent, the structure of the entities remaining in the local tenant storage data store in view of a structure of the second version of the entities;
• and
• updating the content of the entities remaining in the local tenant storage data store in view of content of the second version of entities and customer data previously written by the application server into some of the sub-set of the first version of entities.

A non-transitory, computer-readable medium storing program code associated with a system having a shared storage data store containing a first version of tables with original content and a local tenant storage data store to contain information associated with a tenant's application server, the program code executable by a processor of a database interface agent to cause the processor to perform a tenant-based upgrade method comprising:

• entering a copy-on-access mode such that:
• as an application server accesses a sub-set of the first version of tables, the sub-set is migrated from the shared storage data store to the local tenant storage data store, and associated materialization flags are maintained indicating that the sub-set has been migrated,
• as the application server writes customer data into some of the sub-set of the first version of tables, modification flags are maintained indicating that those tables have received customer data;
• initiating, by the computer processor of the database interface agent, an upgrade process to install a second version of tables from the shared storage data store, wherein the first version of the tables is utilized by the application server during the upgrade process;
• entering a copy-on-write mode such that:
• as the application server accesses an additional sub-set of the first version of tables, the addition sub-set is not migrated from the shared storage data store to the local tenant storage data store, and associated materialization flags are not maintained,
• as the application server writes customer data into some of the first version of tables, modification flags are maintained indicating that those tables have received customer data;
• deleting, from the local tenant storage data store, tables having flags that indicate the table was migrated but did not receive customer data;
• updating the structure of the tables remaining in the local tenant storage data store in view of a structure of the second version tables;
• and
• updating the content of the tables remaining in the local tenant storage data store in view of content of the second version of tables and customer data previously written by the application server into some of the sub-set of the first version of tables.