Efficient reference counting in content addressable storage

A computer system for managing database storage, comprising:

• one or more processors;
• memory;
• content storage, a content index, and a reference table all stored in the memory, wherein the content index identifies content chunks and the reference table stores references to each content chunk;
• and
• one or more programs stored in the memory, the one or more programs comprising instructions executable by the one or more processors for:
• receiving for storage a first object comprising one or more content chunks, wherein the first object is identified by a unique object ID and each content chunk has a unique offset within the first object;
• and
• for each respective content chunk:
• (a) constructing a respective content hash of the respective content chunk;
• (b) looking up the respective content hash in the content index;
• (c) when the respective content hash is not found in the content index:
• (1) storing the respective content chunk at a respective set of one or more locations in the content storage;
• and
• (2) inserting a record into the content index that includes the respective content hash and specifies the set of one or more locations where the respective content chunk is stored in the content storage;
• (d) when the respective content hash is found in the content index, forgoing inserting a record into the content index;
• and
• (e) inserting a respective reference record into the reference table, wherein the respective reference record includes the respective content hash and the object ID.

A non-transitory computer readable storage medium storing one or more programs configured for execution by one or more processors of a computer system to manage database storage in a database storage system, wherein the database storage system has content storage, a content index that identifies content chunks, and a reference table that stores references to each content chunk, and wherein the one or more programs comprise instructions for:

• receiving for storage a first object comprising one or more content chunks, wherein the first object is identified by a unique object ID and each content chunk has a unique offset within the first object;
• and
• for each respective content chunk:
• (a) constructing a respective content hash of the respective content chunk;
• (b) looking up the respective content hash in the content index;
• (c) when the respective content hash is not found in the content index:
• (1) storing the respective content chunk at a respective set of one or more locations in the content storage;
• and
• (2) inserting a record into the content index that includes the respective content hash and specifies the set of one or more locations where the respective content chunk is stored in the content storage;
• (d) when the respective content hash is found in the content index, forgoing inserting a record into the content index;
• and
• (e) inserting a respective reference record into the reference table, wherein the respective reference record includes the respective content hash and the object ID.