Apparatus and method for read consistency in a log mining system
A computer readable storage medium includes executable instructions to receive a specification for requested data in a log based replication system where data changes are retrieved from both a transaction log and a database. It is determined that the requested data is compromised. A search for a data image containing the requested data is initiated. The data image is accessed to secure the requested data. The requested data is returned.
1. A computer readable storage medium, comprising executable instructions to:
receive a specification for requested data in a log based replication system where data changes are retrieved from both a transaction log and a database;
receive a specification that characterizes a logical change number associated with the requested data;
determine that the requested data is compromised in the transaction log, wherein the requested data is compromised if the requested data is at least two of: not logged in the transaction log, partially logged in the transaction log, encrypted, or compressed;
search for a data image outside the transaction log containing the requested data as of a specified log change number;
access the data image to secure the requested data;
return the requested data; and
generate at least one composite record, based at least in part on the returned data.
2. The computer readable storage medium of claim 1 further comprising executable instructions to receive a specification that characterizes a record.
3. The computer readable storage medium of claim 1 further comprising executable instructions to receive a specification that characterizes a column.
4. The computer readable storage medium of claim 1 wherein the specification forms part of a query.
5. The computer readable storage medium of claim 1 wherein the executable instructions to determine include executable instructions to determine that the data is not logged.
6. The computer readable storage medium of claim 1 wherein the executable instructions to determine include executable instructions to determine that the data is partially logged.
7. The computer readable storage medium of claim 1 wherein the executable instructions to determine include executable instructions to determine that the data is encrypted.
8. The computer readable storage medium of claim 1 wherein the executable instructions to determine include executable instructions to determine that the data is compressed.
9. The computer readable storage medium of claim 1 wherein the executable instructions to search for a data image include executable instructions to search for a data snapshot.
10. The computer readable storage medium of claim 1 wherein the executable instructions to search for a data image include executable instructions to search for a temporal log.
11. The computer readable storage medium of claim 1 further comprising executable instructions to append a warning to data retrieved from the database when a data image is not available.
12. The computer readable storage medium of claim 1 further comprising executable instructions to replicate the requested data in a database.
13. The computer readable storage medium of claim 1 further comprising executable instructions to replicate the requested data in a memory.
14. The computer readable storage medium of claim 1 further comprising executable instructions to replicate the requested data in a file.
15. The computer readable storage medium of claim 1 further comprising executable instructions to replicate the requested data in a warehouse.
16. A method, comprising:
receiving, at a computer system, a specification for requested data in a log based replication system where data changes are retrieved from both a transaction log and a database;
receiving, at the computer system, a specification that characterizes a logical change number associated with the requested data;
determining, at the computer system, that the requested data is compromised in the transaction log, wherein the requested data is compromised if the requested data is at least two of: not logged in the transaction log, partially logged in the transaction log, encrypted, or compressed;
searching for a data image outside the transaction log containing the requested data current as of a specified log change number;
accessing the data image with the computer system to secure the requested data;
returning the requested data; and
generating at least one composite record based at least in part on the returned data.
17. A computer system, comprising:
a central processing unit; and
a computer readable storage medium, comprising instructions executable by the central processing unit to cause the computer system to:
receive a specification for requested data in a log based replication system where data changes are retrieved from both a transaction log and a database;
receive a specification that characterizes a logical change number associated with the requested data;
determine that the requested data is compromised in the transaction log, wherein the requested data is compromised if the requested data is at least two of: not logged in the transaction log, partially logged in the transaction log, encrypted, or compressed;
search for a data image outside the transaction log containing the requested data current as of a specified log change number;
access the data image to secure the requested data;
return the requested data; and
generate at least one composite record, based at least in part on the returned data.