Patch-up operations on invalidity data

One or more non-transitory computer-readable media storing instructions which, when executed by one or more processors, cause:

• maintaining, on persistent storage, a database that is accessible to a plurality of database server instances;
• wherein each database server instance of the plurality of database server instances is executing on a corresponding node of a plurality of nodes;
• storing a persistent-format copy of a mirrored data set persistently, within the database, on a plurality of coarse-granularity items;
• storing a mirror-format copy of the mirrored data set in an in-memory-unit within volatile memory of a particular node of the plurality of nodes;
• wherein the mirror-format copy of the mirrored data is divided into courser-granularity items;
• wherein each courser-granularity item in the mirror-format copy is divided into finer-granularity items;
• storing, within the particular node, invalidity data that indicates which information, within the mirror-format copy, is invalid;
• wherein the invalidity data includes:
• finer-granularity invalidity data that indicates, on a per-finer-granularity-item basis, invalidity of the information within the mirror-format copy at a first level of granularity;
• and
• coarser-granularity invalidity data that indicates, on a per-coarser-granularity-item basis, invalidity of the information within the mirror-format copy at a second level of granularity that is coarser than the first level of granularity;
• receiving, at the particular node from a particular computing device, a particular query;
• and
• in response to receiving the particular query, a particular database server instance executing on the particular node performing a patch-up operation on the invalidity data.

A system comprising;

• a memory;
• one or more processors communicatively coupled to the memory and configured to:
• maintain, on persistent storage, a database that is accessible to a plurality of database server instances;
• wherein each database server instance of the plurality of database server instances is executing on a corresponding node of a plurality of nodes;
• store a persistent-format copy of a mirrored data set persistently, within the database, on a plurality of coarse-granularity items;
• store a mirror-format copy of the mirrored data set in an in-memory-unit within volatile memory of a particular node of the plurality of nodes;
• wherein the mirror-format copy of the mirrored data is divided into courser-granularity items;
• wherein each courser-granularity item in the mirror-format copy is divided into finer-granularity items;
• store, within the particular node, invalidity data that indicates which information, within the mirror-format copy, is invalid;
• wherein the invalidity data includes:
• finer-granularity invalidity data that indicates, on a per-finer-granularity-item basis, invalidity of the information within the mirror-format copy at a first level of granularity;
• and
• coarser-granularity invalidity data that indicates, on a per-coarser-granularity-item basis, invalidity of the information within the mirror-format copy at a second level of granularity that is coarser than the first level of granularity;
• receive, at the particular node from a particular computing device, a request to commit one or more transactions to the database;
• and
• in response to receiving the request to commit the one or more transactions to the database, a particular database server instance executing on the particular node performing a patch-up operation on the invalidity data.