Preventing staleness in query results when using asynchronously updated indexes

A method, the method comprising:

• providing, by one or more processors, an asynchronously updated index for a main dataset in a database system;
• providing, by one or more processors, a time-sequenced log data of modifications to the main dataset, wherein the log data of modifications includes at least one of (i) an addition, (ii) an update and (iii) a deletion of affected entries of the main dataset after a cutoff time of a last asynchronous index update;
• receiving, by one or more processors, a query of the main dataset;
• joining, by one or more processors, the main dataset with the time-sequenced log data resulting in a first intermediate result comprising one or more entry of the main dataset after the cutoff time, wherein the one or more entry is at least one of (i) inserted, (ii) updated, and (iii) deleted;
• processing, the one or more processors, the query by keeping the one or more entries satisfying the query by emulating a function of the asynchronously updated index access resulting in a second intermediate result;
• filtering, by one or more processors, at least one of (i) an out updated dataset entry and (ii) a deleted dataset entry from the asynchronously updated index using the time-sequenced log data building a lookup table;
• processing, by one or more processors, the query against the base table using the lookup table resulting in a third intermediate result;
• and
• building, by one or more processors, a union of the second intermediate result and the third intermediate result defining a final result of the query.