Pruning techniques for processing top K queries

A system comprising:

• one or more hardware processors;
• and
• at least one memory storing instructions that cause the one or more hardware processors to perform operations comprising:
• receiving a top K query directed at a table, the top K query comprising a first clause to sort a result set in an order and a second clause that specifies that the result set is limited to a specific number of rows from the table;
• generating a query plan for the top K query, the query plan comprising a table scan operator and a top K operator positioned downstream of the table scan operator;
• based on the query plan, configuring a set of execution nodes to comprise the table scan operator and the top K operator positioned downstream of the table scan operator, each execution node in the set of execution nodes comprising at least one of the one or more hardware processors;
• identifying, by the table scan operator, a first set of rows from the table, the first set of rows having the specific number of rows;
• determining, by the top K operator, a current boundary based on the first set of rows;
• generating, by the table scan operator, a pruned scan set based on the current boundary determined by the top K operator;
• identifying, by the table scan operator, a second set of rows from the table based on the pruned the scan set;
• and
• providing the result set responsive to the top K query based on the first and second set of rows, the result set being limited to the specific number of rows specified by the second clause of the top K query.

A computer-storage medium comprising instructions that, when executed by one or more processors of one or more machines, configure the one or more machines to perform operations comprising:

• receiving a top K query directed at a table, the top K query comprising a first clause to sort a result set in an order and a second clause that specifies that the result set is limited to a specific number of rows from the table;
• generating a query plan for the top K query, the query plan comprising a table scan operator and a top K operator positioned downstream of the table scan operator;
• based on the query plan, configuring a set of execution nodes to comprise the table scan operator and the top K operator positioned downstream of the table scan operator, each execution node of the set of execution nodes comprising at least one of the one or more processors;
• identifying, by the table scan operator, a first set of rows from the table, the first set of rows having the specific number of rows;
• determining, by the top K operator, a current boundary based on the first set of rows;
• generating, by the table scan operator, a pruned scan set based on the current boundary determined by the top K operator;
• identifying, by the table scan operator, a second set of rows from the table based on the pruned the scan set;
• and
• providing the result set responsive to the top K query based on the first and second set of rows, the result set being limited to the specific number of rows specified by the second clause of the top K query.