Runtime pruning for top K queries

A system comprising:

• at least one hardware processor;
• and
• at least one memory storing instructions that cause the at least one hardware processor 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 based on a column of the table and a second clause that specifies a limit on a number of results provided in response to the query;
• initiating execution of the top K query on the table, the initiating of the execution of the top K query comprising:
• generating a query plan for processing the top K query, the query plan comprising a top K node and a table scan node;
• determining run-time pruning is applicable to the top K query based on whether the table scan node is a child node or dependent child node of the top K node;
• and
• based on determining run-time pruning is applicable to the top K query, adding a reference to the top K node in the table scan node, the reference enabling the table scan node to request a current boundary from the top K node at run-time;
• determining, by the top K node, the current boundary based on a set of values identified by the table scan node in scanning the table;
• performing the run-time pruning during execution of the top K query on the table using the current boundary, the run-time pruning comprising:
• performing read-version pruning on a scanset of the table scan node using the current boundary during the scanning of the scanset, the scanset comprising multiple versions of the table, the performing of the read-version pruning comprising pruning data from one or more older versions of the table from the scanset;
• generating a filter using the current boundary;
• and
• using the filter to:
• remove one or more scanning ranges from the scanset of the table scan node based on the column being a key column of the table;
• or
• filter values scanned by the table scan node based on the column being a non-key column of the table;
• and
• returning the result set based on the run-time pruning performed during execution of the top K query on the table.

A computer-storage medium comprising instructions that, when executed by one or more processors of a machine, configure the machine 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 based on a column of the table and a second clause that specifies a limit on a number of results provided in response to the query;
• initiating execution of the top K query on the table, the initiating of the execution of the top K query comprising:
• generating a query plan for processing the top K query, the query plan comprising a top K node and a table scan node;
• determining run-time pruning is applicable to the top K query based on whether the table scan node is a child node or dependent child node of the top K node;
• and
• based on determining run-time pruning is applicable to the top K query, adding a reference to the top K node in the table scan node, the reference enabling the table scan node to request a current boundary from the top K node at run-time;
• determining, by the top K node, the current boundary based on a set of values identified by the table scan node in scanning the table;
• performing the run-time pruning during execution of the top K query on the table using the current boundary, the run-time pruning comprising:
• performing read-version pruning on a scanset of the table scan node using the current boundary during the scanning of the scanset, the scanset comprising multiple versions of the table, the performing of the read-version pruning comprising pruning data from one or more older versions of the table from the scanset;
• and
• generating a filter using the current boundary and using the filter to:
• remove one or more scanning ranges from a scanset of the table scan node based on the column being a key column of the table;
• or
• filter values scanned by the table scan node based on the column being a non-key column of the table;
• and
• returning the result set based on the run-time pruning performed during execution of the top K query on the table.