Abstract: A database system is operable to assign a first node as a task monitoring node for a task and assign a second node as a task execution node for the task. The task is executed via the first node and the second node based on the first node sending a plurality of polls to the second node, the second node initiating execution of the task based on one of the plurality of polls, the second node sending a plurality of task status data to the first node, the first node maintaining current task status data for the task a shared metadata state based on the plurality of task status data, the second node completing execution of the task and caching task results in memory resources, the first node receiving the task results from the second node; and the second node removing the task results from the memory resources.

Abstract: A node of a database system is operable to execute a shuffle operator based on, during a first temporal period, reserving a first amount of memory, allocating, to each of a plurality of other nodes, a corresponding number of fixed-memory units based on the first amount of memory, and process first data received from the plurality of other nodes in accordance with the corresponding number of fixed-memory units allocated to the each of the plurality of other nodes. During a second temporal period after the first temporal period, the first amount of memory is updated to a second amount of memory based on comparing an available amount of memory with a configured memory threshold, an updated corresponding number of fixed-memory units is re-allocated, and second data received from the plurality of other nodes in accordance with the corresponding number of fixed-memory units is processed.

Abstract: A database system is operable to execute a query based on, during a first temporal period, executing a multiplexer operation in conjunction with a first mode of operation to generate a first plurality of multiplexer output, and executing a load operation upon the first plurality of multiplexer output to generate initial load operation output from the first plurality of multiplexer output. In response to a determination to transition to execution of the multiplexer operation in conjunction with a second mode of operation, the multiplexer operation is further executed in conjunction with the second mode of operation during a second temporal period to generate a second plurality of multiplexer output for processing via the load operation. The load operation is further executed upon the second plurality of multiplexer output to generate further load operation output.

Abstract: A database system operates by: determining a query for execution against a dataset that indicates a filtering predicate denoting a disjunction between a first range-based predicate and a second range-based predicate; accessing distribution data for the dataset indicating a plurality of kernels for a plurality of points in a multi-dimensional space; identifying a first sub-region within the multi-dimensional space corresponding to the first range-based predicate; identifying a second sub-region within the multi-dimensional space corresponding to the second range-based predicate; computing a disjunction probability approximation value based on an average portion summation value across a plurality of portion summation values generated for the plurality of kernels; and executing the query based on the disjunction probability approximation value.

Abstract: A node of a database system is operable to determine, at a first time, to prepare for a shutdown. The shutdown of the node is performed at a second time that is a period of time after the first time based on the node delaying the shutdown until a plurality of currently running processes being run by the node that initiated prior to the first time are determined to be complete. During the period of time after the first time and prior to performing the shutdown, a set of new processing requests are rejected by the node.

Abstract: A database system is operable to execute a query based on, during a first temporal period, executing a multiplexer operation in conjunction with a first mode of operation to generate a first plurality of multiplexer output, and executing a load operation upon the first plurality of multiplexer output to generate initial load operation output from the first plurality of multiplexer output. In response to a determination to transition to execution of the multiplexer operation in conjunction with a second mode of operation, the multiplexer operation is further executed in conjunction with the second mode of operation during a second temporal period to generate a second plurality of multiplexer output for processing via the load operation. The load operation is further executed upon the second plurality of multiplexer output to generate further load operation output.

Abstract: A query processing system operates by: determining a query for execution that indicates a join expression and further indicates a threshold maximum number of output rows for the join expression; determining a query operator execution flow for the join expression that includes performance of two join operations based on the threshold maximum number of output rows for the join expression, wherein a union of output of the two join operations is semantically equivalent to an output of the join expression; and executing the query based on: performing the two join operations in parallel upon sets of input rows; and based on determining a set of output rows outputted by the two join operations has reached the threshold maximum number of output rows, finalizing execution of the query before at least one of the two join operations has finished processing its input rows.

Abstract: A node of a database system is operable to determine, at a first time, to prepare for a shutdown. The shutdown of the node is performed at a second time that is a period of time after the first time based on the node delaying the shutdown until a plurality of currently running processes being run by the node that initiated prior to the first time are determined to be complete. During the period of time after the first time and prior to performing the shutdown, a set of new processing requests are rejected by the node.

Abstract: A database system is operable to generate query output based on executing a plurality of operators of a query operator execution flow for a query. Executing each operator can include generating a set of output query rows based on processing a set of input query rows, maintaining execution tracking data for the each operator that includes at least one counter tracking at least one event type, and generating a set of execution tracking rows based on sampling the execution tracking data. The query output includes a final set of rows corresponding to a query resultant and a final set of execution tracking rows generated by at least one final operator based on an aggregation of a plurality of sets of execution tracking rows generated by the plurality of operators.

Abstract: A database system is operable to determine a query for execution. The database system can execute a left join operation for the query based on receiving a plurality of left input rows, and forwarding all of the plurality of left input rows are forwarded. It is determined whether any right input rows match with each given left input row based on a hash map. When one right input row is identified as matching with the given left input row, a value of right input row is copied and emitted in conjunction with the given left input row. When no right input rows are identified as matching with the given left input row, a null value is emitted in conjunction with the given left input row.

Abstract: A database system is operable to generate query output based on executing a plurality of operators of a query operator execution flow for a query. Executing each operator can include generating a set of output query rows based on processing a set of input query rows, maintaining execution tracking data for the each operator that includes at least one counter tracking at least one event type, and generating a set of execution tracking rows based on sampling the execution tracking data. The query output includes a final set of rows corresponding to a query resultant and a final set of execution tracking rows generated by at least one final operator based on an aggregation of a plurality of sets of execution tracking rows generated by the plurality of operators.

Abstract: A node of a database system is operable to determine, at a first time, to prepare for a shutdown. The shutdown of the node is performed at a second time that is a period of time after the first time based on the node delaying the shutdown until a plurality of currently running processes being run by the node that initiated prior to the first time are determined to be complete. During the period of time after the first time and prior to performing the shutdown, a set of new processing requests are rejected by the node.

Abstract: A database system is operable to determine a query that includes a join expression for execution. A set of input rows are dispersed for processing via a plurality of parallelized join processes in conjunction with executing the join expression based on identifying a first proper subset of the set of input rows based on a null-handling strategy. First rows in the first proper subset are dispersed for processing across the plurality of parallelized join processes in accordance with the null-handling strategy. second rows in a set difference between the set of input rows and the first proper subset are dispersed across the plurality of parallelized join processes in accordance with a join key-based assignment strategy. The set of input rows are processed via the plurality of parallelized join processes.

Abstract: A database system is operable to determine a query operator execution flow that includes a plurality of operators for execution of a corresponding query against a database having a schema that includes a plurality of columns. The query operator execution flow is executed in conjunction with executing the corresponding query against the database based on generating a first plurality of data blocks of a multi-column data stream as first output of a first operator of the plurality of operators, where each data block of the multi-column data stream includes column values for each of the plurality of columns. Executing the query operator execution flow is further based on processing the multi-column data stream as input of a second operator of the plurality of operators serially after the first operator to generate a second plurality of data blocks as second output of the second operator.

Abstract: A database system is operable to determine a query for execution. The database system can execute a left join operation for the query based on receiving a plurality of left input rows, and forwarding all of the plurality of left input rows are forwarded. It is determined whether any right input rows match with each given left input row based on a hash map. When one right input row is identified as matching with the given left input row, a value of right input row is copied and emitted in conjunction with the given left input row. When no right input rows are identified as matching with the given left input row, a null value is emitted in conjunction with the given left input row.