Abstract: The subject technology receives a query plan, the query plan comprising a set of query operations, the set of query operations including at least one aggregation. The subject technology analyzes the at least one aggregation to generate a modified query plan, the modified query plan including at least a top aggregation operator, an intermediate aggregation operator, and a bottom aggregation operator. The subject technology performs, with respect to the intermediate aggregation operator, at least one operation comprising: the subject technology receives an input intermediate data type; the subject technology performs an internalize operation on the input intermediate data type to generate an internal state; the subject technology performs an accumulate operation on the internal state to generate intermediate data; and the subject technology performs an externalize operation on the intermediate data to generate an output data type.

Abstract: Joining data using a disjunctive operator is described. An example computer-implemented method can include generating a query plan for a query, wherein there is a join operator expression for each of a plurality of disjunctive predicates and each join operator expression includes at least a conjunctive predicate and a disjunctive operator. The method may also include generating a bloom filter for each of the plurality of disjunctive operators. The method may further include evaluating each of the plurality of join operator expressions using a corresponding one of the plurality of disjunctive operators and bloom filter for each of the plurality of disjunctive predicates to generate a result set.

Abstract: During a query compilation process, a query is received that is directed to a set of source tables, each source table from the set of source tables being organized into at least one micro-partition and the query including at least one pruning operation. During the query compilation process, a modification of the query is performed for adjusting the at least one pruning operation, the modification being based on a set of statistics collected for previous pruning operations on at least a portion of the set of source tables and a set of heuristics, the set of statistics indicating at least an amount of execution time for each previous query associated with each of the previous pruning operations. The query is compiled including the modification of the query. The compiled query is provided to an execution node of a database system for execution.

Abstract: Queries executed against a materialized view can execute up to orders of magnitude faster than equivalent queries on a source (or base) table. However, although a query can reference a materialized view directly, a user (e.g., query author) may not know about a relevant materialized view. Moreover, if a source table has multiple materialized views generated, the user may not know which materialized view to reference in the query. Thus, embodiments of the present disclosure provide techniques for automatically rewriting queries directed to a source table to utilize existing materialized views.

Abstract: Embodiments of the present disclosure may provide dynamic and fair assignment techniques for allocating resources on a demand basis. Assignment control may be separated into at least two components: a local component and a global component. Each component may have an active dialog with each other; the dialog may include two aspects: 1) a demand for computing resources, and 2) a total allowed number of computing resources. The global component may allocate resources from a pool of resources to different local components, and the local components in turn may assign their allocated resources to local competing requests. The allocation may also be throttled or limited at various levels.

Abstract: Resource provisioning systems and methods are described. In an embodiment, a system includes a plurality of shared storage devices collectively storing database data, an execution platform, and a compute service manager. The compute service manager is configured to determine a task to be executed in response to a trigger event and determine a query plan for executing the task, wherein the query plan comprises a plurality of discrete subtasks. The compute service manager is further configured to assign the plurality of discrete subtasks to one or more nodes of a plurality of nodes of the execution platform, determine whether execution of the task is complete, and in response to determining the execution of the task is complete, store a record in the plurality of shared storage devices indicating the task was completed.

Abstract: Joining data using a disjunctive operator is described. An example computer-implemented method can include receiving a query that includes a first disjunctive predicate involving a first table and a second table. The method may also include determining a first set of rows from the first table and generating a filter from the first set of rows. The method may also further include applying the filter to the second table to generate a second set of rows. Additionally, the method may also include joining the first set of rows and the second set of rows using a first disjunctive operator of the first disjunctive predicate to generate a first results set.

Abstract: Embodiments of the present disclosure may provide a data protection system that performs identification of errors from queries on a database. The data protection system can further identify corrupted data from additional errors, are difficult to detect, and occur between layers of data in the database system. The data protection system can perform corrections of the error data by rebuilding database data or removing the corrupted data.

Abstract: The subject technology selects a most recently created file from a set of files stored in a source table. The subject technology iterates, in the source table, starting from the most recently created file up to an age threshold to select a first set of files for performing a first defragmentation process. The subject technology sets an indication corresponding to a particular file that is a last file, from the first set of files, that meets the age threshold. The subject technology performs the first defragmentation process on the selected first set of files. The subject technology determines that the first defragmentation process was successful.

Abstract: A cluster view method of a database to perform compaction and clustering of database objects, such as database materialized view is shown. The database can comprise a cache to store changes to storage units of tables of the database objects. The cluster view method can implement clustering to remove data based on the cache and clustering to group the data of the materialized view.

Abstract: Joining data using a disjunctive operator using a lookup table is described. An example computer-implemented method can include receiving a query with a set of conjunctive predicates and a set of disjunctive predicates. The method may also include generating a lookup table for each predicate in the sets of conjunctive predicates and disjunctive predicates. The method, for each row in a probe-side table, may also further include looking up a value associated with that row in each of the lookup tables and adding the row to a results set when there is a match. Additionally, the method may also include returning the results set.

Abstract: Embodiments of the present disclosure may provide a dynamic query execution model with fault tolerance and failure recovery techniques. Embodiments of the present disclosure may utilize checkpoints to map processed output files to their corresponding input files. Therefore, if an error occurs in processing one or more files, the system may only need to reschedule processing of selected file(s).

Abstract: Systems, methods, and devices for incrementally refreshing a materialized view are disclosed. A method includes generating a materialized view based on a source table. The method includes merging the source table and the materialized view to generate a merged table to identify whether an update has been executed on the source table that is not reflected in the materialized view. The method includes, in response to detecting an update made to the source table that is not reflected in the materialized view, applying the update to the materialized view.

Abstract: Disclosed herein are embodiments of systems and methods for selecting partitions for reclustering based on distribution of overlapping partitions. In an example, a database platform makes a determination to at least partially recluster a database table that includes data stored across a plurality of partitions. The database platform responsively selects a subset of the partitions. The selecting of the subset includes identifying a point on a domain of a clustering key that corresponds to a local maximum of overlapping partitions, and also includes selecting the subset from among a group of overlapping partitions. The group includes at least one partition that overlaps the identified point on the domain of the clustering key. Each partition in the selected subset is above a reduction goal of overlapping partitions. The database platform at least partially reclusters the selected subset based on the clustering key.

Abstract: Queries executed against a materialized view can execute up to orders of magnitude faster than equivalent queries on a source (or base) table. However, although a query can reference a materialized view directly, a user (e.g., query author) may not know about a relevant materialized view. Moreover, if a source table has multiple materialized views generated, the user may not know which materialized view to reference in the query. Thus, embodiments of the present disclosure provide techniques for automatically rewriting queries directed to a source table to utilize existing materialized views.

Abstract: Embodiments of the present disclosure may provide a dynamic query execution model. This query execution model may provide acceleration by scaling out parallel parts of a query (also referred to as a fragment) to additional computing resources, for example computing resources leased from a pool of computing resources. Execution of the parts of the query may be coordinated by a parent query coordinator, where the query originated, and a fragment query coordinator.

Abstract: The subject technology receives a query plan corresponding to a query. The subject technology executes the query based at least in part on the query plan, the executing including: filtering a first set of files that are to be modified by a merge statement, performing a split operation to send information related to a second set of files to a scan set builder operation in a first portion of the query plan and scan back operation in a second portion of the query plan, performing the scan set builder operation to remove the second set of files from the first set of files, performing a table scan operation based on a third set of files, and performing a first union all operation to combine the first set of data with a second set of data as a first set of combined data.

Abstract: The subject technology receives, during a query compilation process, a query directed to a set of source tables. The subject technology performs, during the query compilation process, a modification of the query for adjusting at least one pruning operation. The subject technology determines, during a pruning process of a second query, the second query directed to a set of files in a database system and including a set of pruning operations on the set of files, whether to perform a pruning cutoff on the set of pruning operations, the pruning process performing a depth first search of a pruner tree structure, the set of files comprising a set of micro-partitions. The subject technology performs the pruning cutoff based on the determining, the pruning cutoff ceasing at least one pruning operation from the set of pruning operations.

Abstract: Joining data using a disjunctive operator is described. An example computer-implemented method can include generating a query plan for a query, wherein there is a join operator expression for each of a plurality of disjunctive predicates and each join operator expression includes at least a conjunctive predicate and a disjunctive operator. The method may also include generating a bloom filter for each of the plurality of disjunctive operators. The method may further include evaluating each of the plurality of join operator expressions using a corresponding one of the plurality of disjunctive operators and bloom filter for each of the plurality of disjunctive predicates to generate a result set.

Abstract: Resource provisioning systems and methods are described. In an embodiment, a system includes a plurality of shared storage devices collectively storing database data, an execution platform, and a compute service manager. The compute service manager is configured to determine a task to be executed in response to a trigger event and determine a query plan for executing the task, wherein the query plan comprises a plurality of discrete subtasks. The compute service manager is further configured to assign the plurality of discrete subtasks to one or more nodes of a plurality of nodes of the execution platform, determine whether execution of the task is complete, and in response to determining the execution of the task is complete, store a record in the plurality of shared storage devices indicating the task was completed.