Abstract: Compiled portions of code generated to perform a query plan at a query engine may be shared with other query engines. A data store, separate from the query engines, may store compiled portions of query code generated for different queries. If a query engine does not have a locally stored compiled portion of query code, then the separate data store may be accessed in order to obtain a compiled portion of query code, allowing reuse of compiled query code across different queries engines for queries directed to different databases.

Abstract: Online restore may be performed between databases with different topologies while applying a custom data distribution. A request to restore a database into a different topology of nodes may be received. A plan to move different portions of the database from a current topology to the new topology made using a general distribution scheme. The plan may be performed to move the different portions of the database into the new topology and the database made available for access using the new topology. A background process may be applied to modify the distribution of the database at the new topology to match a custom distribution scheme that was implemented at the current topology.

Abstract: Compiled portions of code generated to perform a query plan at a query engine may be shared with other query engines. A data store, separate from the query engines, may store compiled portions of query code generated for different queries. If a query engine does not have a locally stored compiled portion of query code, then the separate data store may be accessed in order to obtain a compiled portion of query code, allowing reuse of compiled query code across different queries engines for queries directed to different databases.

Abstract: Scaling of query processing resources for efficient utilization and performance is implemented for a database service. A query is received via a network endpoint associated with a database managed by a database service. Respective response times predicted for the query using different query processing configurations available to perform the query are determined. Those query processing configurations with response times that exceed a variability threshold determined for the query may be excluded. A remaining query processing configuration may then be selected to perform the query.

Abstract: Scaling of query processing resources for efficient utilization and performance is implemented for a database service. A query is received via a network endpoint associated with a database managed by a database service. Respective response times predicted for the query using different query processing configurations available to perform the query are determined. Those query processing configurations with response times that exceed a variability threshold determined for the query may be excluded. A remaining query processing configuration may then be selected to perform the query.

Abstract: Online restore may be performed between databases with different topologies while applying a custom data distribution. A request to restore a database into a different topology of nodes may be received. A plan to move different portions of the database from a current topology to the new topology made using a general distribution scheme. The plan may be performed to move the different portions of the database into the new topology and the database made available for access using the new topology. A background process may be applied to modify the distribution of the database at the new topology to match a custom distribution scheme that was implemented at the current topology.

Abstract: A query that references nested data may have sub-expressions included in a subquery for nested data to perform the query. A first query engine may rewrite the query to include one or more sub-expressions that reference the nested data into a subquery for the nested data as part of generating a plan to perform the query. A second query engine may then be caused to perform the subquery for the nested data. A result of the query may be inclusive of the performance of the subquery at the second query engine.