Snowflake Inc.

Sourav Sikdar

Sangyong Hwang

Li Yan

Walter Zhen Cai

Wesley A Leung

The subject technology receives a first query plan corresponding to a query, the first query plan comprising a set of join nodes, and a join order hint of a target query plan, each join node of the target query plan associated with a hint. The subject technology generates a second query plan to correct a set of vertical positions of a set of terminal nodes of the first query plan following the join order hint of the target query plan. The subject technology generates a third query plan to correct a set of lateral positions of the set of terminal nodes of the second query plan following the join order hint of the target query plan. The subject technology, for each join node from the set of join nodes of the third query plan, indicates that each join node has been hinted. The subject technology generates, after each join node of the third query plan has been indicated as being hinted, the target query plan based at least in part on the third query plan.

Rule based hint application

The subject technology receives a query. The subject technology generates a set of query blocks based on parsing the query. The subject technology stores query block metadata for each query block from the set of query blocks. The subject technology restores a set of logical query block boundaries. The subject technology performs a hash-based query block matching. The subject technology generates, after performing the hash-based query block matching, a final query plan. In an example, if a (same) query is executed again the same logical query blocks would produce the same metadata (e.g., identifier, name and hash). This metadata can be used to match logical query blocks between multiple executions of the same query.

Query block boundary identification

The subject technology tracks a plurality of queries corresponding to a plurality of query plans based on join operations contained in each of the plurality of queries and a previous time of executing each query. The subject technology selects a first query plan among the plurality of query plans. The subject technology determines a value indicating an estimated improvement in execution time of the first query plan in comparison to a previous execution time of a previous query plan. The subject technology attempts to execute a first query using the first query plan. The subject technology determines that a second query plan selected among the plurality of query plans has a second estimated execution time that is less than an estimated execution time of the first query plan. The subject technology executes the first query corresponding to the first query plan at a subsequent time using the second query plan.

Estimated execution time for query execution

The subject technology receives a first query plan corresponding to a first query, the first query plan comprising a new query plan different than a previous query plan for the first query. The subject technology determines a value indicating an estimated improvement in execution time of the first query plan in comparison to a previous execution time of the previous query plan. The subject technology, in response to determining that the value is greater than a threshold value, attempting to execute the first query using the first query plan, the attempting comprising determining that a second query plan selected among a plurality of query plans has a second estimated execution time that is less than an estimated execution time of the first query plan, and executing the first query at a subsequent time using the second query plan.

Dynamic query execution using estimated execution time

The subject technology receives a first query plan corresponding to a first query, the first query plan comprising a new query plan different than a previous query plan for the first query. The subject technology determines a value indicating an estimated improvement in execution time of the first query plan in comparison to a previous execution time of the previous query plan. The subject technology determines that the value is greater than a threshold value. The subject technology, in response to the value being greater than the threshold value, executes the first query using the first query plan.

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Houston, TX, United States of America

Sourav Sikdar