Filtered hash table generation for performing hash joins
First Claim
Patent Images
1. A system, comprising:
- a memory to store program instructions which, if performed by at least one processor, cause the at least one processor to perform a method to at least;
receive a database query that causes a hash join that joins two tables of a database;
identify a first one of the two tables as a build table for the hash join and a second one of the two tables as the probe table for the hash join;
filter data included in a hash table generated from a portion of the build table to perform the hash join according to a filter generated from a scan of the probe table that indicates which data in the probe table can satisfy a predicate for the hash join; and
return a result of the database query based, at least in part, on the performance of the hash join.
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Abstract
Filtered generation of hash tables may be implemented as part of performing a hash join. A database query may be received that causes a hash join to be performed in order to join two database tables. A filtered generated from a scan of one of the tables that indicates which data in the table can satisfy a join predicate for the hash join may be applied to generate a hash table from a portion of the other table. The filtered hash table may then be used to evaluate whether portions of the tables can be joined in satisfaction of the join predicate for the hash join.
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Citations
20 Claims
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1. A system, comprising:
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a memory to store program instructions which, if performed by at least one processor, cause the at least one processor to perform a method to at least; receive a database query that causes a hash join that joins two tables of a database; identify a first one of the two tables as a build table for the hash join and a second one of the two tables as the probe table for the hash join; filter data included in a hash table generated from a portion of the build table to perform the hash join according to a filter generated from a scan of the probe table that indicates which data in the probe table can satisfy a predicate for the hash join; and return a result of the database query based, at least in part, on the performance of the hash join. - View Dependent Claims (2, 3, 4)
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5. A method, comprising:
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responsive to a database query that causes a hash join that joins a first table and a second table of a database; filtering data included in a hash table generated from a portion of the first table to perform the hash join according to a filter generated from a scan of the second table that indicates which data in the second table can satisfy a predicate for the hash join. - View Dependent Claims (6, 7, 8, 9, 10, 11, 12, 13)
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14. A non-transitory, computer-readable storage medium, storing program instructions that when executed by one or more computing devices cause the one or more computing devices to implement:
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receiving a database query that causes a hash join that joins a first table and a second table of a database; filtering data included in a hash table generated from a portion of the first table to perform the hash join according to a filter generated from a scan of the second table that indicates which data in the second table can satisfy a predicate for the hash join; and returning a result of the database query based, at least in part, on the performance of the hash join. - View Dependent Claims (15, 16, 17, 18, 19, 20)
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Specification