Reordering predicates for disjunction of conjunctions database queries

A system comprising:

• one or more computers;
• and
• a computer-readable medium coupled to the one or more computers having instructions stored thereon which, when executed by the one or more computers, cause the one or more computers to perform operations comprising:
• receiving, at a database system, a query for a database table, wherein the query includes a set of parameter values;
• determining that the query corresponds to a disjunction of conjunctions query;
• identifying, by a runtime execution engine of the database system, from a pre-compiled query plan, a matrix of the runtime execution engine that represents the disjunction of conjunctions query that includes a matrix row for each conjunction included in the query and a matrix column for each database column referenced in an inner predicate in a conjunction;
• estimating, for each database column referenced in an inner predicate in a conjunction and based on the set of parameter values, an estimated selectivity of each inner predicate of the disjunction of conjunctions query that references the database column;
• aggregating, for each database column referenced in an inner predicate in a conjunction, estimated selectivities of inner predicates of the disjunction of conjunctions query that reference the database column, to generate an aggregated estimated selectivity for the database column;
• determining, based on aggregated estimated selectivities of database columns referenced in an inner predicate in a conjunction, a matrix column evaluation order for evaluating inner predicates in the matrix for the disjunction of conjunctions query;
• and
• evaluating the disjunction of conjunctions query by evaluating the inner predicates in matrix columns of the matrix based on the matrix column evaluation order and the set of parameter values.

A computer program product encoded on a non-transitory storage medium, the product comprising non-transitory, computer readable instructions for causing one or more processors to perform operations comprising:

• receiving, at a database system, a query for a database table, wherein the query includes a set of parameter values;
• determining that the query corresponds to a disjunction of conjunctions query;
• identifying, by a runtime execution engine of the database system, from a pre-compiled query plan, a matrix of the runtime execution engine that represents the disjunction of conjunctions query that includes a matrix row for each conjunction included in the query and a matrix column for each database column referenced in an inner predicate in a conjunction;
• estimating, for each database column referenced in an inner predicate in a conjunction and based on the set of parameter values, an estimated selectivity of each inner predicate of the disjunction of conjunctions query that references the database column;
• aggregating, for each database column referenced in an inner predicate in a conjunction, estimated selectivities of inner predicates of the disjunction of conjunctions query that reference the database column, to generate an aggregated estimated selectivity for the database column;
• determining, based on aggregated estimated selectivities of database columns referenced in an inner predicate in a conjunction, a matrix column evaluation order for evaluating inner predicates in the matrix for the disjunction of conjunctions query;
• and
• evaluating the disjunction of conjunctions query by evaluating the inner predicates in matrix columns of the matrix based on the matrix column evaluation order and the set of parameter values.