Sap Se

Oliver Horn

Till Merker

Paul Willems

Robert Schulze

Joerg Fellmann

Thomas Legler

Wolfgang Stephan

Lars Fricke

Klaus Otto Mueller

Andreas Amler

Timm Steinbeck

Marius Eich

Cheng-Lun Li

The present disclosure involves systems, software, and computer implemented methods for using worst-case predicate selectivity for database query plans. One example method includes identifying a query that includes an initial set of parameter values for a set of predicates. An order of predicate evaluation is determined for a query plan by determining a worst-case selectivity for each predicate and ordering the predicates based on the worst-case selectivities. A second instance of the query is received that includes a second set of parameter values. The second instance of the query is executed, to generate a query result, using the query plan and the second set of parameters by evaluating the set of predicates based on the second set of parameters and the order of predicate evaluation determined based on the worst-case selectivities. The query result is provided in response to the second instance of the query.

Using worst-case predicate selectivity for database query plans

Methods, systems, and computer-readable storage media for a set of pipelines that enable selective skipping of dictionary scans and/or index lookups when processing queries in database management systems, such that dictionary scans and/or index lookups are only executed when needed, eliminating unnecessary execution of dictionary scans and/or index lookups to improve efficiency of the database system in terms of reducing load on technical resources and improve query performance by reducing latency in returning query results.

Selective skipping of dictionary scans and/or index lookups during query processing in database systems

Methods and systems for object-based text searching using group score expressions are provided. A method may include receiving a query including a request to search specified columns of a table for a set of search terms, and a group score filter for use in filtering the table based at least on a group score associated with a plurality of groups of rows of the table, determining the group score for each of a plurality of groups of rows of the table, filtering the table based at least on the group score filter included in the query and the group score determined for each of the plurality of groups of rows of the table, and providing at least one group of rows of the plurality of groups of rows that includes at least the portion of the set of search terms.

Object-based text searching using group score expressions

Systems and methods are provided for text searching using partial score expressions. A method may include receiving a query to search for a search term in at least a first column of a first table and a second column of a second table, scanning the first column and the second column for at least a portion of the search term, generating a first partial score table, generating a second partial score table, determining a combined score for each row in the first column and/or the second column containing at least the portion of the search term based at least on a join of the first partial score table and the second partial score table, and providing, in response to the query and based at least on the combined score, a row of the first column and/or the second column including at least the portion of the search term.

Text searching using partial score expressions

In some example embodiments, there may be provided a method including detecting a query operator of a predetermined type requiring a sorting or a scanning responsive to the query operator at a column-oriented database; determining a sorted dictionary at the column-oriented database is eligible for direct access by at least checking that the column-oriented database provides sorted dictionary access and that dictionary collation and a collation of the query operator are the same; when the sorted dictionary is eligible, reading directly from the sorted dictionary a batch of sorted values; and processing, based on the batch sorted values read from the sorted dictionary, the query operator.

Efficient computation of order by, order by with limit, min, and max in column-oriented databases

A method, a system, and a computer program product for executing a query in a database system. A query plan for execution of a query is generated. The query requires access to at least one table stored in a database system. One or more occurrences of one or more duplicate predicates is detected in the query plan. In response to detecting a first occurrence of the duplicate predicates, one or more intermediate query execution results responsive to the duplicate predicates are generated. The generated intermediate query execution results are cached. Query execution results incorporating cached intermediate query execution results being responsive to each occurrence of the duplicate predicates subsequent to the first occurrence of the duplicate predicates in the query plan are generated.

Evaluation of duplicated filter predicates

A method, a system, and a computer program product for analysis of query filtering mechanisms for table fragments. A query plan for execution of a query is generated. The query requires access to at least one table stored in a database system. The query includes one or more filter predicates. The table is partitioned into a plurality of fragments. A determination whether a fragment in the table is compressed and whether the fragment is associated with an index is made. A filter predicate is selected for processing the fragment. For the selected filter predicate, a filter evaluation of the selected filter predicate for the fragment is determined. The filter evaluation of the selected predicate is executed for the fragment.

Filter evaluation for table fragments

A method, a system, and a computer program product for executing a query. The query requiring access to one or more tables stored in a database system is executed. The query includes one or more filter predicates. Using a unique key value corresponding to a first predicate, at most one row in the tables including a portion of data matching the unique key value is identified. Using filter values corresponding to the filter predicates, another portion of data in the identified row is compared to the filter values to determine whether that portion of data matches the filter values. Based on the comparison, a result of the execution of the query is outputted. The result includes data stored in the identified row upon determination that the data matches the unique key value corresponding to the first filter predicate and the filter values corresponding to remaining filter predicates. Otherwise, the result is empty.

Unique key lookup with additional filter

A method, a system, and a computer program product for executing a query. A query plan for execution of a query is generated. The query requires access to at least one table stored in a database system. The query includes one or more filter predicates. A filter predicate in the one or more filter predicates is selected. For the selected filter predicate, a plurality of cost function values associated executing a filter evaluation of the selected filter predicate are determined. Filter evaluation of the selected predicate is executed in accordance with at least one determined cost function value in the plurality of cost function values.

Cost heuristic for filter evaluation

In some aspects, there is provided a method for database query execution planning. In some aspects, a method may include receiving, at a database execution engine, a query; generating, by the database execution engine, a query algebra for the query, the query algebra optimized by a query optimizer at the database execution engine; generating, based on the optimized query algebra, a query plan for execution, the query plan including pre-compiled code and code generated just-in-time; and executing, by the database execution engine, at least part of the query plan including pre-compiled code and code generated just-in-time. Related systems, methods, and articles of manufacture are also described.

Query plan execution engine

A system for generating a query plan is provided. In some example embodiments, the system performs operations comprising: determining, at a query execution engine, a first primitive call for implementing a query operation on data at a database; performing the query operation by at least sending, to a data management engine coupled to the database, the first primitive call for execution by the data management engine; and determining, based at least on a result of the first primitive call, a result of the query operation. Related methods and articles of manufacture, including computer program products, are also described.

Application programming interface for database access

In some example embodiments, a system is provided for executing a primitive call that implements a query operation. The system may include a data processor and a memory. The memory may store instructions that result in operations when executed by the data processor. The operations may include: executing, at an data management engine, the primitive call by at least performing a first operation with respect to a value identifier set, the value identifier set including one or more value identifiers, and the primitive call being configured to access a database storing a plurality of value identifiers; and generating, based at least on a result of the first operation, a result for the primitive call. Related methods and articles of manufacture, including computer program products, are also described.

Processing a query primitive call on a value identifier set

A system for query execution and planning with pipelining and pump operators is provided. In some implementations, the system performs operations comprising identifying a plurality of operators for executing a query, the plurality of operators including a first operator and a second operator, generating a pump operator when the first operator comprises a table scan operator, and/or generating a query plan for execution of the query, the query plan comprising the pump operator and the second operator. The operations can further include executing the pump operator to at least retrieve a portion of a database table, generate a first data portion based on the portion of the database table, and provide the first data portion for the second operator. Related systems, methods, and articles of manufacture are also described.

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Nussloch, Germany

Oliver Horn