Abstract: An in-memory database system stores the entirety of a database that is being operated on by a database system within main memory. The database includes a table that comprises a plurality of rows including a particular row. The database table comprises a first version of the particular row having a first valid time, and a second version having a second valid time. Index(es) are associated with the database table. Each index is implemented as a lock-free data structure and references the plurality of rows, including referencing the first and second versions of the particular row. A transaction acting on the first version of the particular row is executed. The first version of the particular row is visible to the transaction based on the first valid time and the second version of the particular row being not visible to the transaction based on the second valid time.

Abstract: A data system in which a parent transaction that has multiple nested transactions has isolation between the nested transactions. Each of at least some of the plurality of operations are included within a nested transaction within the parent transaction. For each of at least some of the nested transactions, a begin transaction identifier is assigned to the nested transaction; and on or around completion of the nested transaction, a completion transaction identifier is assigned as a statement identifier at least one object version operated upon by the nested transaction. Visibility of a particular version of an object to an active nested transaction may be verified by comparing the begin transaction identifier of the active nested transaction to the statement identifier of the particular version of the object. The comparison is done such that visibility achieves the proper isolation between nested transactions.

Abstract: An in-memory database system stores the entirety of a database that is being operated on by a database system within main memory. The database includes a table that comprises a plurality of rows including a particular row. The database table comprises a first version of the particular row having a first valid time, and a second version having a second valid time. Index(es) are associated with the database table. Each index is implemented as a lock-free data structure and references the plurality of rows, including referencing the first and second versions of the particular row. A transaction acting on the first version of the particular row is executed. The first version of the particular row is visible to the transaction based on the first valid time and the second version of the particular row being not visible to the transaction based on the second valid time.

Abstract: An in-memory database system includes database table stored in system memory. The database table comprises a plurality of rows including a particular row. Data corresponding to each row is stored entirely in the system memory. The database table comprises a first version of the particular row having a first valid time, and a second version having a second valid time. Index(es) are associated with the database table. Each index is implemented as a lock-free data structure and references the plurality of rows, including referencing the first and second versions of the particular row. A first transaction acting on the first version of the particular row is executed. The first version of the particular row is visible to the first transaction based on the first valid time and the second version of the particular row being not visible to the first transaction based on the second valid time.

Abstract: Performing database queries. A method includes receiving a particular database query. The method further includes accessing a query plan based on the particular database query. The query plan has operators and specific operational parameters associated with each of the operators. The association of operators and specific operational parameters is specific to the particular database query. From the query plan, the method further includes instantiating a plurality of compiled code templates. Each code template includes executable code that when executed performs functionality of one of the operators from the query plan with the specific operational parameters applied in the compilation. The method further includes binding the code templates together using programmatic control flow to create a functioning program.

Abstract: Mitigating problems related to the Halloween problem including where update operations potentially allow the record to be visited more than once during the operation. A method includes accessing an instance of a data store operation statement. The instance of the data store operation statement is executed causing an update or delete to an old version of data store record or creation of a data store record resulting in a new version of the data store record in the case of an update or creation of a data store record and a deleted version of the data store record in the case of a delete in the data store. The instance of the data store operation statement is correlated with the new version of the data store record or the deleted version of the data store record.

Abstract: A data system in which a parent transaction that has multiple nested transactions has isolation between the nested transactions. Each of at least some of the plurality of operations are included within a nested transaction within the parent transaction. For each of at least some of the nested transactions, a begin transaction identifier is assigned to the nested transaction; and on or around completion of the nested transaction, a completion transaction identifier is assigned as a statement identifier at least one object version operated upon by the nested transaction. Visibility of a particular version of an object to an active nested transaction may be verified by comparing the begin transaction identifier of the active nested transaction to the statement identifier of the particular version of the object. The comparison is done such that visibility achieves the proper isolation between nested transactions.

Abstract: An in-memory database system includes database table stored in system memory. The database table comprises a plurality of rows including a particular row. Data corresponding to each row is stored entirely in the system memory. The database table comprises a first version of the particular row having a first valid time, and a second version having a second valid time. Index(es) are associated with the database table. Each index is implemented as a lock-free data structure and references the plurality of rows, including referencing the first and second versions of the particular row. A first transaction acting on the first version of the particular row is executed. The first version of the particular row is visible to the first transaction based on the first valid time and the second version of the particular row being not visible to the first transaction based on the second valid time.

Abstract: Performing database queries. A method includes receiving a particular database query. The method further includes accessing a query plan based on the particular database query. The query plan has operators and specific operational parameters associated with each of the operators. The association of operators and specific operational parameters is specific to the particular database query. From the query plan, the method further includes instantiating a plurality of compiled code templates. Each code template includes executable code that when executed performs functionality of one of the operators from the query plan with the specific operational parameters applied in the compilation. The method further includes binding the code templates together using programmatic control flow to create a functioning program.

Abstract: Mitigating problems related to the Halloween problem including where update operations potentially allow the record to be visited more than once during the operation. A method includes accessing an instance of a data store operation statement. The instance of the data store operation statement is executed causing an update or delete to an old version of data store record or creation of a data store record resulting in a new version of the data store record in the case of an update or creation of a data store record and a deleted version of the data store record in the case of a delete in the data store. The instance of the data store operation statement is correlated with the new version of the data store record or the deleted version of the data store record.

Abstract: A computer system includes a memory and a processor coupled to the memory. The processor is configured to execute instructions that cause execution of an in-memory database system that includes one or more database tables. Each database table includes a plurality of rows, where data representing each row is stored in the memory. The in-memory database system also includes a plurality of indexes associated with the one or more database tables, where each index is implemented by a lock-free data structure. Update logic at the in-memory database system is configured to update a first version of a particular row to create a second version of the particular row. The in-memory database system includes a non-blocking garbage collector configured to identify data representing outdated versions of rows.

Abstract: Performing database queries. A method includes receiving a particular database query. The method further includes accessing a query plan based on the particular database query. The query plan has operators and specific operational parameters associated with each of the operators. The association of operators and specific operational parameters is specific to the particular database query. From the query plan, the method further includes instantiating a plurality of compiled code templates. Each code template includes executable code that when executed performs functionality of one of the operators from the query plan with the specific operational parameters applied in the compilation. The method further includes binding the code templates together using programmatic control flow to create a functioning program.

Abstract: Running a transaction against a database that allows the transaction to be automatically retried when the transaction fails such that certain transaction failures that cause the transaction to be automatically retried are not visible to an entity that receives data as a result of the execution of the transaction. A first set of statements of a transaction is identified by identifying statements that will cause a change in the database state. A second set of statements is identified, that result in data being generated to be sent to the entity. The method further includes executing the first set of statements to change the database. The method further includes running the second set of statements separately from the first set of statements to generate data to be sent to the entity.

Abstract: Mitigating problems related to the Halloween problem including where update operations potentially allow the record to be visited more than once during the operation. A method includes accessing an instance of a data store operation statement. The instance of the data store operation statement is executed causing an update or delete to an old version of data store record or creation of a data store record resulting in a new version of the data store record in the case of an update or creation of a data store record and a deleted version of the data store record in the case of a delete in the data store. The instance of the data store operation statement is correlated with the new version of the data store record or the deleted version of the data store record.

Abstract: Performing database queries. A method includes receiving a particular database query. The method further includes accessing a query plan based on the particular database query. The query plan has operators and specific operational parameters associated with each of the operators. The association of operators and specific operational parameters is specific to the particular database query. From the query plan, the method further includes instantiating a plurality of compiled code templates. Each code template includes executable code that when executed performs functionality of one of the operators from the query plan with the specific operational parameters applied in the compilation. The method further includes binding the code templates together using programmatic control flow to create a functioning program.

Abstract: Mitigating problems related to the Halloween problem including where update operations potentially allow the record to be visited more than once during the operation. A method includes accessing an instance of a data store operation statement. The instance of the data store operation statement is executed causing an update or delete to an old version of data store record or creation of a data store record resulting in a new version of the data store record in the case of an update or creation of a data store record and a deleted version of the data store record in the case of a delete in the data store. The instance of the data store operation statement is correlated with the new version of the data store record or the deleted version of the data store record.

Abstract: Mitigating problems related to the Halloween problem including where update operations potentially allow the record to be visited more than once during the operation. A method includes accessing an instance of a data store operation statement. The instance of the data store operation statement is executed causing an update or delete to an old version of data store record or creation of a data store record resulting in a new version of the data store record in the case of an update or creation of a data store record and a deleted version of the data store record in the case of a delete in the data store. The instance of the data store operation statement is correlated with the new version of the data store record or the deleted version of the data store record.

Abstract: The subject disclosure relates to a concurrency control technique that ensures isolation among concurrently execution transactions optimistically in a multiversion database by applying two optional tests at the end of a read-write transaction: validating the visibility of the read set of the read-write transaction(s) and phantom detection by re-scanning and confirming no new version have appeared in the view. Depending on desired level of isolation, both, one or none of the test are applied. Each version of a data record in an applicable database can be assigned two timestamps indicating the lifetime the version. The value of a version timestamp, though assigned, may be conditional on a transaction committing.

Abstract: Mitigating problems related to the Halloween problem including where update operations potentially allow the record to be visited more than once during the operation. A method includes accessing an instance of a data store operation statement. The instance of the data store operation statement is executed causing an update or delete to an old version of data store record or creation of a data store record resulting in a new version of the data store record in the case of an update or creation of a data store record and a deleted version of the data store record in the case of a delete in the data store. The instance of the data store operation statement is correlated with the new version of the data store record or the deleted version of the data store record.

Abstract: A computer system includes a memory and a processor coupled to the memory. The processor is configured to execute instructions that cause execution of an in-memory database system that includes one or more database tables. Each database table includes a plurality of rows, where data representing each row is stored in the memory. The in-memory database system also includes a plurality of indexes associated with the one or more database tables, where each index is implemented by a lock-free data structure. Update logic at the in-memory database system is configured to update a first version of a particular row to create a second version of the particular row. The in-memory database system includes a non-blocking garbage collector configured to identify data representing outdated versions of rows.