Abstract: Methods, systems, and computer-readable storage media for determining that a first transaction results in a first version of data stored in a page in a database system, the first version being stored in a version space and the data being stored in a table space, in response to the first version, providing a version table for the page, the version table including a set of cells each cell corresponding to a record in the page, setting a version table pointer of the page to point to the version table, and setting a version pointer of a first cell to point to the first version in the version space, the first cell corresponding to a record of the data in the page.

Abstract: Methods, systems, and computer-readable storage media for online defragmentation of memory in database systems by applying an IX-lock to each table having data stored in a marked page in a set of marked pages, generating a record map including key-value pairs, each being associated with a record location in a marked page, a value of each key-value pair initially set to a first value, iteratively executing the online defragmentation to delete data from marked pages and add the data to non-sparse pages, at least one iteration including applying a try-lock to a record in a marked page, and at iterations of the online defragmentation, updating the record map to change the value of at least one key-value pair from the first value to the second value, the second value representing that data of a marked page has been deleted from the marked page and added to a non-sparse page.

Abstract: An in-memory database server hosting a tenant of a multi-tenant software architecture can receive a definition of a custom data field that is unique to an organization having isolated access to the tenant. The custom data field can extend a standard table defined by central metadata stored at a system tenant of the multi-tenant software architecture. Tenant private metadata that includes the definition can be stored in memory accessible only to the tenant. A tenant-dependent table that includes the custom data field can be formed, for example by retrieving central metadata defining the standard table from the system tenant and adding the custom data field using the definition. The tenant-dependent table can be presented for access via a database client at the organization. Related systems, articles of manufacture, and computer-implemented methods are disclosed.

Abstract: A system includes initiation of recovery from a crash of a database instance and, during the recovery, identification of a subset of pages of a memory image of the database instance which are not reusable and replacement of the identified subset of pages with corresponding pages of the savepoint image.

Abstract: A system includes initiation of recovery from a crash of a database instance and, during the recovery, identification of a subset of pages of a memory image of the database instance which are not reusable and replacement of the identified subset of pages with corresponding pages of the savepoint image.

Abstract: An in-memory database server hosting a tenant of a multi-tenant software architecture can receive a definition of a custom data field that is unique to an organization having isolated access to the tenant. The custom data field can extend a standard table defined by central metadata stored at a system tenant of the multi-tenant software architecture. Tenant private metadata that includes the definition can be stored in memory accessible only to the tenant. A tenant-dependent table that includes the custom data field can be formed, for example by retrieving central metadata defining the standard table from the system tenant and adding the custom data field using the definition. The tenant-dependent table can be presented for access via a database client at the organization. Related systems, articles of manufacture, and computer-implemented methods are disclosed.

Abstract: Restoring a database image of a secondary database system comprises initializing the database image from a recovery image that includes metadata logs and non-metadata logs, of which at least one metadata log includes an undo log of non-committed data that is applied to the initialized database image. A first pagelist and first indexes are then rebuilt based on first data segments of the database image and the corresponding metadata objects. The database image is then updated by replaying the metadata redo log generated from the undo log, the metadata logs, and the non-metadata logs. Then, a second pagelist and second indexes for the database system are rebuilt based on second data segments of the database image and the corresponding non-metadata objects, while each of the first data segments is statically separated from the second data segments in physical memory space. Related apparatus, systems, techniques and articles are also described.

Abstract: The disclosure relates a display apparatus comprising: a signal input receiver receives a plurality of signals which are different in kind from each other, a plurality of encoders provided respectively corresponding to the plurality of signals, and perform encoding of a corresponding mode according to the kinds of at least one signal input to the signal input receiver among the plurality of signals, a first interface transmits a signal obtained by serializing the encoded signal, a second interface deserializes the signal received from the first interface, a plurality of decoders provided respectively corresponding to the plurality of encoders, and perform decoding and restoring the deserialized signal into the at least one signal, and a display displays an image based on the at least one restored signal.

Abstract: A system and method, including determining, by a processor, distinction bit positions for index keys of a database index; determining, by the processor, concatenation of the bits of the index keys; and generating a record of the concatenation. Other systems and methods include collecting, by a processor, index keys of a database index in parallel, wherein data pages of a target table are evenly distributed to a plurality of processor cores; scanning, by each of the cores the data pages to extract compressed keys and corresponding record identifiers; sorting, by a plurality of the processor cores, pairs of the compressed key and corresponding record identifier in accordance with a parallel sorting algorithm; generating an index tree in a bottom-up fashion; and storing a record of the generated index tree.

Abstract: A hybrid database table is stored as both a row and a column store. One or more techniques may be employed alone or in combination to enhance performance of the hybrid table by regulating access to, and/or the size of, the processing-intensive column store data. For example during an insert operation, the column store data may be searched for a uniqueness violation only after certain filtering and/or boundary conditions have been considered. In another technique, a hybrid table manager may control movement of data to the column store based upon considerations such as frequency of access, or underlying business logic. In still another technique, querying of the hybrid table may result in a search of the column store data only after an initial search of row store data fails to return a result.

Abstract: Improved database consistency and consistency checking may be provided by cross-referenced split data storage for irregular fields using auxiliary pointers. A fixed-size memory slot may be allocated to a database table in a database system, where the fixed-size memory slot has an address. A variable-size memory slot may be allocated to the database table, where the variable-size memory slot has a different address. For an irregular field in the database table, one or more properties of the irregular field may be stored in the fixed-size memory slot. The one or more properties may include a first pointer which may have the address of the variable-size memory slot. For the irregular field in the database table, at least a portion of data of the irregular field and a second pointer, which may have the address of the fixed-size memory slot, may be stored in the variable-size memory slot.

Abstract: Technologies are described for restarting an application while maintaining data in memory (e.g., using shared memory). For example, shared memory can be associated with an application. The shared memory can also be associated with a holder process to maintain the shared memory from the time the application stops to the time the application starts again. When the application starts, the shared memory can be associated with the started application. In addition, restart of in-memory databases can be provided using shared memory. For example, in-memory data can be maintained when a database process or database management system stops and starts (e.g., during a restart).

Abstract: Technologies are described for restarting an application while maintaining data in memory (e.g., using shared memory). For example, shared memory can be associated with an application. The shared memory can also be associated with a holder process to maintain the shared memory from the time the application stops to the time the application starts again. When the application starts, the shared memory can be associated with the started application. In addition, restart of in-memory databases can be provided using shared memory. For example, in-memory data can be maintained when a database process or database management system stops and starts (e.g., during a restart).

Abstract: Improved database consistency and consistency checking may be provided by cross-referenced split data storage for irregular fields using auxiliary pointers. A fixed-size memory slot may be allocated to a database table in a database system, where the fixed-size memory slot has an address. A variable-size memory slot may be allocated to the database table, where the variable-size memory slot has a different address. For an irregular field in the database table, one or more properties of the irregular field may be stored in the fixed-size memory slot. The one or more properties may include a first pointer which may have the address of the variable-size memory slot. For the irregular field in the database table, at least a portion of data of the irregular field and a second pointer, which may have the address of the fixed-size memory slot, may be stored in the variable-size memory slot.

Abstract: A hybrid database table is stored as both a row and a column store. One or more techniques may be employed alone or in combination to enhance performance of the hybrid table by regulating access to, and/or the size of, the processing-intensive column store data. For example during an insert operation, the column store data may be searched for a uniqueness violation only after certain filtering and/or boundary conditions have been considered. In another technique, a hybrid table manager may control movement of data to the column store based upon considerations such as frequency of access, or underlying business logic. In still another technique, querying of the hybrid table may result in a search of the column store data only after an initial search of row store data fails to return a result.

Abstract: A hybrid database table is stored as both a row and a column store. One or more techniques may be employed alone or in combination to enhance performance of the hybrid table by regulating access to, and/or the size of, the processing-intensive column store data. For example during an insert operation, the column store data may be searched for a uniqueness violation only after certain filtering and/or boundary conditions have been considered. In another technique, a hybrid table manager may control movement of data to the column store based upon considerations such as frequency of access, or underlying business logic. In still another technique, querying of the hybrid table may result in a search of the column store data only after an initial search of row store data fails to return a result.

Abstract: A system and method, including determining, by a processor, distinction bit positions for index keys of a database index; determining, by the processor, concatenation of the bits of the index keys; and generating a record of the concatenation. Other systems and methods include collecting, by a processor, index keys of a database index in parallel, wherein data pages of a target table are evenly distributed to a plurality of processor cores; scanning, by each of the cores the data pages to extract compressed keys and corresponding record identifiers; sorting, by a plurality of the processor cores, pairs of the compressed key and corresponding record identifier in accordance with a parallel sorting algorithm; generating an index tree in a bottom-up fashion; and storing a record of the generated index tree.

Abstract: An in-memory database server hosting a tenant of a multi-tenant software architecture can receive a definition of a custom data field that is unique to an organization having isolated access to the tenant. The custom data field can extend a standard table defined by central metadata stored at a system tenant of the multi-tenant software architecture. Tenant private metadata that includes the definition can be stored in memory accessible only to the tenant. A tenant-dependent table that includes the custom data field can be formed, for example by retrieving central metadata defining the standard table from the system tenant and adding the custom data field using the definition. The tenant-dependent table can be presented for access via a database client at the organization. Related systems, articles of manufacture, and computer-implemented methods are disclosed.

Abstract: A computer implemented method is provided. The method comprises initializing a first database image of a first database system based on a recovery image comprising committed transactions, visible uncommitted transactions, and undo logs associated with the visible uncommitted transactions, undoing the visible uncommitted transactions using the undo logs, generating redo logs from the undo logs, replaying the redo logs to create invisible uncommitted transactions, and after replaying the redo logs, replaying transaction logs received from a second database system. Related apparatus, systems, techniques and articles are also described.

Abstract: Technologies are described for performing proactive memory allocation (e.g., pre-allocation). Proactive memory allocation (e.g., proactive memory page allocation) can be provided for applications, such as database applications. For example, an application can be associated with a free memory pool (e.g., a free memory pool containing free memory pages). A dedicated thread of the application can monitor the free memory pool and perform proactive memory allocation when needed (e.g., when the amount of memory in the pool is low). For example, the dedicated thread can obtain new free memory from the operating system and add it to the pool.