Abstract: The disclosed techniques reduce a responsiveness time for a secondary node state of a database in switching from a second computing node to replace a first computing node acting in a primary node state, with both computing nodes performing the same database queries. The second node receives information regarding queries performed by the first node while in the primary state. In some embodiments, the second node retrieves, from a transaction log, log records detailing operations performed for database transactions. In some embodiments, the second node inserts, based on the log records, data records of the transactions into an in-memory cache of the second node that stores chains of database records from different transactions. Upon receiving sufficient information to switch to the primary state, the second node changes a mode of operation during failover making a committed transaction available for reads by subsequent database queries prior to record reordering.

Abstract: Techniques are disclosed relating to restarting a database node. A database node may allocate memory segments that include a restart segment for storing data records. The database node may spawn processes to read a log and replay log records of the log to update the restart segment to store data records. The database node may determine to perform a restart operation to transition from a first mode to a second mode. Performing the restart operation may include ceasing reading the log at a stop position and storing, based on the stop position, database state information that enables the processes to resume reading the log from the stop position. The database node may further deallocate the memory segments except for the restart segment and terminate the processes. After performing the restart operation, the database node may spawn the processes, which may resume reading the log based on the database state information.

Abstract: Techniques are disclosed relating to building an in-memory multi-level data structure useable to determine presence or absence of key ranges in files consisting of database records. In various embodiments, a computer system operates a database, including maintaining a set of records having a set of corresponding keys that are accessible in key-sorted order and generates a multi-level data structure that facilitates key range lookups against the set of records. The generating may include accessing ones of the set of keys in key-sorted order and determining, for a particular accessed key that includes a set of characters, an intermediate level within the multi-level data structure and a subset of the characters of the particular accessed key for insertion. The computer system may insert, starting at the intermediate level, information that identifies the subset of characters, with the inserting being performed without traversing any levels before the intermediate level.

Abstract: Techniques are disclosed relating to merge operations for multi-level data structures, such as log-structured merge-trees (LSM trees). A computer system may store, in a database, a plurality of files as part of an LSM tree and a plurality of database key structures. A given one of the plurality of database key structures may indicate, for a corresponding one of the plurality of files, a set of key ranges derived from database records that are included in the corresponding file. The computer system may determine, using ones of the plurality of database key structures, a key range overlap that is indicative of an extent of overlap of key ranges from a set of the plurality of files with respect to a particular key range. Based on the determined key range overlap, the computer system may assign a priority level to a merge operation that involves the set of files.

Abstract: Techniques are disclosed relating to merge operations for multi-level data structures, such as log-structured merge-trees (LSM trees). A computer system may store, in a database, a plurality of files as part of an LSM tree and a plurality of database key structures. A given one of the plurality of database key structures may indicate, for a corresponding one of the plurality of files, a set of key ranges derived from database records that are included in the corresponding file. The computer system may determine, using ones of the plurality of database key structures, a key range overlap that is indicative of an extent of overlap of key ranges from a set of the plurality of files with respect to a particular key range. Based on the determined key range overlap, the computer system may assign a priority level to a merge operation that involves the set of files.

Abstract: Techniques are disclosed relating to index metadata that is usable for accessing multi-level data structures. A computer system may operate a database, including maintaining a set of records having a set of corresponding keys. The computer system may create multi-level data structures that facilitate key range lookups against those records. A given multi-level data structure may store key information indicative of a subset of the corresponding keys. The computer system may create separate index metadata that is usable for accessing the multi-level data structures. The index metadata may specify indications of key information that is stored in the multi-level data structures and locations of the multi-level data structures. The computer system may perform a key range lookup that includes using the index metadata to determine a particular set of the multi-level data structures whose key information corresponds to a key range of the key range lookup.

Abstract: Techniques are disclosed relating to building an in-memory multi-level data structure useable to determine presence or absence of key ranges in files consisting of database records. In various embodiments, a computer system operates a database, including maintaining a set of records having a set of corresponding keys that are accessible in key-sorted order and generates a multi-level data structure that facilitates key range lookups against the set of records. The generating may include accessing ones of the set of keys in key-sorted order and determining, for a particular accessed key that includes a set of characters, an intermediate level within the multi-level data structure and a subset of the characters of the particular accessed key for insertion. The computer system may insert, starting at the intermediate level, information that identifies the subset of characters, with the inserting being performed without traversing any levels before the intermediate level.

Abstract: Techniques are disclosed relating to merge operations for multi-level data structures, such as log-structured merge-trees (LSM trees). A computer system may store, in a database, a plurality of files as part of an LSM tree and a plurality of database key structures. A given one of the plurality of database key structures may indicate, for a corresponding one of the plurality of files, a set of key ranges derived from database records that are included in the corresponding file. The computer system may determine, using ones of the plurality of database key structures, a key range overlap that is indicative of an extent of overlap of key ranges from a set of the plurality of files with respect to a particular key range. Based on the determined key range overlap, the computer system may assign a priority level to a merge operation that involves the set of files.

Abstract: Disclosed herein are methods for retrieving data from a database. An embodiment operates searching for a key in a first index. The method determines that the searching will require a storage access request and issues the storage access request. The method continues searching for the key in a second index.

Abstract: Disclosed herein are methods for retrieving data from a database. An embodiment operates searching for a key in a first index. The method determines that the searching will require a storage access request and issues the storage access request. The method continues searching for the key in a second index.

Abstract: Disclosed herein are methods for retrieving data from a database. An embodiment operates searching for a key in a first index. The method determines that the searching will require a storage access request and issues the storage access request. The method continues searching for the key in a second index.

Abstract: Distributing work in a distributed computing environment that includes multiple nodes. An individual node can receive a work assignment, which can then be divided into a plurality of work units. A first work unit can then be distributed to a first worker node. At least a portion of the first work unit can be re-distributed to a second worker node in response to determining that the first worker node has experienced a failure condition with respect to the first work unit.

Abstract: Disclosed herein are system, method, and computer program product embodiments for utilizing a backup catalog to perform synchronized backup and recovery of heterogeneous database systems. An embodiment operates by performing a global data backup of a heterogeneous database system comprising a first database management system (DBMS) at a first server and a second DBMS at a second server and recording a global data backup entry identifying the global data backup into a backup catalog. Upon receiving log backup notifications regarding asynchronous log backups on the first server and the second server, log backup entries identifying the asynchronous log backups are recorded into the backup catalog. To successfully perform a point-in-time recovery, the embodiment operates by using the backup catalog to identify data and log backups required for the recovery of the first and second servers to a recovery timestamp associated with the point-in-time recovery.

Abstract: Disclosed herein are system, method, and computer program product embodiments for accelerating database queries containing bitmap-based conditions. An embodiment operates by determining a bitmap, where the bitmap represents a set of rows that have satisfied a conjunct that precedes a negated condition in a query expression and restricting the evaluation of the negated condition to the set of rows represented by the bitmap.

Abstract: Disclosed herein are system, method, and computer program product embodiments for utilizing a backup catalog to perform synchronized backup and recovery of heterogeneous database systems. An embodiment operates by performing a global data backup of a heterogeneous database system comprising a first database management system (DBMS) at a first server and a second DBMS at a second server and recording a global data backup entry identifying the global data backup into a backup catalog. Upon receiving log backup notifications regarding asynchronous log backups on the first server and the second server, log backup entries identifying the asynchronous log backups are recorded into the backup catalog. To successfully perform a point-in-time recovery, the embodiment operates by using the backup catalog to identify data and log backups required for the recovery of the first and second servers to a recovery timestamp associated with the point-in-time recovery.

Abstract: Disclosed herein are system, method, and computer program product embodiments for accelerating database queries containing bitmap-based conditions.

Abstract: Disclosed herein are methods for retrieving data from a database. Various embodiments operate by breaking a predicate tree into one or more predicate tree fragments and then executing the various fragments in parallel. The execution of each of the predicate tree fragments results in a bitmap fragment. The bitmap fragments from the execution of the predicate tree fragments can be then combined into a resulting bitmap.

Abstract: Embodiments include systems, methods and computer-readable mediums for accelerating a database query containing multiple predicates connected conjunctively. The database system receives a database query on a table. The database query includes a first predicate and a second predicate connected conjunctively. The database system produces a search space that satisfies a pre-filter for the first predicate. The search space represents rows of the table that satisfy the first predicate. The database system then applies the search space to evaluation of the second predicate. In one embodiment, the first predicate is a LIKE predicate requesting rows matching a search string in a column, and the pre-filter is a word index representing rows of the table containing a token of the search string in the column.

Abstract: Disclosed herein are methods for retrieving data from a database. An embodiment operates searching for a key in a first index. The method determines that the searching will require a storage access request and issues the storage access request. The method continues searching for the key in a second index.

Abstract: Distributing work in a distributed computing environment that includes multiple nodes. An individual node can receive a work assignment, which can then be divided into a plurality of work units. A first work unit can then be distributed to a first worker node. At least a portion of the first work unit can be re-distributed to a second worker node in response to determining that the first worker node has experienced a failure condition with respect to the first work unit.