摘要:
Disclosed herein are system, method, and computer program product embodiments for altering the data type of a column in a database. An embodiment operates by converting an original dictionary associated with a column into a new dictionary. The new dictionary stores the values of the original dictionary using a different data type. An index vector containing the keys of the original dictionary is then updated to contain the associated keys of the new dictionary. Because the size of the original dictionary is often substantially smaller than the number of rows in the associated column, this dictionary conversion decreases the computation cost to the database system of altering the data type of the column and reduces or even minimizes database downtime for users.
摘要:
Log records are accessed as part of a database operation in a database. The log records log insert, update, and delete operations in the database and include, for each row, a row position, a fragment identifier (ID), and a row ID. Thereafter, as part of the database operation, rows specified by the log records are located by: using the fragment identifier and the row position within the corresponding record of the log if the fragment with the corresponding fragment identifier is still available, otherwise, using the row identifier within the corresponding record of the log to look up the row position in an index of a corresponding row identifier column. The database operation is then finalized using the located rows. Related apparatus, systems, techniques and articles are also described.
摘要:
Log records are accessed as part of a database operation in a database. The log records log insert, update, and delete operations in the database and include, for each row, a row position, a fragment identifier (ID), and a row ID. Thereafter, as part of the database operation, rows specified by the log records are located by: using the fragment identifier and the row position within the corresponding record of the log if the fragment with the corresponding fragment identifier is still available, otherwise, using the row identifier within the corresponding record of the log to look up the row position in an index of a corresponding row identifier column. The database operation is then finalized using the located rows. Related apparatus, systems, techniques and articles are also described.
摘要:
Methods, systems, and computer program products are provided to manage a database system. The method includes locking during a database system idle time access by the database system to a data page of a data allocation unit, compressing during the database system idle time a data stored in the locked data page, and recording during the database system idle time an indication that the compressed and locked data page includes free storage space, wherein unlocked data pages of the data allocation unit are accessible by the database system during the compressing of the data stored in the locked data page. Thus, the data page may be compressed during idle time and the space freed therein may be used during a subsequent run time without the need for a reorganization of the data pages within the corresponding table (as in, for example, operation of a reorg+rebuild SQL command combination).