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A dense index in databases is a file with pairs of keys and pointers for every record in the data file. Every key in this file is associated with a particular pointer to a record in the sorted data file. In clustered indices with duplicate keys, the dense index points to the first record with that key. [3]
SQL was initially developed at IBM by Donald D. Chamberlin and Raymond F. Boyce after learning about the relational model from Edgar F. Codd [12] in the early 1970s. [13] This version, initially called SEQUEL (Structured English Query Language), was designed to manipulate and retrieve data stored in IBM's original quasirelational database management system, System R, which a group at IBM San ...
Source deduplication ensures that data on the data source is deduplicated. This generally takes place directly within a file system. The file system will periodically scan new files creating hashes and compare them to hashes of existing files. When files with same hashes are found then the file copy is removed and the new file points to the old ...
An empty file has a minimum disk size that depends on the disk block size, which can also be referred to as cluster size or IO block size, that depends in turn on the filesystem. This IO block size can be discovered through different utilities in the operating system, such as stat in Unix systems. [2] [3] Typically 4096 bytes.
The difference is an exact number of quarters of an hour up to 95 (same minutes modulo 15 and seconds) if the file was transported across zones; there is also a one-hour difference within a single zone caused by the transition between standard time and daylight saving time (DST). Some, but not all, file comparison and synchronisation software ...
The join operation defined for relational databases is often referred to as a natural join (⋈). In this type of join, two relations are connected by their common attributes. MySQL's approximation of a natural join is the Inner join operator. In SQL, an INNER JOIN prevents a cartesian product from occurring when there are two tables in a query.
ACFS [2] is a standard-based POSIX (Linux, UNIX) and Windows cluster file system with full cluster-wide file and memory mapped I/O cache coherency and file locking. ACFS provides direct I/O for Oracle database I/O workloads. ACFS implements indirect I/O however for general purpose files that typically perform small I/O for better response time.
Stores file owner POSIX file permissions Creation timestamps Last access/ read timestamps Last metadata change timestamps Last archive timestamps Access control lists Security/ MAC labels Extended attributes/ Alternate data streams/ forks Metadata checksum/ ECC File system Bcachefs: Yes Yes Yes Yes Yes No Yes Yes Yes Yes Bcachefs: BeeGFS: Yes ...