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A SELECT statement retrieves zero or more rows from one or more database tables or database views. In most applications, SELECT is the most commonly used data manipulation language (DML) command. As SQL is a declarative programming language, SELECT queries specify a result set, but do not specify how to calculate it.
A write ahead log is an append-only auxiliary disk-resident structure used for crash and transaction recovery. The changes are first recorded in the log, which must be written to stable storage, before the changes are written to the database. [2] The main functionality of a write-ahead log can be summarized as: [3] Allow the page cache to ...
The pgBadger PostgreSQL log analyzer generates detailed reports from a PostgreSQL log file. [107] pgDevOps pgDevOps is a suite of web tools to install & manage multiple PostgreSQL versions, extensions, and community components, develop SQL queries, monitor running databases and find performance problems. [108] Adminer
If a database crashes, the recovery process has to apply all transactions, both uncommitted as well as committed, to the data-files on disk, using the information in the redo log files. Oracle must re-do all redo-log transactions that have both a BEGIN and a COMMIT entry (roll forward), and it must undo all transactions that have a BEGIN entry ...
Increasingly, the Oracle database products compete against open-source software relational and non-relational database systems such as PostgreSQL, MongoDB, Couchbase, Neo4j, ArangoDB and others. Oracle acquired Innobase , supplier of the InnoDB codebase to MySQL , in part to compete better against open source alternatives, and acquired Sun ...
The nested set model is a technique for representing nested set collections (also known as trees or hierarchies) in relational databases.. It is based on Nested Intervals, that "are immune to hierarchy reorganization problem, and allow answering ancestor path hierarchical queries algorithmically — without accessing the stored hierarchy relation".
Database activity monitoring (DAM, a.k.a. Enterprise database auditing and Real-time protection [1]) is a database security technology for monitoring and analyzing database activity. DAM may combine data from network-based monitoring and native audit information to provide a comprehensive picture of database activity.
It generally follows PostgreSQL syntax, but does not enforce type checking by default. [8] [9] This means that one can, for example, insert a string into a column defined as an integer. Although it is a lightweight embedded database, SQLite implements most of the SQL standard and the relational model, including transactions and ACID guarantees ...