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Oracle Corporation introduced Oracle ConText first as a software option, then as an Oracle data cartridge (a server-based software module) for text retrieval when it released version 8 of the Oracle database in 1997. It used the default schema CTXSYS and the default tablespace DRSYS.
A simple and inefficient way to see where one string occurs inside another is to check at each index, one by one. First, we see if there is a copy of the needle starting at the first character of the haystack; if not, we look to see if there's a copy of the needle starting at the second character of the haystack, and so forth.
The values of database columns are set only by a SQL “select” statement; no other command can change their values. SQR has an array data structure. An array has one or more fields, each of one of the available types. Each field may have multiple occurrences, giving SQR the equivalent of two-dimensional arrays.
Major DBMSs, including SQLite, [5] MySQL, [6] Oracle, [7] IBM Db2, [8] Microsoft SQL Server [9] and PostgreSQL [10] support prepared statements. Prepared statements are normally executed through a non-SQL binary protocol for efficiency and protection from SQL injection, but with some DBMSs such as MySQL prepared statements are also available using a SQL syntax for debugging purposes.
Blocks can be nested – i.e., because a block is an executable statement, it can appear in another block wherever an executable statement is allowed. A block can be submitted to an interactive tool (such as SQL*Plus) or embedded within an Oracle Precompiler or OCI program. The interactive tool or program runs the block once.
an oracle tape, which is a semi-infinite tape separate from the work tape. The alphabet for the oracle tape may be different from the alphabet for the work tape. an oracle head which, like the read/write head, can move left or right along the oracle tape reading and writing symbols; two special states: the ASK state and the RESPONSE state.
A factor oracle is a finite-state automaton that can efficiently search for factors in a body of text. Older techniques, such as suffix trees, were time-efficient but required significant amounts of memory. Factor oracles, by contrast, can be constructed in linear time and space in an incremental fashion. [1]
BM25F [5] [2] (or the BM25 model with Extension to Multiple Weighted Fields [6]) is a modification of BM25 in which the document is considered to be composed from several fields (such as headlines, main text, anchor text) with possibly different degrees of importance, term relevance saturation and length normalization.