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Since we can have pointers to int , and pointers to char , and pointers to any structures we've defined, and in fact pointers to any type in C, it shouldn't come as too much of a surprise that we can have pointers to other pointers. If we're used to thinking about simple pointers, and to keeping clear in our minds the distinction between the pointer itself and what it points to , we should be able to think about pointers to pointers, too, although we'll now have to distinguish between the pointer, what it points to, and what the pointer that it points to points to. (And, of course, we might also end up with pointers to pointers to pointers, or pointers to pointers to pointers to pointers, although these rapidly become too esoteric to have any practical use.) The declaration of a pointer-to-pointer looks like int **ipp; where the two asterisks indicate that two levels of pointers are...

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PostgreSQL Tutorial Prev Chapter 1. Introduction Next A Short History of Postgres The Berkeley Postgres Project Implementation of the Postgres DBMS began in 1986. The initial concepts for the system were presented in [STON86] and the definition of the initial data model appeared in [ROWE87]. The design of the rule system at that time was described in [STON87a]. The rationale and architecture of the storage manager were detailed in [STON87b]. Postgres has undergone several major releases since then. The first "demoware" system became operational in 1987 and was shown at the 1988 ACM-SIGMOD Conference. We released Version 1, described in [STON90a], to a few external users in June 1989. In response to a critique of the first rule system ([STON89]), the rule system was redesigned ([STON90b]) and Versio...