Re: Max registers in postgresql 7.4

janettedoe(at)hotmail(dot)com ("Ruby Deepdelver") writes:
> Hello, I'm having trouble in find certain information, i've search
> over the web and through the documentation but i haven't had lucky.
> I need to know if there is some limit in the amount of registers that
> the database can manage, and if so, how much is that maximun.
> Thanks in advanced, Ruby.

It is not evident what you mean by "registers."

The meaning I usually take is nicely documented in FOLDOC:
<http://wombat.doc.ic.ac.uk/foldoc/foldoc.cgi?register>

"register

1. One of a small number of high-speed memory locations in a
computer's CPU. Registers differ from ordinary random access memory in
several respects:

There are only a small number of registers (the "register set"),
typically 32 in a modern processor though some, e.g. SPARC, have as
many as 144. A register may be directly addressed with a few bits. In
contrast, there are usually millions of words of main memory (RAM),
requiring at least twenty bits to specify a memory location. Main
memory locations are often specified indirectly, using an indirect
addressing mode where the actual memory address is held in a register.

Registers are fast; typically, two registers can be read and a third
written -- all in a single cycle. Memory is slower; a single access
can require several cycles.

The limited size and high speed of the register set makes it one of
the critical resources in most computer architectures. Register
allocation, typically one phase of the back-end, controls the use of
registers by a compiled program."

Databases don't usually manage registers; that normally involves some
combination of the operating system (which may have some conventions
as to what registers are used for what purposes) and the compilers
used to compile code.

The "maximum number of registers" is normally a function of what the
manufacturer of your computer's CPU has designed; DBMS implementors
cannot increase the number.
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