On 2024-02-13 01:53:25 +0530, veem v wrote: > On Mon, 12 Feb 2024 at 03:40, Peter J. Holzer <hjp-pgsql@xxxxxx> wrote: > > The fixed width types are those that the CPU can directly process: > Integers with 16, 32 and 64 bits, floating point numbers with 32 and 64 > bits. The CPU can read and write them with a single memory access, it > can do arithmetic with a single instruction, etc. > > Number/Numeric are not native types on any CPU. To read them the CPU > needs several memory accesses (probably one per byte unless you get > really clever) and then it can't do any calculations with them > directly, instead it has run a subroutine which does operations on > little chunks and then puts those chunks together again - basically the > same as you do when you're doing long addition or multiplication on > paper. So that's not very efficient. > > > So it looks like the fixed length data type(like integer, float) should be the > first choice while choosing the data type of the attributes wherever possible, > as these are native types. (Like choosing "Integer/float" over "Numeric", > "Char" over "Varchar" etc). Please do not conflate "char(n)" with native machine types like int or float. These are very different things. A char(n) is string of fixed but arbitrary length. This is not something a CPU can process in a single instruction. It has to go over it character by character. There is almost never a reason to use char(n). Just use varchar(n) or in the case of PostgreSQL just varchar or text. > However I do see even in Oracle databases, we have Integer type too, Not really. INTEGER is just an alias for NUMBER(38) in Oracle (see for example https://docs.oracle.com/en/database/oracle/oracle-database/19/sqlqr/Data-Types.html). It's not the same as an INTEGER in PostgreSQL. hp -- _ | Peter J. Holzer | Story must make more sense than reality. |_|_) | | | | | hjp@xxxxxx | -- Charles Stross, "Creative writing __/ | http://www.hjp.at/ | challenge!"
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