which is better one big query or multiple small query? [closed]

Question

which is better and efficient? one big query then just process the fetched query in the php or from php function will just create a loop function that queries small data. Please consider also that the table can be big (thousands of raw). Thanks.

Comments table

id | parent | msg ---+--------+---------       1  |   0    | hello    2  |   1    | hi       3  |   2    | whats up        4  |   3    | yow        5  |   1    | hellow    6  |   2    | nice        7  |   0    | great    

Expected output is this:

        Array         (             [0] => Array                 (                     [id] => 1                     [parent] => 0                     [value] => hello                     [child] => Array                         (                             [0] => Array                                 (                                     [id] => 2                                     [parent] => 1                                     [value] => hi                                     [child] => Array                                         (                                             [0] => Array                                                 (                                                     [id] => 3                                                     [parent] => 2                                                     [value] => whats up                                                     [child] => Array                                                         (                                                             [0] => Array                                                                 (                                                                     [id] => 4                                                                     [parent] => 3                                                                     [value] => yow                                                                 )                                                         )                                                 )                                             [1] => Array                                                 (                                                     [id] => 6                                                     [parent] => 2                                                     [value] => nice                                                 )                                         )                                 )                             [1] => Array                                 (                                     [id] => 5                                     [parent] => 1                                     [value] => hellow                                 )                         )                 )             [1] => Array                 (                      [id] => 7                     [parent] => 0                     [value] => great                 ) 

Answer 1

As a rule of thumb, the less queries the better.

This is a good question but this has been answered multiple times.

Is it better to return one big query or a few smaller ones?

Multiple small queries vs a single long query. Which one is more efficient?

One big query vs. many small ones?

Which one is faster single big query or few small queries?

What is faster, a big joined query with more PHP or multiple small selects with less PHP?

Should I use one big SQL Select statement or several small ones?

https://dba.stackexchange.com/questions/76973/what-is-faster-one-big-query-or-many-small-queries

https://dba.stackexchange.com/questions/35277/is-it-better-to-separate-a-big-query-into-multiple-smaller-queries