What do the three parameters of rabbitmq's basic_qos prefetch method mean?

when using php-amqplib to operate rabbitmq, it is found that basic_qos has three parameters
prefetch_size prefetch_count global

global and prefetch_count roughly understand the meaning of these two parameters

but the meaning of the first parameter, prefetch_size, is a little unclear, and many materials on the Internet say that rabbitmq does not support it, but the official website does not seem to see that the parameter prefetch_size is not supported, so it is confused

.
Mar.18,2021

prefetch_size
maximum number of bytes of unacked messages;
prefetch_count
maximum number of unacked messages;
global:
limit objects of the above restrictions, false= limits individual consumers; true= limits the entire channel

set prefetch count: for each consumer
global specify false,


mark.
I wonder if prefetch count is positive for channel, how do you set the prefetch count for each consumer to be different?

MySQL Query : SELECT * FROM `codeshelper`.`v9_news` WHERE status=99 AND catid='6' ORDER BY rand() LIMIT 5
MySQL Error : Disk full (/tmp/#sql-temptable-64f5-1b2c02a-2b027.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
MySQL Errno : 1021
Message : Disk full (/tmp/#sql-temptable-64f5-1b2c02a-2b027.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
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