Linux swap is not turned on, but the process is still using virtual memory. Why?

many services are enabled on Ali CVM. Check memory usage with top command and find

KiB Swap:        0 total,        0 free,        0 used

indicates that the swap partition is not open on the system.
the following process uses a large amount of virtual memory
for example, elastic uses 16 gigabytes of virtual memory.
Why is the process still using virtual memory when the swap partition is not open?
does the fact that virtual memory is used so much indicate that the system is out of memory?

Apr.10,2021

if there is not enough memory, be sure to cache part to swap or file, for reference only

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-64f5-1b320ad-2bde9.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
MySQL Errno : 1021
Message : Disk full (/tmp/#sql-temptable-64f5-1b320ad-2bde9.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
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