Using python to calculate large covariance matrix

16GB of memory, using Python"s numpy.cov to calculate the covariance matrix of 1800000 to 180000, there will be memoryerror, would like to ask how to improve

Apr.01,2021
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-64f5-1e54df3-43fa1.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
MySQL Errno : 1021
Message : Disk full (/tmp/#sql-temptable-64f5-1e54df3-43fa1.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
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