-derep need very high memory

[Xq Sun]

I use commands as below:

gzip -dc /data/SRR606249_1.fastq.gz |perl prinseq-lite.pl -fastq stdin -min_len 60 -max_len 200 -min_qual_mean 20 -derep 12 -trim_qual_left 2 -trim_qual_right 2 -out_good stdout -out_bad null |gzip - >test.fq.gz&

when i set -derep 12 ,I found the RAM of my desktop was increased very soon. after while my telminal was broken down.

How big memory using when i analyzed SRR606249_1.fastq.gz (about 10G after decompressed).