I am trying to add a long DNA sequence into my database. Reading some other threads here, it was suggested to use CRC32 as a way to implement a unique constraint on fields where the length of the string is too long for unique key.

I am trying to check if a DNA sequence already exists in my database by converting it with String::CRC32 into CRC32 hash. However, I can't seem to use pack or unpack to properly store the data type for comparison to my database. 
my $crc32=crc32("$sequence"); #check crc32 of sequence
my $th=$dbh->prepare(qq(SELECT COUNT(1) FROM Sequence WHERE Seq_Checks
+um=$crc32)); #check if it already exists
$th->execute();
my $test=$th->fetch()->[0];
print "$test\n"; #output if it exists

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This gives me a segmentation fault this is mySQL 5.7 and perl 5.22.1

UPDATE: Good lord. After reading a lot about the CRC32 function in SQL. I learned that it spits out a 32bit unsigned integer which is basically 0-4million something. So this whole time I assumed it was giving me binary so I was storing it binary. I switched it to unsigned int size 10 and that is the exact size of 32bit. So I don't have to mess with binary values.

In reply to checking mySQL database for unique CRC32 as proxy for long string by diyaz

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