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It was suggested to me that I use a database to help prune out duplicate entries (based on 12-digit id numbers) in data I'm processing. I had previously been using a hash, but it starts to choke by 55 million entries. So I fired up DBI::SQLite to give it a try. And I was shocked by what I found.

I simply must have something wrong, because inserting into an sqlite database seems to be occurring at a rate of only 5 per second for me; just writing raw to hashes was going between 11,000 and 20,000 per second. This is unbelievably, unusably slow. What is going on?

#!/usr/bin/perl use strict; use warnings; use v5.16.0; use lib 'lib'; use DBI; use Carp 'croak'; my $dbh = db_handle('vals.db'); my $sql_table = <<"SQL"; CREATE TABLE IF NOT EXISTS data ( klout INTEGER ); SQL $dbh->do($sql_table); my $sql_insert_statement = "INSERT INTO data (klout) VALUES (?)"; my $sth = $dbh->prepare($sql_insert_statement); my $start = time; foreach (1..1000) { $sth->execute($_); } say "Total time: ", (time - $start); # 180 seconds sub db_handle { my $db_file = shift or croak "db_handle() requires a database name"; no warnings 'once'; return DBI->connect ( "dbi:SQLite:dbname=$db_file", "", #no username "", #no password { RaiseError => 1, PrintError => 0, AutoCommit => 1 }, ) or die $DBH::errstr; }

In reply to DBI::SQLite slowness by Endless

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