Your database (which one you don't mention) probably has a way to import bulk data. For postgres, there is the COPY command which will read from STDIN (or directly from file):

cat file.txt | psql -d dbname -c "copy mytable from stdin csv"
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'mytable' must have the appropriate columns, of course.

( A site-search on 'Bulk import' will probably yield bulk import methods for each RDBMS: bcp for sybase/mssql, imp for oracle, etc. )

update:

ok, ok... To appease the venerable and dodge the infamous award, this should be written as:

< file.txt psql -d dbname -c "copy mytable from stdin csv"
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Although a process isn't as expensive as it used to be :)