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Re^2: DBI execute_array

by DamianKaelGreen (Acolyte)
on Apr 23, 2014 at 17:20 UTC ( #1083400=note: print w/replies, xml ) Need Help??


in reply to Re: DBI execute_array
in thread DBI execute_array

Good trick! Except there should be an extra set of parenthesis in your join statement in order for the 100 question elements to be passed to the join function as a list :

 my $sql = "INSERT INTO temp_selectedTitles values ". join(", ", ("(?)") x 100);

Also, because the example used only one element in each row, it was not quite clear to me that the above example did not just create a single row with 100 columns (it does not). It was also unclear from the example how you might apply this concept when inserting rows that have multiple columns. After playing around with it a little, I was able to get something like the following to work:

$dbh->do("CREATE TABLE IF NOT EXISTS temp_selectedTitles (title VARCHA +R(128), author VARCHAR(128), location VARCAR(128))"); my $number_of_rows_waiting_to_commit = 0; my @chunk_of_values_for_database = (); foreach my $book (@books) { push (@chunk_of_values_for_database, $book); push (@chunk_of_values_for_database, $authors{$book}); push (@chunk_of_values_for_database, $locations{$book}); $number_of_rows_waiting_to_commit++; if ($number_of_rows_waiting_to_commit >= 100){ my $sql = "INSERT IGNORE INTO $DT_table (title, author, locati +on) VALUES ".join(", ", ("(?, ?, ?)") x $number_of_rows_waiting_to_co +mmit); my $store_1 = $dbh->prepare($sql); $store_1->execute(@chunk_of_values_for_database); $number_of_rows_waiting_to_commit = 0; @chunk_of_values_for_database = (); } } my $sql = "INSERT IGNORE INTO $DT_table (title, author, location) VALU +ES ".join(", ", ("(?, ?, ?)") x $number_of_rows_waiting_to_commit); my $store_2 = $dbh->prepare($sql); $store_2->execute(@chunk_of_values_for_database);

Note that I actually tested this on a table with 6 columns and inserted 10,000 rows at a time instead of 100. It probably will work for more than that, but there may be limits to the size of the $sql string that you pass to the DBI and that in turn gets passed to whatever database you are using. Also, too large of a string could potentially cause a penalty in performance. But from what I've found, this trick does indeed speed up the process tremendously.

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