How to convert a list of attribute-value pairs into a flat table whose columns are attributes - sql

Question

I'm trying to convert a csv file containing 3 columns (ATTRIBUTE_NAME,ATTRIBUTE_VALUE,ID) into a flat table whose each row is (ID,Attribute1,Attribute2,Attribute3,....). The samples of such tables are provided at the end.
Either Python, Perl or SQL is fine. Thank you very much and I really appreciate your time and efforts!
In fact, my question is very similar to this post, except that in my case the number of attributes is pretty big (~300) and not consistent across each ID, so hard coding each attribute might not be a practical solution.
For me, the challenging/difficult parts are:
There are approximately 270 millions lines of input, the total size of the input table is about 60 GB.
Some single values (string) contain comma (,) within, and the whole string will be enclosed with double-quote (") to make the reader aware of that. For example "JPMORGAN CHASE BANK, NA, TX" in ID=53.
The set of attributes is not the same across ID's. For example, the number of overall attributes is 8, but ID=53, 17 and 23 has only 7, 6 and 5 respectively. ID=17 does not have attributes string_country and string_address, so output blank/nothing after the comma.
The input attribute-value table looks like this. In this sample input and output, we have 3 ID's, whose number of attributes can be different depending on we can obtain such attributes from the server or not.
ATTRIBUTE_NAME,ATTRIBUTE_VALUE,ID
num_integer,100,53
string_country,US (United States),53
string_address,FORT WORTH,53
num_double2,546.0,53
string_acc,My BankAcc,53
string_award,SILVER,53
string_bankname,"JPMORGAN CHASE BANK, NA, TX",53
num_integer,61,17
num_double,34.32,17
num_double2,200.541,17
string_acc,Your BankAcc,17
string_award,GOLD,17
string_bankname,CHASE BANK,17
num_integer,36,23
num_double,78.0,23
string_country,CA (Canada),23
string_address,VAN COUVER,23
string_acc,Her BankAcc,23
The output table should look like this. (The order of attributes in the columns is not fixed. It can be sorted alphabetically or by order-of-appearance.)
ID,num_integer,num_double,string_country,string_address,num_double2,string_acc,string_award,string_bankname
53,100,,US (United States),FORT WORTH,546.0,My BankAcc,SILVER,"JPMORGAN CHASE BANK, NA, TX"
17,61,34.32,,,200.541,Your BankAcc,GOLD,CHASE BANK
23,36,78.0,CA (Canada),VAN COUVER,,Her BankAcc,,

Answer 1

This program will do as you ask. It expects the name of the input file as a parameter on the command line.
Update Looking more carefully at the data I see that not all of the data fields are available for every ID. That makes things more complex if the fields are to be kept in the same order as they appear in the file.
This program works by scanning the file and accumulating all the data for output into hash %data. At the same time it builds a hash %headers, that keeps the position each header appears in the data for each ID value.
Once the file has been scanned, the collected headers are sorted by finding the first ID for each pair that includes information for both headers. The sort order for that pair within the complete set must be the same as the order they appeared in the data for that ID, so it's just a matter of comparing the two position values using <=>.
Once a sorted set of headers has been created, the %data hash is dumped, accessing the complete list of values for each ID using a hash slice.
Update 2 Now that I realise the sheer size of your data I can see that my second attempt was also flawed, as it tried to read all of the information into memory before outputting it. That isn't going to work unless you have a monster machine with about 1TB of memory!
You may get some mileage from this version. It scans twice through the file, the first time to read the data so that the full set of header names can be created and ordered, then again to read the data for each ID and output it.
Let me know if it's not working for you, as there's still things I can do to make it more memory-efficient.
use strict;
use warnings;
use 5.010;
use Text::CSV;
use Fcntl 'SEEK_SET';
my $csv = Text::CSV->new;
open my $fh, '<', $ARGV[0] or die qq{Unable to open "$ARGV[0]" for input: $!};
my %headers = ();
my $last_id;
my $header_num;
my $num_ids;
while (my $row = $csv->getline($fh)) {
next if $. == 1;
my ($key, $val, $id) = #$row;
unless (defined $last_id and $id eq $last_id) {
++$num_ids;
$header_num = 0;
$last_id = $id;
print STDERR "Processing ID $id\n";
}
$headers{$key}[$num_ids-1] = ++$header_num;
}
sub by_position {
for my $id (0 .. $num_ids-1) {
my ($posa, $posb) = map $headers{$_}[$id], our $a, our $b;
return $posa <=> $posb if $posa and $posb;
}
0;
}
my #headers = sort by_position keys %headers;
%headers = ();
print STDERR "List of headers complete\n";
seek $fh, 0, SEEK_SET;
$. = 0;
$csv->combine('ID', #headers);
print $csv->string, "\n";
my %data = ();
$last_id = undef;
while () {
my $row = $csv->getline($fh);
next if $. == 1;
if (not defined $row or defined $last_id and $last_id ne $row->[2]) {
$csv->combine($last_id, #data{#headers});
print $csv->string, "\n";
%data = ();
}
last unless defined $row;
my ($key, $val, $id) = #$row;
$data{$key} = $val;
$last_id = $id;
}
output
ID,num_integer,num_double,string_country,string_address,num_double2,string_acc,string_award,string_bankname
53,100,,"US (United States)","FORT WORTH",546.0,"My BankAcc",SILVER,"JPMORGAN CHASE BANK, NA, TX"
17,61,34.32,,,200.541,"Your BankAcc",GOLD,"CHASE BANK"
23,36,78.0,"CA (Canada)","VAN COUVER",,"Her BankAcc",,

Answer 2

Use Text::CSV from CPAN:
#!/usr/bin/env perl
use strict;
use warnings;
# --------------------------------------
use charnames qw( :full :short );
use English qw( -no_match_vars ); # Avoids regex performance penalty
use Text::CSV;
my $col_csv = Text::CSV->new();
my $id_attr_csv = Text::CSV->new({ eol=>"\n", });
$col_csv->column_names( $col_csv->getline( *DATA ));
while( my $row = $col_csv->getline_hr( *DATA )){
# do all the keys but skip if ID
for my $attribute ( keys %$row ){
next if $attribute eq 'ID';
$id_attr_csv->print( *STDOUT, [ $attribute, $row->{$attribute}, $row->{ID}, ]);
}
}
__DATA__
ID,num_integer,num_double,string_country,string_address,num_double2,string_acc,string_award,string_bankname
53,100,,US (United States),FORT WORTH,546.0,My BankAcc,SILVER,"JPMORGAN CHASE BANK, NA, TX"
17,61,34.32,,,200.541,Your BankAcc,GOLD,CHASE BANK
23,36,78.0,CA (Canada),VAN COUVER,,Her BankAcc,,