Fsdb::Filter::dbmerge2(3)

NAME
dbmerge2 - merge exactly two inputs in sorted order based on the the specified columns

SYNOPSIS
    dbmerge2 --input A.fsdb --input B.fsdb [-T TemporaryDirectory] [-nNrR] column [column...]

or
    cat A.fsdb | dbmerge2 --input B.fsdb [-T TemporaryDirectory] [-nNrR] column [column...]

DESCRIPTION
Merge exactly two sorted input files, producing one sorted result. Inputs can both be specified with "--input", or one can come from standard input and the other from "--input".

Inputs must have identical schemas (columns, column order, and field separators).

Dbmerge2 consumes a fixed amount of memory regardless of input size.

Although described above as a command line too, the command line version of dbmerge2 is not installed by default. Dbmerge2 is used primarily internal to perl; dbmerge(1) is the command-line tool for user use.

Warning: we do not verify that each input is actually sorted. In correct merge results will occur if they are not.

OPTIONS
General option:

--saveoutput $OUT_REF
    Save output writer (for integration with other fsdb filters).

<-T TmpDir>
    where to put tmp files. Also uses environment variable TMPDIR, if -T is not specified. Default is /tmp.

Sort specification options (can be interspersed with column names):

-r or --descending
    sort in reverse order (high to low)

-R or --ascending
    sort in normal order (low to high)

-n or --numeric
    sort numerically

-N or --lexical
    sort lexicographically

This module also supports the standard fsdb options:

-d  Enable debugging output.

-i or --input InputSource
    Read from InputSource, typically a file name, or "-" for standard input, or (if in Perl) a IO::Handle, Fsdb::IO or Fsdb::BoundedQueue objects.

-o or --output OutputDestination
    Write to OutputDestination, typically a file name, or "-" for standard output, or (if in Perl) a IO::Handle, Fsdb::IO or Fsdb::BoundedQueue objects.

--autorun or --noautorun
    By default, programs process automatically, but Fsdb::Filter objects in Perl do not run until you invoke the run() method. The "--(no)autorun" option controls that behavior within Perl.

--header H
    Use H as the full Fsdb header, rather than reading a header from then input.

--help
    Show help.

--man
    Show full manual.

SAMPLE USAGE

  Input:
File a.fsdb:

    #fsdb cid cname
    11 numanal
    10 pascal

File b.fsdb:

    #fsdb cid cname
    12 os
    13 statistics

  Command:
    dbmerge2 --input a.fsdb --input b.fsdb cname

or

    cat a.fsdb | dbmerge2 --input b.fsdb cname

  Output:
    #fsdb      cid     cname
    11 numanal
    12 os
    10 pascal
    13 statistics
    #  | dbmerge2 --input a.fsdb --input b.fsdb cname

SEE ALSO
dbmerge(1), dbsort(1), Fsdb(3)

CLASS FUNCTIONS

  new
    $filter = new Fsdb::Filter::dbmerge2(@arguments);

Create a new object, taking command-line arguments.

  set_defaults
    $filter->set_defaults();

Internal: set up defaults.

  parse_options
    $filter->parse_options(@ARGV);

Internal: parse command-line arguments.

  setup
    $filter->setup();

Internal: setup, parse headers.

  run
    $filter->run();

Internal: run over each rows.

AUTHOR and COPYRIGHT
Copyright (C) 1991-2019 by John Heidemann <johnh@isi.edu>

This program is distributed under terms of the GNU general public license, version 2. See the file COPYING with the distribution for details.