1DBMERGE(1)            User Contributed Perl Documentation           DBMERGE(1)
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NAME

6       dbmerge - merge all inputs in sorted order based on the the specified
7       columns
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SYNOPSIS

10           dbmerge --input A.fsdb --input B.fsdb [-T TemporaryDirectory] [-nNrR] column [column...]
11
12       or
13           cat A.fsdb | dbmerge --input - --input B.fsdb [-T
14       TemporaryDirectory] [-nNrR] column [column...]
15
16       or
17           dbmerge [-T TemporaryDirectory] [-nNrR] column [column...] --inputs
18       A.fsdb [B.fsdb ...]
19

DESCRIPTION

21       Merge all provided, pre-sorted input files, producing one sorted
22       result.  Inputs can both be specified with "--input", or one can come
23       from standard input and the other from "--input".  With "--xargs", each
24       line of standard input is a filename for input.
25
26       Inputs must have identical schemas (columns, column order, and field
27       separators).
28
29       Unlike dbmerge2, dbmerge supports an arbitrary number of input files.
30
31       Because this program is intended to merge multiple sources, it does not
32       default to reading from standard input.  If you wish to list - as an
33       explicit input source.
34
35       Also, because we deal with multiple input files, this module doesn't
36       output anything until it's run.
37
38       dbmerge consumes a fixed amount of memory regardless of input size.  It
39       therefore buffers output on disk as necessary.  (Merging is implemented
40       a series of two-way merges, so disk space is O(number of records).)
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42       dbmerge will merge data in parallel, if possible.  The <--parallelism>
43       option can control the degree of parallelism, if desired.
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OPTIONS

46       General option:
47
48       --xargs
49           Expect that input filenames are given, one-per-line, on standard
50           input.  (In this case, merging can start incrementally.
51
52       --removeinputs
53           Delete the source files after they have been consumed.  (Defaults
54           off, leaving the inputs in place.)
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56       -T TmpDir
57           where to put tmp files.  Also uses environment variable TMPDIR, if
58           -T is not specified.  Default is /tmp.
59
60       --parallelism N or -j N
61           Allow up to N merges to happen in parallel.  Default is the number
62           of CPUs in the machine.
63
64       --endgame (or --noendgame)
65           Enable endgame mode, extra parallelism when finishing up.  (On by
66           default.)
67
68       Sort specification options (can be interspersed with column names):
69
70       -r or --descending
71           sort in reverse order (high to low)
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73       -R or --ascending
74           sort in normal order (low to high)
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76       -n or --numeric
77           sort numerically
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79       -N or --lexical
80           sort lexicographically
81
82       This module also supports the standard fsdb options:
83
84       -d  Enable debugging output.
85
86       -i or --input InputSource
87           Read from InputSource, typically a file name, or "-" for standard
88           input, or (if in Perl) a IO::Handle, Fsdb::IO or Fsdb::BoundedQueue
89           objects.
90
91       -o or --output OutputDestination
92           Write to OutputDestination, typically a file name, or "-" for
93           standard output, or (if in Perl) a IO::Handle, Fsdb::IO or
94           Fsdb::BoundedQueue objects.
95
96       --autorun or --noautorun
97           By default, programs process automatically, but Fsdb::Filter
98           objects in Perl do not run until you invoke the run() method.  The
99           "--(no)autorun" option controls that behavior within Perl.
100
101       --help
102           Show help.
103
104       --man
105           Show full manual.
106

SAMPLE USAGE

108   Input:
109       File a.fsdb:
110
111           #fsdb cid cname
112           11 numanal
113           10 pascal
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115       File b.fsdb:
116
117           #fsdb cid cname
118           12 os
119           13 statistics
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121       These two files are both sorted by "cname", and they have identical
122       schemas.
123
124   Command:
125           dbmerge --input a.fsdb --input b.fsdb cname
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127       or
128
129           cat a.fsdb | dbmerge --input b.fsdb cname
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131   Output:
132           #fsdb      cid     cname
133           11 numanal
134           12 os
135           10 pascal
136           13 statistics
137           #  | dbmerge --input a.fsdb --input b.fsdb cname
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SEE ALSO

140       dbmerge2(1), dbsort(1), Fsdb(3)
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143       Copyright (C) 1991-2018 by John Heidemann <johnh@isi.edu>
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145       This program is distributed under terms of the GNU general public
146       license, version 2.  See the file COPYING with the distribution for
147       details.
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151perl v5.28.1                      2019-02-02                        DBMERGE(1)
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