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
8

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
20       or
21           { echo "A.fsdb"; echo "B.fsdb" } | dbmerge --xargs column
22       [column...]
23

DESCRIPTION

25       Merge all provided, pre-sorted input files, producing one sorted
26       result.  Inputs can both be specified with "--input", or one can come
27       from standard input and the other from "--input".  With "--xargs", each
28       line of standard input is a filename for input.
29
30       Inputs must have identical schemas (columns, column order, and field
31       separators).
32
33       Unlike dbmerge2, dbmerge supports an arbitrary number of input files.
34
35       Because this program is intended to merge multiple sources, it does not
36       default to reading from standard input.  If you wish to list - as an
37       explicit input source.
38
39       Also, because we deal with multiple input files, this module doesn't
40       output anything until it's run.
41
42       dbmerge consumes a fixed amount of memory regardless of input size.  It
43       therefore buffers output on disk as necessary.  (Merging is implemented
44       a series of two-way merges, so disk space is O(number of records).)
45
46       dbmerge will merge data in parallel, if possible.  The "--parallelism"
47       option can control the degree of parallelism, if desired.
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OPTIONS

50       General option:
51
52       --xargs
53           Expect that input filenames are given, one-per-line, on standard
54           input.  (In this case, merging can start incrementally.)
55
56       --removeinputs
57           Delete the source files after they have been consumed.  (Defaults
58           off, leaving the inputs in place.)
59
60       -T TmpDir
61           where to put tmp files.  Also uses environment variable TMPDIR, if
62           -T is not specified.  Default is /tmp.
63
64       --parallelism N or -j N
65           Allow up to N merges to happen in parallel.  Default is the number
66           of CPUs in the machine.
67
68       --endgame (or --noendgame)
69           Enable endgame mode, extra parallelism when finishing up.  (On by
70           default.)
71
72       Sort specification options (can be interspersed with column names):
73
74       -r or --descending
75           sort in reverse order (high to low)
76
77       -R or --ascending
78           sort in normal order (low to high)
79
80       -n or --numeric
81           sort numerically
82
83       -N or --lexical
84           sort lexicographically
85
86       This module also supports the standard fsdb options:
87
88       -d  Enable debugging output.
89
90       -i or --input InputSource
91           Read from InputSource, typically a file name, or "-" for standard
92           input, or (if in Perl) a IO::Handle, Fsdb::IO or Fsdb::BoundedQueue
93           objects.
94
95       -o or --output OutputDestination
96           Write to OutputDestination, typically a file name, or "-" for
97           standard output, or (if in Perl) a IO::Handle, Fsdb::IO or
98           Fsdb::BoundedQueue objects.
99
100       --autorun or --noautorun
101           By default, programs process automatically, but Fsdb::Filter
102           objects in Perl do not run until you invoke the run() method.  The
103           "--(no)autorun" option controls that behavior within Perl.
104
105       --header H
106           Use H as the full Fsdb header, rather than reading a header from
107           then input.
108
109       --help
110           Show help.
111
112       --man
113           Show full manual.
114

SAMPLE USAGE

116   Input:
117       File a.fsdb:
118
119           #fsdb cid cname
120           11 numanal
121           10 pascal
122
123       File b.fsdb:
124
125           #fsdb cid cname
126           12 os
127           13 statistics
128
129       These two files are both sorted by "cname", and they have identical
130       schemas.
131
132   Command:
133           dbmerge --input a.fsdb --input b.fsdb cname
134
135       or
136
137           cat a.fsdb | dbmerge --input b.fsdb cname
138
139   Output:
140           #fsdb      cid     cname
141           11 numanal
142           12 os
143           10 pascal
144           13 statistics
145           #  | dbmerge --input a.fsdb --input b.fsdb cname
146

SEE ALSO

148       dbmerge2(1), dbsort(1), Fsdb(3)
149

151       Copyright (C) 1991-2020 by John Heidemann <johnh@isi.edu>
152
153       This program is distributed under terms of the GNU general public
154       license, version 2.  See the file COPYING with the distribution for
155       details.
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159perl v5.34.0                      2021-07-22                        DBMERGE(1)
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