1Fsdb::Filter::dbsort(3)User Contributed Perl DocumentatioFnsdb::Filter::dbsort(3)
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NAME

6       dbsort - sort rows based on the the specified columns
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SYNOPSIS

9           dbsort [-M MemLimit] [-T TemporaryDirectory] [-nNrR] column [column...]
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DESCRIPTION

12       Sort all input rows as specified by the numeric or lexical columns.
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14       Dbsort consumes a fixed amount of memory regardless of input size.  (It
15       reverts to temporary files on disk if necessary, based on the -M and -T
16       options.)
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18       The sort should be stable, but this has not yet been verified.
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20       For large inputs (those that spill to disk), dbsort will do some of the
21       merging in parallel, if possible.  The --parallel option can control
22       the degree of parallelism, if desired.
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OPTIONS

25       General option:
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27       -M MaxMemBytes
28           Specify an approximate limit on memory usage (in bytes).  Larger
29           values allow faster sorting because more operations happen in-
30           memory, provided you have enough memory.
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32       -T TmpDir
33           where to put tmp files.  Also uses environment variable TMPDIR, if
34           -T is not specified.  Default is /tmp.
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36       --parallelism N or -j N
37           Allow up to N merges to happen in parallel.  Default is the number
38           of CPUs in the machine.
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40       Sort specification options (can be interspersed with column names):
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42       -r or --descending
43           sort in reverse order (high to low)
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45       -R or --ascending
46           sort in normal order (low to high)
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48       -t or --type-inferred-sorting
49           sort fields by type (numeric or leicographic), automatically
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51       -T or --no-type-inferred-sorting
52           sort fields only as specified based on "-n" or "-N"
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54       -n or --numeric
55           sort numerically
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57       -N or --lexical
58           sort lexicographically
59
60       This module also supports the standard fsdb options:
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62       -d  Enable debugging output.
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64       -i or --input InputSource
65           Read from InputSource, typically a file name, or "-" for standard
66           input, or (if in Perl) a IO::Handle, Fsdb::IO or Fsdb::BoundedQueue
67           objects.
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69       -o or --output OutputDestination
70           Write to OutputDestination, typically a file name, or "-" for
71           standard output, or (if in Perl) a IO::Handle, Fsdb::IO or
72           Fsdb::BoundedQueue objects.
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74       --autorun or --noautorun
75           By default, programs process automatically, but Fsdb::Filter
76           objects in Perl do not run until you invoke the run() method.  The
77           "--(no)autorun" option controls that behavior within Perl.
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79       --header H
80           Use H as the full Fsdb header, rather than reading a header from
81           then input.
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83       --help
84           Show help.
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86       --man
87           Show full manual.
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SAMPLE USAGE

90   Input:
91           #fsdb cid cname
92           10 pascal
93           11 numanal
94           12 os
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96   Command:
97           cat data.fsdb | dbsort cname
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99   Output:
100           #fsdb      cid     cname
101           11 numanal
102           12 os
103           10 pascal
104           #  | dbsort cname
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SEE ALSO

107       dbmerge(1), dbmapreduce(1), Fsdb(3)
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CLASS FUNCTIONS

110   new
111           $filter = new Fsdb::Filter::dbsort(@arguments);
112
113       Create a new object, taking command-line arguments.
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115   set_defaults
116           $filter->set_defaults();
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118       Internal: set up defaults.
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120   parse_options
121           $filter->parse_options(@ARGV);
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123       Internal: parse command-line arguments.
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125   setup
126           $filter->setup();
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128       Internal: setup, parse headers.
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130   segment_start
131           $self->segment_start(\@rows);
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133       Sorting happens internally, to handle large things in pieces if
134       necessary.
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136       call "$self-"segment_start> to init things and to restart after an
137       overflow "$self-"segment_overflow> to close one segment and start the
138       next, and "$self-"segment_merge_finish> to put them back together
139       again.
140
141       Note that we don't invoke the merge code unless the data exceeds some
142       threshold size, so small sorts happen completely in memory.
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144       Once we give up on memory, all the merging happens by making passes
145       over the disk files.
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147   segment_next_output
148           $out = $self->segment_next_output($input_finished)
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150       Internal: return a Fsdb::IO::Writer as $OUT that either points to our
151       output or a temporary file, depending on how things are going.
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153   segment_overflow
154           $self->segment_overflow(\@rows, $input_finished)
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156       Called to sort @ROWS, writing them to the appropriate place.
157       $INPUT_FINISHED is set if all input has been read.
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159   segment_merge_start
160           $self->segment_merge_start($fn);
161
162       Start merging on file $FN.  Fork off a merge thread, if necessary.
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164   segment_merge_finish
165           $self->segment_merge_finish();
166
167       Merge queued files, if any.  Just call dbmerge(1) to do all the real
168       work.
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170   run
171           $filter->run();
172
173       Internal: run over each rows.
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AUTHOR and COPYRIGHT

176       Copyright (C) 1991-2018 by John Heidemann <johnh@isi.edu>
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178       This program is distributed under terms of the GNU general public
179       license, version 2.  See the file COPYING with the distribution for
180       details.
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184perl v5.34.1                      2022-04-04           Fsdb::Filter::dbsort(3)