DBMERGE(1)

📦
version 3.9 · 3 versions
, in epel 9

💅 DBMERGE(1) — like, the merge manual, bestie

okay so real quick: this is dbmerge from the User Contributed Perl Documentation section of the manual, and honestly? she's an icon. let's get into it 🫶

✨ NAME ✨

dbmerge — merge all your inputs into one sorted result, sorted by the columns you specifiy. yes. the columns. the ones you named. 💅

🦋 SYNOPSIS 🦋

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

or

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

or

dbmerge [-T TemporaryDirectory] [-nNrR] column [column...] --inputs A.fsdb [B.fsdb ...]

or

{ echo "A.fsdb"; echo "B.fsdb" } | dbmerge --xargs column [column...]

🌸 DESCRIPTION 🌸

So the whole vibe: you hand her a bunch of pre-sorted input files and she merges them all into one sorted result. that's it, that's the post 💖

You can name your inputs with --input, or with --inputs, or do the cute mixed thing where one comes from standard input and the other comes from --input. And with --xargs, every single line of standard input is a filename for input. one per line, no cap.

⚠️ heads up bestie: inputs must have identical schemas — same columns, same column order, and same field separators. no mixing and matching, she will not be doing that 🙈

Unlike dbmerge2, dbmerge supports an arbitrary number of input files. literally as many as you want. main character energy 👑

And because this program is built to merge multiple sources, she does not default to reading from standard input. you want stdin? use - as the input source. periodt.

Also, because we're dealing with multiple input files, this module doesn't output anything until it's run. like, nothing. she's cooking. 🔥

dbmerge consumes a fixed amount of memory regardless of input size. iconic. so she buffers output on disk as necessary. (the merging is implemented as a series of two-way merges and possibly an n-way merge at the end, so disk space is O(number of records).)

dbmerge will merge data in parallel, if possible. the --parallelism option can control the degree of parallelism, if you're feeling controlling 🎀

✨ OPTIONS ✨

general option(s):

  • --xargs — expect that input filenames are given, one-per-line, on standard input. (in this case, merging can start incrementally. slay.)
  • --removeinputs — delete the source files after they've been consumed. (defaults off, so your inputs stay right where they are 💖)
  • -T TmpDir — where to put tmp files. also uses the environment variable TMPDIR if -T isn't specified. default is /tmp.
  • --parallelism N or -j N — allow up to N merges to happen in parallel. default is the number of CPUs in the machine. she's built different.
  • --endgame (or --noendgame) — enable endgame mode, extra parallelism when finishing up. (on by default. we love a strong finish 🫶)

sort specification options (these can be interspersed with column names, iykyk):

  • -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

also, this module 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. (hi, that's this 💅)

🎀 SAMPLE USAGE 🎀

input:

File a.fsdb:

#fsdb cid cname
11 numanal
10 pascal

File b.fsdb:

#fsdb cid cname
12 os
13 statistics

These two files are both sorted by "cname", and they have identical schemas. perfect match, honestly 🌈

command:

dbmerge --input a.fsdb --input b.fsdb cname

or

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

output:

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

like?? ate and left no crumbs 👑

🌈 SEE ALSO 🌈

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

go read those too, bestie, they're all part of the family 🦋

Copyright (C) 1991-2024 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.

and that's the whole page, bestie ✨ this one's from perl v5.32.1, dated 2024-08-02, and it's DBMERGE(1) — go merge something iconic 💅🎀

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