in reply to Re^2: key value in text format
in thread key value in text format

I second SQlite. I use it a lot, and if your dataset is big(ish), you don't want to be parsing flat files for every lookup.

How you store this depends on just how many [ key1=value1, key2=value2] there are.
If there is a fixed list of 'key1','key2' and it's not too many: bite the bullet and add the columns.

Otherwise, you get to use a link (This is Database 101. search for 'database normalization')

each record should be
[id], field1, field2

then in a separate table
[link_id], key1, value1
[link_id], key2, value2

[download]

You can also have a 3rd table with
[link_id], source_file_name
or whatever other metadata you need to keep.

SQLite very kindly has a magic ROWID column. It wont' return it on SELECT *, but will on SELECT ROWID,*.
Of course you get to do two queries for each lookup: SELECT ROWID,* FROM main_data and then SELECT * FROM extra_data WHERE link_id = ?

HTH.

TO clarify: if your 'real' data is 
name=bob, age=75, [ hair=balding, glasses=bifocal]
name=john, age=20, [ sport=chess ]

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Then you get:
Primary table:
1, bob, 45
2, john, 20

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lookup table:
1,hair,balding
1,glasses,bifocal
2,sport,chess

[download]

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Re^4: key value in text format
by pwagyi (Monk) on Nov 07, 2019 at 02:05 UTC

    The link method to handle key/value pair is a good idea. but I think I might just go with JSON (column) for all key/value pairs. What is the trade-off between the two approaches?

[reply]
      Searchability.

      using a linked table, you can do 
      SELECT 
  * 
FROM 
  main_data 
WHERE 
  ROWID IN (
    SELECT link_id 
    FROM extra_data
    WHERE key1 = ?
    AND value1 LIKE ?
  )

      [download]

      Consider also:
      do you want to put a storage method (JSON) inside a different storage method (SQL)?
[reply]
[d/l]
        Modern databases understand JSON and can search inside the structure, see e.g. MariaDB or PostgreSQL.
        map{substr$_->[0],$_->[1]||0,1}[\*||{},3],[[]],[ref qr-1,-,-1],[{}],[sub{}^*ARGV,3]
[reply]
[d/l]

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