Import data from JSON to PostgreSQL via command line on Windows

Want to import data from JSON Lines (JSONL) to PostgreSQL via Command Line Interface (CLI) on Windows?

Using pg-cmd, a Command Line Interface (CLI) client for PostgreSQL, you can import data from JSON Lines to PostgreSQL easily and fast. Direct Interaction or Scripting and Automation.

• No need to install PostgreSQL client library.
• Convenient to deploy to cloud. No need to run installation file, just uncompress and run, immediately.
• Commands are entered into a terminal or command prompt, accessed from local or remote (like SSH).
• Support Windows, Linux, and MacOS.

Download pg-cmd Windows version
pg-cmd.windows-386.zip
pg-cmd.windows-amd64.zip

JSON Lines text format, also called newline-delimited JSON (NDJSON), or Line-delimited JSON (LDJSON). JSON Lines files may be saved with the file extension .jsonl, *.ndjson, *.ldjson.

Import data from JSON Lines to PostgreSQL via command line on Windows

1. In interactive mode:

pg-cmd> load table=media_messages 
      > datafile=f:\media_messages.json 
      > filetype=json;

2. In batch mode:

pg-cmd dsn="pan:withdata@192.168.0.102:3306/test" task=load table=media_messages datafile=f:\media_messages.json filetype=json quit=y

“loadtype=replace” will delete all data in table before inserting.

See parameters detail.

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More about pg-cmd – Command Line Interface (CLI) tool for PostgreSQL

JSON → PostgreSQL reference

Type mapping

Value kind	in JSON	in PostgreSQL
Int	1234 (number)	integer
Bigint	9007199254740993	bigint
Decimal	1234.56 (number)	numeric(p,s)
Float	1.234e10 (number)	double precision
Text	"text" (string)	varchar(n)
Long text	"multi-line\ntext" (escaped newline inside a string)	text
Date	"2026-09-18" (string)	date
Datetime	"2026-09-18T14:30:00Z" (string)	timestamp
Binary	"base64:..." (string)	bytea
Boolean	true / false (boolean)	boolean
JSON	nested object or array, kept as structure	jsonb

Dialect differences

JSON is a file format and PostgreSQL is a database server, so the target has to be told the types the file never carried - the rows below are where the two sides diverge.

Property	in JSON	in PostgreSQL
port	—	5432
identifiers	Double quotes; backslash escapes	"double quotes"
row limit	—	LIMIT n
dates	No date type: dates arrive as strings and the reader must p...	timestamp, timestamptz, date, time
long text	—	TEXT
binary	Not supported natively - base64 inside a string	BYTEA
separator	Braces and commas	—
encoding	UTF-8 by definition	—
typing	string, number, boolean, null, object, array - no date type	—
shape	Nested objects and arrays	Tables of rows and columns
ceiling	Whole document is usually parsed into memory	—

Command line

Side	Command
PostgreSQL	pg_dump or COPY ... TO
PostgreSQL (load)	COPY ... FROM

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