Install & first query

This page gets you from a clean Python environment to a working query against a real Informix server in five minutes. We’ll use the official IBM Informix Developer Edition Docker image so you don’t need an Informix license.

Prerequisites

• Python 3.10 or newer
• Docker, for the dev server (skip if you already have an Informix instance)
• 4 GB of free RAM for the dev container

1. Install the driver

uv (recommended)

uv add informix-driver

pip

pip install informix-driver

poetry

poetry add informix-driver

That’s the entire dependency. No system packages, no LD_LIBRARY_PATH, no libcrypt.so.1.

2. Start the dev container

docker run -d --name informix-dev \
  -e LICENSE=accept \
  -p 9088:9088 \
  -p 9089:9089 \
  --privileged \
  icr.io/informix/informix-developer-database:15.0.1.0.3DE

The image takes ~90 seconds to initialize. Watch the logs until you see oninit running:

docker logs -f informix-dev

Tip

The --privileged flag is required by the dev image — it tries to manage shared memory limits. For production servers this isn’t a thing.

3. Run your first query

Save this as hello.py:

import informix_db

with informix_db.connect(
    host="127.0.0.1",
    port=9088,
    user="informix",
    password="in4mix",
    database="sysmaster",
    server="informix",
) as conn:
    cur = conn.cursor()
    cur.execute(
        "SELECT FIRST 5 dbsname, tabname "
        "FROM systables WHERE tabid > 99"
    )
    for row in cur.fetchall():
        print(row)

Then:

python hello.py

You should see five rows from Informix’s system catalog. If you do, congratulations — you’ve spoken SQLI to an IBM database from pure Python with zero native code in the call stack.

What just happened

When informix_db.connect() returned, the driver had:

1. Opened a TCP socket to 127.0.0.1:9088
2. Sent an SQ_INFO PDU containing client capabilities (locale, byte order, app name)
3. Received the server’s identification (IBM Informix Dynamic Server Version 15.0.1.0.3)
4. Negotiated authentication via SQ_PASSWD
5. Opened the sysmaster database via SQ_DBOPEN
6. Returned a Connection object ready for queries

cur.execute() sent an SQ_PREPARE PDU with your SQL, parsed the response into a column descriptor, sent SQ_DESCRIBE, then SQ_OPEN to start the cursor. cur.fetchall() issued SQ_FETCH PDUs and decoded each SQ_TUPLE payload via per-column readers.

If you want to see this happen byte-by-byte, the architecture page walks through the wire protocol with annotated captures.

4. Try parameter binding

with informix_db.connect(host="127.0.0.1", port=9088, user="informix",
                        password="in4mix", database="sysmaster",
                        server="informix") as conn:
    cur = conn.cursor()
    cur.execute(
        "SELECT tabname FROM systables WHERE tabid = ?",
        (1,),
    )
    print(cur.fetchone())

? and :1 both work — Informix’s native paramstyle is numeric, but ? is supported as a synonym.

5. Use the connection pool

For real applications, prefer the pool:

import informix_db

pool = informix_db.create_pool(
    host="127.0.0.1", port=9088,
    user="informix", password="in4mix",
    database="sysmaster", server="informix",
    min_size=2, max_size=10,
    acquire_timeout=5.0,
)

with pool.connection() as conn:
    cur = conn.cursor()
    cur.execute("SELECT 1 FROM systables WHERE tabid = 1")
    print(cur.fetchone())

pool.close()

The pool is thread-safe and has a per-connection wire lock — accidental sharing across threads doesn’t corrupt the wire stream, though PEP 249 advice still holds (one connection per thread).

What’s next

1. Going async? Async with FastAPI → walks through a real FastAPI app with the async pool.

2. Connecting to production? Connect with TLS → covers TLS-listener configuration and bring-your-own-context patterns.

3. Bulk-loading? Bulk inserts (executemany) → — and the 53× transaction-vs-autocommit gotcha you’ll hit otherwise.

4. Migrating from IfxPy? Migrate from IfxPy → covers the API differences and the things IfxPy does that we don’t (yet).