pykx

KDB-X Python

KDB-X Python is the Python-first interface to kdb+ and q. import pykx as kx

For full Column methods, DB API, IPC details, type mapping: see reference.md

Critical Patterns (Common Mistakes)

Column API for WHERE: Use Operators, Not Strings

# CORRECT: kx.Column with Python operators
table.select(where=kx.Column('price') > 100)
table.select(where=(kx.Column('sym') == 'AAPL') & (kx.Column('price') > 150))

# WRONG — string-based where does NOT work
table.select(where='price > 100')         # WRONG!
table.select(where='sym = `AAPL')         # WRONG!

Combining WHERE Conditions: Use & | ~ (Not and/or/not)

# CORRECT: bitwise operators with parentheses
where=(kx.Column('sym') == 'AAPL') & (kx.Column('price') > 100)   # AND
where=(kx.Column('sym') == 'AAPL') | (kx.Column('sym') == 'GOOG') # OR
where=~(kx.Column('size') < 100)                                   # NOT

# WRONG — Python keywords don't work with Column objects
where=kx.Column('sym') == 'AAPL' and kx.Column('price') > 100     # WRONG!

RawQConnection: Async + Queue Then poll_send/poll_recv

# CORRECT: async construction, queue query, then poll_send/poll_recv
q = await kx.RawQConnection(host='localhost', port=5000)
q('select from trades')          # Queue the query (not sent yet)
q.poll_send()                    # Send queued queries
result = q.poll_recv()           # Receive response

# WRONG — poll_send does NOT take a query string
q.poll_send('select from trades')   # WRONG! poll_send takes amount, not query
# WRONG — RawQConnection requires async construction
with kx.RawQConnection(...) as q:   # WRONG! use await, not sync with

Creating pykx Objects

qlist = kx.toq([1, 2, 3])                      # LongVector (auto)
qlist = kx.toq([1, 2, 3], kx.FloatVector)      # Explicit type
qtable = kx.toq(df)                             # DataFrame -> Table
kx.random.random(10, 100.0)                     # 10 random floats 0-100