Mirrors Phase 10's read implementation in the opposite direction —
extends the SQ_FILE (98) handler with optype 2 (read-from-client)
support. Users register bytes in cursor.virtual_files; the server's
filetoblob('path', 'client') call streams them up via SQ_FILE_READ
(106) chunks. Same architectural pivot as Phase 10 — avoids the
heavy SQ_FPROUTINE+SQ_LODATA stack.
Wire protocol (per IfxSqli.receiveSQFILE case 2 line 5103+):
* Server sends [short SQ_FILE=98][short optype=2][short bufSize]
[int readAmount][short SQ_EOT]
* Client responds [short 106][int totalAmount] then chunks
[short 106][short chunkSize][padded data]... terminated by SQ_EOT
API:
* Low-level: cur.virtual_files['/sentinel'] = data, then SQL with
filetoblob('/sentinel', 'client')
* High-level: cur.write_blob_column(sql, blob_data, params, clob=False)
— substitutes BLOB_PLACEHOLDER token in the SQL with filetoblob()
(or filetoclob for CLOB columns) and registers the bytes
automatically. Cleans up virtual_files after the call.
The BLOB_PLACEHOLDER design was chosen over magic ?-binding because:
* bytes already maps to BYTE type (legacy in-row blobs) for ?-params
* Method on BlobLocator doesn't work for inserts (no locator yet)
* PLACEHOLDER is unmistakable at the call site
Closes the smart-LOB loop in pure Python — Phase 9's tests and
Phase 10's read fixtures previously used JDBC to seed test data.
Phase 11 eliminated that dependency: tests/test_smart_lob.py and
tests/test_smart_lob_read.py now self-seed via write_blob_column.
Bonus: integration test runtime 5.78s → 2.78s (no more per-fixture
JVM spawns). Project goal "pure Python, no native deps" now true
for the test suite too.
Tests: 9 integration tests in test_smart_lob_write.py covering
* BLOB short, multichunk (51KB), empty, binary-safe (256 values)
* BLOB UPDATE
* BLOB multi-row INSERTs
* CLOB via filetoclob
* validation (rejects SQL without BLOB_PLACEHOLDER)
* virtual_files cleanup
Total: 64 unit + 126 integration = 190 tests.
SELECT on BLOB or CLOB columns no longer requires raw byte interpretation.
The 72-byte server-side locator is wrapped in a typed BlobLocator or
ClobLocator (frozen dataclass) so the column is recognizable as
"server-side reference, not actual bytes".
Wire-protocol findings:
* Smart-LOB columns DON'T appear with their nominal type codes (102/101)
in SQ_DESCRIBE. They surface as UDTFIXED (41) with extended_id 10
(BLOB) or 11 (CLOB) and encoded_length=72 (locator size).
* Retrieving the actual bytes requires SQ_FPROUTINE (103) RPC to
invoke ifx_lo_open, plus SQ_LODATA (97) for chunked transfer, plus
another SQ_FPROUTINE for ifx_lo_close. That's a Phase 10 lift —
roughly 2x the protocol surface of Phase 8.
Server config needed (added to Phase 7 setup):
* sbspace: onspaces -c -S sbspace1 ...
* default sbspace: onmode -wm SBSPACENAME=sbspace1
What ships in Phase 9:
* informix_db.BlobLocator(raw: bytes) — 72-byte frozen wrapper
* informix_db.ClobLocator(raw: bytes) — distinct type, same shape
* Row decoder branch in _resultset.parse_tuple_payload
* Wire constants SQ_LODATA=97, SQ_FPROUTINE=103, SQ_FPARAM=104
Tests:
* 11 unit tests in test_blob_locator_unit.py (no Informix needed) —
construction, immutability, equality, hash, repr safety, size
validation.
* 4 integration tests in test_smart_lob.py — fixture seeds via JDBC
reference client (smart-LOB writes also need deferred protocols).
* RefBlob.java helper in tests/reference/ for seeding via JDBC.
Total: 64 unit + 111 integration = 175 tests.
Locator design note: __repr__ omits the raw bytes (they're opaque to
the client). Same-bytes locators of different families compare
unequal — BlobLocator(x) != ClobLocator(x) — to avoid silent type
confusion.
