Data Type Support

db2-node maps Db2 wire values into plain JavaScript values. The Rust protocol layer recognizes Db2 for z/OS built-in scalar types, including the LOB families documented by IBM: CLOB, DBCLOB, and BLOB. See IBM's Data types in Db2 for z/OS reference for the server-side type definitions.

JavaScript Mappings

Db2 for z/OS type	JavaScript value	Notes
SMALLINT	number	16-bit signed integer
INTEGER	number	32-bit signed integer
BIGINT	number	Returned through Node's numeric path; use casts to character/decimal if exact JS-safe integer handling is required above Number.MAX_SAFE_INTEGER.
FLOAT(n), REAL, DOUBLE	number	Non-finite wire values are normalized to 0 at the JS boundary.
DECIMAL, NUMERIC	string	Preserves precision and scale.
DECFLOAT(16), DECFLOAT(34)	string	Preserves decimal floating-point text.
CHAR, VARCHAR, long character data	string	CCSID-aware decoding for UTF-8 and common EBCDIC z/OS flows.
GRAPHIC, VARGRAPHIC	string	Public typeName is shown as CHAR(n) / VARCHAR(n) with db2TypeName preserving GRAPHIC(n) / VARGRAPHIC(n).
CLOB	string	z/OS external LOB materialization is handled by the production cleanup modes.
DBCLOB	string	Decoded as character data, with db2TypeName: "DBCLOB" in metadata.
BINARY, VARBINARY	Buffer	Binary values are returned as Node buffers.
BLOB	Buffer	Inline and materialized BLOB values are returned as Node buffers.
DATE	string	Db2 text form, for example 2026-05-08.
TIME	string	Db2 text form.
TIMESTAMP(p) WITHOUT TIME ZONE	string	Descriptor length controls precision.
TIMESTAMP(p) WITH TIME ZONE	string	Returned as Db2's text form when the server exposes it through DRDA timestamp metadata.
ROWID	string	Hex string such as 0xDEADBEEF....
XML	string	XML document/content text.
BOOLEAN	boolean	Supported when the server supports Boolean columns.
Distinct types	Source type mapping	Db2 distinct types use the representation of their source built-in type.

All nullable columns return null when the server value is SQL NULL.

Parameters

Parameterized queries use server-provided input descriptors when Db2 supplies them. When the driver must infer a parameter type, JavaScript values map as follows:

JavaScript input	Inferred Db2 value
number integer in 32-bit range	INTEGER
larger integer number	BIGINT
fractional number	DOUBLE
string	VARCHAR
boolean	BOOLEAN
null	SQL NULL when Db2 provides input metadata
Buffer, Uint8Array, or number array	binary value suitable for BINARY, VARBINARY, or BLOB parameters

For exact DECIMAL, DECFLOAT, DATE, TIME, TIMESTAMP, XML, and LOB parameter typing, cast the parameter in SQL:

await client.query('VALUES CAST(? AS DECFLOAT(34))', ['123456789.00001'])
await client.query('INSERT INTO docs (body) VALUES (CAST(? AS CLOB(1M)))', [xmlText])
await client.query('INSERT INTO files (payload) VALUES (CAST(? AS BLOB(1M)))', [buffer])

z/OS LOB Safety

For Db2 for z/OS, LOB queries can leave external data frames queued after the requested rows are materialized. The default production mode disconnects and warm-replaces a connection when cleanup cannot be verified. Active close mode (DB2_ZOS_LOB_CLOSE_AFTER_MATERIALIZE=1) sends CLSQRY, drains remaining EXTDTA, and only reuses the socket after Db2 acknowledges the close.

Aggregate or scalar queries that filter CLOB-like text with LIKE or NOT LIKE use a large statement package EXCSQLSTT path by default on Db2 for z/OS, even when the result itself is not a LOB. Set DB2_ZOS_LIKE_PREDICATE_EXCSQLSTT=0 only while diagnosing package-specific behavior.

See Getting Started for the production mode tradeoffs.

Source Coverage

This matrix is based on the IBM Db2 for z/OS 12 data type categories: numeric, character, graphic, binary, LOB, datetime, row ID, XML, distinct types, and nullable values. User-defined array types are not exposed as ordinary scalar row values by this driver; use SQL to unnest or serialize arrays before returning them to Node.js.