01008WARNINGTier 3 — Handle with care✅ HIGH confidence

implicit zero bit padding

Category: WarningVersions: All Postgres versions

What this means

SQLSTATE 01008 is raised when a bit-string value is implicitly padded with zero bits to fit the declared length of a BIT(n) column. The statement succeeds but data was silently altered.

Why it happens

1Inserting or updating a BIT(n) column with a shorter bit string than n bits

How to reproduce

Inserting a short bit string into a fixed-length BIT column.

trigger — this will ERROR

CREATE TABLE flags (f BIT(8));
INSERT INTO flags VALUES (B'101'); -- padded to 00000101

WARNING: implicit zero bit padding

Fix 1: Provide the exact bit width expected by the column

When inserting bit strings into BIT(n) columns.

fix

INSERT INTO flags VALUES (B'00000101');

Why this works

Supplying the full bit width prevents implicit padding and avoids the warning.

Sources

📚 Official docs: https://www.postgresql.org/docs/current/errcodes-appendix.html

🔧 Source ref: Class 01 — Warning

Confidence assessment

✅ HIGH confidence

Standard SQL warning for bit-string padding. Stable across all Postgres versions.