SHARE ROW EXCLUSIVE · Lock Modes

Definition

Conflicts with the ROW EXCLUSIVE, SHARE UPDATE EXCLUSIVE, SHARE, SHARE ROW EXCLUSIVE, EXCLUSIVE, and ACCESS EXCLUSIVE lock modes. This mode protects a table against concurrent data changes, and is self-exclusive so that only one session can hold it at a time.

Acquired by CREATE TRIGGER and some forms of ALTER TABLE.

Compatibility

Compare different transactions holding locks on the same table.

× Conflicting modes

· Compatible modes

View the full compatibility matrices

Commands acquiring this mode

SQL command	Object, phase and conditions
CREATE TRIGGER	Lock the table that owns the trigger. Source
LOCK TABLE … IN SHARE ROW EXCLUSIVE MODE	Request this table mode explicitly. Omitting IN MODE defaults to ACCESS EXCLUSIVE. Source
ALTER TABLE … ENABLE / DISABLE TRIGGER	Enable or disable triggers, including the applicable USER, ALL, REPLICA and ALWAYS forms. Source
ALTER TABLE … ADD FOREIGN KEY [NOT VALID] (referencing table)	Both referencing and referenced tables take SHARE ROW EXCLUSIVE. NOT VALID skips the initial data check, not this lock. Source
ALTER TABLE … ADD FOREIGN KEY [NOT VALID] (referenced table)	The referenced table also takes SHARE ROW EXCLUSIVE, not merely ACCESS SHARE. Source

Commands may acquire additional locks. See all command associations.

Other lock modes

Sources

PostgreSQL 18 · Sampled build REL_18_STABLE · 753057e340da. Conflicts, definitions and command associations refer to this fixed source build. SQL links retain the selected version.

Local English manual · Online manual

Pinned source files

Manual source: explicit locking 753057e340da
Table lock conflict definitions 753057e340da
Row lock mode definitions 753057e340da

Source collection date: 2026-09-27.