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Locks [Oracle]

Lock modes

There are five lock modes in Oracle. The absence of a lock (which can be counted as sixth lock type) is called a null lock.

null

Abbreviation: NL

row shared

Abbreviation: SS

row exclusive

Abbreviation RX(?) or SX. SX apaprently stands for subexclusive lock.

share

Abbreviation: S

share row exclusive

Abbreviation: SRX(?) or SSX

exclusive

Abbreviation: X

Lock types

Transaction Lock

Abbreviation: TX

TM ??

Thread checkpoint enqueue

Abbreviation: TC

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