Transactions & COPY

SQL Reference: Transactions

Transaction control, savepoints, isolation semantics, and autocommit behavior.

Transaction Control

SQL

BEGIN;
-- ... your SQL statements ...
COMMIT;     -- persist all changes atomically
ROLLBACK;   -- discard all changes

Autocommit

Single statements outside an explicit BEGIN block run in implicit autocommit mode. The system begins a transaction, executes the statement, and commits (or rolls back on error). Retryable TiKV errors trigger automatic retry with backoff.

Savepoints

SQL

BEGIN;
INSERT INTO users (name) VALUES ('Alice');

SAVEPOINT sp1;
INSERT INTO users (name) VALUES ('Bob');
ROLLBACK TO SAVEPOINT sp1;  -- Bob's insert is undone

RELEASE SAVEPOINT sp1;     -- destroys savepoint, merges state
COMMIT;  -- only Alice is committed

Savepoint behavior matches PostgreSQL: duplicate names are allowed (most recent is targeted), RELEASE destroys the named savepoint and all later ones, ROLLBACK TO re-establishes the savepoint for reuse.

Isolation Level

Default transaction mode is pessimistic with Snapshot Isolation provided by TiKV. Each transaction sees a consistent snapshot of the database at its start time.

Sequence Behavior

Sequence advances (nextval) are non-transactional — they survive transaction rollbacks, matching PostgreSQL behavior.

Failed Transaction State

When an error occurs in a transaction, it enters a failed state. Only ROLLBACK, COMMIT, and END are accepted. All other statements return an error. This matches PostgreSQL behavior.

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SQL Reference: COPY

Bulk data import and export.

SQL

-- Import from file (via client)
COPY table_name FROM STDIN;

-- Import from Parquet (with parquet extension)
COPY table_name FROM '/data/file.parquet' FORMAT parquet;

Text, CSV, and Parquet formats are supported for COPY FROM.