Date & Time

CLOCK_TIMESTAMP

PostgreSQL

Mengembalikan timestamp aktual saat fungsi dipanggil. Berbeda dengan NOW/CURRENT_TIMESTAMP yang tetap sama dalam satu transaksi.

Tipe hasil: timestamp with time zone

Syntax

SQL

CLOCK_TIMESTAMP()

Parameter

Fungsi ini tidak memerlukan parameter.

Contoh Penggunaan

Timestamp Real-time

SQL

1 SELECT 
2   CLOCK_TIMESTAMP() AS call_1,
3   pg_sleep(1),
4   CLOCK_TIMESTAMP() AS call_2;

CLOCK_TIMESTAMP berubah setiap pemanggilan.

Hasil

call_1	call_2
2024-01-15 14:30:45.001	2024-01-15 14:30:46.002

NOW vs CLOCK_TIMESTAMP

SQL

1 SELECT 
2   NOW() AS transaction_time,
3   CLOCK_TIMESTAMP() AS actual_time
4 FROM generate_series(1, 3);

NOW tetap sama, CLOCK_TIMESTAMP berbeda setiap row.

Hasil

transaction_time	actual_time
2024-01-15 14:30:45	2024-01-15 14:30:45.001
2024-01-15 14:30:45	2024-01-15 14:30:45.002
2024-01-15 14:30:45	2024-01-15 14:30:45.003

Logging Execution Time

SQL

1 INSERT INTO process_logs (step, timestamp)
2 VALUES 
3   (Start, CLOCK_TIMESTAMP()),
4   (Processing, CLOCK_TIMESTAMP()),
5   (End, CLOCK_TIMESTAMP());

Logging dengan timestamp berbeda per step.

Kembali ke PostgreSQL Functions

1	SELECT
2	CLOCK_TIMESTAMP() AS call_1,
3	pg_sleep(1),
4	CLOCK_TIMESTAMP() AS call_2;

1	SELECT
2	NOW() AS transaction_time,
3	CLOCK_TIMESTAMP() AS actual_time
4	FROM generate_series(1, 3);

1	INSERT INTO process_logs (step, timestamp)
2	VALUES
3	(Start, CLOCK_TIMESTAMP()),
4	(Processing, CLOCK_TIMESTAMP()),
5	(End, CLOCK_TIMESTAMP());