Granting consent to receive the Cybertec Newsletter by electronic means is voluntary and can be withdrawn free of charge at any time.įurther information can be found in the privacy policy. Yes, I would like to receive information about new products, current offers and news about PostgreSQL via e-mail on a regular basis. Granting consent to receive the CYBERTEC Newsletter by electronic means is voluntary and can be withdrawn free of charge at any time.įurther information can be found in the privacy policy. Weitere Informationen finden Sie in der Datenschutzerklärung. Ich kann diese Zustimmung jederzeit widerrufen. Ja, ich möchte regelmäßig Informationen über neue Produkte, aktuelle Angebote und Neuigkeiten rund ums Thema PostgreSQL per E-Mail erhalten. If you want to learn more about PostgreSQL check out Laurenz Albe’s blog post about HOT Updates Do you need a constant return value or do you really need the current time? Depending on what is needed PostgreSQL provides the right function for you. When working with time it is important to understand which time of timestamp is needed. Test=*# SELECT clock_timestamp(), pg_sleep(1), clock_timestamp() Ĭlock_timestamp | pg_sleep | clock_timestamp Here is an example showing how this works: It does NOT guarantee to return different values but in reality it “almost” does. The important thing is that this function will return different values all the time. clock_timestamp(): “Real time”įinally, there is the clock_timestamp() function which returns the current timestamp. It merely changes when the next statement starts. Statement_timestamp | pg_sleep | statement_timestamp Test=*# SELECT statement_timestamp(), pg_sleep(1), statement_timestamp() The following listing shows how this works: You can rely on the fact that the same result will be returned throughout the entire (top level) operation. In this case the timestamp will change inside your transaction but not inside your statement. In addition to now() there is also a way to find the timestamp of your current operation. Sporadically this can cause bugs, because people expect time to change - which is not so in this case, by design. The following listing shows an example:Īs you can see, the timestamp is absolutely constant and does not change at all. The idea is to have a function which “freezes time” and returns the same value throughout the transaction. The most common way to determine time is to ask for “transaction time”. When writing code, it is important to be aware of those subtle differences to ensure that your program is doing exactly what it’s supposed to do: now(): Determining transaction time in PostgreSQL Basically, there are three functions we might use to figure out what time it is:ĭepending on what kind of time you want, different functions have to be called. While this seems like an easy question the answer isn’t as clear-cut as you might expect. One question many people keep asking: How can I find the current timestamp? What time is it? In this tutorial, you have learned how to use the PostgreSQL LOCALTIMESTAMP function to return the date and time at which the current transaction starts.PostgreSQL provides all kinds of time-related functions. The LOCALTIMESTAMP function returns a TIMESTAMP value without time zone while the CURRENT_TIMESTAMP function returns a TIMESTAMP with time zone. (1 row) Code language: CSS ( css ) Remarks To get the timestamp of the current transaction with specific fractional seconds precision, you use the precision argument as follows: SELECT LOCALTIMESTAMP( 2) Code language: SQL (Structured Query Language) ( sql ) The following example shows how to get the current date and time of the current transaction: SELECT LOCALTIMESTAMP The LOCALTIMESTAMP function returns a TIMESTAMP value that represents the date and time at which the current transaction starts. The precision argument specifies fractional seconds precision of the second field. The LOCALTIMESTAMP function accepts one argument: The following illustrates the syntax of the LOCALTIMESTAMP function: LOCALTIMESTAMP(precision) The PostgreSQL LOCALTIMESTAMP function returns the current date and time at which the current transaction starts.
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