On time serial

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Contents Exit focus mode. Is this page helpful? The CS pin for the micro-SD card is pin 4. This shield can be connected to the Arduino in two ways.

One way is to simply stack it on top of the Arduino. The second way is to use jumpers and connect the ICSP headers between the boards. If using wires, pin 10 is the Chip Select CS pin.

For this tutorial, we will just stack the shield on top of the Arduino. If you want to learn more about the Arduino, check out our Ultimate Guide to the Arduino video course.

For our project, we will use three libraries — the SPI library, the Time library, and the Ethernet library.

See Figure 2 below as a guide. After installing the libraries into the IDE, use keyword include to add them to our sketch. The next step is to create global variables and objects. Some variables that are worth mentioning here are the byte mac[] , the IPAddress timeSrvr , and the byte messageBuffer[48]. The byte array mac[] contains the MAC address that will be assigned for the ethernet shield.

This is a unique identifier for the shield in the network. The server IP we will use is After populating the setup function, we will create code inside loop to display the current date and time on the serial monitor. To make our code easy to manage, we will create functions to help us in the process of requesting, parsing, and displaying time data from the NTP server. The function digitalClockDisplay and its helper function printDigits uses the Time library functions hour , minute , second , day , month , and year to get parts of the time data and send it to the serial monitor for display.

To communicate with the NTP server, we first need to send a request packet. TimescaleDB also enforces uniqueness in each chunk individually. Maintaining uniqueness across chunks can affect ingesting performance dramatically. The most common approach to fix the issue with the primary key is to create a composite key and include the time dimension as proposed in the question.

If the index on the time dimension is not needed no queries only on time is expected , then the index on time dimension can be avoided:. It is also possible to use an integer column as the time dimension. It is important that such column has time dimension properties: the value is increasing over time, which is important for insert performance, and queries will select a time range, which is critical for query performance over large database. The common case is for storing unix epoch.

However, I doubt the queries will select the range on it. For completeness SQL will be:. What meaning does that id have? Isn't it just identifying a unique details, ts combination? Or can there meaningfully be two values that have the same timestamp and the same details but different ids that actually has some sort of semantic meaning.

It seems to me that that is somewhat nonsensical, in which case, I would do a primary key on details, ts which should provide you the uniqueness condition that you need. I do not know if your ORM will like this, they tend to be overly dependent on generated primary keys because, among other things, not all databases support composite primary keys. But in general, my advice for cases like this is to actually use a composite primary key with logical meaning.

Now if you actually care about multiple messages with the same details at the same timestamp, I might suggest a table structure something like.

I wish that ORMs were better about doing this sort of thing, but you can usually trick ORMs into reading from other tables or a view over them because then they think they can't update records there etc, which is why they need to have the generated PK. Then it just means that there's a little bit of custom ingest code to write that inserts into the hypertable.

It's often better to do this anyway because, in general, I've found that ORMs don't always follow best practices for high volume inserts, and often don't use bulk loading techniques. The rest of your relational model, which is the part that the ORM excels at doing can live in the ORM and then have a minor integration here with a bit of custom SQL and a few custom methods.

Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Collectives on Stack Overflow. He also says Adnan received another phone call - the p. The cell tower that originates these calls covers Leakin Park. In court, Jay identifies two phone calls - at p. Skip to main content. Adnan's Call Log Call. Adnan goes to the Woodlawn Public Library to check his email. Has conversation with Asia.

Track coach Michael Sye testified that practice was usually from to or p. At the meeting point off Edmondson Ave. Adnan and Jay smoke a blunt at Patapsco State Park. They stay there for about 30 minutes.