This sequence is an automatically-incremented integer that increases with each subsequent row inserted into metric_staging. All this to say, metric_staging is usually very small, and is never larger than one payload (~1k-1M rows).Īfter reviewing the design of the metric_staging table, we remembered that we had made the primary key of the table a sequence. If Step 2 passes successfully, that means the parsed payload is clean and we’re good to move it to the main time series metric table. Roll back the previous command, and restore the transaction state to what it was at the time of the save point.Insert the parsed payload into metric_stagging.Make a new save point within the current transaction. It’s a helper table that we use to validate the payload before inserting it in the final target. The purpose of this metric_staging table is to serve as a temporary storage for metrics as they move down the data processing pipeline. To figure out what was going on, we dug into the design of our metric_staging table. Behind the scenes, both tools will invoke COPY FROM STDIN or COPY TO STDOUT, allowing you to work with files accessible to you without worrying about what the Postgres server can or can't access.INSERT INTO metric_staging ( "timestamp", "value", "channel", "sensor_type_id" ) VALUES ( " 19:10:25-07", 25. Using either tool, you will be able to specify a file path from the client-side perspective. If you're in a hurry, the above option is the simplest to get you going.Īlternatively, you can use either psql \copy command ( psql is a popular command line tool for interacting with Postgres) or the pgAdmin GUI. And if the server is running remotely, make sure that the file path is something that can be accessed by the Postgres server user. If you're on a Mac or Linux, use the '/tmp' directory - again, this is accessible by all users. The Public user home directory is readable and writeable by all users on the system. If Postgres is on your computer, and you're running Windows for example, move the file you're trying to read temporarily to 'C:\Users\Public' or write your file out to this directory. The simplest option is to change the file location to one the server does have access to. Similarly, if the server is running remotely on another computer, it won't be able to access files for reading or writing on your own computer. It therefore can't read or write to files that, for example, reside under your own personal home directory. If the Postgres server is running locally on your computer, it will be running under a user account that's different from your own. The COPY command is executed from the viewpoint of the server, not the client. The most common reason permission will be denied is because the Postgres server cannot access the file at the location you specified. When you're using these commands if you're getting a "Permission Denied" error, here's the likely reason why and how to fix it. Likewise, COPY TO is used to export data from a table or a query result to a file. COPY FROM is commonly used to import data from a file (CSV, plain text, etc.) in to PostgreSQL.
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