A single PostgreSQL server can contain many databases. Let’s explore three different approaches to list databases in PostgreSQL!
Basic SELECT Query to Retrieve Tables Inside INFORMATION_SCHEMA in PostgreSQLA very simple query to get all the tables inside this SCHEMA would be to write something like this.select * from information_schema.tables This would return a table like this.Output:...
PostgreSQLprovides aRENAME COLUMNclause that is used with the collaboration ofALTER TABLEcommand to rename a column. TheRENAME COLUMNcommand allows us to rename a single or multiple columns.PostgreSQLdoesn’t provide the“IF EXISTS”option for the“RENAME COLUMN”command. This write-up will explain ...
Partitioning may be a good solution, as It can help divide a large table into smaller tables and thus reduce table scans and memory swap problems, which ultimately increases performance. Partitioning helps to scale PostgreSQL by splitting large logical tables into smaller physical tables that can be...
Let’s set up a new table in PostgreSQL and use it to look at a few helpful ways that DISTINCT can remove duplicates and reveal useful information from the data. First, connect to psql terminal: /usr/pgsql-11/bin/psql -U postgres postgres ...
In the above example, the table “MediaType” has 5 records. By using OFFSET with the number 3, we are able to skip the first 3 records and displaying only the remaining ones. Example 3 Using LIMIT and OFFSET in the same query. ...
8. Consider Disabling Remote Access to PostgreSQL This action alone eliminates a host of substantial attack vectors. Again, this can be set in the pg_hba.conf. If remote access to the database is required, SSH to server housing the database and use a local connection thereafter. Alternatively...
CREATE TABLE sales_2024 PARTITION OF sales FOR VALUES FROM ('2024-01-01') TO ('2025-01-01'); Query Example: PostgreSQL will automatically target the relevant partition: SELECT * FROM sales WHERE transaction_date = '2024-06-15';
You have a table address and want to check if there’s already a row with address_id = 100 existing. You can use COUNT to check: SELECT COUNT(*) FROM address WHERE address_id = 100; But if you are looking for a faster query with a yes/no answer: SELECT EXISTS(SELECT 1 FROM ...
How can I write a query to check if a PostgreSQL (10.x) table is a temporary table? I looked at the pg_class system table, but couldn't find any column about whether the relation is temporary. SELECT * FROM pg_class WHERE False; relname | relnamespace | reltype | reloftype | ...