PostgreSQL: Difference between revisions
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== Tips == | == Tips == | ||
* 'Upserting' (INSERT turning into an UPDATE if there is a conflict) can be achieved by adding <code>ON CONFLICT UPDATE</code> to the end of the INSERT | * 'Upserting' (INSERT turning into an UPDATE if there is a conflict) can be achieved by adding <code>ON CONFLICT DO UPDATE</code> to the end of the INSERT | ||
* Only inserting if a value doesn't exist can be achieved by adding <code>ON CONFLICT DO NOTHING</code> to the end of the INSERT | * Only inserting if a value doesn't exist can be achieved by adding <code>ON CONFLICT DO NOTHING</code> to the end of the INSERT | ||
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* <code>SHOW TABLES</code> becomes <code>\dt</code> (<code>\dt+</code> for additional info) | * <code>SHOW TABLES</code> becomes <code>\dt</code> (<code>\dt+</code> for additional info) | ||
* <code>DESCRIBE tbl</code> becomes <code>\d tbl</code> (<code>\d+ tbl</code> for additional info) | * <code>DESCRIBE tbl</code> becomes <code>\d tbl</code> (<code>\d+ tbl</code> for additional info) | ||
* <code>EXPLAIN</code> becomes <code>EXPLAIN ANALYZE</code> (very different output, much more detail in some respects but also harder to interpret) | |||
== Links == | == Links == | ||
* [https://wiki.postgresql.org/wiki/Don't_Do_This Don't Do This] - list of things not to do in PostgreSQL, with explanations. | * [https://wiki.postgresql.org/wiki/Don't_Do_This Don't Do This] - list of things not to do in PostgreSQL, with explanations. | ||
Latest revision as of 10:38, 6 January 2022
Ubuntu installation
Install PostgreSQL and its contrib package:
sudo apt install postgresql postgresql-contrib
Create a new user (with the same username as your Linux login):
sudo -u postgres createuser --interactive
Create a database:
createdb my_test_db
Connect via psql:
psql -d my_test_db
Tips
- 'Upserting' (INSERT turning into an UPDATE if there is a conflict) can be achieved by adding
ON CONFLICT DO UPDATEto the end of the INSERT - Only inserting if a value doesn't exist can be achieved by adding
ON CONFLICT DO NOTHINGto the end of the INSERT
Comparison with MySQL
- Both default to using a socket for local connections on Unix hosts (instead of TCP/IP)
SHOW TABLESbecomes\dt(\dt+for additional info)DESCRIBE tblbecomes\d tbl(\d+ tblfor additional info)EXPLAINbecomesEXPLAIN ANALYZE(very different output, much more detail in some respects but also harder to interpret)
Links
- Don't Do This - list of things not to do in PostgreSQL, with explanations.