Dave's PostgreSQL Stuff

  Occasionally, you will need to capture data when working with a database. You can cut-n-paste or use a shell command like script . In typical PostgreSQL fashion, psql  has two ways to save your output. The First Way You must invoke psql with the --log-file-<filename> or -L <filename> option. The entire session will be recorded. stoker@ThinkPad:~$ psql --log-file=/tmp/psqllog demo Password for user stoker: psql (17.4 (Ubuntu 17.4-1.pgdg24.04+2)) Type "help" for help. demo=# \d ledger                    Table "public.ledger"      Column     |  Type   | Collation | Nullable | Default ----------------+---------+-----------+----------+---------  id             | integer |           |          |  tx_id          | integer |        ...

PostgreSQL is equivalent to a Swiss Army Knife in the database world. There are things in PostgreSQL that are very simple to use, while in another database, they take many more steps to accomplish. But sometimes, the knife has too many blades, which can cause confusion. This is one of those cases. COPY and \COPY I needed a quick dump of a table as part of an ETL (Extract, Transform, and Load - official definition, Exorcism, Trauma, and Lost-sleep - unofficially) to port some data. The COPY command is a quick way to output and write the data to a file.  The two copy commands below illustrate adding a delimiter and then writing the output to a table. demo=# select * from z;  a | b  |  c   ---+----+-----  1 | 10 | 100  2 | 20 | 200  3 | 30 | 300  4 | 40 | 400 (4 rows) demo=# copy z to stdout (DELIMITER ','); 1,10,100 2,20,200 3,30,300 4,40,400 demo=# copy z to '/tmp/z' (DELIMITER ','); COPY 4 demo=#  The trick is that  you must...

 Artificial Intelligence is one of those conundrums where the ability to have some tasks handled for you contrasts with a mix of ego and pride that it may be better than you at those tasks.  I recently wrote a blog using another database about an AI-generated SQL that was quite sophisticated . But what about asking an AI to create a table with a specification like a DBA/SRE/Analyst might receive? I used Grok and entered the following prompt: Write the SQL to create a table on a PostgreSQL version 17 server to record data on customers. The data will include a first name, a last name, an address, a birthdate, and a unique UUID primary key. Partition the data by the year of birth. And produce some test data of at least ten records. I am sure many of us have started large projects given less instruction.  Notice: I did not denote the format for the address (US Post Office's format, or UK, or other). Nor did I set a name length. I wanted to see what assumptions were made by t...