(A bit of a tangent from crypto 101)
Core contepts:
Higher-level language constructs like floats and strings can all be represented as a series of bytes
1 byte = 8 bits
| // Use Gists to store code you would like to remember later on | |
| console.log(window); // log the "window" object to the console |
| $('a').each( function(index, item){ | |
| item.target = '_blank'; | |
| }); |
| import json | |
| import simplejson # pip install simplejson | |
| import pickle | |
| import cPickle | |
| import marshal | |
| import yaml # pip install pyyaml | |
| import ujson # pip install ujson | |
| from cStringIO import StringIO | |
| import bson # pip install bson |
Javascript has two kinds of scope:
var keywords creates the variable in the current scope
var is unnecessary (see below)var, then Javascript goes up the “scope chain” to see if it’s already been declared
Postgres is usually run automatically on my laptop. I also have a weekly cronjob that does brew update and brew upgrade which sometimes bumps the version of portgres that I'm running. Newer versions of the postgres server software aren't necessarily compatible with the older version's data directory structure, and so you need to "upgrade" your database to see all of your old data in the upgraded postgres server.
Trying to start the database manually with
pg_ctl -D /usr/local/var/postgres -l /usr/local/var/postgres/server.log start
Which gives an error message and tells me where to look (note that I passed in the log directory when I ran the command)
waiting for server to start.... stopped waiting
pg_ctl: could not start server
| # 1. download a copy of prod db to localhost | |
| # connect to remote redis database and | |
| # download a snapshot of the entire database | |
| # to a local file on your filesystem | |
| # via https://stackoverflow.com/a/61365048/625840 | |
| # docs https://redis.io/docs/manual/cli/#remote-backups-of-rdb-files | |
| redis-cli -u $PROD_REDIS_URL --rdb dump.rdb |
| """ | |
| Example of setting up multiple click commands within one file. | |
| Run these commands with: | |
| python /path/to/file.py do-foo --foo 'hello world' | |
| Note that click converts '_' to '-' in function name | |
| """ |
string interpolation
val foo = 1
var bar = "one is $foo"
var baz = "two is ${foo + 1}"
Unit is a placeholder return value for functions that don't actually return a meaninfgul value. It is the default return type for any function if one is not specified explicitly. Nothing is a placeholder return value for functions that should never actually return (ie they throw an exception or have infinite loop). Good SO discussion on differences.
For when you need to insert or update millions of rows and don't want to mess around with scripting to batch individual SQL commands, it's worth using postgres's built in, super-fast support for importing and exporting data from the CSV file format.
Note: that we're using the \COPY command and not the COPY command, since it allows us to work with files locally available on our machine and not worry about transferring files to the database server's file system.
Via the psql manual on \COPY:
Performs a frontend (client) copy. This is an operation that runs an SQL COPY command, but instead of the server reading or writing the specified file, psql reads or writes the file and routes the data between the server and the local file system. This means that file accessibility and privileges are those of the local user, not the server, and no SQL superuser privileges are required.