- HTML SEO
Title Description Social Media Tags Viewport metadata <meta name=”viewport” content=”width=device-width, initial-scale=1″/>
- Linux prepend content to a file
Prepend content to a file Use sed with -i option. You can also specify the line to which the content will prepend to. sed -i ” ‘1s/^/package home;/” Home.java Prepend content to multiple files Here I need to add a package to 200 java files. To do this manual would be tedios. for f […]
- CSS Margin
margin properties are used to create space around elements, outside of any defined borders. margin: top right bottom left; margin: 10px 15px 20px 25px; top – 10px right – 15px bottom – 20px left – 25px margin: top right/left bottom; margin: 10px 20px 25px; top – 10px right/left – 20px bottom – 25px…
- Elasticsearch – Mappings, and Why You Should Write Your Own
Dynamic mapping guesses a field's type from the first document it sees, and it guesses from ONE document. A price that happens to arrive as 120 becomes a long and the next listing at 119.50 is a problem. Writing an explicit mapping, what dynamic: strict buys, multi-fields, and the constraint that shapes everything afterwards: a field's type cannot be changed once it has been written.
- Postgres – Transactions, Isolation and Locking
BEGIN, COMMIT, ROLLBACK, and what Postgres promises in between. Read Committed versus Repeatable Read versus Serializable, shown with two real psql sessions rather than described. SELECT FOR UPDATE, the lost update it prevents, deadlocks and the ordering rule that avoids them, advisory locks, and the idle-in-transaction connection that blocks your next deploy.