mirror of
https://github.com/jbranchaud/til
synced 2026-01-03 15:18:01 +00:00
21 lines
903 B
Markdown
21 lines
903 B
Markdown
# Create An Index Without Locking The Table
|
|
|
|
When creating an index for a column, the process of building the index will
|
|
lock the column's table. For small datasets this isn't a concern because the
|
|
index will take no time at all to create. For larger datasets, the lock could
|
|
last long enough to create meaningful downtime. This can all be avoided by
|
|
telling Postgres to build the index concurrently.
|
|
|
|
```sql
|
|
create index concurrently idx_book_isbns on books(isbn);
|
|
```
|
|
|
|
Creating the index this way will take a bit longer and put more strain on
|
|
machine resources, but it allows concurrent inserts, updates, or deletes on the
|
|
table. In other words, you can add an index to a large table in a production
|
|
environment without bringing down your app.
|
|
|
|
Read more about the [details and potential
|
|
caveats](https://www.postgresql.org/docs/current/sql-createindex.html#SQL-CREATEINDEX-CONCURRENTLY)
|
|
in the docs.
|