Skip to content

docs: clarify Lambda DB pool sizing and sequential query behavior #213

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
jbeard4 wants to merge 1 commit into
base: develop
Choose a base branch
from
Open

docs: clarify Lambda DB pool sizing and sequential query behavior #213

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
6 changes: 6 additions & 0 deletions README.md
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -58,9 +58,15 @@ All configuration options can be passed to the server using environment variable
* `DATABASE_HOST` - The URL at which the database is hosted
* `DATABASE_USER` - The username used to connect to the database
* `DATABASE_PASSWORD` - The password used to connect to the database
* `DATABASE_POOL_MAX` - Maximum number of DB connections used by one API process (Default: `1`)
* `DATABASE_POOL_MIN` - Minimum number of DB connections used by one API process (Default: `0`)
* `DATABASE_CLIENT_MIN_MESSAGES` - Postgres `client_min_messages` level. Keep as `ignore` with RDS Proxy to avoid connection pinning from session-level `SET` commands (Default: `ignore`)
* `DATABASE_KEEP_DEFAULT_TIMEZONE` - When `true`, sequelize will not issue `SET TIME ZONE ...` per connection, which avoids RDS Proxy session pinning (Default: `true`)

### Lambda connection pooling note

This codebase uses multiple `Promise.all(...)` blocks around DB work (for example metadata lookups and chunked location queries). In AWS Lambda, setting `DATABASE_POOL_MAX=1` is still safe, because requests are handled one at a time per invocation environment and sequelize will queue concurrent query promises onto the single available connection. Keep in mind that pool size `1` can increase per-request latency for endpoints that fan out into many DB calls.

Environment variables depends on the operating system, but can generally be set in the command-line when running the server.

For example, on Linux/Mac:
Expand Down
Loading