Limits & Constraints

Limits & Constraints

Resource limits and constraints across the db9 engine and extensions.

Engine Limits

Resource	Limit
Statement timeout	60s (default)
Idle transaction timeout	600s / 10 min (default)

Statement timeout can be changed per session

The default statement timeout of 60 seconds can be overridden per session with SET statement_timeout = '120s'. Long-running operations like index builds or data migrations may need this adjustment.

| View nesting depth | 64 levels | | Pending portals per connection | 32 | | Timestamp precision | Microseconds |

Fractional-second precision is applied to columns

DB9 timestamps have microsecond precision, matching standard PostgreSQL. A TIMESTAMP(n) or TIMESTAMPTZ(n) column rounds stored values to the declared precision, both on insert and on ALTER COLUMN ... TYPE. The typmod is not applied in a cast expression ('...'::timestamp(3) keeps full microseconds), and TIME(n) / TIMETZ(n) columns ignore it entirely.

| Encoding | UTF-8 only |

HTTP Extension Limits

Resource	Limit
Connect timeout	1s
Total timeout	5s
Max request body	256 KiB
Max response body	1 MiB
Max calls per statement	100
Max concurrent per tenant	20

fs9 Extension Limits

Resource	Limit
Max file size	100 MB
Max glob total size	100 MB
Max file traversal	10,000 files
Max directory recursion	10 levels

pg_cron Limits

Resource	Limit
Job execution timeout	Default: 5 minutes; max: 30 minutes

Unsupported PostgreSQL Features

The following PostgreSQL features are not supported:

• SMALLINT / INT2 type — aliased to INTEGER (32-bit)
• REAL / FLOAT4 type — aliased to DOUBLE PRECISION (64-bit)
• CHAR(n) fixed-length type — aliased to VARCHAR(n) (no padding semantics)
• Microsecond timestamp precision (millisecond only)

One clarification on a feature often assumed missing: LISTEN / NOTIFY is supported, but only over a direct pgwire connection — a session has to stay open to receive notifications, and notifications are delivered on commit. The stateless HTTP SQL API can send NOTIFY but cannot receive notifications; a LISTEN issued over it returns a LISTEN command tag and then never delivers anything.