Insert only keys absent from a destination.
Postgres: NOT EXISTS supports a set-based missing-row insert in a single-writer example.
CREATE TABLE sales (id INTEGER PRIMARY KEY, team VARCHAR(10), amount INTEGER, units INTEGER);
INSERT INTO sales VALUES (1,'A',10,2),(2,'A',20,1),(3,'B',30,3),(4,'B',40,2);
CREATE TABLE archive_sales (id INTEGER PRIMARY KEY,amount INTEGER);
INSERT INTO archive_sales VALUES (1,10);
INSERT INTO archive_sales (id,amount) SELECT s.id,s.amount FROM sales s WHERE NOT EXISTS (SELECT 1 FROM archive_sales a WHERE a.id=s.id);
SELECT COUNT(*),SUM(amount) FROM archive_sales;Expected output EXAMPLE
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Details
Requires PostgreSQL 18. Run in an empty scratch schema using psql or a SQL client. Result rows below use | between columns, without headers; client display formatting may differ. NOT EXISTS supports a set-based missing-row insert in a single-writer example. The CREATE and INSERT statements provide all input data. Run the complete example in a fresh scratch database or schema.
Concurrent writers still need an appropriate transaction or dialect-specific conflict-handling policy; the primary key remains the final uniqueness guard.
Tested on Ubuntu 24.04.5 LTS · · PostgreSQL 18.6 (Debian 18.6-1.pgdg13+2) · bash 5.2.21-2ubuntu4; coreutils 9.4-3ubuntu6.3; psycopg 3.2.10; pymssql 2.3.8
Test inputs, results and environment
The exact published code ran in a dedicated Linux test container with prepared inputs. Snippet process uid 65534 with a read-only root filesystem and temporary working files. Database services use a private internal Docker network without published ports. Fresh scratch schema/database for each case; test database administrator credentials are confined to these disposable services. Fixtures and output records are isolated from the application database. Testing covers this example and its stated checks, not every input, operating system, or runtime version. The Linux container shares its host's kernel; this is not a native Windows test.
- Architecture / host kernel
- x86_64 / 6.18.54.1-microsoft-standard-WSL2
- Snippet identity / locale
- uid=65534, gid=65534 (unprivileged process) / C.UTF-8
- Interpreter invocation
Execute the exact SQL in a fresh database/schema; serialize result rows with | separators- Container image ID
sha256:ec91410a8f6ec3e985830b5e3a0560306d36f8c1c5ccd91a6699abe707123fa3- Code SHA-256
6217c03871a15adf3bc9ccb21556b68baa44233fd18e6ff84904347a0ea19f10- Dependencies
- bash 5.2.21-2ubuntu4; coreutils 9.4-3ubuntu6.3; psycopg 3.2.10; pymssql 2.3.8
Test input setup
These are the prepared inputs used by the test harness. See Details above for the prerequisites and how to run this example.
# No input files required.
Observed standard output
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Exit code: 0. Standard error: empty. Validation: Exact stdout comparison. System-dependent values above are one recorded run.