Extensions

Extensions are linked into the pgmem build statically. CREATE EXTENSION works for every name below without installing anything.

Bundled

Group	Extensions
Procedural language	plpgsql
Types and operators	citext, hstore, ltree, cube, seg, isn, intarray, lo, earthdistance
Text search and fuzzy matching	pg_trgm, fuzzystrmatch, unaccent, dict_int, dict_xsyn
Indexes	btree_gist, btree_gin, bloom
Vectors	vector (pgvector 0.8.6)
Cryptography and IDs	pgcrypto, uuid-ossp
Table functions and sampling	tablefunc, tsm_system_rows, tsm_system_time
Inspection and statistics	pg_stat_statements, pgstattuple, pageinspect, pg_buffercache, pg_freespacemap, pg_visibility, amcheck, pg_prewarm
Loadable module	auto_explain (LOAD 'auto_explain', not CREATE EXTENSION)

Snowball stemming dictionaries and every encoding conversion are linked in as well.

pgcrypto without OpenSSL. pgcrypto’s OpenSSL and zlib layers are replaced by calls into Go’s crypto, math/big and compress packages. Digests, AES, Blowfish, DES, 3DES and CAST5, OpenPGP encryption with RSA or ElGamal keys, and OpenPGP compression all work, and messages made by GnuPG decrypt. fips_mode() is always false, and bzip2-compressed OpenPGP packets are unsupported, as upstream.

Not bundled

Extensions outside that list fail with module is not linked into this pgmem build. Some are out of scope by design:

• background workers, such as pg_cron and pg_partman’s worker, because single-user mode has no postmaster to start them;
• outbound network access, such as dblink and postgres_fdw;
• other language runtimes, such as plv8, plperl and plpython;
• PostGIS, for its size and its dependency chain.

Use a container for tests that need them.

How an extension is added

The selection rule is simple: extensions that most managed services (Amazon RDS, Google Cloud SQL) and PGlite offer, ORM-facing ones first.

1. Append the contrib name to CONTRIB_MODULES in wasm/build.sh. Its control, SQL and data files are copied into the share tree that ships with the module.
2. For an extension outside the PostgreSQL tree, add a lock file with repository, version and checksum, and a compile step in build.sh, as for pgvector.
3. Rebuild with ./wasm/build.sh and regenerate the Go with ./wasm/gen-aot.sh.
4. Vendor the extension’s upstream regression files into testdata/regress/<name> and list them in regress_test.go, so the suite replays them against pgmem.
5. Commit one extension per commit.

Each module is compiled with its _PG_init and magic-block symbols renamed, and a generated table lets a static replacement for dlopen find them. That is what makes CREATE EXTENSION work without dynamic linking.