zhukang 1c7abd81d1 All 310 Manus skill-hub community skills as a Kortix marketplace registry

- 310 registry:skill items, 1528 files, 7 categories (hub tags)
- registry.json generated by @kortix/registry buildRegistry
- nested SKILL.md in sn-da-* renamed SUBSKILL.md (no phantom skills)
- provenance + licenses: SOURCES.md

2026-09-15 13:37:20 +08:00

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title	description	tags
Storage Layout and Tablespaces	PGDATA directory structure, TOAST, fillfactor, tablespaces, and disk management	postgres, storage, pgdata, toast, fillfactor, tablespaces, disk, operations

Storage Layout and Tablespaces

PGDATA Structure

base/ — database files (one subdirectory per database, named by OID)
global/ — cluster-wide shared catalogs (pg_database, pg_authid, pg_tablespace)
pg_wal/ — WAL files
pg_xact/ — transaction commit status

"Cluster" in PostgreSQL = single instance with one PGDATA, not an HA cluster. Each table/index = one or more files, split into 1GB segments. Tables have companion _fsm (free space map) and _vm (visibility map); indexes have _fsm only (no _vm), except hash indexes.

Visibility Map and Free Space Map

_vm tracks all-visible pages — VACUUM skips these
_fsm tracks free space per page — INSERT uses this to find pages with room
Both are small files but critical for performance

TOAST

TOAST triggers when a row exceeds ~2KB. Large values are compressed and/or moved out-of-line to pg_toast.pg_toast_<oid> tables. Strategies: PLAIN (no TOAST), EXTENDED (compress+out-of-line, default for text/bytea), EXTERNAL (out-of-line, no compression — use for pre-compressed data), MAIN (compress, avoid out-of-line). TOAST tables bloat like regular tables — they need VACUUM. SELECT * fetches all TOAST columns; always SELECT only needed columns. Move large rarely-accessed columns to separate tables.

Fillfactor

Controls how full pages are packed (default 100%). Lower fillfactor (70–80%) leaves room for HOT (Heap-Only Tuple) updates, which avoid index entries and reduce bloat on UPDATE-heavy tables. Keep 100% for insert-only or read-mostly tables. ALTER TABLE t SET (fillfactor = 70);

Tablespaces

pg_default (base/), pg_global (global/) are built-in. Custom tablespaces: symbolic links in pg_tblspc/ to other filesystem locations. Use for separating hot data (SSD) from archives (HDD). Moving tablespaces requires exclusive lock on affected tables.

Disk Monitoring

pg_database_size('dbname'), pg_total_relation_size('tablename'), pg_relation_size('tablename')
Monitor disk usage: >80% = at risk; >90% = critical (VACUUM may fail if disk capacity is insufficient)
Check inode usage (df -i) — can run out even with free space
pg_wal/ suddenly large = check replication slots and archiving

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