| common | Common utilities, springtail_init() should be called in every main; logging, exceptions, concurrent queues, thread pool, etc. |
| storage | Threaded storage layer; B-tree, extent and schema handling and definition |
| pg_repl | Low-level Postgres replication; connecting to primary and decoding replication messages |
| pg_log_mgr | Consumes Postgres replication stream to log, process log, extracts transaction start/commit, inserts commit records into a queue to be consumed by the committer. The committer is responsible for applying log changes to the tables and committing them. |
| write_cache | Cache for holding dirty extents by XID; indexed by Table ID, Extent ID, XID and primary key value |
| xid_mgr | Persistently stores last committed XID |
| benchmarks | Code for benchmarking file system performance (for distributed file systems) |
| proto | gRPC protocol definitions |
| sys_tbl_mgr | System table service & cache; accessed via Thrift; centralizes management of system table metadata |
| proxy | Postgres Proxy that handles read/write splitting sending writes to primary, and reads to FDWs |
| pg_fdw | Postgres frontend query nodes implemented using Postgres Foreign Data Wrapper (FDW) extension; also includes the ddl_daemon for managing DDL changes for the FDW (to create/alter foreign tables) |
| redis | Redis helper classes |
| admin_http | Embedded internal http server |
| pg_ext | Postgres extension related |
