This topic describes the file storage of PolarDB for PostgreSQL(Compatible with Oracle).
- The data and WAL logs of the primary node and read-only nodes are stored in shared storage.
- The configuration files, log files, and temporary files are stored on each node.
- The commit log (clog) file of the primary node is stored in shared storage. The clog file of a read-only node is maintained on the read-only node.
- The pg_control file of the primary node is stored in shared storage. The pg_control file of a read-only node is read from the shared storage only when the database is started, and maintained in the memory after the database is started.
Directory or file | Description | Storage path |
---|---|---|
base | The subdirectory of each database. | Shared storage |
global | The directory of cluster-wide tables. | |
pg_tblspc | The table space. | |
pg_wal | The directory of write-ahead logging (WAL) logs. | |
pg_dynshmem | The file that is used by the dynamic shared memory. | One copy on each node |
pg_snapshots | The exported snapshots. | |
pg_replslot | The replication slot data. | |
pg_stat_tmp | The temporary files for the statistics subsystem. | |
pg_stat | The persistent files for the statistics subsystem. | |
pg_serial | The information about committed serializable transactions. | |
pg_xact | The transaction log file. |
|
pg_commit_ts | The time when the transaction is committed. | |
pg_multixact | The information about sub-transactions. | |
pg_version | The version information. | One copy on each node |
postgresql.auto.conf | The parameter configuration file, which has a higher priority over the postgresql.conf file. | |
postmaster.opts | The file that records the database parameters that are specified before a server start. | |
postmaster.pid | A lock file that records information such as the process ID of postmaster, database directory, start time of postmaster, and port number. | |
postgresql.conf | The configuration file of parameters. | |
pg_hba.conf | The file that is used to control client authentication. | |
pg_ident.conf | The file that records mappings between the names of operating system users and database users. |