This topic describes the limits of PolarDB for PostgreSQL.

Node typeMaximum number of files
polar.pg.x4.medium1048576
polar.pg.x4.large2097152
polar.pg.x4.xlarge2097152
polar.pg.x8.xlarge4194304
polar.pg.x8.2xlarge8388608
polar.pg.x8.4xlarge12582912
polar.pg.x8.12xlarge20971520

Maximum number of files: includes user table files, database system table files (approximately 1,000), and log files. An Apsara PolarDB table (non-partition table) occupies three files: data file, visibility map file, and FSM file. Each index indicates a file if indexes are used. The following error message appears when you create a table after the maximum number of files is reached:

could not create file

In this case, you need to delete some tables or upgrade the specifications of your cluster.

Table 1. Other limits
ItemLimit
Root privilege of databasesPolarDB for PostgreSQL does not support the superuser privilege. Instead, it supports the polar_superuser privilege as a subset of the superuser privilege.
dblink/fdwNot supported.